US 1598300 A
Description (OCR text may contain errors)
Aug., 31?., 1926,.
' www@ D. E. MORAN FOUNDATION AND THE LIKE Filed August 5 A A A applied in several different ways on the Paume-'d Aug. 31', 1926.
UNiTED STATES DANIEL E. vIVIIOB'AN, 0F MENDHAM, NEW. JERSEY.
FOUNDATION ANI) THE LIKE.
Application filed August My invention provides a method of treating or manipulating certain soils to increase their .loadcarrying capacity or strength. The soil or earth thus treatedmay be 1used as a building foundation carrying heavy downward pressures, or as fioor slabs and walls for coifer dams and similar excavations or as a consolidated mass through which tunnels can be driven or in various other analogous ways.
The ordinary supersaturated or highly.
watered natural deposit (wet-earth or mud) offers very little resistance to stresses imposed up,on it tending to change its shape or to displace it laterally and upward. I propose to Ichange such wet earth into a shale-like material practically impervlous to water and Kcapable of resisting tension as well as compression, and greatly improved in resistance to change of volume or shape and to lateral displacement.
I first provide vertical drains fairly close together depending on the special character of the material. I also exert lateral compression on the mass of earth surrounding the drains. The pressure may be applied by the drains themselves during their construction; or it may be applied by drivingsolid wooden or concrete piles, by stock-ramming, andin similar ways referred to hereinafter in detail. Or the lateral pressure may be same job. The process is intended for soils which cannot be dewatered merely by" gravity orvordinary drainage, and in which a considerable pressure externally applied is necessary to squeeze out the water to the desired extent. This is what happens in such soils when a building erected thereon settles; The soil is compacted by the expulsion of the water laterally (in which term we include upwardly). The resistance of the water to expulsion is so great that the building settles slowly.l Sometimes it `takes several years to reach a condition of equi-- librium where the resistance of the remain-,-
ing water to separation from the earth particles is equal to the load, and settling stops. Such settlement, being generally only a few inches, does not involve the application of an extrardinaryv amount of work, measured in foot pounds. For any ordinary case we 5,'1925. seriai No. 48,193.
can by the present invention eliminate the water beforehand and in a comparatively brief period,-bringing the soil to the condltion corresponding to that occurring after a year or two of servicein support of a building. This prompt dewatering is due to the fact that the pressure can be far more widely distributed throughout the area and depth of the stratum and at a higher pressure by the devices which I employ, than it can be' by the building itself and that the distance that the water must travel in the material is reduced.
The accompanying` drawings illustrate embodiments of my invention.
Fig. 1 is a plan showing an arrangement y a half-plan' CTI apparatus andstructures involved being capable ofwide variation. l For example, al v ery great number of ways may be utilized to exert lateral pressurel in the soil and to the required depth.,
I have illustrated in Fig. 3 a sand-ramming pile but I may use expanding mandrels, liquid or gas pressure devices, solid wooden orl concrete piles or devices for ramming in pervious or impervious material, such as,
sand lor a concrete 'mixture The stockramming may extend the full depth of the pipev or belimi'ted to a desired level.
The pressure-producing means may be 7 used aselements of construction, as in tunnels or coifer dams, or as piles in foundations. The provision of drains facilitates the driving of ordinary wooden or concrete point-bearing piles by. reducing the resistance-to driving andthe danger of upliftl and lateral movement of l the piles and of the mass.
Referringnon/'particularly to Fig. A3, a
pipe 1 with a detachable point 2 at its lower end is driven to the required depth, and its lower end filled with sand 3 introduced through a pipe 4. An annular ram 5 is lifted and dropped on the sand, which drives the point 2 ofthe pile down and drives the sand out laterally against the surrounding earth as indicated. The quantity of sand and the extent ofthe hammering operation will determine roughly the diameter of the resulting column of sand; the column being extended upward by continuing the supply of sand as the casing 1 is lifted. Such an operation produces a vertical drain and at the same time compresses the earth surrounding the drain so as to .force out of it a quantity of water greatly in excess of that which would flow out by gravity alone.
