JP2002129556A - Method for installing slope stabilizing anchor, and the slope stabilizing anchor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an installation technique for a slope stabilizing anchor, capable of increasing shearing strength for an anchor means against a sliding failure occurring on the sliding surface of a boundary between a stabilized ground and a surface layer part, which constitute a slope, making the diameter of an anchor installing bore hole smaller, and suppressing the occurrence of the sliding failure by increasing a resistance action on the sliding failure occurring on the sliding surface. SOLUTION: A reinforcing pipe 11 composed of a steel pipe, etc., is externally fitted on the side of the head of an anchor shaft body 3 and 10 anchored partially to the stabilized ground 7 such as a bedrock, etc., and the end of the reinforcing pipe 11 is inserted to a deeper position than the sliding surface 8 formed in a boundary surface between the stabilized ground 7 and the surface layer part 6 for the purpose of allowing a shear load based on the sliding failure occurring on the sliding surface 8 to be received by the shaft body 10 and the reinforcing pipe 11. The shaft body 10 and the reinforcing pipe 11 are set in such a state as not to be bound to each other, and tensile force exerted on the shaft body 10 is exerted as compressive force against the layer part 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slope stabilizing anchor for stabilizing a slope such as a naturally formed slope or a slope formed by artificial cut or embankment.

[0002]

2. Description of the Related Art Conventionally, this type of slope stabilizing anchor has a form in which an anchor shaft is directly inserted into the ground, such as a case where a lock bolt is used as an anchor shaft, or a deformed PC steel rod. It is widely known that an anchor shaft is formed from such a material and a free length portion is formed by externally fitting a sheath made of polyethylene or the like.
No. 46277). Incidentally, the sheath used in the latter prior art is for cutting the edge between the tensile steel material and the ground to form an unconstrained free length portion, and the anchoring action on the ground at that portion. It was not something to share.

[0003] In general, the slope is often formed of a ground structure having a surface layer which is easily moved above a stable ground such as a rock. It is well known that the boundary surface between the stable ground and the surface layer is liable to cause a slip failure, and is therefore called a slip surface. Thus, it goes without saying that a shear load based on slip failure acts on the anchor shaft penetrating the slip surface. In addition, the strength as a slope stabilizing anchor is greatly affected by the proof stress against a shear load based on slip failure, that is, the shear strength. That is, the shear strength against slip failure is a major factor that determines the strength of the anchor for slope stabilization. In a conventional anchor for stabilizing a slope, as described above, a structure in which a shear load based on slip failure is received only by the anchor shaft body has been adopted.
Therefore, since the anchor shaft alone needed to have a sufficient cross-sectional area to receive the total shear load based on sliding failure, a large outer diameter was also used as the anchor shaft, The drilling hole became large, a large drilling device was required, and the construction cost increased. Furthermore, in the case of a so-called ground anchor, which employs an anchor rod made of PC steel stranded wire or the like as the anchor shaft,
Since a larger hole is required, a large hole drilling device is required, and the construction cost tends to increase.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned conventional technical circumstances, and has been developed in view of the slip failure which occurs on the slip surface at the boundary between the stable ground and the surface layer constituting the slope. It is an object of the present invention to provide a slope stabilizing anchor construction technique capable of improving the shear strength as an anchoring means for an anchor, and to further reduce the drilling diameter for anchor installation. Further, it is intended to provide a slope stabilizing anchor construction technology capable of suppressing the occurrence of a slip failure by increasing a resistance action against a slip failure generated on a slip surface formed at a boundary surface between a stable ground and a surface layer. Aim.

[0005]

According to the present invention, a reinforcing pipe made of steel pipe or the like is externally fitted to the head side of an anchor shaft part of which is fixed to a stable ground such as rock, By inserting the tip of the reinforcing pipe deeper than the slip surface formed at the boundary surface between the stable ground and the surface layer, a shear load based on slip failure occurring on the slip surface is caused by the anchor shaft and the reinforcing pipe. We adopted the technical means of receiving. Thereby, the shear load shared by the anchor shaft is reduced by the amount shared by the reinforcing pipe. Therefore, the cross-sectional area of the anchor shaft body can be reduced and the drilling hole for insertion can be reduced by the amount reduced by the sharing of the reinforcing pipe. Furthermore, if the anchors have the same form, the number of installations can be reduced. The space between the inner wall of the hole and the anchor shaft can be used as the insertion space for the reinforcing pipe.

