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Publication numberUS3648467 A
Publication typeGrant
Publication dateMar 14, 1972
Filing dateApr 23, 1970
Priority dateAug 27, 1969
Also published asDE2029487A1, DE2029487B2, DE2029487C3
Publication numberUS 3648467 A, US 3648467A, US-A-3648467, US3648467 A, US3648467A
InventorsOgawa Mitsuro
Original AssigneeFudo Construction Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Machines for continuously forming sand piles
US 3648467 A
Abstract
A machine for continuously forming sand piles comprises a casing with a hopper connected thereto near its upper end. A vibratory pile driver is mounted at the upper end of the casing above the hopper and a ram is mounted in the casing for undergoing reciprocatory movement therein under the action of a drive means which is independent of the pile driver. The ram carries a tamping plate at its lower end and in the lowermost end stroke position, the tamping plate is located a small distance above the lower end of the casing. As the casing is being lifted from the ground after being sunk therein and sand has been supplied to the casing via the hopper, the ram is reciprocably moved in the casing as the latter is continuously lifted and while the vibratory pile driver is continuously operated.
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United States Patent 51 3,648,467

Ogawa Mar. 14, 1972 [54] MACHINES FOR CONTINUOUSLY FOREIGN PATENTS OR APPLICATIONS FORMING SAND PILES Mitsuro Ogawa, 31, l chome, Tanabehonmachi, Higashisumiyoshi-ku,, Japan Filed: Apr. 23, 1970 Appl. No.: 31,324

Inventor;

[30] Foreign Application Priority Data Aug. 27, i969 Japan ..44/68l70 U.S.Cl ..6l/53.64,6l/ll,6l/63 Int. Cl. .E02d 5/38, E02d 7/38, E02d 3/10 Field oiSearch ..6l/ll, 13,535, 53.64, 53.66,

[56] References Cited UNITED STATES PATENTS 3,498,066 3/1970 Nishimura et a] ..61/1 1 3,420,063 III 969 Bodine, Jr ..61/11 3,184,924 5/1965 Stanau ..6l/53.64 X

296,908 I917 Germany ..6l/53.52

Primary Examiner-Jacob Shapiro Attamey-Waters, Roditi, Schwartz & Nissen [57] ABSTRACT A machine for continuously forming sand piles comprises a casing with a hopper connected thereto near its upper end. A vibratory pile driver is mounted at the upper end of the casing above the hopper and a ram is mounted in the casing for undergoing reciprocatory movement therein under the action of a drive means which is independent of the pile driver. The ram carries a tamping plate at its lower end and in the lowermost end stroke position, the tamping plate is located a small distance above the lower end of the casing. As the casing is being lifted from the ground after being sunk therein and sand has been supplied to the casing via the hopper, the ram is reciprocably moved in the casing as the latter is continuously lifted and while the vibratory pile driver is continuously operated.

7 Claims, 17 Drawing Figures PAIENTEBMAR 14 I972 SHEET 1 BF 3 FIG. 2

I II 1 I'M FATENTEU MAR 14 1972 DEPTH SHEET 2 [1F 3 PATENTEUMAR 14 I972 3,648 A67 SHEET 3 [If 3 HG 9 HG l0 TIME E 2 s Q (3 PRIQR ART l! FG. PRIOR ART TIME CIEPTH MACHINES FOR CONTINUOUSLY FORMING SAND PILES The present invention relates to machines for continuously forming sand piles which are to be settled in the soft ground for the purpose of stabilizing the soft ground.

As a method of stabilizing the soft ground, there has been known a so-called Sand Drain Method whereby a large number of sand piles are settled in the soft ground and then a load is imposed on the ground surface thereby causing the water contained in the soft ground to be discharged to the ground surface by way of drain formed by the above-mentioned sand piles thus dehydrating and hardening the soil.

Furthermore, there has been known another method whereby a large number of compacted sand piles, each having a diameter larger than that of the casing pipe adapted to settle said sand piles, are formed in the soft ground and a pressure is applied by each pile to the surrounding soft ground, respectively, thereby causing water within the soft ground to be discharged rapidly to the ground surface through said sand piles, thus compacting, dehydrating and hardening the soft ground ranging from the desired depth to the ground surface.