In many situations the top soil is not suitable as a working platform, as men, horses or plant in motion convert the top surface into a sea of mud. I have in such cases laid a ioor of concrete to provide a working platform on which the superstructure was started, comprising first the footings or mat used in distributing the load of columnsor walls.
In my method, using stock ramming or liquid or gas pressure to produce lateral pressure in the mass, the intensity of lateral pressure used near the upper surface of the mass is limited, as lateral pressure will produce lateral and upward motion more easily near the surface than at depths, and liquid or gaseous pressure would blow out.
I, therefore, in such cases, may construct amat of concrete over the entire area of support, arranging at the proper points to have vertical cylindrical openings, properly spaced to coincide with the location of the velrtical drains and the pressure-producing p1 es.
The vertical drains may be constructed before 'the-mat, or afterward, but in any case each vertical drain should have a free -outlet through the mat. The pressure-producing piles should be constructed after the mat has set a reasonable time. The pipe pile or expanding Inandrel may be driven .through the hole provided for it. c The stock ramming can be performed in the ordinary manner, but with better results, especially near the upper end.
If compressed air or water pressure is used to expand the vertical hole in the mass,
then the hole through the mat may be lined with a steel pipe, eoncreted or grouted so as to be air tight and watertight, and with top connections for theK water or gas pressure conveying pipe.
The mat will serve as a pressure retaining cap to the pair or water used and will also act as a load to prevent the mass'risinglocally near to the pipe, as a result of lateral pressure. q
After the mass is compressed the hole may be concreted.
At any time grout under pressure may, be used under the mat.
For a better understanding of the invention, I will describe the application of it to a specific example. A structure was set on a reinforced concrete base or slab 5 feet thick and about 80 feet wide by 11,0 feet long, an area of 8,800 feet. IThe slab was placed on natural material, the under side of the slab being placed about 10 feet below the surface of the ground.
Below the slab, the natural material was, for a depth of 15 feet, a dry sandy clay soil, through which ran small openings like worm holes. These holes above water level were filled with air. At a depth of 50 feet below the slab rock was encountered, practically level. Above the rock, and below the dry soil, the material was wet and would normally be described as a wet clay. v
l After completion of the structu e the" total load on the mat was 26,400,000 pr'unds; under which the mat settled 2 inch s. When the building was loaded, in ninety days the total load was doubled and inthis period there was a settlement of 2 feet. There was no apparent movement of the top surface of the adjacent unloaded areas, but water appeared vas springs Howing through the concrete slabs and even in places through pervious joints in the concrete walls resting on the slab although the water level in the soil, except at the site of the silo, had not changed and was 15 feet below the level at which water a peared in the slab. It was evident that tie only source of water was from the saturated clay bed, 15 feet -below the slab. The settlement was principally the result of the consolidation of the super- 'saturated clay bed.
The work or energy involved in the settlement was approximately 52,800,000 foot pounds or 26 horse power for one hour. The displacement of the mat in moving 2 feet was (8,800 2) 19,600 cubic feet. This volumetric change in the soil was chiefly` in the upper 40 feet; the lower 10 feety iinmediately above the rock contained solid rock fragments and dense blue clay.
To produce the same el'eet before erecting the building we must artiriully displace 2 cubic feet per square foot of area. Or an additional 2 cubic feet of new material must be introduced for euclr s nare foot of surface and 40 feet of dept. This is a five per cent consolidation. In such a case I would drive sand-piles serving asdrains yon 10 feet centers, arranged in squares. or bet ter staggered so as to'have one preliminary drain pile to every 100 square feet of area. This preliminary pile may have a cross-section of 1 square foot.
I would drive approximately 130 of these preliminary l drains spaced over an area 90l X 120. I would thendrive approximately 390 ressure-exerting piles, interspaced equally 1 pile 1 sq. n. section x 4o'- 4ocu. fc. 3 pile 1% sq. ft. Section X 40=180 cu. It. e
Total 220cu.!t. This total displacement is slightly in excess of the theoretical requirements.
