US3665717A

US3665717A - Method and apparatus for installing elongated rods in unstable earth formations

Info

Publication number: US3665717A
Application number: US106341A
Authority: US
Inventors: Gerald T Sweeney; Oliver E Erdman
Original assignee: SOIL SAMPLING SERVICE Inc
Current assignee: Aardvark Corp
Priority date: 1971-01-14
Filing date: 1971-01-14
Publication date: 1972-05-30
Anticipated expiration: 1989-05-30
Also published as: CA944167A

Abstract

The method and apparatus are an improvement on the patentee''s earlier method and apparatus for installing an elongated rod in an earth formation by the steps of installing a tubular casing in a tunnel in a face of the formation, inserting the rod in the casing, and then retracting the casing from the tunnel. According to the new method, they install and retract the casing through a liquid seal adjacent the face of the formation, and charge a liquid medium into the tunnel through the seal to pressurize the tunnel about the casing, and to retain the formation about the rod when the casing is retracted from the tunnel.

Description

United States Patent Sweeney et al.

[54] METHOD AND APPARATUS FOR INSTALLING ELONGATED RODS IN UNSTABLE EARTH FORMATIONS [72] Inventors: Gerald T. Sweeney; Oliver E. Erdman,

UNITED STATES PATENTS Lawton ..61/53.68 X

Lagerstrom ..61/53.64 X

Sweeney et a1. .1 ..6l/53.68 X

Primary Examiner-Dennis L. Taylor Attorney-Christensen & Sanborn [57] ABSTRACT The method and apparatus are an improvement on the patentees earlier method and apparatus for installing an elongated rod in an earth formation by the steps of installing a tubular casing in a tunnel in a face of the formation, inserting the rod in the casing, and then retracting the casing from the tunnel. According to the new method, they install and retract the casing through a liquid seal adjacent the face of the formation, and charge a liquid medium into the tunnel through the seal to pressurize the tunnel about the casing, and to retain the formation about the rod when the casing is retracted from the tunnel.

19 Claims, 8 Drawing figures fxig RVZ Patented May 30, 1972 1 3,665,717

' 4 Sheets-Swat 1 IIHIIIH INVENTORS? GERALD r \su/E BY out ER 1 EAD Patented May 30, 1972 4 Sheets-Sheet 2 V INVENTORS,

GER/41D I 511/55 NE) BY OLIVER 5 mom/v -%zzlwm%wm ATTORNEYS Patented May 30, 1972 4 shoots-Shot 5 INVENTORS' JTTOANEY? Patented May 30, 1972 I \ATNU m lull-IIIIIIIII 4 Shoots-Shut 4 INVENTORS" GER/11D T. SWEENEY BY OLIVER E. ERDMA/V ATTORNEYS METHOD AND APPARATUS FOR INSTALLING ELONGATED RODS IN UNSTABLE EARTH FORMATIONS FIELD OF THE INVENTION This invention relates to a means and technique for installing elongated rods in earth formations, and in particular, to the installation of such rods in earth formations which are unstable that is, which tend to collapse and fill any excavation which is made in them.

BACKGROUND OF THE INVENTION INCLUDING CERTAIN OBJECTS THEREOF In our US. Pat. No. 3,391,543, we described a means and technique for installing elongated rods in such formations. The principal object of the present invention is to provide a means and technique of this nature whereby such rods can be installed in earth formations which are so unstable as to tend to collapse and bind or restrain a tunnelling mechanism such as a drill casing inserted therein. Another object is to provide a means and technique of this nature whereby the rods can be installed without shrinking the formation that is, without producing a substantial net excavation in the formation. A

further object is to provide a means and technique of this nature which is applicable to the same types of rods listed in out patent, and to the same distances, directions, weights and strengths of material recited in connection with these types of rods. Other objects include the provision of a means and technique of this nature for installing soil anchors in highly water saturated earth formations below rivers and harbors, as well as for the installation of drain pipes in water laden sand beds or other aquifers which are so highly saturated as to generate a hydraulic pressure of 25 psi or greater. Still further objects will become apparent from the description of the invention which follows hereafter.

