CA2132660A1 - Soil fragmentation members and multiple lateral support structures for improved soil mixing and efficient boring for use on multi-shaft auger soil mixing apparatus - Google Patents
Soil fragmentation members and multiple lateral support structures for improved soil mixing and efficient boring for use on multi-shaft auger soil mixing apparatusInfo
- Publication number
- CA2132660A1 CA2132660A1 CA002132660A CA2132660A CA2132660A1 CA 2132660 A1 CA2132660 A1 CA 2132660A1 CA 002132660 A CA002132660 A CA 002132660A CA 2132660 A CA2132660 A CA 2132660A CA 2132660 A1 CA2132660 A1 CA 2132660A1
- Authority
- CA
- Canada
- Prior art keywords
- soil
- shaft
- auger
- mixing
- borehole
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
- E02D3/12—Consolidating by placing solidifying or pore-filling substances in the soil
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
- E02D3/12—Consolidating by placing solidifying or pore-filling substances in the soil
- E02D3/126—Consolidating by placing solidifying or pore-filling substances in the soil and mixing by rotating blades
Abstract
SOIL FRAGMENTATION MEMBERS AND MULTIPLE LATERAL
SUPPORT STRUCTURES FOR IMPROVED SOIL MIXING AND
EFFICIENT BORING FOR USE ON MULTI-SHAFT AUGER SOIL MIXING
APPARATUS
ABSTRACT OF THE INVENTION
An apparatus for constructing subterranean structures, soil-chemicals mixture or soil-agents mixture by using a multi-shaft auger machine to mix soil with a chemical hardener in situ in a borehole. As the auger shafts of the multi-shaft auger machine penetrate the soil, a plurality of lateral support structures shear soil and provide additional lateral support. The plurality of lateral support structures are spaced vertically by a length no greater than thirty feet. Additionally, soil fragmentation members attached to the lateral support structures fragment soil reconsolidations to aid in mixing of soil. The soil fragmentation members have a length no greater than the difference between the radius of at least one auger blade and the radius of the shaft and no less than one-third the difference between the radius of at least one auger blade and the radius of the shaft. The shearing and fragmentation of the soil result in a more homogenous mixture of the chemical hardener and the soil through which the auger passes. In addition, the shearing and fragmentation of the soil reduces the energy necessary for mixing. Prevention of reagglomeration of soil is most beneficially observed in clay or clay-like soils.
SUPPORT STRUCTURES FOR IMPROVED SOIL MIXING AND
EFFICIENT BORING FOR USE ON MULTI-SHAFT AUGER SOIL MIXING
APPARATUS
ABSTRACT OF THE INVENTION
An apparatus for constructing subterranean structures, soil-chemicals mixture or soil-agents mixture by using a multi-shaft auger machine to mix soil with a chemical hardener in situ in a borehole. As the auger shafts of the multi-shaft auger machine penetrate the soil, a plurality of lateral support structures shear soil and provide additional lateral support. The plurality of lateral support structures are spaced vertically by a length no greater than thirty feet. Additionally, soil fragmentation members attached to the lateral support structures fragment soil reconsolidations to aid in mixing of soil. The soil fragmentation members have a length no greater than the difference between the radius of at least one auger blade and the radius of the shaft and no less than one-third the difference between the radius of at least one auger blade and the radius of the shaft. The shearing and fragmentation of the soil result in a more homogenous mixture of the chemical hardener and the soil through which the auger passes. In addition, the shearing and fragmentation of the soil reduces the energy necessary for mixing. Prevention of reagglomeration of soil is most beneficially observed in clay or clay-like soils.
Description
~ ` 213~6~0 1 BAC~GRo~ND
3 1. Fi~lA of the Inv~ntlon 4 The present invention relates to multi-shaft auger s system~ and procefises for mixing soil with a chemical 6 hardener in situ to form soil-cement columns, walls, piles, : -7 grids and monolithic blocks of overlapping columns. More 8 particularly, the present invention is directed to g improvements in auger shafts which permit more efficient penetration and improved mixing of the chemical hardener 1l with the soil which forms the soil-cement columns, walls, 12 piles, grids, and monolithic block of columns.
13 . . .-~
1~ 2. The Relevant Technoloq~
For a number of years, multi-shaft auger machines have 16 been used to construct soil-cement columns in the ground without having to excavate the soil by boring into the ground, in~ecting a chemical hardener and mixing the 19 chemical hardener with the soil. These columns are ~.
20 sometimes referred to as "soilcrete" columns. Soilcrete is 21 a term applied to a mixture of soil and a chemical hardener, which sets up as a solid mass, much like concrete. A
~ "soilcrete" column is one of the most common products of in 24 situ mixing of soil and chemical hardener, so it is used as ¦ - P~ge 2 -~ 2132660 1 a generic term to describe the hardened product of in situ 2 soil mixing.
3 1. Fi~lA of the Inv~ntlon 4 The present invention relates to multi-shaft auger s system~ and procefises for mixing soil with a chemical 6 hardener in situ to form soil-cement columns, walls, piles, : -7 grids and monolithic blocks of overlapping columns. More 8 particularly, the present invention is directed to g improvements in auger shafts which permit more efficient penetration and improved mixing of the chemical hardener 1l with the soil which forms the soil-cement columns, walls, 12 piles, grids, and monolithic block of columns.
13 . . .-~
1~ 2. The Relevant Technoloq~
For a number of years, multi-shaft auger machines have 16 been used to construct soil-cement columns in the ground without having to excavate the soil by boring into the ground, in~ecting a chemical hardener and mixing the 19 chemical hardener with the soil. These columns are ~.
20 sometimes referred to as "soilcrete" columns. Soilcrete is 21 a term applied to a mixture of soil and a chemical hardener, which sets up as a solid mass, much like concrete. A
~ "soilcrete" column is one of the most common products of in 24 situ mixing of soil and chemical hardener, so it is used as ¦ - P~ge 2 -~ 2132660 1 a generic term to describe the hardened product of in situ 2 soil mixing.
3 The chemical hardener is injected directly into the 4 80il in situ, and mixed with the soil by an auger. The term 5 ~chemical hardener" includes any chemicals and agents that 6 can be added and mixed with soil to cause chemical reactions 7 resulting in the formation of soil-cement structural units.
8 Examples of suitable chemicals and agents are: portland 9 cement, lime, fly ash, kiln dust, cement-based hardeners, ~o bitumen, resin, power plant residues, bentonite, salts, 11 acids, sodium and calcium silicates, calcium aluminates, and 12 sulfates. The chemical reactions include pozzolanic 13 reaction ~cementation), hydration, ion-exchange, polymerization, oxidation, and carbonation. The results of 15 these chemical reactions include changes in the physical 16 properties of soil such as strength and permeability and/or 17 the change of chemical properties such as the reduction of 18 the toxicity level in contaminated soil or sludge.
19 The chemical hardener is added in a slurry form.
20 Therefore, the term "slurry" as used herein is defined as 21 including chemical hardener. Cement slurry has also been z called cement grout or cement milk in some of the previous 23 techniques.
2~ Upon hardening, the soil-cement columns possess some 25 characteristics of lower strength concrete columns, but they - Pzlgl3 3 -~ 2132~
1 are constructed without the expense and time-consuming 2 process of removing and replacing the soil with concrete.
3 In some cases, non-hardening soil-chemical or soil agent 4 mixtures are also de~irable.
s Soil-cement column8 have been arranged in a variety of -6 patterns depending on the desired application. Soil-cement 7 columns are used to improve the load bearing capacity of 8 soft soils, such as sandy or soft clay soils. The columns 9 are formed deep in the ground to help support surface 10 construction on soft soils. -~
19 The chemical hardener is added in a slurry form.
20 Therefore, the term "slurry" as used herein is defined as 21 including chemical hardener. Cement slurry has also been z called cement grout or cement milk in some of the previous 23 techniques.
2~ Upon hardening, the soil-cement columns possess some 25 characteristics of lower strength concrete columns, but they - Pzlgl3 3 -~ 2132~
1 are constructed without the expense and time-consuming 2 process of removing and replacing the soil with concrete.
3 In some cases, non-hardening soil-chemical or soil agent 4 mixtures are also de~irable.
s Soil-cement column8 have been arranged in a variety of -6 patterns depending on the desired application. Soil-cement 7 columns are used to improve the load bearing capacity of 8 soft soils, such as sandy or soft clay soils. The columns 9 are formed deep in the ground to help support surface 10 construction on soft soils. -~
11 In other cases, the soil-cement columns have been 1Z overlapped to form boundary walls, excavation support walls, 13 low to medium capacity soil-mixed caissons, and for the in - .
1~ situ fixation of contaminated soil or toxic wastes.
. ~ .
15 To produce soil-cement columns, a multi-shaft auger ~ -16 machine bores holes in the ground and simultaneously mixes 17 the soil with a slurry or slurries of chemical hardener 1~ pumped from the surface through the auger shaft to the end , . ~ ~
19 of the auger. Multiple columns are prepared while the soil-20 cement mixture or soil-chemical mixture is still soft to 21 form continuous walls of geometric patterns within the soil z depending on the purpose of the soil-cement columns.
23 Because the soil is mixed in situ and because the soil-2~ cement wall i5 formed in a single process, the construction 25 period is shorter than for other construction methods.
26 . ~
¦ - Page 4 -21~266~
1 Obviously, the costs of forming soil-cement columns are le88 2 than traditional methods requiring excavation of the soil, 3 constructing forms, and then pouring concrete into the forms in order to form the concrete pillars or walls. In 5 addition, because the 80il iS not removed from the ground, 6 there i~ comparatively less material produced in situ by 7 such processes that must be disposed of during the course of 8 construction.
9 Figure 1 illustrates a conventional multi-shaft auger o machine as the machine would appear in operation. Each shaft of the multi-shaft auger machine, i8 shown generically 12 as shaft 20. The power for rotating the shaft is generated 13 by a motor 26 and transferred to the upper end of each shaft 24 through a gearbox 22. This configuration is an 15 example of a means for rotating the shafts by generating power and transferring the power to the shaft. Auger blades 17 are securely affixed to the lower end of each shaft for boring downward through the soil to auger boreholes.