\ Fig. 1 illustrates the arrangement described, the drains being indicated at 6 and the `ressur`eproducing piles at 7.
I these piles were made of concrete the cost of material and mixing would be about $8,000, compared with, a cost 'of about $1,000, if they were of sand. l
More important than the above saving is the fact that in the material described it would be impractical to drive the concrete /piles to the depth required. The first piles to prompt drainage and moreover a less' would compress the mass, without affording any .opportunity for the water to escape and it would be impossible to drive additional.
piles, exce t after allowing an unreasonable time for t e water to escape, (no draining system having been established) unless the lmaterial was displaced laterally or upward', which would result in reducing the value [of the piles already driven.
Using -my method, the load of the structure wouldbe distributed over the consolidated mass by a distributing mat 8 or foot- .ings The mat would then rest on a consolidated mass comprising vertical columns of consolidated sand spaced uniformly in the mass of consolidated and partially dewatered granular material. Both the sand and the original, but dewatered mass are capable ofsupporting the unit-load which the structurewill place onl themat. If wooden or concrete piles are used, the safe will be greatly increasedby the change vin character of the surrounding material due pressure-producing number of piles w1ll suffice because the' material between the piles can be safely counted on to carry a part or. all of the load.
By my invention, silty material such as that forming the bed of some harbors can be converted into a reliable, water tight, pressure-resisting material capable of acting as a cofferdam wall. i J l Where the material in ,place does not'reach the water surface it will lbe necessary to build an upward extension between the top of the consolidated natural material and the water surface. Where the material, as in marshes, swamps,.etc., extends up to or above water level, thewall formed by my invention will alone be suflicient. In the latter case I will proceed substantially as follows I will first determme the shape and dimensions ofthe excavation to be made and the general character of the material below the bottom of the excavation. If the excavation requires protection against the bottom lifting, as well as against lateral motion, I will create a bottom and walls of consolidated material by means herein described. If the excavationrequires protection against lateral motion only, I will create only walls of consolidated material.
In constructing thev bottom (if required) I will drive pipe piles to a sufficient depth below the proposed excavation depth to give a floor slab of consolidated material ofample thickness to resist uplift, when the excavation, or a predetermined section of the excavation, is made.
I will consolidate this section by constructto the surface, and secondly by ilterposing depth and width so that the consolidated material thereby produced will connect with the floor (if floor be needed) or with an impervious and compact substratum, or if there be neither floor nor impervious su'bstratum, then to vsuch depth as may be necessary to provide a solid foundation for the wall below the level of the excavation to be made.
I may construct a single closed wall; in
` plan having the form of a circle, ellipse,
square or polygon, enclosing the entire ex- 'cavation, or in certain cases I may prefer to `consolidate the enclosed area as well as the ing first a series of vertical drains extending required walls, or to consolidate a part. of
the enclosed area, so as to sub-divide the. operation,'or, in` general, I may consolidate such parts or portions of the mass as to facilitate the work to be performed.
An example is shown in Figs 5 and 6. The level of a piece of marshy ground is indicated at 9 in whichvit is desired to make a circular excavation 10, of which the floor and side walls are to 'be consolidated. Drains are first o ened from' the top of the marsh to the leve '12 to which the consolidation is tobe carried, and pressure piles 13 are ldriven as explained above tocompact 12 only/t0 the level of the bottom 14 of the 26 shortly above intended excavation. Around the excavation are driven drainage piles 15` andpressure piles 16, the stock-ramming of the latter being carried clear up to the surface 9. Thereafter the excavation is made and the ffoor and wall thereof (extending roughly to the line 17) will have been strengthened sufficiently to hold their shape and to serve as a coiier dam to hold back water from the excavation.