SUMMARY OF THE INVENTION These objects and advantages are realized by a means and technique of our invention wherein, when carrying out our earlier-technique of installing a tubular casing in a tunnel in a face of the formation, inserting the rod in the casing, and then retracting the casing from the tunnel, we install and retract the casing through a liquid seal adjacent the face of the formation, and charge a liquid medium into the tunnel through the seal to pressurize the tunnel about the casing, and to retain the formation about the rod when the casing is retracted from the tunnel. We may also charge a cure-hardenable liquid medium into the tunnel through the seal around the rod, after the casing is retracted from the tunnel, to close the mouth of the tunnel about the rod.

The casing is in the form of a plurality of sections which are attachable lengthwise thereof, and is installed in successive stages between which the sections are added to the casing while the liquid medium is charged into the tunnel through the seal around the casing. Otherwise, the liquid medium is normally charged into the tunnel through the casing during the installation stages thereof.

The liquid medium charged into the tunnel during the retraction of the casing may be a cure-hardenable grout which is nondisplaceable by the formation when hardened.

The liquid seal is formed by a tubular device which is sealed to the formation adjacent the face thereof. Where the formation has a layer of relatively stable material adjacent the face thereof, the tunnel is normally excavated through an opening in the layer after the tubular device is sealed thereabout. For example, where the formation is laterally supported by sheet metal piling, the opening in the same may be formed in two progressively radially enlarged stages between which a plug of cure-hardened grout is formed between the opening and the face of the formation, and a nipple-like sleeve device is installed around the outside of the opening and sealed to the piling. n the other hand, where the formation includes a layer of relatively stable earth material adjacent the face thereof,

the opening in the same may be formed in two progressively longitudinally enlarged stages between which a gland-like sleeve device is installed in the opening and sealed to the layer by plugging the annular gap between the opening and the sleeve. The gap may be plugged by a fluid inflatable bladder on the sleeve; or it may be plugged by injecting cure-hardenable grout around the sleeve.

In the presently preferred embodiments of the invention, the tubular sealing device has a check-valved fluid inlet therein which communicates with the passage through the body thereof, for the introduction of the liquid medium into the tunnel therethrough. The device also has a pressure relief valve thereon which communicates with .the passage to discharge material excavated from the tunnel.

The device may also have a gate valve therein which is operable to close the passage through the body thereof at a point between the inlet and the end of the device through which the casing is introduced into the passage.

The face of the formation need not be vertically inclined when using our means and technique, but in fact, may be more horizontally inclined, including those situations where the rod must be installed through an overhead face. Also, the formation need not be unstable because of the water therein, but in fact, may be constituted by a dry material such as sand which nevertheless tends to collapse any excavation which is made in it.

DESCRIPTION OF THE DRAWINGS These features will be better understood by reference to the accompanying drawings which illustrate the invention, firstly, as it is applied to the installation of a soil anchor in a waterbearing earth formation supported by sheet metal piling; and secondly, as it is applied to the installation of a horizontal drain in a water-bearing formation supported by a facial layer of relatively water-impervious clay.

In the drawings,

FIG. 1 is a part perspective view of the pile-supported formation, illustrating the first step in a method of forming an opening in the piling through which the installation procedure can be conducted;

FIG. 2 is a similar view illustrating a second step in the method;

FIG. 3 is a side elevational view of a tractor-mounted version of the rod-installing apparatus described in the aforementioned patent, as the apparatus is used in practicing the present invention through the opening in the piling;

FIG. 4 is a part cross-sectional view through the pile-supported formation after the apparatus has been used to install the casing, and a cable for the anchor has been inserted therein;

FIG. 5 is a similar view of the formation at the plane of the piling, illustrating a device for sealing and pressurizing the formation during the installation of the casing, as well as the patented means for retracting the casing from the formation;

FIG. 6 is a composite cross-section view of the formation, illustrating the grouting of the cable and the closing of the opening in the piling;

FIG. 7 is a third part perspective view of the formation after the installation procedure has been completed and the opening has been closed; and

FIG. 8 is a view similar to that of FIG 5 illustrating the installation of the horizontal drain, and in particular, the sealing device used in this connection.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, it will be seen that the earth formation 2 in the embodiment in FIGS. 1-7 is laterally supported by a system of vertically installed sheet metal piling 4 which is ribbed or corrugated to give it increased strength. In order to tunnel into the formation 2 through the piling 4 without the necessity for using a combination metal and earth drilling bit on the drill rod 6, the first step in the over-all operation is to substitute a secondary seal of cure-hardenable grout 8 for a portion 10 of the piling. The grout 8 is injected into the formation through a small-sized opening 12 in the portion, and after it has cured, the portion 10 is cut away or otherwise removed to expose the seal 8. Typically, the removed portion 10 is disc-shaped in configuration as shown, and has a diameter slightly greater than the tunnel 14 to be excavated in the formation.