19 As the multi-shaft auger machine penetrates the soil, 20 the soil is broken loose and a chemical hardener slurry is 21 in~ected into the soil. The chemical hardener is be pumped 22 from the surface through the auger shafts, which are hollow, 23 to the lower ends of each shaft. The augers penetrate, 2~ break loose, and lift ~he soil so that it is mixed with the 25 slurry by the action of intermittent soil mixing paddles 28 , 2l3266a 1 and intermittent auger blades 30 which are spaced throughout z the length of the shaft. The horizontal and vertical mixing 3 of the auger blades 30 and the soil mixing paddles 28 4 produces a column having a homogeneous mixture of the soil s and the chemical hardener.
6 Figure 2 illustrates the details of a prior art three-7 shaft auger machine. The three-shaft auger machine contains 8 two outer shafts 31a and 31b and a center shaft 32 each g having an upper end (not shown) and a lower end shown generally on the two outer shafts as 33a and 33b and on center shaft as 34. Outer auger blades 36a and 36b and 12 center auger blades 38 penetrate undisturbed soil as the 13 shafts rotate and propel the shafts downward to auger 1~ boreholes. The outer auger blades 36a and 36b and center auger blades 38 are securely affixed to lower ends 33a, 33b 16 and 34 of outer shafts 31a and 31b and center shaft 32. The 1~ outer auger blades 36a and 36b are vertically offset from center auger blades 38. The outer auger blades 36a and 36b 19 and center auger blade 38 each possess auger cutting 20 edges 40 which cuts into the soil at the bottom of each 21 borehole. Auger teeth 42 are preferably secured to the ~;
22 cutting edge of the first and second auger blades in order 2~ to assist in soil penetration in clay or rocky soils.
24 Generally, each shaft on a multi-shaft auger machine 25 with three or more shafts rotates in a direction opposite -26 .
- P~ge 6 --2l32~a 1 the rotation of adjacent shafts. As shown in Figure 2, 2 auger blade 38 attached to the lower end 34 of center 3 shaft 32 has a spiral configuration opposite the auger 4 blades attached to the lower ends 33a and 33b of outer shafts 31a and 31b. Thus, if center shaft 32 rotated in a 6 clockwise direction, outer shafts 31a and 31b would rotate 7 in a counter-clockwise direction.
During operation the auger machine starts to penetrates 9 downward through the soil. The process of penetrating downward i5 often referred to as an auguring stroke~ As the 11 auger blades move down, the injection of slurry through the 12 auger shaft is initiated. As the slurry exits the auger 13 shaft, it is mixed with the soil by the auger blades and .
mixing paddles along the length of each auger.
The resulting soil and slurry mixture is referred to as 16 a "column set" or "borehole". The use of the term 17 ~borehole~ does not necessarily mean that soil is removed to create a hole. Although some soil is deposited on the 19 surface due to expansion of the soil as it i8 brcken loose 20 and mixed, the majority of the soil remains below the 21 surface as it is mixed. Moreover, use of the term "column 22 Bet~ may refer to a single in situ column set formation or 23 it may generically refer to wall formations or continuous 2~ large-area soil formations. Such columns are sometimes ¦ - P~ge 7 -.
2l32~6a 1 referred to as "piles". The column set may be extended to 2 form a grid or a monolithic block of overlapping columns.
3 The mixing ratio of the slurry to the soil is determined on the basis of the 50il conditions which are 5 determined and reported prior to commencing the boring of the columns. The soil-slurry mixing ratio is not decided on 7 the basis of the strength conditisns of the continuous wall 8 alone, but such factors as the soil type and condition, and 9 the state of ground water are also taken into consideration -in order to obtain a mixing ratio which will result in a substantially homogenous wall which has the desired strength 12 and permeability characteristics. In some cases, special chemical slurries are mixed with in situ soil to stabilize 1~ and/or solidify various pollutants in the soil -- a procedure named in situ solidification and stabilization or 16 in situ fixation.
Slurry is continuously pumped through the center of the 1~ auger shaft and mixed with the soil as the augers penetrate 19 and are then withdrawn from the borehole. In a typical process about 60 percent to 80 percent of the slurry i8 21 injected as the augers penetrate downward and the remainder 22 is injected as the augers are withdrawn. According to this Z3 method, the mixing process is repeated as the augers are z~ withdrawn from the borehole. Auger speed and slurry output 25 . :
¦ - Page 8 -~, . , ., ,~ : :
~ 213266~
1 quantities are also set to meet the soil conditions of the 2 site and the purposes of soil mixing work.
3 The resulting mixing of soil and chemical hardener is 4 sometimes referred to as "soilcrete" because the hardener s mixture often possesses some physical properties similar to 6 concrete. Nevertheless, use of the term "soilcrete" does not mean that soil is mixed with concrete or that the 8 chemical hardener always contains cement. If cement slurry g is u~ed, the preferred term to describe the hardened mixture is soil-cement.
Due to the tremendous forces required to push the shaft 12 downward and to turn the augers and the shaft, as well as the tendency of the multiple shafts to diverge due to varying soil conditions encountered by each shaft, a lateral 15 support structure i8 provided to prevent diversion of the 16 auger shafts out of a parallel configuration while 17 concomitantly allowing the shafts to rotate. The lateral support structure, generally illustrated at 50, is located 19 about each respective shaft such that the lateral support 20 structure does not rotate as each respective shaft rotates 21 in the soil. A~ the lateral support structure 50 serves to 22 maintain the auger shafts in a parallel configuration, the , 23 lateral support structure must be located fairly near to the 2~ lower ends of the shafts where the impact of rocks and 25 varying soil textures has the most effect on the shafts.
2132~6~
1 The lateral support structure 50 typically takes the 2 form of nonrotating bands 52 surroùnding each shaft, 3 stabilizing bars 54 securely connecting the nonrotating bands to maintain proper shaft alignment and clamps 56a s and 56b securely attached to the nonrotating bands opposite 6 the ~tabilizer bars 54 to provide additional support.
7 The nonrotating bands 52 surround the shafts in an area 8 between upper cylindrical collars 58 and lower cylindrical 9 collars 60, the cylindrical collars are formed around the o periphery of each shaft. The use of bearings and the 11 configuration of the nonrotating bands and the upper and 12 lower cylindrical collars allow the shafts to rotate within 13 the nonrotating bands 52 while the nonrotating bands remain stationary.
As the augers penetrate new soil, the soil is loosened 16 and fQrced past the lateral support structure 50 by the 17 action of the rotating auger blades pushing more soil up 1~ from below. After passing the lateral support structure, 19 the soil is re~ixed with mixing paddles attached to the zo shaft above the lateral support structure. ~;
Zl This auger system works well in sandy or porous soils, 22 however, problems are encountered when auguring in cohesive ,~
z3 soils such as clay or silt and with slurries having a low 2~ water content. When the auger blades located at the end of z5 each shaft encounter such soils and slurries, the augers 2~
"~
-~ 213266~
1 shear and fragment the soil only to have the soil 2 reaggregate before passing the lateral support structures 3 which support the shafts. This reaggregation or 4 reagglomeration of soil can form a cylindrical plug which 5 impedes optimal mixing as the plug rotates with the shaft.
6 The natural tendency of cohesive soils such as clay or silt 7 to coalesce is further exacerbated by the injection of the 8 slurry, particularly slurries with a low water content, as 9 the slurry increases the tendency of clay and silt to prematurely reagglomerate.
When sufficient pressure is exerted on the plug by the 12 action of the augers on new soil being forced up from below, 13 the clay plug is forced around the lateral support structure into the area of the borehole above the lateral support 15 structure. Once the cylindrical plug reaches the mixing 16 blades located above the lateral support structure, the 17 cylindrical plug must once again be sheared, fragmented and thoroughly mixed with the slurry. The cylindrical plug 19 reformed beneath the lateral support structure must undergo 20 essentially the same process above the lateral support 21 structure as the process the soil was subjected to below the 22 structure. The mixing blades and paddles located on the 23 shafts above the lateral support structure must not only mix 2~ the soil but also reshear and refragment it. The additional 25 shearing and fragmenting results in a reduced rate of ~ 21326~3 1 progress by the auger machine through the soil. Further, z there is significantly less homogenous mixing of the soil 3 with the slurry which results in columns having decreased strength.
s The need ~or ~hearing and fragmenting the soil and slurry a~ove the support structure requires the use of much 7 more energy which impedes optimal mixing. This energy must 8 be deducted from the total energy available for penetrating 9 new soil layers. This reduction in available energy results o in less efficient boring, both in rate of progress through the soil and in the thoroughness of mixing of the soil with 12 the slurry.
13 From the foregoing, it will be appreciated that what i8 ., 1~ needed in the art is a multi-shaft auger system for mixing 15 soil with a chemical hardener in situ, which provides for a 16 more homogenous mixture of a chemical hardener slurry and 17 soils when utilized with soils tending to coalesce and with slurries with a low water content.
19 It would be another advancement in the art to provide a 20 multi-shaft auger system for mixing soil with a chemical 21 hardener in situ, which improves the efficiency of systems 22 utilized in soils tending to coalesce and with slurries with 2~ a low water content.
2~.
25 . .;.
26 . .~.
1 OB;~CT8 AND BRIBF 8~RY OF THE ~ NTION
z It is an object of the present invention to provide 3 apparatus and methods for a multi-shaft auger system for mixing soil with a chemical hardener in situ which yields a s homogenous mixture of a chemical hardener slurry and soils when utilized with soils tending to coalesce and with 7 slurries with ~ low water content.
8 It is another ob;ect of the present invention to 9 provide apparatus and methods for a multi-shaft auger system o for mixing soil with chemical hardener in situ which improves the efficiency of systems utilized in soils tending 12 to coalesce and with slurries with a low water content.
13 To achieve the foregoing objects, and in accordance - .
1~ situ fixation of contaminated soil or toxic wastes.
. ~ .
15 To produce soil-cement columns, a multi-shaft auger ~ -16 machine bores holes in the ground and simultaneously mixes 17 the soil with a slurry or slurries of chemical hardener 1~ pumped from the surface through the auger shaft to the end , . ~ ~
19 of the auger. Multiple columns are prepared while the soil-20 cement mixture or soil-chemical mixture is still soft to 21 form continuous walls of geometric patterns within the soil z depending on the purpose of the soil-cement columns.