The sand pile forming machines used in the above-mentioned two methods for forming sand piles-are mostly of the type provided with a vibratory pile driver at the top of the casing pipe on account of a good executing efiiciency.

However, in the conventional methods of forming sand piles utilizing the pile forming machines of the above type, there exist the following defects, i.e., in the sand drain method as mentioned above utilizing the conventional type sand forming machine, the process of sand pile forming is carried out in the following manner; that is, at first the vibratory pile driver of the machine is actuated to drive the casing pipe into the soil down to a predetermined depth. The casing pipe is then filled with sand inside thereof, and thereafter, while the vibratory pile driver is still being operated, the casing pipe is pulled continuously upward, thus forming a sand pile.

In the above method of sand pile forming, the sand pile formed in the ground in many cases is not effective enough to serve as a drain either by having its diameter rendered too small at some point or by being cut off due to the pressure of the surrounding soil. If the sand within the casing pipe is compacted for the purpose of eliminating the above defects, the sand would be plugged inside the casing pipe. Thus, it becomes difficult to discharge the sand downwardly from the casing pipe during the pull-out process of said casing pipe, and as a result the sand pile to be formed would rather be cut off in the process.

Next, a sand pile being compacted and having a diameter larger than that of the casing pipe is formed in the following manner with the above-mentioned conventional machines for forming sand piles. That is, after the casing pipe has been driven to a predetermined depth into the soil by actuating the vibratory pile drive, the casing pipe is pulled slightly upward while the vibratory pile driver is being operated. The cavity created at the lower portion of the casing pipe by the above pulling action is then filled with sand. This sand is fed into the casing pipe from the top thereof. The casing pipe is again driven-in so as to cause the sand fed down into the above cavity to be compacted. Then, the casing pipe is again pulled slightly upward, thereafter repeating the same process until a compacted sand pile is formed consecutively up to the ground surface.

Therefore, the repetition of pulling-out and driving-in of the casing pipe is the essential operation required for the forming of a compacted sand pile having a diameter larger than that of the casing pipe when using the conventional sand pile forming machines. In the process of forming such a compacted sand pile, the compacted sand pile being formed will have such a shape that resembles inverted cones piled up, rather than having a unifonn diameter throughout its length, in the case when the ground is extremely soft. Consequently, it is impossible to obtain a compact sand pile with a uniform diameter throughout its length unless the cycle of pulling and driving the casing pipe is made very small. For this reason, it is impossible to increase the executing efficiency of forming a compact sand pile with the conventional sand pile forming machines.

Next, the process of discharging the sand toward the lower portion of the casing pipe, when pulling out the casing pipe, will be described hereinafter.

Even if the sand being supplied into the casing pipe is caused to vibrate and is turned into a fluidal state by the vibration of the pipe due to the operation of the vibratory pile driver, the discharging of the sand toward the lower portion of the casing pipe will be prevented by additional mechanisms provided at the lower portion of the casing pipe, such as a narrow portion or an opening and closing cover, thus making it difficult to discharge the sand smoothly. Therefore, for the purpose of improving the sand discharging process, there has been adopted conventionally a method whereby sand is discharged forcibly by sending compressed air into the casing pipe. In the case when the discharged quantity of sand is small with respect to the withdrawing volume of the casing pipe, even though the method of sending compressed air is adopted, the sand pile to be formed becomes slender by the pressure of the surrounding soil or by the pressure of excess pore water and also is disrupted halfway due to the surrounding soft soil being backflowed into the casing pipe. Therefore, the continuity of the sand pile to be formed] in many cases becomes difficult to obtain even if the supply of sand is sufficient with respect to the total sand quantity of the sand pile.

It is an object of the present invention toeliminate the above-mentioned deficiencies inherent in the sand pile forming process using the conventional sand pile forming machines by providing an improved sand pile forming machine capable of continuously and efficiently fonning, not only a sand pile having almost the same diameter as that of the casing pipe used in the sand drain method, but also a compacted sand pile having a diameter larger than that of the casing pipe.