In constructing tunnels, I drive two lines of vertical drains paralleling the ,axis of the Atunnel but outside of the lines of side excavation. I then consolidate the mass between the lateral lines of drains by pressure-producing piles. In constructing the pressureproducing piles, I use a granular material impervious to water when producing lateral pressure at the levels of the invert and roof, so as to avoid leaks when excavating the tunnel section. i c
In order to supply crete or wooden piles as pressure-produc.- ing piles, so as to form a concrete or timber supporting element extending between the consolidated mass forming the roof andthe consolidatedmass forming the floor of the excavation to be made.
These concrete or timber columns will serve as temporary support for the roof during the excavationof the tunnel and can bev removed when or after the permanent lining is in place.
An exampleis shown in vertical crosssection in Fig. 6. The surface of the earth is' indicated at are sunk drainage piles 19 and pressure piles 20. In the latter impervious material is used outside of the line of excavation 21, up to the top line 22 of the intended consolidation and down to the bottom level 23 thereof. rIhe piles 24" are pressure piles, using concrete and below the tunnel crosssection. A lining subsequently built in the tunnel is shown at 27. The drains and pressure-producing iles consolidate the earth between the leve s 22 and`23 and the planes 28 and 29 at opposite sides. The `earth in this cross-section is strengthenedso as to hold its shape and facilitate the excavating and lining of the tunnel.
The depth to which the consolidation is carried will depend on the character of the material and the intended load, both' of which can be determined beforehand, the depth being to rock or hardpan orto any material encountered which is sufficiently compact in its natural state to support the load imposed on it without undue volume change. The drains are referred to as vertical, byfwhich I mean that they shall have at least a vertical component thou h they may be oblique as, for example, in raining temporary support to the roof while excavating I may use con-` 18. Along the desired line.
between the levels 25 and' a mass of conical form. The drains should be pressure-resisting so as to remain open during the compacting of the surrounding material, They may be made of a great variety of materials which are pervious to water; such as unglazed terra cotta, porous tubes of concrete or mortar, sand, slag, gravel or other granular material permitting a free passage of water. In some materials a hole may be bored with an ordinary post hole auger and filled with material which permits a fiow of water but holds back the solid material of the surrounding mass. -'The granular material may be tamped in 'order to completely fill the hole and to compress the surroundin mass. In other materials it is not practicable to maintain an open` hole, and methods involving the sinking of hollow piles must be resorted to. An example of such a method has been described in connection with Fig. 3 above. And there are many other ways of achieving the same purpose,
The drainage piles, as I call them, may be applied in such a way as to also produce lateral compression, and my invention may be practiced with such piles alone properly distributed according to the nature of the earth and the intended loading. Or, as first described, such drainage piles may be supplemented by others generally of a simpler character and designed solely or chiefly for producing lateral compression. y
The chief advantage of the invention arises from the use of vertical drains, whereby the frictional resistance to be overcome in the dewatering of the mass is reduced and the time required for dewatefring is shortened according to the extent of subdivision of the mass by the drainage and pressure piles. .Thus the mass can ybe cheaply and .rapidly dewatered and compressed beforehand, to the same or a greater extent which has been common in the dations and loaded buildings acting over a longer period of time.
Various modifications of the -process and details described may be made by those skilled in the art without departing from the invention as defined in the following claims.
What I claim is'v:-
1. The'method of strengthening a body of earth which `consists in forming vdrains at numerous points in the area of the mass and compacting the material laterally also at numerous points to force the water out of it by Way of such drains.
2. The method of preparing a body of earth to Serve as a. foundation for a structure which consists in determining beforehand the extent' to which it would be compacted by the weight of thestructure and dewatering and compacting the earth to sublio stantially the determined extent by forming un vertical drains therein and applying lateral 5. .The combination in a body of earth pressure to the mass. A of pressure-resisting Vertical drains for 10 3. The method of claim 1, rst laying a Water and means for exerting lateral presmat on the earth and then draining and sure on the earth surrounding said drains. F compacting the earth beneath the mat. ln Witness whereof, l have hereunto signed 4l. The method of claim 1, compacting the my name. material by driving pressure-producing piles about the drains. DANIEL E. MORAN.