The tunneling procedure is carried out in the manner described in our patent, by using a ported, check-valve-controlled, detachable bit 16 which is greater in diameter than the drill rod 6, and by charging water or other liquid medium through the rod into the tunnel during the drilling operation to flush the excavated material out through the annular space 18 between the rod and the wall of the tunnel 14. The drill rod 6 is assembled in successive stages from lO-foot sections of steel tubing 6' which are threaded at their ends to be flush-coupled with one another into the necessary length of rod. After the tunnel 14 is completed, the cable 20 for the anchor is inserted in the rod, a grouting material 22 is charged up the rod about the cable, and then the rod is retracted from the tunnel in successive stages, after each of which the section at the end of the rod adjacent the mouth of the tunnel is detached and removed from the rod. Grout is also charged into the rod about the cable 20 during each retraction stage, as shall be explained. In each case, the grout 22 is charged through, and held in the rod about the cable, by a piston device 24 which is advanced from one end section 6' to the next during each retraction stage, and locked in the latter section between stages while the one end section is detached and removed from the rod.

In earth formations 2 having a high hydrostatic head, such as water-bearing sand formations below the surface of a river or harbor, it may also be necessary to pressurize the tunnel about the rod, during the entire operation. This is particularly true where the operation must be conducted without producing a substantial net shrinkage in the formation, as for example, where construction work in the area depends on a stabilized earth condition thereabout. Accordingly, in such cases, the tunnel 14 is sealed and pressurized during the installation procedure by the means and technique illustrated in FIGS. 3, and 6.

Referring to these figures, it will be seen that a nipple-like sealing device 26 is bolted to the face of the piling 4 about the disc-shaped opening 28 therein, using bolts 29 which are welded to the face of the piling in a circle about the opening. The sealing device 26 includes a pair of

coaxial sleeves

30 and 32, the adjacent ends of which are flanged and bolted to a hand-operated gate valve 34 interposed therebetween. The sleeves are adapted to have the drill rod 6 installed therethrough, when the valve 34 is open, and since the operation is generally conducted at an angle to the face of the piling, the leading end portion of the forward sleeve 32 is truncated at such angle, and the end itself is equipped with an annular flange 36 having a suitably spaced number of apertures therein to enable the device to be secured over the bolts 29 with an elastomeric sealing ring 38 interposed therebetween. In addition, the trailing end portion of the rearward sleeve 30 is equipped with an elastomeric packing gland 40 which is adapted to constrict about the drill rod 6 during the operation by reason of its interposition between an annular rib 42 in the sleeve 30 and a compression cap 44 which is threaded into the trailing end of the same about the rod. Thus, the device 26 is adapted to maintain a liquid seal between the piling and the rod as water is charged into the tunnel through the rod; so that the charge operates to pressurize the tunnel about the rod during the operation.

Between each drilling stage, however, when the drillstock 46 of the rod-installing apparatus 48 is disconnected from the rod 6 to enable the addition of another section 6' to the same, it is necessary to maintain the pressure in the tunnel by other means. Thus, the tunnel is charged with additional liquid medium through the sealing device 26 itself; and for this purpose, the forward sleeve 32 of the device is equipped with a tee 50 having a check-valved fluid inlet 52 threaded therein which is fed throughout the operation by a small hydraulic pump (not shown) to maintain a preset pressure in the tunnel. The pump operates in conjunction with a heavy duty pressure relief valve 54 on the device, which not only regulates the pressure in the tunnel, but also discharges the excavated material to the outside as the tunneling operation proceeds. The pressure relief valve 54 is housed in another tee 56 on the forward sleeve, and is equipped with a gate valve 58 on one side thereof, the function of which will be explained shortly.

Typically a pressure of ten psi or greater, above that of the formation, is maintained in the tunnel by the setting of the pressure relief valve.

To form the head 60 of the anchor, the grouting material which is charged into the forward end of the tunnel ahead of the piston, has a low shrinkage and high compression strength. Thereafter, however, as the drill rod is being retracted, the grouting material is reduced to a weak lime and cement mixture 62 so as to back-fill the tunnel 14 with a material which has a high shrinkability, yet is capable of preventing substantial shrinkage in the formation 2.

The inlet 52 may also be used to pressurize the tunnel dur ing the retraction process, although this is generally unnecessary when installing soil anchors. In any event, however, it is usually necessary to close the opening 28 in the piling after the last section of rod has been retracted therefrom, and the inlet is used for this purpose. As seen in FIG. 5, the cable 20 is measured and cut to a length designed to terminate it at a point between the sleeve gate valve 34 and the piling. When the last section of rod has been withdrawn behind or to the left of the gate valve, both it and the gate valve 58 in conjunction with the pressure relief valve, are closed, and a high-compressionstrength, low-shrinkability grouting material 64 is injected into the opening through the inlet 52. See FIG. 6. Thus, when the grouting 64 is hard and the sealing device 26 is removed, the opening 28 is effectively plugged by the same, although enough of the cable 20 remains exposed, or is subsequently exposed, to enable it to be connected to the piling. See FIG. 7. The bolts 29 may also be removed.

In the embodiment of FIG. 8, a water laden sand formation 66 is laterally supported by a natural embankment 68 of clay or the like which must be penetrated to release the water through a horizontal drain 70. Moreover, if the operation is to be successful, it is necessary, as in the earlier embodiment, to seal and pressurize the formation during the installation of the drain. Thus, the operation is again carried out through a sealing device, which in this instance, however, is inserted in the water impervious material to form a gland-like seal 72 between the casing 6 and the material. The device 72 comprises a pair of coaxial sleeves 74 and 76 which are coupled together by a standard female coupling 78 to a combined length of ten feet. The rearward sleeve 76 not only has a packing 80 and compression cap 82 associated therewith, as in the earlier embodiment; but is also equipped with a checkvalved fluid inlet 84 and a gate-valved pressure relief valve 86, that are similar to those on forward sleeve 30 in the earlier embodiment. The pressure relief valve 86 is on the discharge side of the gate valve 88 in this instance, however, for ease of cleaning; and is cooperable with a slotted opening 90 in the housing 92 for the same.

The device 72 operates to form a seal between the water impervious material and the rod 6, by means of a flexible rubber bladder 94 which is annular in shape and installed about the last three feet of the forward sleeve 74 for insertion in the embankment. The circumferential edges of the bladder are vulcanized to the sleeve to form an envelope 96 which can be inflated through a tube 98 that is extendible from the bladder to a point outside of the embankment. At the start of the operation, a 10-foot long hole 100 which is slightly larger in diame ter than the sleeve is augered out of the embankment; and after the sleeve is inserted in the hole with the bladder thereon, either water, oil, or air is introduced into the bladder to inflate the same until it forms a snug packing gland between the sleeve and the wall of the hole. Thereafter, the operation is conducted in the same manner as the earlier embodiment, although for the purposes of a drain, a water medium is used through the operation. After the rod and device are removed, however, grouting is applied to the mouth of the opening in the embankment, about the drain, to seal off the annular space therebetween.

Alternatively, an elongated pipe may be. grouted or otherwise cemented into the water impervious stratum of the embankment, to form a sealing gland.

Also, where the embankment has considerable height above the mouth of the tunnel, it may be practical to use elevational head, rather than a pump head, to pressurize the tunnel, as for example, where the liquid tailings which escape from the sealing device during the excavation process are raised and stored at a point above the mouth of the tunnel for this purpose.

Similarly, one can subject the invention to many other modifications and additions without departing from the scope and spirit of the same as defined in the claims following.

What is claimed is:

1. 1n the process of installing an elongated rod in an earth formation by the steps of installing a tubular casing in a tunnel in a face of the formation, inserting the rod in the casing, and then retracting the casing from the tunnel, the improvement comprising the steps of installing and retracting the casing through a liquid seal adjacent the face of the formation, and charging a liquid medium into the tunnel through the seal to pressurize the tunnelabout the casing, and to retain the formation about the rod when the casing is retracted from the tunnel.

2. The process according to claim 1 further comprising charging a cure-hardenable liquid medium into the tunnel through the seal around the rod, after the casing is retracted from the tunnel, to close the mouth of the tunnel about the rod.

3. The process according to claim 1 wherein the casing is in the form of a plurality of sections which are attachable lengthwise thereof, and is installed in successive stages between which the sections are added to the casing while the liquid medium is charged into the tunnel through the seal around the casing.