If a self-piercing type anchor shaft having a drill bit at the tip is used as the anchor shaft, efficient installation work is possible. In this case, the reinforcing pipe can be inserted using the gap between the inner wall of the drilled hole formed by the drill bit and the anchor shaft. In addition, if the space between the anchor shaft and the reinforcing pipe is set to the unconstrained state and the free length is set, the tensile force acting on the anchor shaft is compressed to the surface layer between the stable ground and the ground. Since the surface layer acts as a force, the surface layer is tightened so as to be pressed against the slip surface, thereby contributing to stabilization of the surface layer.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is widely applied as a slope stabilizing anchor for stabilizing a slope such as a naturally formed slope or a slope formed by artificial cut or embankment. can do. The anchor shaft body may be a hollow one such as a self-drilling type or another drilling type lock bolt, a solid one such as a deformed PC steel rod, or a tension made of PC steel stranded wire. It may be a material. Further, as the reinforcing pipe which is fitted to the anchor shaft body, a steel pipe is appropriate, but not limited to a steel pipe, such as a stainless steel pipe, as long as it has a strength capable of reducing a shear load acting on the anchor shaft body. An appropriate tube can be adopted.
Further, it is also possible to inject a grout material or the like between the anchor shaft body and the reinforcing pipe to set a restrained state. Since the tensile force acting on the shaft acts as a compressive force on the surface layer and tightens against the slip surface, stabilization of the surface layer can be promoted.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 10 are operation explanatory views illustrating the operation procedure of the method for installing a slope stabilizing anchor according to the present invention. As shown in the drawing, in the present embodiment, a case is shown in which an anchor shaft body 3 composed of a lock bolt having a drill bit 2 at the tip is used as the slope stabilizing anchor 1. In this construction, first, as shown in FIG. 1, the earliest anchor shaft body 3 having the drill bit 2 at the distal end is set on the mounting portion 5 of the drilling device 4, and the surface layer portion 6 is formed. A hole insertion operation for inserting the anchor shaft body 3 while drilling a hole is started.
In the figure, reference numeral 7 denotes a stable ground made of rock or the like, and reference numeral 8 denotes a slip surface formed on a boundary surface between the stable ground 7 and the surface layer portion 8.

When the drilling operation of the earliest anchor shaft body 3 is completed, as shown in FIGS. 2 and 3, the second, third,... The anchor shaft body 10 is connected to continue drilling insertion work. Then, the necessary anchor shafts 3 and 10 are connected, and when a predetermined amount of the anchor shafts in front of the anchor shafts 3 and 10 are inserted into the stable ground 7, the hole insertion work of the anchor shafts 3 and 10 is completed. Then, the procedure shifts to the next work of inserting the outer pipe of the reinforcing pipe. The diameter of the drill bit 2 is set to be larger than the outer diameter of the anchor shafts 3 and 10, and a gap is formed between the inner wall of the drill hole formed by the drill bit 2 and the anchor shafts 3 and 10. A part is formed. The state of insertion of the anchor shaft bodies 3 and 10 into the stable ground 7 is determined so that the distal end of the reinforcing pipe 11 described later can be easily inserted into the stable ground 7.

As shown in FIGS. 5 and 6, when the reinforcing pipe 11 is inserted into the outside of the hole, the reinforcing pipe 11 made of a steel pipe or the like is externally fitted to the anchor shafts 3, 10. And the anchor shafts 3 and 10 are inserted using the gaps. A packing 12 is provided at the tip of the reinforcing tube 11 of the present embodiment, and a mark 13 is provided near the end on the head side. As shown in FIG. 7, the fastening nut 14 is screwed into the upper end portion of the anchor shaft 10 protruding from the reinforcing pipe 11 and tightened, so that the packing 12 at the distal end of the reinforcing pipe 11 is connected to the connecting member 9. Are formed so as to be fitted and adhered to the tapered surface formed at the end of the. Further, the positional relationship regarding the close contact state is configured to be confirmed by the mark 13. In the case where a lock bolt or the like of another drilling type is used as the anchor shaft, instead of the above-described operation process, after forming a predetermined hole with a drilling device, the anchor shaft is inserted into the hole. By inserting an anchor shaft body with a reinforcing pipe in which the reinforcing pipe is externally fitted in a sealed state, the construction state shown in FIG. 7 is reached.

Next, as shown in FIG. 8, a supply pipe 16 for an injection material such as a grout material is connected to the upper end of the anchor shaft 10 via an injection adapter 15 to feed the injection material by pressure. The injected injection material is sent to the drill bit 2 through the hollow portions of the anchor shafts 3 and 10, flows out through a passage formed in the drill bit 2 portion, and flows out to the outside through the drilling inner wall. It is supplied to the gap with the anchor shaft 3. The injected material supplied to the gap between the inner wall of the borehole and the anchor shaft 3 is
Furthermore, since the gas flows through the gap between the inner wall of the hole and the reinforcing pipe 11 and leaks from the upper end to the ground surface, the completion of filling can be confirmed. Since the inside of the reinforcing tube 11 is in a sealed state, the injection material does not flow into the inside of the reinforcing tube 11 and is set as a free length portion in an unconstrained state.