23 Because the soil is mixed in situ and because the soil-2~ cement wall i5 formed in a single process, the construction 25 period is shorter than for other construction methods.
26 . ~
¦ - Page 4 -21~266~
1 Obviously, the costs of forming soil-cement columns are le88 2 than traditional methods requiring excavation of the soil, 3 constructing forms, and then pouring concrete into the forms in order to form the concrete pillars or walls. In 5 addition, because the 80il iS not removed from the ground, 6 there i~ comparatively less material produced in situ by 7 such processes that must be disposed of during the course of 8 construction.
9 Figure 1 illustrates a conventional multi-shaft auger o machine as the machine would appear in operation. Each shaft of the multi-shaft auger machine, i8 shown generically 12 as shaft 20. The power for rotating the shaft is generated 13 by a motor 26 and transferred to the upper end of each shaft 24 through a gearbox 22. This configuration is an 15 example of a means for rotating the shafts by generating power and transferring the power to the shaft. Auger blades 17 are securely affixed to the lower end of each shaft for boring downward through the soil to auger boreholes.
19 As the multi-shaft auger machine penetrates the soil, 20 the soil is broken loose and a chemical hardener slurry is 21 in~ected into the soil. The chemical hardener is be pumped 22 from the surface through the auger shafts, which are hollow, 23 to the lower ends of each shaft. The augers penetrate, 2~ break loose, and lift ~he soil so that it is mixed with the 25 slurry by the action of intermittent soil mixing paddles 28 , 2l3266a 1 and intermittent auger blades 30 which are spaced throughout z the length of the shaft. The horizontal and vertical mixing 3 of the auger blades 30 and the soil mixing paddles 28 4 produces a column having a homogeneous mixture of the soil s and the chemical hardener.
6 Figure 2 illustrates the details of a prior art three-7 shaft auger machine. The three-shaft auger machine contains 8 two outer shafts 31a and 31b and a center shaft 32 each g having an upper end (not shown) and a lower end shown generally on the two outer shafts as 33a and 33b and on center shaft as 34. Outer auger blades 36a and 36b and 12 center auger blades 38 penetrate undisturbed soil as the 13 shafts rotate and propel the shafts downward to auger 1~ boreholes. The outer auger blades 36a and 36b and center auger blades 38 are securely affixed to lower ends 33a, 33b 16 and 34 of outer shafts 31a and 31b and center shaft 32. The 1~ outer auger blades 36a and 36b are vertically offset from center auger blades 38. The outer auger blades 36a and 36b 19 and center auger blade 38 each possess auger cutting 20 edges 40 which cuts into the soil at the bottom of each 21 borehole. Auger teeth 42 are preferably secured to the ~;
22 cutting edge of the first and second auger blades in order 2~ to assist in soil penetration in clay or rocky soils.
24 Generally, each shaft on a multi-shaft auger machine 25 with three or more shafts rotates in a direction opposite -26 .
- P~ge 6 --2l32~a 1 the rotation of adjacent shafts. As shown in Figure 2, 2 auger blade 38 attached to the lower end 34 of center 3 shaft 32 has a spiral configuration opposite the auger 4 blades attached to the lower ends 33a and 33b of outer shafts 31a and 31b. Thus, if center shaft 32 rotated in a 6 clockwise direction, outer shafts 31a and 31b would rotate 7 in a counter-clockwise direction.
During operation the auger machine starts to penetrates 9 downward through the soil. The process of penetrating downward i5 often referred to as an auguring stroke~ As the 11 auger blades move down, the injection of slurry through the 12 auger shaft is initiated. As the slurry exits the auger 13 shaft, it is mixed with the soil by the auger blades and .
mixing paddles along the length of each auger.
The resulting soil and slurry mixture is referred to as 16 a "column set" or "borehole". The use of the term 17 ~borehole~ does not necessarily mean that soil is removed to create a hole. Although some soil is deposited on the 19 surface due to expansion of the soil as it i8 brcken loose 20 and mixed, the majority of the soil remains below the 21 surface as it is mixed. Moreover, use of the term "column 22 Bet~ may refer to a single in situ column set formation or 23 it may generically refer to wall formations or continuous 2~ large-area soil formations. Such columns are sometimes ¦ - P~ge 7 -.
2l32~6a 1 referred to as "piles". The column set may be extended to 2 form a grid or a monolithic block of overlapping columns.
3 The mixing ratio of the slurry to the soil is determined on the basis of the 50il conditions which are 5 determined and reported prior to commencing the boring of the columns. The soil-slurry mixing ratio is not decided on 7 the basis of the strength conditisns of the continuous wall 8 alone, but such factors as the soil type and condition, and 9 the state of ground water are also taken into consideration -in order to obtain a mixing ratio which will result in a substantially homogenous wall which has the desired strength 12 and permeability characteristics. In some cases, special chemical slurries are mixed with in situ soil to stabilize 1~ and/or solidify various pollutants in the soil -- a procedure named in situ solidification and stabilization or 16 in situ fixation.
Slurry is continuously pumped through the center of the 1~ auger shaft and mixed with the soil as the augers penetrate 19 and are then withdrawn from the borehole. In a typical process about 60 percent to 80 percent of the slurry i8 21 injected as the augers penetrate downward and the remainder 22 is injected as the augers are withdrawn. According to this Z3 method, the mixing process is repeated as the augers are z~ withdrawn from the borehole. Auger speed and slurry output 25 . :
¦ - Page 8 -~, . , ., ,~ : :
~ 213266~
1 quantities are also set to meet the soil conditions of the 2 site and the purposes of soil mixing work.
3 The resulting mixing of soil and chemical hardener is 4 sometimes referred to as "soilcrete" because the hardener s mixture often possesses some physical properties similar to 6 concrete. Nevertheless, use of the term "soilcrete" does not mean that soil is mixed with concrete or that the 8 chemical hardener always contains cement. If cement slurry g is u~ed, the preferred term to describe the hardened mixture is soil-cement.
Due to the tremendous forces required to push the shaft 12 downward and to turn the augers and the shaft, as well as the tendency of the multiple shafts to diverge due to varying soil conditions encountered by each shaft, a lateral 15 support structure i8 provided to prevent diversion of the 16 auger shafts out of a parallel configuration while 17 concomitantly allowing the shafts to rotate. The lateral support structure, generally illustrated at 50, is located 19 about each respective shaft such that the lateral support 20 structure does not rotate as each respective shaft rotates 21 in the soil. A~ the lateral support structure 50 serves to 22 maintain the auger shafts in a parallel configuration, the , 23 lateral support structure must be located fairly near to the 2~ lower ends of the shafts where the impact of rocks and 25 varying soil textures has the most effect on the shafts.
2132~6~
1 The lateral support structure 50 typically takes the 2 form of nonrotating bands 52 surroùnding each shaft, 3 stabilizing bars 54 securely connecting the nonrotating bands to maintain proper shaft alignment and clamps 56a s and 56b securely attached to the nonrotating bands opposite 6 the ~tabilizer bars 54 to provide additional support.
7 The nonrotating bands 52 surround the shafts in an area 8 between upper cylindrical collars 58 and lower cylindrical 9 collars 60, the cylindrical collars are formed around the o periphery of each shaft. The use of bearings and the 11 configuration of the nonrotating bands and the upper and 12 lower cylindrical collars allow the shafts to rotate within 13 the nonrotating bands 52 while the nonrotating bands remain stationary.
As the augers penetrate new soil, the soil is loosened 16 and fQrced past the lateral support structure 50 by the 17 action of the rotating auger blades pushing more soil up 1~ from below. After passing the lateral support structure, 19 the soil is re~ixed with mixing paddles attached to the zo shaft above the lateral support structure. ~;
Zl This auger system works well in sandy or porous soils, 22 however, problems are encountered when auguring in cohesive ,~
z3 soils such as clay or silt and with slurries having a low 2~ water content. When the auger blades located at the end of z5 each shaft encounter such soils and slurries, the augers 2~
"~
-~ 213266~
1 shear and fragment the soil only to have the soil 2 reaggregate before passing the lateral support structures 3 which support the shafts. This reaggregation or 4 reagglomeration of soil can form a cylindrical plug which 5 impedes optimal mixing as the plug rotates with the shaft.
6 The natural tendency of cohesive soils such as clay or silt 7 to coalesce is further exacerbated by the injection of the 8 slurry, particularly slurries with a low water content, as 9 the slurry increases the tendency of clay and silt to prematurely reagglomerate.
When sufficient pressure is exerted on the plug by the 12 action of the augers on new soil being forced up from below, 13 the clay plug is forced around the lateral support structure into the area of the borehole above the lateral support 15 structure. Once the cylindrical plug reaches the mixing 16 blades located above the lateral support structure, the 17 cylindrical plug must once again be sheared, fragmented and thoroughly mixed with the slurry. The cylindrical plug 19 reformed beneath the lateral support structure must undergo 20 essentially the same process above the lateral support 21 structure as the process the soil was subjected to below the 22 structure. The mixing blades and paddles located on the 23 shafts above the lateral support structure must not only mix 2~ the soil but also reshear and refragment it. The additional 25 shearing and fragmenting results in a reduced rate of ~ 21326~3 1 progress by the auger machine through the soil. Further, z there is significantly less homogenous mixing of the soil 3 with the slurry which results in columns having decreased strength.
s The need ~or ~hearing and fragmenting the soil and slurry a~ove the support structure requires the use of much 7 more energy which impedes optimal mixing. This energy must 8 be deducted from the total energy available for penetrating 9 new soil layers. This reduction in available energy results o in less efficient boring, both in rate of progress through the soil and in the thoroughness of mixing of the soil with 12 the slurry.
13 From the foregoing, it will be appreciated that what i8 ., 1~ needed in the art is a multi-shaft auger system for mixing 15 soil with a chemical hardener in situ, which provides for a 16 more homogenous mixture of a chemical hardener slurry and 17 soils when utilized with soils tending to coalesce and with slurries with a low water content.
19 It would be another advancement in the art to provide a 20 multi-shaft auger system for mixing soil with a chemical 21 hardener in situ, which improves the efficiency of systems 22 utilized in soils tending to coalesce and with slurries with 2~ a low water content.
2~.
25 . .;.
26 . .~.