It is another object of the present invention to provide an improved sand pile forming machine capable of continuously forming a sand pile which has a desirable shape with a uniform diameter throughout its length, there being no disruption nor any irregularly narrow portions.

It is still further object of the present invention to provide an improved sand pile fonning machine capable of freely and continuously forming a compacted sand pile whose diameter varies along it length so as to be well-adapted to the characteristics of each of the different layers of the soft ground.

The characteristic features of the sand pile forming machine according to the present invention, for the purpose of attaining the the above objects, consist in that a forcibly and vertically reciprocating mechanism, which. is to be driven by a driving means other than the above-mentioned vibratory pile driver, is provided inside the casing pipe and at the upper portion of the sand feeding hopper of the casing pipe with the vibratory pile driver disposed at the top portion thereof, whereby the upper end of a ra'mmer being inserted into said casing pipe is connected to the forcibly and vertically reciprocating mechanism. The rammer is provided at its lower end with a tamping plate. The rammer and the tamping plate are then caused to perform by force a vertically reciprocating motion, respectively, within the casing pipe, as the result of the operation of said forcibly and vertically reciprocating mechanism. Moreover, the tamping plate is disposed such that at its lowest movable point, the position of said tamping plate is to be situated at a small distance above the lower end of the casing pipe.

The characteristic features of the present invention will become more apparent from the following descriptions with reference to the appended drawings.

FIG. 1 is a side view, partly in cross section, showing an embodiment of the machine for continuously forming sand piles according to the present invention, which illustrates in block diagram the driving source of a forcibly and vertically reciprocating mechanism utilizing a hydraulic piston;

FIG. 2 is a sectional view taken along the line A-A of FIG.

FIG. 3 is a perspective view of an embodiment of the compacting plate composed of a plurality of radial vertical plates in the machine according to the present invention, with the lower portion of the casing pipe partly cut out;

FIG. 4 is a side view of an embodiment of the compacting plate composed of an opening and closing plate made of a pair of semicircular plates being connected with each other by a hinge in the machine according to the present invention, with the lower portion of the casing pipe partly cut out;

FIG. 5 illustrates the relation of the vibrations and periodic pressure applications imposed on the sand at the lower portion within the casing pipe beneath the compacting plate in the case of forming a sand pile using the machine according to the present invention;

FIG. 6 illustrates the stages of the sand pile forming process carried out by the machine according to the present invention;

FIGS. 7 through illustrate the relationships between the diameter of the sand pile to be formed by the machine according to the present invention and the pulling speed of the casing pipe; in which FIG. 7 is a graphic representation showing three different pulling speeds at which a casing pipe driven to a predetermined depth is pulled out continuously and almost at a uniform speed;

FIG. 8 illustrates the shapes of three sand piles formed, each corresponding to the pulling speeds shown in FIG. 7, respectively;

FIG. 9 is a graphic representation showing the stage in the process in which a casing pipe being driven into the soil to a predetermined depth is pulled out, the pulling speeds being made to vary;

FIG. 10 illustrates the shape of the sand pile formed at the pulling speeds shown in FIG. 9;

FIG. 1 l is a graphic representation showing, as a reference, the relationship between the pulling and driving of a casing pipe in case of forming a compacted sand pile with a diameter larger than that of the casing pipe using a conventional sand pile forming machines; and

FIG. 12 illustrates, as a reference, the shape of a sand pile formed by the repetition of pulling and driving of a casing pipe as shown in FIG. 11.