4. The process according to claim 3 wherein the liquid medium is charged into the tunnel through the casing during the installation stages thereof.

5. The process according to claim 3 wherein the liquid medium charged into the tunnel during the retraction of the casing is a cure-hardenable grout which is non-displaceable by the formation when hardened. v

6. The process according to claim 1 wherein the liquid seal is formed by a tubular device which is sealed to the formation adjacent the face thereof.

7. The process according to claim 6 wherein the formation has a layer of relatively stable material adjacent the face thereof, and the tunnel is excavated through an opening in the layer after the tubular device is sealed thereabout.

,8. The process according to claim 7 wherein the opening in the layer is formed in two progressively radially enlarged stages between which a plug of cure-hardened grout is formed between the opening and the face of the formation, and a nipple-like sleeve device is installed around the outside of the opening and sealed to the layer.

9. The process according to claim 7 wherein the opening in the layer is formed in two progressively longitudinally enlarged stages between which a gland-like sleeve device is installed in the opening and sealed to the layer by plugging the annular gap between the opening and the sleeve.

10. The process according to claim 9 wherein the gap is plugged by a fluid inflatable bladder on the sleeve-like device.

11. In apparatus for installing an elongated rod in an earth formation by the steps of installing a tubular casing in a tunnel in a face of the formation, inserting a rod in the casing, and then retracting the casing from the tunnel, the improvement comprising means for formingla liquid seal ad'acent the face of the formation through WhlC the casing can e installed and retracted, and means for charging a liquid medium into the tunnel through the seal to pressurize the tunnel about the easing, and to retain the formation about the rod when the casing is retracted from the tunnel.

12. The apparatus according to claim 11 wherein the latter means are adapted to charge the liquid through the seal around the casing.

13. The apparatus according to claim 11 wherein the liquid seal forming means includes a tubular device which is adapted to be sealed to the formation adjacent the face thereof.

14. The apparatus according to claim 13 wherein the tubular device includes a nipple-like sleeve device which is adapted to be installed around an opening in a layer of relatively stable material adjacent the face of the formation, through which the tunnel is excavated.

15. The apparatus according to claim 13 wherein the tubular device includes a gland-like sleeve device which is adapted to be installed in an opening in a layer of relatively stable earth material adjacent the face of the formation, through which the tunnel is excavated.

16. The apparatus according to claim 15 wherein the sleevelike device has a fluid inflatable bladder formed thereon.

17. The apparatus according to claim 13 wherein the tubular device has a check-valved fluid inlet therein which communicates with the passage through the body thereof, for the introduction of the liquid medium into the tunnel therethrough.

18. The apparatus according to claim 17 wherein the tubular device also has a pressure relief valve thereon which communicates with the passage to discharge material excavated from the tunnel.

19. The apparatus according to claim 17 wherein the tubular device also has a gate valve therein which is operable to close the passage at a point between the inlet and the end of the device through which the casing is introduced into the passage.

Claims

1. In the process of installing an elongated rod in an earth formation by the steps of installing a tubular casing in a tunnel in a face of the formation, inserting the rod in the casing, and then retracting the casing from the tunnel, the improvement comprising the steps of installing and retracting the casing through a liquid seal adjacent the face of the formation, and charging a liquid medium into the tunnel through the seal to pressurize the tunnel about the casing, and to retain the formation about the rod when the casing is retracted from the tunnel.

5. The process according to claim 3 wherein the liquid medium charged into the tunnel during the retraction of the casing is a cure-hardenable grout which is non-displaceable by the formation when hardened.

8. The process according to claim 7 wherein the opening in the layer is formed in two progressively radially enlarged stages between which a plug of cure-hardened grout is formed between the opening and the face of the formation, and a nipple-like sleeve device is installed around the outside of the opening and sealed to the layer.

11. In apparatus for installing an elongated rod in an earth formation by the steps of installing a tubular casing in a tunnel in a face of the formation, inserting a rod in the casing, and then retracting the casing from the tunnel, the improvement comprising means for forming a liquid seal adjacent the face of the formation through which the casing can be installed and retracted, and means for charging a liquid medium into the tunnel through the seal to pressurize the tunnel about the casing, and to retain the formation about the rod when the casing is retracted from the tunnel.

16. The apparatus according to claim 15 wherein the sleeve-like device has a fluid inflatable bladder formed thereon.