1 OB;~CT8 AND BRIBF 8~RY OF THE ~ NTION
z It is an object of the present invention to provide 3 apparatus and methods for a multi-shaft auger system for mixing soil with a chemical hardener in situ which yields a s homogenous mixture of a chemical hardener slurry and soils when utilized with soils tending to coalesce and with 7 slurries with ~ low water content.
8 It is another ob;ect of the present invention to 9 provide apparatus and methods for a multi-shaft auger system o for mixing soil with chemical hardener in situ which improves the efficiency of systems utilized in soils tending 12 to coalesce and with slurries with a low water content.
13 To achieve the foregoing objects, and in accordance - .
14 w~ th the invention as embodied and broadly described herein, 15 a multi-~haft auger system for mixing soil with a chemical 16 hardener in situ is provided in which the multi-shaft auger apparatus comprises at least two substantially parallel shafts, each shaft having an upper end and a lower end.
19 The shafts are rotated in one configuration by a motor zo which transfers power through a gearbox attached to the 21 upper end of each shaft. This configuration is an example 22 of a means for rotating the shafts by generating power and 23 transferring the power to the shaft.
2~ At the lower end of each respective shaft, auger blades 25 are securely afflxed to facilitate boring downward through i",,.-:~3~
. ~
1 the soil as the shafts rotate. The auger blades are capable 2 of penetrating undisturbed soil as the shafts rotate and 3 propelling the shafts downward to auger boreholes. Auger blades are an example of a means for boring downward through s the soil to auger a borehole.
6 As the auger shaft travels downward, the auger blades 7 break up the undisturbed soil and pushes it in an upward 8 direction while concomitantly a chemical hardener slurry is 9 injected into the soil and mixed together. The chemical o hardener is pumped from the surface through the auger 11 shafts, which are hollow, to openings formed in the lower 12 end of each of the shafts and in the auger blades which 13 discharge the chemical hardener. This configuration is an - .
14 example of a means for injecting the chemical hardener into the soil through the shaft during the auger of the borehole.
16 The means for injecting the chemical hardener enables the in 17 situ formation of a hardened soil-cement column set.
1~ The auger shafts are maintained in a parallel 19 configuration by a lateral support structure. The lateral 20 support structure is located about each respective shaft 21 such that the lateral support structure does not rotate as ~-22 each respective shaft rotates in the soil. The lateral 23 support structure comprises nonrotating bands, at least one 2~ stabilizer bar depending on the number of shafts and two 25 clamps. The nonrotating bands surround the shafts in an 26 . .:
_ 21326~0 ~ area between upper cylindrical collars and lower cylindrical 2 collars. The cylindrical collars are formed around the 3 periphery of each shaft. The use of bearings and the 4 configuration of the nonrotating bands and the upper and 5 lower cylindrical collars allow the shafts to rotate within 6 the nonrotating band~ while the nonrotating bands remain 7 stationary. Proper spacing between the shafts and proper 8 alignment of the shafts is maintained by the stabilizer bar 9 which securely connects the nonrotating bands. The clamps o are securely attached to the nonrotating bands opposite the stabilizer bar to provide additional support.
12 In one embodiment of the present invention, a plurality 13 of lateral support structures are spaced vertically apart -along the shafts to provide more lateral support than merely 15 one lateral support structure. Additionally, when at least ~-16 two lateral support structures are spaced vertically apart 0:
17 by a length no greater than thirty feet, the undesirable reagglomerated or coalesced plugs formed after passing by 19 the auger blades at the lower end of shaft are sheared.
20 Decreasing the space between the lateral support structures 21 increases the ability of the lateral support structures to Z2 shear soils and slurries which typically coalesce below the Z3 single support structure of conventional multi-shaft auger 2~ machines. Additionally, increasing the ability of the 25 lateral support structures to shear minimizes the ro~ation : ~ ~- ....................... .. .
,,.. :" ~ '' ' ' - ~ .
2132~6~
1 of coalesced soils or slurries with the shaft, consequently 2 the homogeneity of the mixtures is improved.
3 In another e~bodiment of the present invention, 4 undesirable reagglomerated or coalesced plugs formed after s passing by the auger blades at the lower end of the shaft 6 are fragmented by at least one soil fragmentation member 7 secured to a lateral support structure. Fragmentation 8 members are secured to a lateral support structure at an 9 orientation normal to the shafts and protruding radially 10 outward. ~;
11 Fragmenting the plugs improves the ability of the 12 apparatus to achieve a homogenous mixture as the plugs tend 13 to rotate with the shaft which impedes the mixing process.
1~ Homogenous mixtures are desirable as the greater the homogeneity, the greater the strength will be of the columns 16 formed from the mixtures. Additionally, the resistance 1~ encountered by the entire apparatus as it passes deeper into 18 the 80il iS reduced which increases the efficiency of the 19 apparatus.
Soil fragmentation members can be attached to any 21 number of the vertically spaced lateral support structures æ or only one of the lateral support structures.
23 Additionally, a soil fragmentation member can be placed on 2~ either a nonrotating band, a support bar or a clamp.
¦ - Page 16 -1^ 2132660 1 Intermittent 80il mixing paddles and intermittent auger 2 blades are utilized above the lateral support structures to ~
3 provide horizontal and vertical mixing. Utilization of the ~ J
80il fragmentation members and a plurality of lateral 5 support structures to fragment and shear the reagglomerated 6 coalesced soil be~ore the soil encounters the intermittent ~ .
7 soil mixing paddles and intermittent auger blades improves 8 the ability to achieve homogenous mixtures when utilized in ~ -g soils tending to coalesce and with slurries having a low :.
1D water content. The intermittent soil mixing paddles and .:
intermittent auger blades are an example of a means for ...
12 mixing the chemical hardener with the soil above the support ~s s ructurc. -17 ~?~\`~t ' 22 .
24 ~ ë
i51 ~
_p-~gel7_ ~
. Z132660 1 BRIEF DEE~CRIPq~ION OF T~E DRAWING8 2 In order that the manner in which the above-recited and 3 other advantages and objects of the invention are obtained, a more particular description of the invention briefly 5 described above will be rendered by reference to specific 6 embodiments thereof which are illustrated in the appended ~:
~ drawings and which represent the best mode presently 8 contemplated for implementing the invention. Understanding -9 that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of 11 its 3cope, the invention will be described with additional :~
12 specificity and detail through the use of the accompanying 13 drawings in which:
1~ Figure l is a vertical cross-sectional view 15 illustrating the environment in which prior art auger shafts 16 operate; . :
17 Figure 2 is a perspective view of the lower ends of a 1~i three-auger system like those used in the prior art; . -~
19 Figure 3 is an enlarged perspective view of the lower ~
19 The shafts are rotated in one configuration by a motor zo which transfers power through a gearbox attached to the 21 upper end of each shaft. This configuration is an example 22 of a means for rotating the shafts by generating power and 23 transferring the power to the shaft.
2~ At the lower end of each respective shaft, auger blades 25 are securely afflxed to facilitate boring downward through i",,.-:~3~
. ~
1 the soil as the shafts rotate. The auger blades are capable 2 of penetrating undisturbed soil as the shafts rotate and 3 propelling the shafts downward to auger boreholes. Auger blades are an example of a means for boring downward through s the soil to auger a borehole.
6 As the auger shaft travels downward, the auger blades 7 break up the undisturbed soil and pushes it in an upward 8 direction while concomitantly a chemical hardener slurry is 9 injected into the soil and mixed together. The chemical o hardener is pumped from the surface through the auger 11 shafts, which are hollow, to openings formed in the lower 12 end of each of the shafts and in the auger blades which 13 discharge the chemical hardener. This configuration is an - .
14 example of a means for injecting the chemical hardener into the soil through the shaft during the auger of the borehole.
16 The means for injecting the chemical hardener enables the in 17 situ formation of a hardened soil-cement column set.
1~ The auger shafts are maintained in a parallel 19 configuration by a lateral support structure. The lateral 20 support structure is located about each respective shaft 21 such that the lateral support structure does not rotate as ~-22 each respective shaft rotates in the soil. The lateral 23 support structure comprises nonrotating bands, at least one 2~ stabilizer bar depending on the number of shafts and two 25 clamps. The nonrotating bands surround the shafts in an 26 . .:
_ 21326~0 ~ area between upper cylindrical collars and lower cylindrical 2 collars. The cylindrical collars are formed around the 3 periphery of each shaft. The use of bearings and the 4 configuration of the nonrotating bands and the upper and 5 lower cylindrical collars allow the shafts to rotate within 6 the nonrotating band~ while the nonrotating bands remain 7 stationary. Proper spacing between the shafts and proper 8 alignment of the shafts is maintained by the stabilizer bar 9 which securely connects the nonrotating bands. The clamps o are securely attached to the nonrotating bands opposite the stabilizer bar to provide additional support.
12 In one embodiment of the present invention, a plurality 13 of lateral support structures are spaced vertically apart -along the shafts to provide more lateral support than merely 15 one lateral support structure. Additionally, when at least ~-16 two lateral support structures are spaced vertically apart 0:
17 by a length no greater than thirty feet, the undesirable reagglomerated or coalesced plugs formed after passing by 19 the auger blades at the lower end of shaft are sheared.
20 Decreasing the space between the lateral support structures 21 increases the ability of the lateral support structures to Z2 shear soils and slurries which typically coalesce below the Z3 single support structure of conventional multi-shaft auger 2~ machines. Additionally, increasing the ability of the 25 lateral support structures to shear minimizes the ro~ation : ~ ~- ....................... .. .
,,.. :" ~ '' ' ' - ~ .
2132~6~
1 of coalesced soils or slurries with the shaft, consequently 2 the homogeneity of the mixtures is improved.
3 In another e~bodiment of the present invention, 4 undesirable reagglomerated or coalesced plugs formed after s passing by the auger blades at the lower end of the shaft 6 are fragmented by at least one soil fragmentation member 7 secured to a lateral support structure. Fragmentation 8 members are secured to a lateral support structure at an 9 orientation normal to the shafts and protruding radially 10 outward. ~;
11 Fragmenting the plugs improves the ability of the 12 apparatus to achieve a homogenous mixture as the plugs tend 13 to rotate with the shaft which impedes the mixing process.
1~ Homogenous mixtures are desirable as the greater the homogeneity, the greater the strength will be of the columns 16 formed from the mixtures. Additionally, the resistance 1~ encountered by the entire apparatus as it passes deeper into 18 the 80il iS reduced which increases the efficiency of the 19 apparatus.