FIGS. 1 and 2 shows respectively an embodiment of the machine for continuously forming sand piles according to the present invention, in which a vibratory pile driver 2 is attached at the top of the casing pipe 1 for use in forming sand piles. An oil pressure piston 3, which is a forcibly and vertically reciprocating mechanism, is at attached at the upper portion within said casing pipe 1. This oil pressure piston 3 is driven by a driving source other than said vibratory pile driver 2, that is, the piston 3 is driven by an outside driving source comprising an oil pressure unit 4, electromagnetic servo-valve 5 and a control device 6 therefor. Next, a rammer 7 is inserted into the above-mentioned casing pipe 1; the upper end of the rammer 7 is connected to the oil pressure piston 3; and the lower end of the rammer 7 is attached to a circular tamping plate 8, said rammer 7 and tamping plate 8 being so constituted as to perform a forcibly and vertically reciprocating motion by the operation of the oil pressure piston 3. The tamping plate 8, furthermore, is so disposed that at its lowest movable point, the tamping plate is situated at a small distance above the lower end of the casing pipe. Moreover, swing stopping plates 9 of a radial shape are securely attached to the rammer 7, said plates 9 being disposed at an appropriate distance from each other. The plates 9 serve to prevent transverse swing in case of the vertical movement of the rammer 7, in addition to aiding the downward flow of sand supplied from the hopper 10. In the machine of the present invention as described above, the vibratory. pile driver attached to the top of the casing pipe 1 can be of thetype wherein the casing of the vibration generatconnected directly to the casing pipe 1, or of the type wherein an impact converting mechanism is provided between the casing of the vibration generating mechanism and the casing pipe 1.

In the embodiment as shown in FIG. 1, there is illustrated the oil pressure piston 3 is the forcibly and vertically reciprocating mechanism. This mechanism is by no means limited to an oil pressure piston, and it is possible to adopt other forcibly and vertically reciprocating mechanisms of appropriate types.

Furthermore, the tamping plate provided at the lower end of the rammer 7 should not be limited to the one as shown in FIG. 1, and it is possible to use, for example, the type as shown in FIG. 3 wherein vertical plates 8' are securely attached in radial form to the lower end of the rammer 7. The rammer may also be as shown in FIG. 4 wherein an opening and closing plate consisting of a pair of semicircular plates 8" are joined together by a hinge and can be opened only in downward direction in an inverted V shape.

The embodiments of the machine for continuously forming sand piles according to the present invention as explained heretofore, and now the sand pile forming for the purpose of stabilizing the soft ground by using the machine of the present invention shall be described in detail hereinafter.

First, with reference to FIG. 6 the process of forming a compacted sand pile having a diameter larger than that of the easing pipe in the soft ground and the operation of the machine shall be explained.

As shown in FIG. 6 (a), a sand plug 11 is provided at the lower end of the casing pipe 1 of the machine according to the present invention. As shown in FIG. 6 (b), the vibratory pile driver 2 is actuated and the casing pipe 1 is driven into the soft ground to the required depth. Then, an appropriate quantity of sand is supplied from the hopper 10 into the casing pipe 1. The supply of the above-mentioned sand is carried out during the process of pulling out the casing pipe 1 to be described hereinafter. Next, as shown in FIG. 6 (c) and (d), while the vibratory pile driver 2 is being operated continuously, the easing pipe 1 is pulled out continuously upward at an appropriate speed simultaneous with the actuation of the forcibly and vertically reciprocating mechanism 3 during the above pullingout process. While the sand 12 flowing downward beneath the tamping plate 8 is being compacted at the lower end inside of the casing pipe I, the sand 12 is forcibly discharged from the lower end of the casing pipe by means of the tamping plate 8 thereby forming continuously a compacted sand pile l3 having a diameter larger than that of the casing pipe 1.

In the process of forming a sand pile 13 as shown in FIG. 6, the pulling speed of the casing pipe 1 is comparatively slow so that the sand pile 13 thus formed will be a compacted sand pile with a diameter larger than the diameter D of the casing pipe 1. However, if the pulling speed is increased, the sand pile formed will have a diameter substantially equal to the diameter D of the casing pipe 1. The relationship between the pulling speed of the casing pipe I and the diameter of the sand pile formed is asshown in FIGS. 7 and 8. Through the relationship between the pulling speed of the casing pipe I and the diameter of the sand pile to be formed prior to the actual work it becomes possible to freely form not only a sand pile 13' with a diameter substantially equal to the diameter D of the casing pipe I as shown in FIG. 8 (a) but also a compacted sand pile 13 with a diameter larger than that of the casing pipe I as shown in FIG. 8 (b) and (c), by means of the machine according to the present invention.

Furthermore, as shown in FIGS. 9 and 10, it is also possible to freely form a sand pile 13' whose diameter varies along its length by causing the pulling speed of the casing pipe to be changed during the pulling process. It is therefore possible to form a compacted sand pile whose diameter changes in accordance with each layer of the ground in cases when the characteristic of the soft ground changes in a layer pattern.

Next, the compacting and forcible discharging of sand in the sand pile forming process using the machine of the present invention shall be explained hereinafter. When the casing pipe 1 is subjected to the pulling process after the casing pipe 1 has been driven into the soil down to a predetermined depth, the vibration created by the vibratory pile driver and imparted to the casing pipe 1 is also imparted to the sand being supplied previously into the pipe 1. The sand is then caused to flow downward within the pipe 1 beneath the tamping plate 8 in a fluidal state. As shown in FIG. 5, this sand is subjected to a vibratory periodic pressure (V,,+V,), i.e., the sum of the vibration V, of the casing pipe 1 with the forcible, vertical, reciprocating motion V of the tamping plate 8. It has been recognized in soil mechanics that a static pressurizing is effective in addition to vibration in sand compacting by vibration, so that the sand flowed down beneath the tamping plate 8 by the above-mentioned vibration and the periodic pressure (V,,+ V is compacted effectively at the lower end and inside of the casing pipe 1. Furtherhomre, the sand is forcibly discharged from the lower end of the casing pipe 1 by the stroke of the tamping plate 8. In the case when the added pressure from the tamping plate 8 exceeds the bearing capacity of the sand pile to be formed thereunder, the said to be discharged will be enlarged outwardly outside of the outer periphery of the casing pipe 1 as the pulling action of the casing pipe 1 has halted.

Consefiiueiitly, as described heretofore, it becomes possible to freely and continuously form a compacted sand pile with a diameter larger than that of the casing pipe 1, without forming a sand pile having the same diameter as that of the casing pipe 1. In the case when the bearing capacity of the sand pile to be formed is larger than the pressure applied by the tamping plate 8, it is also possible to automatically raise the entire machine, including the casing pipe, by the reaction of the pressure applied to the tamping plate 8 while forming the sand pile, without lifting the entire machine by a rope or the like during the process of pulling-out the casing pipe 1.

Next, the vibration of the vibratory pile driver 2 and the forcibly and vertically reciprocating motion of the forcibly and vertically reciprocating mechanism 3 will be explained hereinafter. The vibration V, to be imparted to the casing pipe I by the vibratory pile driver 2 is normally about 400 to 1,500 c.p.m. in frequency and to 30 mm. in amplitude. Whereas, the forcible, vertical, reciprocating motion (V to be imparted to the tamping plate 8 by the forcibly and vertically reciprocating mechanism 3 is about 30 to 60 c.p.m. in frequency and about one-sixth D to D in stroke (D is the diameter of the casing pipe 1 to be used). The values of V, and V given above are considered practical from the viewpoint of the output of the forcibly and vertically reciprocating mechanism 3. Moreover, it has been determined through experiments that those values are appropriate from the standpoint of maintaining uniformity in the diameter of the sand pile to be formed.

The above-mentioned frequency should be adjusted properly within the range of 30 to 60 c.p.m. depending on the water content of the sand to be used, the size of the sand grain, and the quality of the sand or the like. Moreover, such an ad justment can be effected by means of the control device 6 of the electromagnetic servo-valve 5 in the case of the embodiment shown in FIG. 1.