[0012] After the injection material is cured, the operation shifts to an axial force introduction operation. In this axial force introduction work, as shown in FIGS. 9 and 10, the tightening nut 14 is once removed, and the supporting plate 17 and the tightening jig 18 are inserted.
4 are screwed together and tightened to form the anchor shafts 3, 10
, A tensile force is introduced as a predetermined axial force. The support plate 1
A washer may be interposed above 7 as needed. Thus, the installation work of the slope stabilizing anchor 1 is completed.

FIG. 11 is an explanatory view showing an installation state of the slope stabilizing anchor 1 after the above-described installation work has been completed. As shown in the figure, in this embodiment, a part of the anchor shaft body 10 connected via the foremost anchor shaft body 3 and the connecting member 9 constituting each slope stabilizing anchor 1, and the anchor shaft body A part of the reinforcing pipe 11 which is fitted to the outer surface of the connecting member 10 and is closely attached to the connecting member 9 is installed in a state of being inserted into the stable ground 7. Therefore, the shear load based on the slip failure generated on the slip surface formed at the boundary surface between the stable ground 7 and the surface layer 6 above the stable ground 7 acts on the anchor shaft 10 and the reinforcing pipe 11, and the anchor shafts It will be received by 10 and the reinforcing tube 11. as a result,
Since the shear load acting on the anchor shaft 10 is reduced by the sharing of the reinforcing pipe 11, the anchor shafts 3, 1
It is possible to reduce the outer diameter by reducing the cross-sectional area of zero.

The anchor shaft 10 penetrating the surface layer 6 above the stable ground 7 is covered by the reinforcing pipe 11 and is set as a free length part which is not restrained with respect to the surface layer 6. You. That is, the portion of the anchor shaft 3 that is inserted into the stable ground 7 and is not covered by the reinforcing tube 11 functions as a fixing portion, penetrates the surface layer, and the portion of the anchor shaft 10 that is covered by the reinforcing tube 11 is non-fixed. Function as a unit. Therefore, the tensile force as the axial force introduced into the anchor shafts 3 and 10 in FIG. 10 adds a compressive force P to the surface layer portion 6 between the anchor shafts 3 and 10 and the stable ground 7 via the support plate 17. Will be. As a result, the surface layer 6 is compacted and the compression force P
Is pressed against the slip surface 8. Therefore, on the slip surface 8, the resistance to slip failure acting between the surface layer 6 and the stable ground 7 is also increased, and the stabilization of the surface layer 6 is promoted.

FIG. 12 is a partially enlarged view illustrating the head of the slope stabilizing anchor 1 after the installation is completed. As shown,
It is effective in terms of rust prevention if a waterproof packing 19 is attached to the end of the reinforcing pipe 11 so as to be sandwiched between the fastening jig 18. FIG. 13 is a one-side sectional view showing the reinforcing pipe 11 in an enlarged manner. The packing 12 attached to the distal end of the reinforcing pipe 11 of this embodiment has a cross-sectional shape that is inclined on both the inner and outer surfaces as shown in the figure. The inclination of the inner surface has an effect of guiding along the tapered surface formed at the end of the connecting member 9 and bringing both surfaces into close contact. FIG. 14 is a one-side cross-sectional view showing another embodiment of the reinforcing pipe in an enlarged manner. This embodiment employs a form in which the packing 21 is fitted along the inner wall of the distal end portion of the reinforcing pipe 20. As a material of the packings 12, 19, and 21, rubber, resin, and the like are appropriate. It is desirable that each member constituting the slope stabilizing anchor 1 is subjected to a rust-preventive treatment such as hot-dip galvanizing, rust-preventive painting, or resin coating as necessary.

FIGS. 15 to 17 are operation explanatory diagrams illustrating the operation procedure of another embodiment according to the present invention. In this embodiment, operations similar to those in the above embodiment are performed up to the operation of injecting the injection material shown in FIGS. Then, after the injection material is hardened, the operation shifts to the axial force introduction operation. In the axial force introducing operation in this embodiment, as shown in FIG. 15, the tightening nut 14 is once removed, the support plate 17 is inserted into the anchor shaft body 10, and the tightening jig 18 Instead of the elastic member 22 composed of a coil spring or the like
After the washer 23 is inserted, as shown in FIG. 16, the fastening nut 14 is screwed and tightened again to introduce a tensile force as a predetermined axial force to the anchor shaft bodies 3 and 10. Become. Thereafter, as shown in FIG. 17, the installation work is completed by mounting the two-stage covers 24 and 25 so as to cover the head made of the elastic member 22 and the like.

Thus, according to the present embodiment, the predetermined elastic force of the elastic member 22 continuously acts on the anchor shafts 3 and 10 as a tensile force, and the surface layer 6 of the ground.
In the case where the compressive force P continuously acts via the support plate 17 and the topsoil or the like that forms the surface layer portion 6 is deformed over time, the deformation is caused by the elastic member 2.
2, the compressed state of the surface layer portion 6 can be further permanently stabilized, and an unchanged sliding resistance can be maintained.

[0018]

According to the present invention, the following effects can be obtained. (1) Since the shear load based on the slip fracture acting on the anchor shaft is reduced by the reinforcing pipe, the cross-sectional area of the anchor shaft can be reduced, and the drilling for insertion can be reduced accordingly. This makes it possible to reduce the size of a drilling device and the like, and is also effective in reducing construction costs. Also, when using the same type of anchor, the number of installations can be reduced. (2) If a self-drilling type anchor shaft having a drill bit at the distal end is used as the anchor shaft, the installation work can be performed efficiently, and the drilled inner wall formed by the drill bit and the anchor can be used. It is possible to insert the reinforcing pipe by effectively utilizing the gap with the shaft. In addition, the present invention can be applied to the ground where the surface layer is weak and the drilling cannot be self-supporting. (3) If the space between the anchor shaft and the reinforcing pipe is set to an unconstrained state and the free length is set, the tensile force acting on the anchor shaft acts as a compressive force on the surface layer, and the surface layer is Since it is compacted and pressed against the sliding surface,
The resistance to slip fractures increases, and the stabilization of the surface layer is promoted.

[Brief description of the drawings]

FIG. 1 is a work explanatory view illustrating a work procedure of a method for installing a slope stabilizing anchor according to the present invention.

FIG. 2 is a work explanatory view illustrating a work procedure of the construction method.

FIG. 3 is a work explanatory diagram illustrating a work procedure of the construction method.

FIG. 4 is a work explanatory diagram illustrating a work procedure of the construction method.

FIG. 5 is a work explanatory diagram illustrating a work procedure of the construction method.

FIG. 6 is a work explanatory view illustrating a work procedure of the construction method.

FIG. 7 is a work explanatory view illustrating a work procedure of the construction method.

FIG. 8 is a work explanatory view illustrating a work procedure of the construction method.

FIG. 9 is a work explanatory view illustrating a work procedure of the construction method.

FIG. 10 is a work explanatory diagram illustrating a work procedure of the construction method.

FIG. 11 is an explanatory view showing an installation state of a slope stabilization anchor after installation is completed.

FIG. 12 is a partially enlarged view illustrating a head of a slope stabilizing anchor after installation is completed.

FIG. 13 is a one-side cross-sectional view showing an enlarged reinforcing tube.

FIG. 14 is a one-side cross-sectional view showing another embodiment of the reinforcing pipe in an enlarged manner.

FIG. 15 is a work explanatory diagram illustrating a work procedure of another embodiment according to the present invention.

FIG. 16 is an explanatory work diagram illustrating a work procedure of the embodiment.

FIG. 17 is a work explanatory diagram illustrating a work procedure of the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Anchor for slope stabilization, 2 ... Bit for drilling, 3 ... Anchor shaft body, 4 ... Drilling device, 5 ... Mounting part, 6 ... Surface part, 7
... Stable ground, 8 ... Slip surface, 9 ... Connecting member, 10 ... Anchor shaft, 11 ... Reinforcing tube, 12 ... Packing, 13 ... Mark, 14 ... Tightening nut, 15 ... Injection adapter, 16 ... Injection material supply tube , 17: Support plate, 18: Tightening jig, 19: Waterproof packing, 20: Reinforcement pipe, 21: Packing, 22: Elastic member, 23: Washer, 24, 25: Cover

Claims (4)

[Claims] 1. A method for installing a slope stabilization anchor for stabilizing a slope by installing the slope on a slope, the reinforcement comprising a steel pipe or the like on the head side of an anchor shaft body for fixing a part of the anchor to a stable ground such as a bedrock. By externally fitting the pipe and inserting the tip of the reinforcing pipe deeper than the slip surface formed at the boundary surface between the stable ground and the surface layer, the shear load based on the slip failure generated on the slip surface is reduced by the anchor. A method for installing a slope stabilizing anchor, wherein the anchor is received by a shaft body and the reinforcing pipe. 2. The method for constructing a slope stabilizing anchor according to claim 1, wherein a self-drilling type anchor shaft having a drill bit at a distal end is used as the anchor shaft. 3. The method for constructing a slope stabilizing anchor according to claim 1, wherein a portion between the anchor shaft and the reinforcing pipe is set to an unconstrained state to form a free-length portion. 4. An anchor shaft part of which is fixed to a stable ground such as a rock, and an outer shaft fitted to the head side of the anchor shaft, and a tip end thereof is provided at a boundary surface between the stable ground and a surface layer. A slope stabilizing anchor, which is used in combination with a reinforcing pipe made of a steel pipe or the like inserted deeper than a slip surface to be formed.