Soil fragmentation members can be attached to any 21 number of the vertically spaced lateral support structures æ or only one of the lateral support structures.
23 Additionally, a soil fragmentation member can be placed on 2~ either a nonrotating band, a support bar or a clamp.
¦ - Page 16 -1^ 2132660 1 Intermittent 80il mixing paddles and intermittent auger 2 blades are utilized above the lateral support structures to ~
3 provide horizontal and vertical mixing. Utilization of the ~ J
80il fragmentation members and a plurality of lateral 5 support structures to fragment and shear the reagglomerated 6 coalesced soil be~ore the soil encounters the intermittent ~ .
7 soil mixing paddles and intermittent auger blades improves 8 the ability to achieve homogenous mixtures when utilized in ~ -g soils tending to coalesce and with slurries having a low :.
1D water content. The intermittent soil mixing paddles and .:
intermittent auger blades are an example of a means for ...
12 mixing the chemical hardener with the soil above the support ~s s ructurc. -17 ~?~\`~t ' 22 .
24 ~ ë
i51 ~
_p-~gel7_ ~
. Z132660 1 BRIEF DEE~CRIPq~ION OF T~E DRAWING8 2 In order that the manner in which the above-recited and 3 other advantages and objects of the invention are obtained, a more particular description of the invention briefly 5 described above will be rendered by reference to specific 6 embodiments thereof which are illustrated in the appended ~:
~ drawings and which represent the best mode presently 8 contemplated for implementing the invention. Understanding -9 that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of 11 its 3cope, the invention will be described with additional :~
12 specificity and detail through the use of the accompanying 13 drawings in which:
1~ Figure l is a vertical cross-sectional view 15 illustrating the environment in which prior art auger shafts 16 operate; . :
17 Figure 2 is a perspective view of the lower ends of a 1~i three-auger system like those used in the prior art; . -~
19 Figure 3 is an enlarged perspective view of the lower ~
20 ends of three-auger shafts utilizing the teachings of the !i-21 present invention wherein the plurality of lateral support 22 structures of the present invention are illustrated; , ;~
Figure 4 is a perspective view of the lower ends of 2~ three-auger shafts utilizing the teachings of the present ..... ..
26 . .
- Pi~ge 18 -~-~
2~3~60 1 invention wherein the fragmentation members of the present 2 invention are illustrated;
3 Figure S is a cross-sectional view of the range of possible lengths for a soil ~ragmentation member, Figure 6a i8 a cross-sectional view of the support 6 structure with soil fragmentation members attached to the :
7 nonrotating bands;
8 Figure 6b is a cross-sectional view of the support 9 structure with soil fragmentation members attached to the nonrotating bands and the clamps;
Figure 6c is a cross-sectional view of the support 12 structure with soil fragmentation members attached to the 13 support bar;
14 Figure 6d is a cross-sectional view of the support 15 structure with soil fragmentation members attached to the 17 support bar and the clamps;
1~
.
22 ' ` .
Figure 4 is a perspective view of the lower ends of 2~ three-auger shafts utilizing the teachings of the present ..... ..
26 . .
- Pi~ge 18 -~-~
2~3~60 1 invention wherein the fragmentation members of the present 2 invention are illustrated;
3 Figure S is a cross-sectional view of the range of possible lengths for a soil ~ragmentation member, Figure 6a i8 a cross-sectional view of the support 6 structure with soil fragmentation members attached to the :
7 nonrotating bands;
8 Figure 6b is a cross-sectional view of the support 9 structure with soil fragmentation members attached to the nonrotating bands and the clamps;
Figure 6c is a cross-sectional view of the support 12 structure with soil fragmentation members attached to the 13 support bar;
14 Figure 6d is a cross-sectional view of the support 15 structure with soil fragmentation members attached to the 17 support bar and the clamps;
1~
.
22 ' ` .
- P~ge 19 -1 DISTAI$ED DE:8CRIPTION OF THE PREFBRRED EMBODIM19NT8 The prQsent invention can be be6t understood with 3 reference to the drawings, wherein like parts are designated 4 with like numerals throughout. The current invention s relates to a novel and inventive multi-sAaft auger soil 6 mixing apparatus for improved soil mixing and efficient 7 boring, particularly in slurries with a low water content 8 and soils which tend to coalesce such as clay and silt. The -~
effect these type of soils and slurries is a decrease in the ~
o homogeneity of the mixture, in the efficiency of the mix~ng -11 process, and in the rate of penetration of the auger shaft 1Z through the soil. An improved auger machine is provided to 13 counteract the deleterious effects of such soils and 1~ slurries.
Figure 3 illustrates a presently preferred embodiment 1~ within the scope of the present invention used in connection 17 with a three-shaft auger machine. Two outer shafts 31a 1~ and 31b and a center shaft 32 each have an upper end (not 19 shown) and a lower end shown generally on the two outer shafts a~ 33a and 33b and on center shaft as 34.
21 The outer shafts and the center shaft are rotated by 22 the power generated by a motor (not shown) and translated to 23 the shafts through a gearbox (not shown) attached to the 24 upper end of each respective shaft. This configuration i8 25 an example of a means for rotating the shafts by generating 26 ~ :
--P21ge 20--.:--2132~60 1 power and transferring the power to the shaft. It will be 2 appreciated that other structures can also be utilized as a 3 means for rotating the shafts.
Outer auger blades 36a and 36b and center auger s blade~ 38 penetrate undisturbed soil as the shafts rotate 6 and propel the shafts downward to auger boreholes. The ~ outer auger blades 36a and 36b and center auger blades 38 8 are securely affixed to lower ends 33a, 33b and 34 of outer 9 shafts 31a and 31b and center shaft 32. The outer auger o blades are vertically offset from center auger blades. The outer auger blades and the center auger blades each possess 12 an auger cutting edge 40 which cuts into the soil at the bottom of each borehole. Auger teeth 42 are preferably 1~ secured to the cutting edge of the first and second auger blades in order to assist in soil penetration in clay or 16 rocky soils. This auger blade configuration provides one 17 example of a means for boring downward through the soil to 18 auger a borehole. It will be appreciated that other 19 embodiments can be utilized as a means for boring downward 20 through the soil to auger a borehole.
21 As the auger shaft travels downward, the auger blades 22 break up the undisturbed soil and pushes it in an upward 23 direction while concomitantly a chemical hardener slurry is 2~ injected into the soil and mixed together. The chemical hardener is pumped from the surface through the auger 26 . -;
- Page 21 ~
' '"' - ~ ~ i 2132~60 1 shafts, which are hollow, to openings formed in the lower 2 end of each of the shafts and in the auger blades which 3 discharge the chemical hardener. This configuration is an 4 ~xa~ple of a means for injecting the chemical hardener into 5 the soil through the shaft during the auger of the borehole.
6 The means for injecting the chemical hardener enables the in 7 situ formation of a hardened soil-cement column set. Other 8 structures, it will be appreciated, can be utilized as a 9 meanB for injecting the chemical hardener into the soil.
As the slurry is absorbed by the broken soil, mixing 11 becomes more difficult. This is especially true with soils 12 such as clay or silt where the introduction of cement slurry 13 tends to exacerbate the tendency of these soils to clump and - .
coalesce in the form of plugs. r 15 Friction between the sides of the borehole and the s edges of the auger blades forces the shafts downward. As 17 the shafts travel downward, the soil through which they pass 18 is mixed and pushed in an upward direction with respect to 19 the downward motion of the shafts. ~ut unlike many auguring 20 devices the soil is not removed from the borehole.
21 Instead, the position of the soil relative to 22 contiguous soil located outside of the borehole remains ,~
23 relatively constant. It is desirable to continuously remix 2~ the soil in an attempt to attain homogeneity of the soil-25 slurry mixture as the shaft passes through that soil.
- P~ge 22 -. ~ ?
1 Continuous mixing can be accomplished by intermittent soil 2 mixing paddles 28 and intermlttent auger blades 30 spaced 3 throughout the length of the shaft. The intermittent 80il 4 mixing paddles and intermittent auger blades are an example 5 of a means for mixing the chemical hardener with the soil.
6 The intermittent 80il mixing paddles 28 and 7 intermittent auger blades 30 are above a lateral support 8 structure, generally illustrated at 50, which is provided to 9 prevent diversion of the auger shafts out of a parallel configuration while concomitantly allowing the shafts to 11 rotate. The lateral support structure is located about each 1Z respective shaft such that the lateral support structure 13 does not rotate as each respective shaft rotates in the - .
1~ soil.
The lateral support structure comprises nonrotating 16 bands 52 surrounding each shaft; stabilizing bars 54 -' 17 securely connecting the nonrotating bands to maintain 1~ parallel shaft alignment; and clamps 56a and 56b, which are-19 securely attached to the nonrotating bands opposite the ~-20 stabilizer bars 54 in order to provide additional support. i~
21 The nonrotating bands 52 surround the sha~ts in an area c~
22 between upper cylindrical collars 58 and lower cylindrical , ~i ;
23 collars 60. The cylindrical collars are formed around the 24 periphery of each shaft. The use of bearings and the 25 configuration of the nonrotating bands and the upper and - Page 23 - ~
~ 2~ 3~6~0 1 lower cylindrical collars allows the shafts to rotate within 2 the nonrotating bands 52 while the nonrotating bands remain 3 stationary. A~ the lateral support structure serves to maintain the auger shafts in a parallel configuration, the 5 lateral support structure is generally located near the 6 lower ends of the shafts where the impact of rocks and 7 varying soil textures has the most effect on the shafts.
8 A plurality of lateral support structures S0 are spaced 9 vertically apart along the shafts to provide more lateral support than merely one lateral support structure.
11 Additionally, it has been determined that when at least two 12 lateral support structures are spaced vertically apart by a 13 length no greater than thirty feet, the undesirable reagglomerated or coalesced plugs formed after passing by --ls the auger blades at the lower end of shaft are sheared.