Next, the shape of the tamping plate 8 will be described. It is necessary to pay special attention to the shape of the tamping plate 8 in order to effectively compact the sane supplied into the casing pipe 1 and, furthermore, to cause the sand to flow smoothly downward beneath the tamping plate 8. In the case of the embodiment as shown in FIG. 1, the upper portion of the tamping plate 8 is formed with a conical shape so that the sand will encounter only a small resistance therefrom as the tamping plate 8 moves upwardly, and, moreover, the sand can flow smoothly downwardly beneath the tamping plate 8 through a gap between the tamping plate 8 and the inner wall of the casing pipe 1. In the case of the embodiment as shown in FIG. 3, the tamping plate 8 is composed of the plurality of vertical plates 8' securely attached to the lower end of the rammer 7 in a radial pattern, so that when the tamping plate 8 is moved upward the resistance encountered by the sand is very small and, furthermore, the sand can flow easily downwardly between the radially formed vertical plates 8'. In the embodiment as shown in FIG. 4,. on the other hand, the tamping plate 8 is an opening and closing plate which is opened only downwardly in an inverted V shape, and is formed by the pair of semicircular plates 8" joined together by a hinge, so that the sand will encounter a small resistance when the tamping plate 8 moves upwardly, and furthermore the sand can flow smoothly downwardly in the gap between the inner wall of the casing pipe 1 and the tamping plate 8.

In the embodiments of the tamping plate 8 as shown in FIGS. l and 3 described heretofore, the area of the transverse section of the tamping plate 8 is about one-fourth of the area of the hollow section of the casing pipe 1. The above-mentioned area ratio between the hollow section of the casing pipe 1 and the cross section of the tamping plate 8 has proven to be best as the result of experiments.

Next, the position of the tamping plate 8 within the casing pipe 1 will be explained. In the process of forming a sand pile by the machine according to the present invention, the sand being supplied into the casing pipe 1 is compacted at the lower end within the casing pipe 1 beneath the tamping plate 8 in a state restricted to the wall of the said casing pipe 1. The sand thus compacted is extruded from the lower end of the casing pipe II by means of the tamping plate 8. Therefore, it is necessary to arrange the tamping plate 8 such that when the tamping plate 8 has been moved to its lowest point the lower end thereof will be situated at an appropriate distance above the lower end of the casing pipe 1. However, if the above-mew tioned distance is too great, the sand will be plugged in the casing pipe beneath the tamping plate 8, making it difficult to extrude the sand from the lower end of the casing pipe 1. However, if the above distance is too little, then the compacting of the sand will not be performed sufficiently inside the casing pipe 1 beneath the tamping plate 8. As the result, the sand pile discharged from the lower end of the casing pipe 1 might be compressed by the soil pressure of the surrounding soil or by the excess pore water pressure, thus producing a sand pile with too small diameter of a sand'pile which is interrupted partway along its length.

It has been recognized through experiments that the best result can be obtained if the position of the tamping plate 8 at its lowest movable point is at a distance of approximately A D to D above the lower end of the casing pipe 1, where D denotes the diameter of the casing pipe 1.

As has been illustrated heretofore, the machine according to the present invention has made it possible to obtain not only a sand pile with a diameter equal to that of the casing pipe to be used in the sand drain method by driving the casing pipe into the ground to a predetermined depth and thereafter pulling the casing pipe continuously upwardly, but also to form a compacted sand pile with a diameter larger than that of the casing pipe freely at a predetermined diameter-expansion ratio by adjusting the pulling speed of the casing pipe to a proper rate.

When a compacted sand pile is to be formed with a diameter larger than that of the casing pipe by means of the conventional sand pile forming machines, it becomes necessary, as shown in FIG. 11, to repeat the pulling and redriving actions of the casing pipe. As a result, the sand pile 14 thus formed will have a shape as shown in FIG. 12, which resembles inverted cones piled up, so that it is impossible to form a good sand pile with a uniform diameter along, its length.

In the case of forming a compacted. sand pile with an expanded diameter by means of the machine according to the present invention, it becomes unnecessary to repeat the pulling and redriving of the casing pipe as in the case of using the conventional sand pile forming machines, so that the execution efficiency in a sand pile forming process can be greatly increased.

Moreover, it becomes possible by the machine according to the present invention to form a sand pile with a shape suitable for use as a drain, without any diameter reduction nor disruption along its length.

Also, in the sand pile forming process using the machine according to the present invention it becomes possible to pull out the casing pipe continuously and furthermore to form a compacted sand pile with any required diameter through the adjustment of the pulling speed. Therefore, the machine for continuously forming sand piles according to the present invention has the advantage, as compared with those conventional sand pile forming machines which require repetition of pulling and redriving, in that the sand pile forming process can be automated quite easily by automatic controlling means.

Furthermore, it becomes possible with the machine of the present invention to freely and continuously form a compacted sand pile with varying diameters corresponding to the character of each layer of the soft ground in case when the soft ground shows different characteristics by layer.

It is especially difficult with the conventional sand pile forming machines to discharge sand from the lower end of the casing pipe if and when the sand to be used is unfavorable in nature, such as, for example, sand with unsuitable grain size, sand containing clayey soil, or sand with a high water content. If the machine according to the present invention is used, however, the discharge of sand is carried out forcibly by the tamping plate, thus making it possible to perform a satisfactory sand discharging operation even when unfavorable sand materials as mentioned above are to be used, whereby sand piles each having a good shape can be formed efficiently.

What is claimed is:

1. A machine for continuously forming sand piles comprising a casing having upper and lower ends, a hopper connected to said casing near the upper end thereof for supplying sand thereto, a vibratory pile driver at the upper end of the casing and above the hopper, ram means in said casing for undergoing reciprocatory movement therein, means at the upper end of the casing engaging the ram means to reciprocate the ram means in the casing, said ram means having a lower end and including a tamping plate at said lower end, said tamping plate having a lowennost end of stroke position in the casing which is a small distance above the lower end of the casing and having a cross-sectional area substantially smaller than the crosssectional area of the casing, and means at the top of the casing by which the casing, can be lifted from the ground after being sunk therein and sand has been supplied via the hopper to the casing, said ram means being reciprocably moved in the casing while the latter is being continuously lifted out of the ground and the vibratory pile driver is operated continuously.

2. A machine as claimed in claim 1, wherein said means to reciprocate the ram means comprises a cylinder, a piston in said cylinder and attached to the ram means, an outside driving source including a pressure fluid source connected to said cylinder, an electromagnetic servo-valve between the pressure fluid source and the cylinder, and means for controlling said electromagnetic servo-valve.

3. A machine as claimed in claim 1, wherein said tamping plate comprises a circular disc including an upper portion of conical shape, the cross section of said tamping plate having an area approximately equal to one-fourth of the area of thecasing.

4. A machine as claimed in claim 1, wherein said tamping plate comprises a plurality of vertical plates disposed in a radial pattern around the axes of reciprocation of the ram means. said plates having a cross-sectional area approximately equal to one-fourth of the area of the casing.

5. A machine as claimed in claim I, wherein said tamping plate comprises an opening and closing plate assembly including a pair of semicircular discs pivotably joined together and capable of opening only by pivoting downwardly to form an inverted V shape.

6. A machine as claimed in claim 1, wherein the distance of said tamping plate above the lower end of said casing at the end of stroke position is between one-half and the full diameter of said casing.

7. A machine as claimed in claim 1, wherein the reciprocatory motion of said tamping plate is approximately 30 to 60 cpm in frequency and its stroke is between one-sixth and the full diameter of said casing.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3184924 *Nov 6, 1961May 25, 1965Heinz StaunauMethod of forming concrete pile in situ
US3420063 *Feb 10, 1966Jan 7, 1969Bodine Albert GSonic process of placement of sand drains
US3498066 *Mar 8, 1968Mar 3, 1970Nishimura MitsuoSoil compacting method and a means therefor
*DE296908C Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3772892 *Jun 9, 1972Nov 20, 1973Ogawa MProcess of installing compacted sand columns in the ground
US4487524 *Sep 17, 1982Dec 11, 1984Fudo Construction Co., Ltd.Method and apparatus of forming sand piles for improving a soft ground
US6517292 *Sep 1, 1999Feb 11, 2003Richard E LandauApparatus to form columns of granular material
US6957930 *Feb 11, 2003Oct 25, 2005Landau Richard EApparatus to form columns of granular material
EP0903441A2 *Sep 17, 1998Mar 24, 1999KELLER GRUNDBAU GmbHMethod and device for placing an additive
Classifications
U.S. Classification405/240
International ClassificationE02D3/00, E02D3/10, E02D3/08
Cooperative ClassificationE02D3/106
European ClassificationE02D3/10C