US3712067A

US3712067A - Method and an apparatus for compacting a loosely packed layer of earth

Info

Publication number: US3712067A
Application number: US00106090A
Authority: US
Inventors: Weele A Van
Original assignee: Tot Aanneming Van Werken Voorheen HJ Nederhorst NV
Current assignee: Tot Aanneming Van Werken Voorheen HJ Nederhorst NV
Priority date: 1970-01-14
Filing date: 1971-01-13
Publication date: 1973-01-23
Anticipated expiration: 1990-01-23
Also published as: JPS492525B1; BE760651A; GB1301404A; DE2101298A1; FR2075521A5; NL7000539A; NL140026B

Abstract

A method of compacting a loosely packed layer of earth. According to this method a tube is vibrated into the earth, which tube accommodates a closing member at a distance from the underside of the tube which substantially corresponds to the distance from the ground level to the upper side of the layer of earth to be compacted. Earth is received in the tube while this tube is being vibrated into the earth, until this earth within the tube strikes the closing member at the time that the underside of the tube has reached approximately the upper side of the layer of earth to be compacted. Hereupon, in the further course of the tube being vibrated downwardly to the required depth, earth is displaced in the layer of earth to be compacted, whereafter the tube is vibratingly lifted and the earth which has been received in the tube leaves the tube and is left in the ground. An apparatus for carrying out this method consists of a tube within which a closing member is accommodated at the appropriate distance from the underside of the tube. This closing member is pervious to air.

Description

van Weele Jan. 23, 1973 METHOD AND AN APPARATUS FOR COMPACTI NG A LOOSELY PACKED LAYER OF EARTH 75] 'i'iweHiB'n 11am i iiiiebisvan Weele,Wad-

[73] Assignee: N. V. tot Aanneming van Werken voorheen H. J. Nederhorst, Gouda, the Netherlands 221 Filed: Jan. 13,1971

21 App1.No.: 106,090

[30] Foreign Application Priority Data Jan. 14, 1970 Netherlands ..7000539 [52] US. Cl. ..61/36 R [51 Int. Cl. ..E02d 3/06 [58] Field of Search ..6l/35, 36, 11,63, 53.64; l75/19,55,56

[56] References Cited UNITED STATES PATENTS 3,498,066 3/1970 Nishimura et al. ..6l/35 X 2,719,029 9/1955 Steuerman ...61/36 R X 2,576,507 11/1951 Gerwick,Jr. ..6l/63 3,352,160 11/1967 Mount ..l75/56 X 3,540,225 11/1970 Muller 6l/53.64 X

3,608,317 9/1971 Landau ..6l/35 X dinxveen. Netherlands Primary Examiner-David J. Williamowsky Assistant Examiner-Philip C. Kannan Attorney-Waters, Roditi, Schwartz & Nissen [57] ABSTRACT A method of compacting a loosely packed layer of earth. According to this method a tube is vibrated into 'the earth, which tube accommodates a closing member at a distance from the underside of the tube which substantially corresponds to the distance from the ground level to the upper side of the layer of earth to be compacted. Earth is received in the tube while this tube is being vibrated into the earth, until this earth within the tube strikes the closing member at the time that the underside of the tube has reached approximately the upper side of the layer of earth to be compacted. Hereupon, in the further course of the tube being vibrated downwardly to the required depth, earth is displaced in the layer of earth to be compacted, whereafter the tube is vibratingly lifted and the earth which has been received in the tube leaves the tube and is left in the ground.

11 Claims, 3 Drawing Figures Displacement compacted Probing rlsistanE PATENIED JAN 23 1975 SHEET 1 BF 2 ststance Displacement compacted Probing re mS E 5 53a V PATENTEDJAH 23 I975 SHEET 2 OF 2 METHOD AND AN APPARATUS FOR COMPACTING A LOOSELY PACKED LAYER OF EARTH BACKGROUND OF THE INVENTION The invention relates to a method of compacting a loosely packed layer of earth as well as to an apparatus for carrying out this method.

According to a known method of compacting loosely packed, non-cohesive layers of earth at a great depth, a vibrator is-introduced into the earth, which vibrator consists of a steel cylinder closed at its lower end with a conical point and attached at its upper end to extension elements via an elastic coupling. The vibrator contains an electric motor which, in operation, drives eccentric impact weights, causing a vibrating motion to be imparted to the vibrator. The vibrator is lowered by supplying water at the point, causing it to descend by its own weight. As soon as the required depth has been reached, the supply of water near the point is shut off, whereupon the water is discharged at the neck of the vibrator. Hereafter, the process of compaction begins and in order to prevent undue subsequent sagging of the ground surface, additional sand is continuously dumped from above. When adequate compaction has been achieved at the required depth, the vibrator and the extension elements are drawn upward by a few decimeters, whereupon the aforementioned operation is repeated. A zone of compacted earth, in particular sand is thus built up.

However, in particular when layers of high density are present above said layers of earth to be compacted,

this known method has the disadvantage, that the lowering operation of the vibrator through these dense upper layers is highly time-consuming.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of compacting a loosely packed layer of earth, wherein this drawback is effectively removed.

To this end, the method according to the invention is characterized in that a tube is vibrated into the earth, said tube accommodating a closing member at a distance from the underside of the tube which substantially corresponds to the distance from the ground level to the upper side of the layer of earth to be compacted, earth being received in the tube while this tube is being vibrated into the earth, until this earth within the tube strikes the closing member at the time that the underside of the tube has reached approximately the upper side of the layer of earth to be compacted, whereupon, in the further course of the tube being vibrated downwardly to the required depth, earth is displaced in the layer of earth to be compacted, whereafter the tube is vibratingly lifted and the earth which has been received in the tube leaves the tube and is left in the ground.

According to the invention a hollow tube is applied, which produces practically no displacement of earth while being passed through the layers situated above the layer of earth to be compacted, because the earth is received in the tube during this operation. This enables the tube to be lowered very rapidly through the upper layers. Only after the lower end of the tube has approximately reached the upper side of the layer of earth which is to be compacted, the closing member prevents any further penetration of earth into the tube, so that the tube from then on functions as though it were closed at the underside.

Thus, while the lower end of the tube is being vibrated into the layer of earth which is to be compacted, the volume of earth displaced thereby will correspond to the volume of the earth-filled portion of the tube that is received in the layer of earth to be compacted.

The tube, after having reached the required depth, is vibratingly lifted leaving the earth contained in the tube behind in the ground, so that the compaction resulting from the earth displacement is preserved.

By varying the lifting rate of the tube the supplementary compaction obtained by the vibration of the tube may be influenced.

The method according to the invention offers substantial advantages as compared to the known method, if the density of the upper layers is of such a nature that these upper layers need not be compacted themselves and if the kinds of soil that occur in these upper layers are suitable indeed for use in compacting the underlying, loosely packed layer of earth.

The invention further relates to an apparatus for carrying out the method described hereinbefore. This apparatus comprises a tube within which an intermediate closing member is accommodated, said closing member being pervious to air.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will hereinafter be explained with reference to the accompanying drawings.

FIG. 1 schematically represents the various phases of the method according to the invention for compacting a loosely packed layer of earth. 4

FIG. 2 is a partial vertical section of a first embodiment of the tube shown in FIG. 1.

FIG. 3 is a partial vertical section of a second embodiment of the tube shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the invention, a loosely packed, noncohesive layer of earth, in particular a sand layer, superposed by dense layers of earth, is compacted. The location of the various layers is established beforehand 'by means of a probing operation.

In the drawing the probing resistance in kg/cm is indicated on the abscissa, while the depth of the earth layers below the ground level in meters is indicated on the ordinate. The result of the probing operation is indicated by the probing graph.

A tube 1, which is open at the underside and which has a diameter of, for example, 60 centimeters, is set up at ground level together with a superposed vibrator 2 (Phase I), and is subsequently vibrated into the earth. A horizontal closing member 3, which is impermeable to earth, is fitted in the tube 1 at a distance a from the underside of this tube 1, which distance substantially corresponds to the distance from the ground level to the upper side of the layer of earth to be compacted.

This tube 1 receives earth 4 while being vibrated into the earth, until this earth 4 within the tube 1 strikes the closing member 3 at the time that the lower end of the tube 1 has reached approximately the upper side of the layer of earth which is to be compacted (Phase II).

While the tube 1 is being vibrated further downwardly to the required depth, earth is displaced in the layer of earth to be compacted. After the tube 1 has attained its final depth (Phase lll), the tube 1 is vibratingly lifted (Phase IV). The earth 4 which has been received in the tube 1 remains behind in the ground, thus preserving the full compaction resulting from the earth displacement.

in order to allow the earth 4 contained in the tube 1 to be discharged during the lifting of the tube 1, the closing member 3 should be pervious to air, so as to prevent the appearance of a vacuum. Further, the closing member 3 should be permeable to water so that sub-soil water may pass therethrough while the tube 1 is being vibrated into the earth.

The portion of the tube 1 situated above the closing member 3 may be filled with a liquid, in particular with water after the tube 1 has been vibrated to the required depth but prior to the lifting of the tube 1. This liquid passes the closing member 3 while the tube 1 is being lifted, which tends to improve the discharge of earth 4 from the tube 1.

In the embodiment shown in FIG. 2 the closing member is a perforated transverse partition plate 3', the size of the perforations being selected in such manner, that no earth can pass.

FIG. 3 shows another embodiment of the tube 1, wherein the closing member consists of a non-return valve 3", which is of particular value if the distance from the ground level to the upper side of the layer of earth to be compacted is smaller than the height of the layer of earth to be compacted. This non-return valve 3" comprises a valve plate 5, which is pivotally mounted on an eccentric transverse shaft 6 connected to the tube 1. The valve plate is shown in the closed position wherein this plate 5 contacts the stops 7. in its opened position the valve plate 5 abuts against a stop 8 and is downwardly inclined. When the tube 1 is vibrated into the earth the valve plate 5 remains open until the earth received in the tube 1 comes into contact with the lower edge of the valve plate 5 and exerts a torque thereon. Due to this torque the valve plate 5 is pivoted toward its closed position and prevents the earth received in the tube 1 to raise beyond this valve plate 5. Earth, in particular sand, is supplied into the tube 1 from the upper side after the tube 1 has been vibrated to the required depth but prior to its withdrawal, which earth passes the valve 3" while the tube 1 is being lifted and remains behind in the ground (Column 9).

The tube 1 is provided with a lower cutting edge 10. In order to prevent clogging of the earth 4 in the tube 1 while the tube 1 is being vibrated into the earth, supply means 11 may feed a lubricant, such as bentonite or water, into the lower end portion of the tube 1, which lubricant reduces the friction between the earth 4 as it enters the tube 1 and the inner surface of the tube 1.

While the tube 1 is being introduced into the earth, a pressure medium may be supplied through at least one supply pipe 12 which extends in the longitudinal direction of the tube 1 and which ends near the underside of the tube 1. This supply pipe is connected to the outer wall of the tube 1.

Although it is possible to use water under pressure as a pressure medium during the vibration of the tube 1 through the upper layers, it is preferable in general not to use water, but a gas, in particular compressed air, as a pressure medium as soon as the underside of the tube 1 has reached the layer of earth which is to be compacted.

The invention is not restricted to the embodiment described hereinabove, which may be varied in different manners within the scope of the appended claims. it is possible, for example, to vibrate an assembly of several tubes into the earth at the same time instead of one single tube 1.

1 claim:

1. A method for compacting a loosely packed layer of earth by a tube having a closing member therein at a distance from the lower end of the tube which distance substantially corresponds to the distance from the ground level to the upper side of the layer of earth to be compacted, comprising the steps of: concurrently driving and vibrating the tube into the earth while permitting the tube to receive earth until the level of earth within the tube reaches the closing member and the lower end of the tube concurrently has reached substantially the upper level of the layer of earth to be compacted; then continuously downwardly driving and vibrating the tube into the layer of the earth to be compacted to a predetermined depth for compacting the displacing the earth contained in the layer of earth to be compacted; and subsequently raising said tube while simultaneously vibrating the latter so as to cause the earth in the tube to be ejected therefrom to remain in the ground upon withdrawal of said tube to replace the earth displaced during said compacting step.

2. The method according to claim 1, comprising the steps of filling a portion of the tube located above the closing member with a liquid after the tube has been vibrated into the earth to the predetermined depth but prior to said raising of the tube, and passing said liquid through the closing member while the tube is being raised.

3. The method according to claim 1, further comprising the steps of supplying earth into the upper end of the tube after the tube has been vibrated into the layer of earth to be compacted, but prior to said raising of the tube, and passing the supplied earth through a valve provided in the closing member while raising the tube, so as to permit the supplied earth to remain in the ground.

4. An apparatus for compacting a loosely packed layer of earth comprising a tube; a cutting edge provided at the lower end of said tube for facilitating the driving operation thereof into the layer of earth and a closing member located within said tube at a substantial distance from the lower end of said tube, said closing member being pervious to air.

5. The apparatus according to claim 4, wherein said closing member is permeable to water.

6. The apparatus according to claim 4 wherein said closing member is a perforated transverse partition plate.

7. The apparatus according to claim 4 wherein said closing member comprises a non-return valve.

8. The apparatus according to claim 4, comprising at least one supply pipe extending along the longitudinal direction of said tube and being connected to the outer wall thereof, said supply pipe having one end mounted adjacent the lower end of said tube and the other end adapted to be connected to a pressure medium supply 10. The apparatus according to claim 9, wherein said source. lubricant is bentonite.

9. The a aratus accordin t l i 8, comprising 11. The apparatus according to claim 9, wherein said supply means for feeding a lubricant into the lower end lubricant is waterportion of said tube. 5

Claims

8. The apparatus according to claim 4, comprising at least one supply pipe extending along the longitudinal direction of said tube and being connected to the outer wall thereof, said supply pipe having one end mounted adjacent the lower end of said tube and the other end adapted to be connected to a pressure medium supply source.

9. The apparatus according to claim 8, comprising supply means for feeding a lubricant into the lower end portion of said tube.

10. The apparatus according to claim 9, wherein said lubricant is bentonite.

11. The apparatus according to claim 9, wherein said lubricant is water.