16 Utilizing multiple lateral support ~tructures creates a 17 shearing effect on the coalesced slurry and soil plugs because the plug cannot continue to rotate with the shaft 19 upon encountering the lateral support structures. The 20 result of minimizing the rotation of coalesced soils or 21 slurries with the shaft i8 an increase in homogeneity of the æ mixtures and a more efficient column foxming process. ,~ r-The vertical spacing between the lateral support 2~ structures can be varied depending on the type of soil or ;
25 the water content of the slurry to achieve an optimal 2~ . ", .~ ., :::: :: :
1 mixture. Lateral support structures spaced less than thirty 2 feet apart provide the benefit of shearing the soil or 3 ~lurry, as well as increasing the lateral support achieved with only one support structure. Decreasing the space s betwee~ the lateral support structures increasés the ability 6 of the lateral æupport structures to shear soils and 7 slurries which typically coalesce below the single support 8 structure of conventional multi-shaft auger machines.
9 Additionally, the spacing between a pair of ad~acent lateral support structurss may be different from the spacing of another pair of ad~acent lateral support structures.
z In another embodiment of the present invention, 13 undesirablQ reagglomerated or coalesced plugs formed after passing by the auger blades at the lower end of the shaft are fragmented by at least one soil fragmentation member 16 secured to a ~ateral support structure. By way of example and not limitation, a fragmentation member in the embodiment 1~ illustrated in Figure 4 comprises two soil fragmentation 19 members 70a and 70b attached to the two clamps 56a and 56b 20 at an orientation normal to the shafts and protruding 21 radially outward. The soil fragmentation members serve to 22 fragment 80il and slurries which coalesce below the lateral ,~
23 support structures and to minimize the rotation of the 2~ coalesced soil or slurry plug with the shaft.
25 . ~.
26 . ::;:
- Page 25 - ~
2~32~60 1 The soil fragmentation members can also be utilized in 2 conjunction with the plurality of vertically spaced lateral 3 support struotures a~ illustrated in Figure 3. Soil 4 fragmentation members can be attached to any number o~ the s vertically spaced lateral support structures or only one of 5 the lateral support structures.
7 The length of the soil fragmentation member can be 8 varied depending on the type of soil being mixed and the 9 water ratio of the slurry. Varying the length of the soil fragmentation members allows for optimal in-situ soil mixing by achieving sufficient fragmentation. Additionally, the 12 80il fragmentation members can have a variety of shapes such 13 as a rectangular shape, a pointed end, a curved hook shape and any other useful shape.
Figure 5 i6 a cross-sectional view of the range of 16 possible lengths for a soil fragmentation member within the 17 scope of the present invention. The length of the soil 18 fragmentation member, represented by reference character L, 19 must be no greater than the difference between the radius of 20 at least one auqer blade and the radius of the shaft, 21 represented by reference character D. Additionally, the 22 length of the 80il fragmentation member must be no less than , one-third the difference between the radius of at least one 2~ auger blade and the radius of the shaft. I~he radius of the auger blades determines the radius of the borehole, ,"', ', l ~ ~
~ 2132~60 1 consequently utilizing soil fragmentation members with a z length no greater than the difference between the radiu~ of 3 at least one auger blade and the radius of the shaft assure~
that no energy i8 108t in friction o~ the soil fragmentat~on 5 members against the sides of the borehole.
6 Cohesive soil such as clay or silt and slurries with a 7 low water content necessitates that the soil fragmentation 8 member extend a length which is no less than one-third the 9 difference between the radius of at least one auger blade and the radius of the shaft. Additionally, when mixing clay or silt in a slurry with a low water content requires that 12 the soil fragmentation members extend an even greater length.
The soil fragmentation member can be placed on either a ls nonrotating band, a support bar or a clamp. Cross seation6 16 of possible configurations are shown in FIGS. 6a-6d.
17 FIGS. 6a and 6b illustrates soil fragmentation me~bers attached to the nonrotating band. FIGS. 6c and 6d 19 illustrate 80il fragmentation members attached to the 20 stabilizer bar.
21 Soil fragmentation members 7Oa and 7Ob serve to improVQ
æ the homogenelty of the clay soil by easing the remixing 23 process in the area above the soil fragmentation 2~ members 70a and 70b. By fragmenting the reconsolidated 2s soil, friction caused by remixing large agglomerations is 26 . '~
- P~ge 27 --~ . . ., :. .
.
213~6 greatly reduced and the efficiency of the boring process 2 through clay soils i8 greatly increased.
3 From the foregoing, it can be seen that the present-invention provides a multi-sha~t auger system for mixing 80il8 with a chemical hardener in situ which fragments 6 reconsolidated soil. The soil fraqmentation provides 7 a mor~ homogeneous mixture of a slurry and a clay soil, 8 resulting in stronger columns.
9 The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be 2 considered in all respects only as illustrative and not 13 restrictive. The scope of the invention is, therefore, 1~ indicated by the appended claims rather than by the 15 foregoing description. All changes which come within the 16 meaning and range of equivalency of the claims are to be 17 embraced within their scope.
1~ ~ ~
19 : . . :
Z3 .
- P~lge 28 -
effect these type of soils and slurries is a decrease in the ~
o homogeneity of the mixture, in the efficiency of the mix~ng -11 process, and in the rate of penetration of the auger shaft 1Z through the soil. An improved auger machine is provided to 13 counteract the deleterious effects of such soils and 1~ slurries.
Figure 3 illustrates a presently preferred embodiment 1~ within the scope of the present invention used in connection 17 with a three-shaft auger machine. Two outer shafts 31a 1~ and 31b and a center shaft 32 each have an upper end (not 19 shown) and a lower end shown generally on the two outer shafts a~ 33a and 33b and on center shaft as 34.
21 The outer shafts and the center shaft are rotated by 22 the power generated by a motor (not shown) and translated to 23 the shafts through a gearbox (not shown) attached to the 24 upper end of each respective shaft. This configuration i8 25 an example of a means for rotating the shafts by generating 26 ~ :
--P21ge 20--.:--2132~60 1 power and transferring the power to the shaft. It will be 2 appreciated that other structures can also be utilized as a 3 means for rotating the shafts.
Outer auger blades 36a and 36b and center auger s blade~ 38 penetrate undisturbed soil as the shafts rotate 6 and propel the shafts downward to auger boreholes. The ~ outer auger blades 36a and 36b and center auger blades 38 8 are securely affixed to lower ends 33a, 33b and 34 of outer 9 shafts 31a and 31b and center shaft 32. The outer auger o blades are vertically offset from center auger blades. The outer auger blades and the center auger blades each possess 12 an auger cutting edge 40 which cuts into the soil at the bottom of each borehole. Auger teeth 42 are preferably 1~ secured to the cutting edge of the first and second auger blades in order to assist in soil penetration in clay or 16 rocky soils. This auger blade configuration provides one 17 example of a means for boring downward through the soil to 18 auger a borehole. It will be appreciated that other 19 embodiments can be utilized as a means for boring downward 20 through the soil to auger a borehole.
21 As the auger shaft travels downward, the auger blades 22 break up the undisturbed soil and pushes it in an upward 23 direction while concomitantly a chemical hardener slurry is 2~ injected into the soil and mixed together. The chemical hardener is pumped from the surface through the auger 26 . -;
- Page 21 ~
' '"' - ~ ~ i 2132~60 1 shafts, which are hollow, to openings formed in the lower 2 end of each of the shafts and in the auger blades which 3 discharge the chemical hardener. This configuration is an 4 ~xa~ple of a means for injecting the chemical hardener into 5 the soil through the shaft during the auger of the borehole.
6 The means for injecting the chemical hardener enables the in 7 situ formation of a hardened soil-cement column set. Other 8 structures, it will be appreciated, can be utilized as a 9 meanB for injecting the chemical hardener into the soil.
As the slurry is absorbed by the broken soil, mixing 11 becomes more difficult. This is especially true with soils 12 such as clay or silt where the introduction of cement slurry 13 tends to exacerbate the tendency of these soils to clump and - .
coalesce in the form of plugs. r 15 Friction between the sides of the borehole and the s edges of the auger blades forces the shafts downward. As 17 the shafts travel downward, the soil through which they pass 18 is mixed and pushed in an upward direction with respect to 19 the downward motion of the shafts. ~ut unlike many auguring 20 devices the soil is not removed from the borehole.
21 Instead, the position of the soil relative to 22 contiguous soil located outside of the borehole remains ,~
23 relatively constant. It is desirable to continuously remix 2~ the soil in an attempt to attain homogeneity of the soil-25 slurry mixture as the shaft passes through that soil.
- P~ge 22 -. ~ ?
1 Continuous mixing can be accomplished by intermittent soil 2 mixing paddles 28 and intermlttent auger blades 30 spaced 3 throughout the length of the shaft. The intermittent 80il 4 mixing paddles and intermittent auger blades are an example 5 of a means for mixing the chemical hardener with the soil.
6 The intermittent 80il mixing paddles 28 and 7 intermittent auger blades 30 are above a lateral support 8 structure, generally illustrated at 50, which is provided to 9 prevent diversion of the auger shafts out of a parallel configuration while concomitantly allowing the shafts to 11 rotate. The lateral support structure is located about each 1Z respective shaft such that the lateral support structure 13 does not rotate as each respective shaft rotates in the - .
1~ soil.
The lateral support structure comprises nonrotating 16 bands 52 surrounding each shaft; stabilizing bars 54 -' 17 securely connecting the nonrotating bands to maintain 1~ parallel shaft alignment; and clamps 56a and 56b, which are-19 securely attached to the nonrotating bands opposite the ~-20 stabilizer bars 54 in order to provide additional support. i~
21 The nonrotating bands 52 surround the sha~ts in an area c~
22 between upper cylindrical collars 58 and lower cylindrical , ~i ;
23 collars 60. The cylindrical collars are formed around the 24 periphery of each shaft. The use of bearings and the 25 configuration of the nonrotating bands and the upper and - Page 23 - ~
~ 2~ 3~6~0 1 lower cylindrical collars allows the shafts to rotate within 2 the nonrotating bands 52 while the nonrotating bands remain 3 stationary. A~ the lateral support structure serves to maintain the auger shafts in a parallel configuration, the 5 lateral support structure is generally located near the 6 lower ends of the shafts where the impact of rocks and 7 varying soil textures has the most effect on the shafts.
8 A plurality of lateral support structures S0 are spaced 9 vertically apart along the shafts to provide more lateral support than merely one lateral support structure.
