US3855804A

US3855804A - Apparatus and method for distending the distensible body of an earth anchor

Info

Publication number: US3855804A
Application number: US00320291A
Authority: US
Inventors: T Herbst; K Finsterwalder
Original assignee: Dyckerhoff & Widmmann AG
Current assignee: Dyckerhoff & Widmmann AG; Dyckerhoff & Widmmann Ag dt
Priority date: 1973-01-02
Filing date: 1973-01-02
Publication date: 1974-12-24
Anticipated expiration: 1991-12-24

Abstract

The invention concerns an arrangement for distending sections of the distending body of an earth anchor in sticky soil and in multiple sections and comprises conveying conduit means with an end embedded in the distending body below earth level and an airside end extending above the distending body for supplying slurry to the distending body below earth level and means above the earth level for supplying the slurry to the conduit means, where the embedded ends of the conduit means are provided with openings for emitting the slurry that constitutes the distention material and each section comprises two distention conduits connected to the embedded end.

Description

Sttes Herbst et a1.

I APPARATUS AND METHOD FOR DISTENDING THE DISTIENSIBLE BODY OF AN EARTH ANCHOR [75] Inventors: Thomas'llerbst, Munich; Klemens Finsterwalder, Socking near Starnberg, both of Germany [73] Assignee: Dyckerhoff & Widmmann Aktiengesellschaft, Munich,

Germany 1 [22] Filed: Jan. 2, 1973 [2]] Appl. No.: 320,291

[52] U.S. Cl 61/53.6, 61/56, (ii/56.5,

, 52/740 [51'] Int. Cl. E0201 5/62, E02d 5/80 [58] Field of Search 61/35, 36, 50, 53.52, 53.6, 61/5362, 39; 52/740 [56] I References Cited I UNITED STATES PATENTS 2,560,619 7/1951 Wertz 61/36 Simons Blatter 61/5358 [451 Dec. 24, 1974 3,494,134 2/1970 Jorge (ml/53.6 X

FOREIGN PATENTS OR APPLICATIONS 767,144 9/1952 Germany 683,407 11/1939 Germany 970,760 10/1958 Germany 61/5362 Primary Examiner-Jacob Shapiro Attorney, Agent, or Firm-Robert H. Jacob [57] I ABSTRACT The invention concerns an arrangement for distending sections of the distending body of an earth anchor in sticky soil and in multiple sections and comprises conveying conduit means with an end embedded in the distending body below earth level and an airside end extending above the distending body for supplying slurry to the distending body below earth level and means above the earth level for supplying the slurry to the conduit means, where the embedded ends of the conduit means are provided with openings for emitting the slurry that constitutes the distention material and each section comprises two distention conduits connected to the embedded end.

3 Claims, 6 Drawing Figures PATENTED UEE24 I974 EMU 1 UP 2 APPTUS lvmruou non nrsrnnnmo DISTENSIBLE BODY or AN CHOIR The invention relates to an apparatus for and a method of successively distending in sections a distensible earth anchor or land tie, and particularly of an earth anchor which is embedded in sticky soil and provided with one or more tension members. For such method and apparatus the invention contemplates the use of a conduit which may be supplied at its airward end with distending material, such as concrete slurry, and which is provided at its earthward side with distending mate rial emitting openings.

An essential part of the so-called distending anchors or land ties is a compression or distention area for establishing an intimate'contact between the ground and the structural element which is to be connected therewith. Fluid is supplied under pressure and hardens after it has been introduced. Frequently this contact is improved by simultaneously injecting the ground or by compacting it if it is not injectable.

For the production of the distendable body a drilling tube has heretofore been used through which the distention is effected. The customary practice in this connection has been to lower the drilling tube to the final depth to mount-the tension member in the tube and then attach a compression head on the air-ward end of the tube through which the ground has been compacted. For the performance of the compressing or distending the drilling tube is retracted step-by-step in order to successively expose sections of the bore hole which have not yet been distended. The disadvantage of this method is that the distending operation can be performed only once and in a predetermined order, that is from the bottom of the bore hole in the direction toward the airward end. Moreover, there is the danger that the distending material rises in the space between the wall of the bore hole and the outer surface of the drilling'tube instead of penetrating into the ground and is dissipated in an uncontrolled manner into other elevated regions.

In order toobtain a secure anchorage in uninjectable grounds and particularly in sticky grounds, it has heretofore been suggested to expand the ground in sections and repeatedly by the application of high distending pressures and to impregnate the ground in this manner with distending material or to compact it in order to obtain an enlarged diameter of the distended body. In

order to accomplish this a pipe section known as a cuff pipe is inserted into the finished bore hole, the wall of which is provided with axially spaced circumferentially distributed holes. The holes of the cuff pipe are covered by external elastic rings which serve as checkvalves to prevent a return of the distending material which is pressed through the openings. The cuff pipe encloses a dual packing device which defines a pipe section presenting a ring of discharge openings and axial movement of the packing device provides for independent supply of distending material through each cuff pipe valve. A disadvantage of this method is that it is unduly laborious due to the repeated insertion and withdrawal of the packer, as well as due to the washing of the cuff pipe at frequent intervals. This method also has the further disadvantage that the individual material emitting openings can be supplied only one after the other if an accurate control of the distending result is required for each opening. Under these circumstances the total distending time of an earth anchor is thus materially increased.

The principal object of the present invention is to provide a possibility to accomplish the required and repeated distending of earth anchors, particularly in sticky soils more securely and faster than heretofore.

In order to accomplish this object with a device of the hereinabove outlined character, the invention contemplates to provide a pair of distending material supply conduits for each distendable section the conduits being in communication with each other at the earthward ends and presenting in unison at least one distending material emitting opening in the respective distention section. At the airward end of the conduit a low regulating valve may be provided.

A single conduit may be provided to serve all distending sections or several single conduits may be combined in one or several multiple channel conduits. Finally, a one-way valve may be provided to connect all or some of the conduits.

The conduits may be wound once orseveral times securely around the tension member of the ground anchor. In this arrangement the loops of the conduits may be positioned in a plane at right angles to the axis of the tension member or they may be spiraled around the axis of the tension member. The distending material emitting openings are suitably arranged at the radially outer periphery of the individual loops.

The distending material emitting openings may also be shielded by a cuff around the distention conduit, the ends of which form a valve-like nozzle which extends radially of the distention conduit.

In carrying out the method in accordance with the invention the distending of each section is carried out simultaneously by both conduits and the conduits are thereafter cleaned by conduit flushing or the distending and the cleansing of the conduits may take place continuously.

The advantage of the invention resides primarily in the fact that it is possible to distend the individual sections along the distending area of an earth anchor as often as desired and in any desired sequence or to perform the distending of several sections simultaneously in a fully satisfactory manner. The principal aim is not an impregnation of the ground with distending material to the largest and fullest extent, but a high degree of strengthening the ground in the annular zone around the anchoring area. Increasing distending pressures in-- dicate the extent of the improved carrying capacity of the ground.

A further advantage of the invention is that an earth anchor which in spite of all precautions has failed because of a weak zone in the soil does not have to be abandoned but can be brought to full carrying capacity by after injection. The invention further provides the possibility to build up a relatively high distention pressure along the entire distention area so that a uniformly strong adhesion is produced along the entire anchoring area which critically affects the carrying capacity of the earth anchor. In like manner, the invention can be used for compression members in the ground, for instance root posts.

Further features and advantageous characteristics of the invention will appear from the following description of several embodiments of the invention in connection with the drawings wherein:

FIG. 1 shows a schematic longitudinal section through an embodiment of the device according to the invention, having one distending section,

FIG. 2 is a schematic longitudinal section of a further embodiment of the invention with one distending section,

FIG. 3 shows a schematic longitudinal section through an embodiment of the invention with three distention sections,

FIG. 4a to 4d show several examples of multiple chamber pipes for the conduits,

FIG. 5 shows a cross section through an earth anchor and illustrates the distending material emitting openings, and

FIG. 6 shows a cross-section through an earth anchor and illustrates the distending material emitting openings in another embodiment of the invention.

In the embodiment shown in FIG. 1 the bore hole 1 illustrated schematically is filled with cement mortar and encloses a tension member not shown. The problem now is to compact the ground along the distending area V by force feeding of distending material in order to obtain an improved cohesion between the distending body 2 and the ground.

For that purpose two distending material conveying conduits are inserted so as to lead to each distending section. According to FIG. 1 the two

conduits

3, 4 are connected at their earthward ends 6. Distending material emitting openings 5 are arranged along the distending section 5.

For the distending operation a pressure head 7 is attached to the airward ends of both

conduits

3 and 4.

The distending material enters into the pressure head 7 in the direction of arrow .8 and is emitted through the openings 5 into the ground or into other hollow spaces. The pressure may be observed by a pressure gauge 9. The ground is compacted by the distending pressure and the produced hollow spaces are filled with distending material. Upon completion of a distending phase the pressure head 7 is removed and water for cleansing.

the conduit system is pumped into the ends of the conduits. The water admission is indicated at 11 and the water emission at 12. The How direction may, of

' course, be reversed.

FIG. 2 shows a modified embodiment of the invention. In this instance a pump 16 is connected to the conduit 13 which is also connected to a pressure gauge 15, whereasthe conduit 14 is also provided with the pressure gauge 17 but leads into a reservoir with distending material via a flow regulating valve 18 and a connecting conduit 19. From the reservoir 20 a conduit 21 leads to the pump 15.

In operation distending material is withdrawn from the reservoir 20 through the conduit 21 in the direction of arrow 22 and is forced into conduit 13. When the flow regulating valve 18 is closed, the entire mass ofthe distending material enters into the ground through the openings 5. The pressure which is indicated by the pressure gauge 17 corresponds to the pressure which exists at the nearest opening 5. If the flow regulating valve 18 is partly or fully opened, the quantity of the distending material which enters the ground and which returns through the conduit 19 depends upon the distending resistance and the flow resistance. In this manner it is possible to regulate the distending pressure or the quantity of the distending material, independently of the pump. The pressure gauge 15 at the pump discharge side indicates the existing reference pressure.

Upon completion of the distending phase, cleansing water is pumped into the conduit system, while the flow regulating valve is kept open. Water entry and emission are again indicated by

arrows

23 and 24. This arrangement of the distending material conducting conduits has the advantage that the distending material remains constantly in motion within the conduit and the system is not apt to become clogged.

As shown in FIG. 3, the distending material conveying conduits which are only schematically indicated in FIGS. 1 and 2 may be multiplied as desired in order to provide several distending sections V V V within the anchoring area which can be controlled independently of each other. In that case the conduits can be coupled together in many different combinations in order to adapt the device to prevailing situations. For instance, in the embodiment shown in FIG. 2 a common supply conduit for several conduits may be provided with distending material emitting openings 5. These conduits may also be partly or entirely connected with each other by one way valves.

FIGS. 4a to 4d show examples of such conduits presenting multiple chamber profiles. In this connection the centrally located conduit is preferably utilized as the delivery conduit and the conduits which are circularly arranged around the central conduit are utilized as return conduits with return openings for the distending material. The individual chambers may also assume different functions. They may serve, for instance, for conveying of distending material or for conveying cleansing water, or for the bunching of wires, or as shielding chambers therefor.

Particular significance is also attached to the distending material conveying openings 5 which are to enable the distending material to reach the interface between the distending body 2 and the ground along the shortest possible way. For that purpose the openings 5 must either be positioned in closest proximity to the interface, or provisions must be made that the distending body 2 is split by tension forces and permits the passage of the distending material into the proper area against low resistance. As a result the distending material is emitted at exactly defined locations and the splitting pressure is kept from becoming too high. The distending material emitting openings should further be so arranged that the material may leave the conduits but is prevented from returning into the conduits. Since the distending operation is usually performed several times in succession at the same place, the intervening cleansing operation should also be effective upon the distending openings 5.

FIGS. 5 and 6 show two embodiments of the arrangement and configuration of the distending material emitting openings 5.

If the tension members 25 (FIG. 5) are located centrally the distending material conveying conduit with the emitting openings may be arranged circularly around the tension member 25 at one or several locations. This circular conduit 26 is connected to the distending

conduits

3 and 4. Distending material emitting openings 27 are distributed over the entire circumference so that the splitting of the distending body 2 and the emission of the distending material may take place at the weakest point 28 of the distending body. In this instance the distending takes place in a substantially radial direction.

If the tension members 29 are arranged on the outside and the conveying conduit are arranged centrally, the conveying conduit 30 is provided with emitting openings 31 which are shielded by a cuff 32. In this instance a weakened zone of the distending body 2 occurs at the place where the two parts of the cuff 32 form a valve-like nozzle 33 so that the distending pressure effects a splitting of the body 2 at that place and the distending material may emerge between two steel tension members 29. The lips within the area of the nozzle 33 are shaped in such a manner that they open only under the pressure acting against them from within and, therefore, permit passage of the distending material in only one direction.

Having now described our invention, what we desire to protect by letters patent is set forth in the appended claims:

1. Arrangement for distending in multiple sections of the distending body of an earth anchor in sticky soil, comprising conveying conduit means having one end embedded in the distending body below earth level and an air side end extending above the distending body for supplying cement slurry or the like to the distending body below the earth level, means above the earth level for supplying cement slurry to said conduit means, said embedded ends of said conduit means having openings for emitting the cement slurry constituting the distention material, each said section comprising two distention conduits connected at said one embedded end, and one-way valve means connecting said distention conduits.

2. Arrangement for distending in multiple sections of the distending body of an earth anchor in sticky soil, comprising conveying conduit means having one end embedded in the distending body below earth level and an air side end extending above the distending body for supplying cement slurry or the like to the distending body below the earth level, means above the earth level for supplying cement slurry to said conduit means, said embedded ends of said conduit means having openings for emitting the cement slurry constituting the distention material, each said section comprising two distention conduits connected at said one embedded end, said distention openings being covered by a cuff disposed around a distention conduit, said cuff having a nose defining a valve the ends of which extend radially of the distention conduit.

3. Method for the multiple distention of the distention body of a ground anchor comprising conveying conduit means in multiple sections of a distending body, placing a part of said means below earth level and placing another part of said means above earth level to define an air side end extending above the distending body, distending each section by supplying slurry to each section and thereupon cleaning the conduits by passing liquid therethrough.

UNITED STATES PATENT oFFicE CETIFICATE 0F COREQTIGN Patent No 5 a Dated December 24 9 finve ntofls) {Ehomas- Herbst, Klemens Finsterwalder It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

The name of the Assignee shoul 1 be:

Dyckerhoff 8c Wid mann Signed and sealed this 18th day of February 1975.

(SEAL) Attest:

- Co MARSHALL DANN RUTH Cu MASON Cissioner of Patents Attesting Officer and Trademarks FORM PC4050 (10-69) USCOMM-DC eosmwes Y A U.S. GQVERNMENT PRINTING OFFICE: 1969 0-366-334