11 Additionally, it has been determined that when at least two 12 lateral support structures are spaced vertically apart by a 13 length no greater than thirty feet, the undesirable reagglomerated or coalesced plugs formed after passing by --ls the auger blades at the lower end of shaft are sheared.
16 Utilizing multiple lateral support ~tructures creates a 17 shearing effect on the coalesced slurry and soil plugs because the plug cannot continue to rotate with the shaft 19 upon encountering the lateral support structures. The 20 result of minimizing the rotation of coalesced soils or 21 slurries with the shaft i8 an increase in homogeneity of the æ mixtures and a more efficient column foxming process. ,~ r-The vertical spacing between the lateral support 2~ structures can be varied depending on the type of soil or ;
25 the water content of the slurry to achieve an optimal 2~ . ", .~ ., :::: :: :
1 mixture. Lateral support structures spaced less than thirty 2 feet apart provide the benefit of shearing the soil or 3 ~lurry, as well as increasing the lateral support achieved with only one support structure. Decreasing the space s betwee~ the lateral support structures increasés the ability 6 of the lateral æupport structures to shear soils and 7 slurries which typically coalesce below the single support 8 structure of conventional multi-shaft auger machines.
9 Additionally, the spacing between a pair of ad~acent lateral support structurss may be different from the spacing of another pair of ad~acent lateral support structures.
z In another embodiment of the present invention, 13 undesirablQ reagglomerated or coalesced plugs formed after passing by the auger blades at the lower end of the shaft are fragmented by at least one soil fragmentation member 16 secured to a ~ateral support structure. By way of example and not limitation, a fragmentation member in the embodiment 1~ illustrated in Figure 4 comprises two soil fragmentation 19 members 70a and 70b attached to the two clamps 56a and 56b 20 at an orientation normal to the shafts and protruding 21 radially outward. The soil fragmentation members serve to 22 fragment 80il and slurries which coalesce below the lateral ,~
23 support structures and to minimize the rotation of the 2~ coalesced soil or slurry plug with the shaft.
25 . ~.
26 . ::;:
- Page 25 - ~
2~32~60 1 The soil fragmentation members can also be utilized in 2 conjunction with the plurality of vertically spaced lateral 3 support struotures a~ illustrated in Figure 3. Soil 4 fragmentation members can be attached to any number o~ the s vertically spaced lateral support structures or only one of 5 the lateral support structures.
7 The length of the soil fragmentation member can be 8 varied depending on the type of soil being mixed and the 9 water ratio of the slurry. Varying the length of the soil fragmentation members allows for optimal in-situ soil mixing by achieving sufficient fragmentation. Additionally, the 12 80il fragmentation members can have a variety of shapes such 13 as a rectangular shape, a pointed end, a curved hook shape and any other useful shape.
Figure 5 i6 a cross-sectional view of the range of 16 possible lengths for a soil fragmentation member within the 17 scope of the present invention. The length of the soil 18 fragmentation member, represented by reference character L, 19 must be no greater than the difference between the radius of 20 at least one auqer blade and the radius of the shaft, 21 represented by reference character D. Additionally, the 22 length of the 80il fragmentation member must be no less than , one-third the difference between the radius of at least one 2~ auger blade and the radius of the shaft. I~he radius of the auger blades determines the radius of the borehole, ,"', ', l ~ ~
~ 2132~60 1 consequently utilizing soil fragmentation members with a z length no greater than the difference between the radiu~ of 3 at least one auger blade and the radius of the shaft assure~
that no energy i8 108t in friction o~ the soil fragmentat~on 5 members against the sides of the borehole.
6 Cohesive soil such as clay or silt and slurries with a 7 low water content necessitates that the soil fragmentation 8 member extend a length which is no less than one-third the 9 difference between the radius of at least one auger blade and the radius of the shaft. Additionally, when mixing clay or silt in a slurry with a low water content requires that 12 the soil fragmentation members extend an even greater length.
The soil fragmentation member can be placed on either a ls nonrotating band, a support bar or a clamp. Cross seation6 16 of possible configurations are shown in FIGS. 6a-6d.
17 FIGS. 6a and 6b illustrates soil fragmentation me~bers attached to the nonrotating band. FIGS. 6c and 6d 19 illustrate 80il fragmentation members attached to the 20 stabilizer bar.
21 Soil fragmentation members 7Oa and 7Ob serve to improVQ
æ the homogenelty of the clay soil by easing the remixing 23 process in the area above the soil fragmentation 2~ members 70a and 70b. By fragmenting the reconsolidated 2s soil, friction caused by remixing large agglomerations is 26 . '~
- P~ge 27 --~ . . ., :. .
.
213~6 greatly reduced and the efficiency of the boring process 2 through clay soils i8 greatly increased.
3 From the foregoing, it can be seen that the present-invention provides a multi-sha~t auger system for mixing 80il8 with a chemical hardener in situ which fragments 6 reconsolidated soil. The soil fraqmentation provides 7 a mor~ homogeneous mixture of a slurry and a clay soil, 8 resulting in stronger columns.
9 The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be 2 considered in all respects only as illustrative and not 13 restrictive. The scope of the invention is, therefore, 1~ indicated by the appended claims rather than by the 15 foregoing description. All changes which come within the 16 meaning and range of equivalency of the claims are to be 17 embraced within their scope.
1~ ~ ~
19 : . . :
Z3 .
- P~lge 28 -
Claims (38)
1. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a hardened soil-cement column set, the apparatus comprising:
(a) at least two substantially parallel shafts, each shaft having an upper end and a lower end;
(b) rotation means for rotating the shafts, the rotation means being attached to each upper end of the shafts;
(c) boring means for boring downward through the soil to auger a borehole, the boring means being securely affixed to each lower end of the shafts;
(d) injection means for injecting the chemical hardener into the soil through the shaft during the auger of the borehole; and (e) a plurality of internal support structures spaced vertically apart along the shafts to provide lateral support, each lateral support structure being located about each respective shaft such that the lateral support structures do not rotate as each respective shaft rotates in the soil.
(a) at least two substantially parallel shafts, each shaft having an upper end and a lower end;
(b) rotation means for rotating the shafts, the rotation means being attached to each upper end of the shafts;
(c) boring means for boring downward through the soil to auger a borehole, the boring means being securely affixed to each lower end of the shafts;
(d) injection means for injecting the chemical hardener into the soil through the shaft during the auger of the borehole; and (e) a plurality of internal support structures spaced vertically apart along the shafts to provide lateral support, each lateral support structure being located about each respective shaft such that the lateral support structures do not rotate as each respective shaft rotates in the soil.
2. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 1, wherein at least two lateral support structures are spaced vertically apart by a length no greater than thirty feet to shear the soil.
3. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a hardened soil-cement column set as recited in Claim 1, further comprising at least one fragmentation member, each fragmentation member being secured to the support structure at an orientation normal to the shafts and protruding radially outward to aid in fragmenting soil and to aid in mixing the soil with the chemical hardener.
4. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 1, wherein the boring means comprises an auger blade affixed to the lower end of each respective shaft, each of said auger blades having either different or approximately the same radius as the radius of contiguous auger blades;
wherein the shafts have a radius; and wherein the fragmentation member has a length no greater than the difference between the radius of at least one auger blade and the radius of the shaft and no less than one-third the difference between the radius of at least one auger blade and the radius of the shaft.
wherein the shafts have a radius; and wherein the fragmentation member has a length no greater than the difference between the radius of at least one auger blade and the radius of the shaft and no less than one-third the difference between the radius of at least one auger blade and the radius of the shaft.
5. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a hardened soil-cement column set as recited in Claim 1, wherein each support structure comprises at least two nonrotating bands, at least one stabilizer bar and two clamps.
6. A multi-shaft auger apparatus for mixing soil with.
a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 5, wherein at least one fragmentation member is secured to at least one of the two clamps of the support structure.
a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 5, wherein at least one fragmentation member is secured to at least one of the two clamps of the support structure.
7. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 5, wherein at least one fragmentation member is secured to at least one of the nonrotating bands.
8. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 5, wherein at least one fragmentation member is secured to at least one stabilizer bar.
9. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a hardened soil-cement column set as recited in Claim 1, further comprising a mixing means for mixing the chemical hardener with the soil above at least one of the lateral support structures.
10. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 9, wherein the mixing means comprises at least one auger blade affixed to each respective shaft and a plurality of soil mixing paddles affixed to each respective shaft.
11. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a hardened soil-cement column set, the apparatus comprising:
(a) at least two substantially parallel shafts, each shaft having an upper end and a lower end;
(b) rotation means for rotating the shafts, the rotation means being attached to each upper end of the shafts;
(c) boring means for boring downward through the soil to auger a borehole, the boring means being securely affixed to each lower end of the shafts;
(d) injection means for injecting the chemical hardener into the soil through the shaft during the auger of the borehole;
(e) a lateral support structure located about each respective shaft such that the lateral support structure does not rotate as each respective shaft rotates in the soil; and (f) at least one fragmentation members, each fragmentation member being secured to a lateral support structure at an orientation normal to the shafts and protruding radially outward to aid in fragmenting soil and to aid in mixing the soil with the chemical hardener.
(a) at least two substantially parallel shafts, each shaft having an upper end and a lower end;
(b) rotation means for rotating the shafts, the rotation means being attached to each upper end of the shafts;
(c) boring means for boring downward through the soil to auger a borehole, the boring means being securely affixed to each lower end of the shafts;
(d) injection means for injecting the chemical hardener into the soil through the shaft during the auger of the borehole;
(e) a lateral support structure located about each respective shaft such that the lateral support structure does not rotate as each respective shaft rotates in the soil; and (f) at least one fragmentation members, each fragmentation member being secured to a lateral support structure at an orientation normal to the shafts and protruding radially outward to aid in fragmenting soil and to aid in mixing the soil with the chemical hardener.
12. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a hardened soil-cement column set as recited in Claim 11, wherein the boring means comprises an auger blade affixed to the lower end of each respective shaft, each of said auger blades having either different or approximately the same radius a the radius of contiguous auger blades;
wherein the shafts have a radius; and wherein the fragmentation member has a length no greater than the difference between the radius of at least one auger blade and the radius of the shaft and no less than one-third the difference between the radius of at least one auger blade and the radius of the shaft.
wherein the shafts have a radius; and wherein the fragmentation member has a length no greater than the difference between the radius of at least one auger blade and the radius of the shaft and no less than one-third the difference between the radius of at least one auger blade and the radius of the shaft.
13. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a hardened soil-cement column set as recited in Claim 11, wherein each support structure comprises at least two nonrotating bands, at least one stabilizer bar and two clamps.
14. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 13, wherein at least one fragmentation member is secured to at least one of the two clamps of the support structure.
15. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 13, wherein at least one fragmentation member is secured to at least one of the nonrotating bands.
16. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 13, wherein at least one fragmentation member is secured to at least one stabilizer bar.
17. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a hardened soil-cement column set as recited in Claim 11, further comprising at least one additional lateral support structures spaced vertically above the support structure along the shafts to provide additional lateral support.
18. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 17, wherein the lateral support structure and an additional lateral support structure are spaced vertically apart by a length no greater than thirty feet to shear the soil.
19. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 17, wherein at least two of the additional lateral support structures are spaced vertically apart by a length no greater than thirty feet to shear the soil.
20. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a hardened soil-cement column set as recited in Claim 11, further comprising a mixing means for mixing the chemical hardener with the soil above at least one of the lateral support structure.
21. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 21, wherein the mixing means comprises at least one auger blade affixed to each respective shaft and a plurality of soil mixing paddles affixed to each respective shaft.
22. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a hardened soil-cement column set, the apparatus comprising:
(a) at least two substantially parallel shafts, each shaft having an upper end and a lower end;
(b) rotation means for rotating the shafts, the rotation means being attached to each upper end of the shafts;
(c) boring means for boring downward through the soil to auger a borehole, the boring means being securely affixed to each lower end of the shafts;
(d) injection means for injecting the chemical hardener into the soil through the shaft during the auger of the borehole;
(e) a plurality of lateral support structures spaced vertically apart along the shafts to provide lateral support, each lateral support structure being located about each respective shaft such that the lateral support structures do not rotate as each respective shaft rotates in the soil; and (f) at least one fragmentation member, each fragmentation member being secured to a lateral support structure at an orientation normal to the shafts and protruding radially outward to aid in fragmenting soil and to aid in mixing the soil with the chemical hardener.
(a) at least two substantially parallel shafts, each shaft having an upper end and a lower end;
(b) rotation means for rotating the shafts, the rotation means being attached to each upper end of the shafts;
(c) boring means for boring downward through the soil to auger a borehole, the boring means being securely affixed to each lower end of the shafts;
(d) injection means for injecting the chemical hardener into the soil through the shaft during the auger of the borehole;
(e) a plurality of lateral support structures spaced vertically apart along the shafts to provide lateral support, each lateral support structure being located about each respective shaft such that the lateral support structures do not rotate as each respective shaft rotates in the soil; and (f) at least one fragmentation member, each fragmentation member being secured to a lateral support structure at an orientation normal to the shafts and protruding radially outward to aid in fragmenting soil and to aid in mixing the soil with the chemical hardener.
23. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 22, wherein at least two lateral support structures are spaced vertically apart by a length no greater than thirty feet to shear the soil.
24. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a hardened soil-cement column set as recited in Claim 22, wherein the boring means comprises an auger blade affixed to the lower end of each respective shaft, each of said auger blades having either different or approximately the same radius as the radius of contiguous auger blades;
wherein the shafts have a radius; and wherein the fragmentation member has a length no greater than the difference between the radius of at least one auger blade and the radius of the shaft and no less than one-third the difference between the radius of at least one auger blade and the radius of the shaft.
wherein the shafts have a radius; and wherein the fragmentation member has a length no greater than the difference between the radius of at least one auger blade and the radius of the shaft and no less than one-third the difference between the radius of at least one auger blade and the radius of the shaft.
25. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a hardened soil-cement column set as recited in Claim 22, wherein each support structure comprises at least two nonrotating bands, at least one stabilizer bar and two clamps.
26. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 25, wherein at least one fragmentation member is secured to at least one of the two clamps of the support structure.
27. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 25, wherein at least one fragmentation member is secured to at least one of the nonrotating bands.
28. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 25, wherein at least one fragmentation member is secured to at least one stabilizer bar.
29. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a hardened soil-cement column set as recited in Claim 22, further comprising a mixing means for mixing the chemical hardener with the soil above at least one of the lateral support structures.
30. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 29, wherein the mixing means comprises at least one auger blade affixed to each respective shaft and a plurality of soil mixing paddles affixed to each respective shaft.
31. A method for in situ formation of a subterranean structure in soil using a multi-shaft auger apparatus having shafts to mix a chemical hardener with soil, the method comprising the steps of:
(a) auguring a borehole downward into and through the soil with an auger apparatus having at least two substantially parallel shafts configured to rotate in the soil with auger blades at the lower end of each respective shaft;
(b) injecting the chemical hardener through the shaft and into the soil during the auger of the borehole;
(c) shearing the soil with a plurality of lateral support structures spaced vertically apart along the shafts to provide lateral support, each lateral support structure being located about each respective shaft such that the lateral support structures do not rotate as each respective shaft rotates in the soil, wherein at least two lateral support structures are spaced vertically apart by a length no greater than thirty feet to shear the soil; and (d) fragmenting soil lifted upwardly by the multi-shaft auger apparatus with at least one soil fragmentation members being secured to a lateral support structure at an orientation normal to the shafts and protruding radially outward to aid in fragmenting soil and to aid in mixing the soil with the chemical hardener;
(e) mixing the soil within the borehole with the chemical hardener;
(f) allowing the soil and chemical hardener blend to cure to form a hardened subterranean structure.
(a) auguring a borehole downward into and through the soil with an auger apparatus having at least two substantially parallel shafts configured to rotate in the soil with auger blades at the lower end of each respective shaft;
(b) injecting the chemical hardener through the shaft and into the soil during the auger of the borehole;
(c) shearing the soil with a plurality of lateral support structures spaced vertically apart along the shafts to provide lateral support, each lateral support structure being located about each respective shaft such that the lateral support structures do not rotate as each respective shaft rotates in the soil, wherein at least two lateral support structures are spaced vertically apart by a length no greater than thirty feet to shear the soil; and (d) fragmenting soil lifted upwardly by the multi-shaft auger apparatus with at least one soil fragmentation members being secured to a lateral support structure at an orientation normal to the shafts and protruding radially outward to aid in fragmenting soil and to aid in mixing the soil with the chemical hardener;
(e) mixing the soil within the borehole with the chemical hardener;
(f) allowing the soil and chemical hardener blend to cure to form a hardened subterranean structure.
32. A method in situ in formation of a subterranean structure as recited in claim 31, wherein each of the auger blades have either different or approximately the same radius as the radius of contiguous auger blades;
wherein the shafts have a radius; and wherein the fragmentation member has a length no greater than the difference between the radius of at least one auger blade and the radius of the shaft and no less than one-third the difference between the radius of at least one auger blade and the radius of the shaft.
wherein the shafts have a radius; and wherein the fragmentation member has a length no greater than the difference between the radius of at least one auger blade and the radius of the shaft and no less than one-third the difference between the radius of at least one auger blade and the radius of the shaft.
33. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a hardened soil-cement column set as recited in Claim 31, wherein each support structure comprises at least two nonrotating bands,.
at least one stabilizer bar and two clamps.
at least one stabilizer bar and two clamps.
34. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 33, wherein at least one fragmentation member is secured to at least one of the two clamps of the support structure.
35. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 33, wherein at least one fragmentation member is secured to at least one of the nonrotating bands.
36. A multi-shaft auger apparatus for mixing soil with a chemical hardener in situ in a borehole to form a soil-cement column set as recited in Claim 33, wherein at least one fragmentation member is secured to at least one stabilizer bar.
37. A method for in situ in a borehole formation of a;
subterranean structure as recited in claim 31, wherein the chemical hardener injected into the soil includes a cement product.
subterranean structure as recited in claim 31, wherein the chemical hardener injected into the soil includes a cement product.
38. A method in situ in a borehole for formation of a subterranean structure as recited in claim 31, further comprising a step of withdrawing the multi-shaft auger apparatus from the borehole while simultaneously blending the soil with the chemical hardener.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/125,567 | 1993-09-23 | ||
| US08/125,567 US5417522A (en) | 1993-09-23 | 1993-09-23 | Soil fragmentation members and multiple lateral support structures for improved soil mixing and efficient boring for use on multi-shaft auger soil mixing apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2132660A1 true CA2132660A1 (en) | 1995-03-24 |
Family
ID=22420338
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002132660A Abandoned CA2132660A1 (en) | 1993-09-23 | 1994-09-22 | Soil fragmentation members and multiple lateral support structures for improved soil mixing and efficient boring for use on multi-shaft auger soil mixing apparatus |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US5417522A (en) |
| CA (1) | CA2132660A1 (en) |
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| US4886400A (en) * | 1988-03-23 | 1989-12-12 | S.M.W. Seiko, Inc. | Side cutting blades for multi-shaft auger system and improved soil mixing wall formation process |
| US4906142A (en) * | 1988-03-23 | 1990-03-06 | S.M.W. Seiko, Inc. | Side cutting blades for multi-shaft auger system and improved soil mixing wall formation process |
| JPH07115902B2 (en) * | 1988-05-06 | 1995-12-13 | 信越化学工業株式会社 | Cement composition for extrusion molding |
| JPH01299914A (en) * | 1988-05-26 | 1989-12-04 | Tenotsukusu:Kk | Multishaft ground improving machine |
| US4909675A (en) * | 1988-08-24 | 1990-03-20 | Osamu Taki | In situ reinforced structural diaphragm walls and methods of manufacturing |
| EP0436954B1 (en) * | 1990-01-11 | 1994-10-05 | Seiko Kogyo Kabushiki Kaisha | Double-tube boring and kneading machine and method of improving foundation ground by employing said double-tube type boring and kneading machine |
-
1993
- 1993-09-23 US US08/125,567 patent/US5417522A/en not_active Expired - Fee Related
-
1994
- 1994-09-22 CA CA002132660A patent/CA2132660A1/en not_active Abandoned
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105064345A (en) * | 2015-08-09 | 2015-11-18 | 张永忠 | Using method for trapezoid stirring pile forming machine |
Also Published As
| Publication number | Publication date |
|---|---|
| US5417522A (en) | 1995-05-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |