JP7590267B2 - Earth retaining wall and construction method of earth retaining wall - Google Patents

Description

The present invention relates to an earth retaining wall and a method for constructing an earth retaining wall.

Conventionally, when constructing a tunnel or the like using the shield method, a vertical shaft reinforced with an earth retaining wall is provided at the starting point or arrival point of the shield excavator. In order to make the earth retaining wall easier to cut with the cutters of the shield excavator, for example, the earth retaining wall may be constructed as an underground continuous wall by lining up multiple vertically extending core materials made of a composite material of hard urethane resin reinforced with glass fiber at specified intervals and burying them in soil cement. When reinforcing the earth retaining wall with anchors, the material of the anchors is made easy to cut with the cutters of the shield excavator, just like the core materials.

The anchor installation method included the steps of drilling an anchor pilot hole in the soil cement section between adjacent core materials, inserting an anchor into the anchor pilot hole, then fixing one end of the anchor into the ground behind the retaining wall, and supporting the other end of the anchor on the core material via a pressure plate.

Japanese Unexamined Patent Publication No. 2-221515 Japanese Patent Application Publication No. 8-85942

However, if there is a layer with low water permeability above the drilling position for the anchor pilot hole, drilling the anchor pilot hole may cause pressurized groundwater to gush out, making it difficult to install the anchor. In particular, if the anchor is not made of steel but is a lightweight one made of resin and reinforcing fiber, the anchor may be pushed back by groundwater, making it difficult to install it in the specified position.
Furthermore, in order to deal with the adverse effects of pressurized groundwater during construction, there have been techniques in which water stop boxes are used to stop water while drilling holes and installing anchors (see Patent Document 1 or Patent Document 2). However, both of these techniques involve welding or bolting to steel earth retaining walls, and as such could not be applied to earth retaining walls constructed from materials that are easy to cut, such as fiber-reinforced resin.

The present invention was made in consideration of the above-mentioned circumstances, and aims to provide an earth retaining wall and a construction method for the wall that can suppress the adverse effects of pressurized groundwater during construction and can be easily cut by the cutter of a shield excavator.

In order to solve the above problems, the present invention proposes the following aspects.

(1) An earth retaining wall according to one aspect of the present invention is an earth retaining wall comprising a diaphragm wall having a core material and soil cement in which the core material is embedded, and an anchor for reinforcing the diaphragm wall, the earth retaining wall having a preliminary hole formed in the soil cement so as to be coaxial with an anchor pilot hole for accommodating the anchor, and a plastic guide tube fitted into the preliminary hole, the anchor being inserted into the plastic guide tube.

The retaining wall of the present invention, which is specified by these characteristics, can be easily cut with the cutter of a shield excavator. In addition, when drilling the pilot holes for the anchors, it is possible to prevent pressurized groundwater from gushing out from between the ground (soil cement) and the outer surface of the resin guide pipe. Even if there is pressurized groundwater in the ground in which the pilot holes for the anchors are drilled, the water that flows out from the drilling casing pipe and the pilot holes for the anchors can be guided to the water stop device. Even if the cut end surface of the soil cement is uneven, it is possible to prevent water from flowing out from between the soil cement and the resin guide pipe. Therefore, it is possible to suppress the adverse effects of pressurized groundwater during construction, and to construct a retaining wall that is easy to cut with the cutter of a shield excavator.

(2) In the above (1), the resin guide pipe may have a flat portion at the end, and the flat portion may be connected with a bolt to a mouth pipe that guides the drilling casing pipe.

The retaining wall of the present invention, which is characterized by these features, can ensure a seal between the plastic guide pipe and the mouth pipe by sandwiching an O-ring between the flat plate portion of the plastic guide pipe and the mouth pipe, and then fastening the mouth pipe with a bolt that penetrates the mouth pipe and is screwed into the female thread.

(3) In the above (2), the nozzle pipe may have a water-stopping device capable of sealing between the nozzle pipe and the drilling casing pipe.

The retaining wall of the present invention, which is characterized by these features, can direct water flowing out from the ground through the mouth pipe to the water stop device.

(4) In any of (1) to (3) above, the inner diameter of the resin guide tube may be 100 mm or more and 500 mm or less.

The retaining wall of the present invention, which is characterized by these features, allows the drilling casing pipe to be inserted inside the cylindrical portion of the resin guide tube when drilling the anchor holes.

(5) In any of the above (1) to (4), the resin guide tube may be reinforced with fiber.

The retaining wall of the present invention, which is characterized by these features, makes it easier to ensure strength against the bearing pressure of the anchors.

(6) In any of the above (1) to (5), the anchor may be supported via a pressure plate, and the resin guide tube may be disposed on the rear side of the pressure plate.

The retaining wall of the present invention, which is characterized by these features, can easily seal off water flowing out from the ground, guide the casing pipe used for drilling holes, and further support the load of the anchors through the pressure plate.

(7) In any of the above (1) to (6), the resin guide tube may be supported by an anti-slip protrusion attached to the core material.

The retaining wall of the present invention, which is characterized by these features, can restrict the downward movement of the plastic guide pipe caused by the vertical component of the anchor reaction force.

(8) A method for constructing an earth retaining wall according to one aspect of the present invention includes the steps of: constructing an earth retaining wall in a state in which a resin guide pipe is embedded in soil cement; and joining a water stop device capable of sealing between the resin guide pipe and a casing pipe for drilling to the resin guide pipe via a mouth pipe;
and a step of passing the drilling casing pipe through the resin guide pipe, the mouth pipe and the water stop device to drill pilot holes for anchors.

This allows the nozzle pipe, the water stop device, and the seals installed on the water stop device to seal off water that leaks through the gap between the drilling casing pipe and the plastic guide pipe. This makes it possible to suppress the adverse effects of pressurized groundwater during construction.

The present invention can suppress the adverse effects of pressurized groundwater during construction and provide a retaining wall that is easy to cut with the cutter of a shield excavator.

FIG. 2 is an explanatory diagram showing a preliminary hole excavation process in the construction method for an earth retaining wall according to an embodiment. FIG. 2 is an explanatory diagram showing a resin guide pipe installation process in the construction method for an earth retaining wall according to an embodiment. FIG. 2 is an explanatory diagram showing a gap sealing process in the construction method for an earth retaining wall according to an embodiment. FIG. 2 is an explanatory diagram showing the anti-slip protrusion installation process in the construction method for the retaining wall according to the embodiment. An explanatory diagram showing the mouth pipe joining process in the construction method of the retaining wall according to the embodiment. FIG. 2 is an explanatory diagram showing a water stop device installation process and an anchor hole drilling process in the construction method for an earth retaining wall according to an embodiment. FIG. 2 is an explanatory diagram showing an anchor insertion process in the construction method for an earth retaining wall according to an embodiment. FIG. 2 is an explanatory diagram showing the mouth pipe removal process in the construction method for an earth retaining wall according to an embodiment. FIG. 2 is an explanatory diagram showing the anchor fixing process in the construction method for an earth retaining wall according to an embodiment. FIG. 2 is a front view of a resin guide tube according to the embodiment. FIG. 11 is a cross-sectional view taken along the line A in FIG. 10 . FIG. 12 is a detailed view of part B in FIG.

Below, with reference to Figs. 1 to 9, an example of an earth retaining wall 100 according to an embodiment of the present invention will be described along with an example of a construction method of the earth retaining wall 100. Fig. 1 is an explanatory diagram showing a preliminary hole drilling step S1 in the construction method of the earth retaining wall 100 according to the embodiment. Fig. 2 is an explanatory diagram showing a resin guide pipe installation step S2 in the construction method of the earth retaining wall 100 according to the embodiment. Fig. 3 is an explanatory diagram showing a gap sealing step S3 in the construction method of the earth retaining wall 100 according to the embodiment. Fig. 4 is an explanatory diagram showing a non-slip protrusion installation step S4 in the construction method of the earth retaining wall 100 according to the embodiment. Fig. 5 is an explanatory diagram showing a mouth pipe joining step S5 in the construction method of the earth retaining wall 100 according to the embodiment. Fig. 6 is an explanatory diagram showing a water stop device installation step S6 and an anchor hole drilling step S7 in the construction method of the earth retaining wall 100 according to the embodiment. Fig. 7 is an explanatory diagram showing an anchor insertion step S8 in the construction method of the earth retaining wall 100 according to the embodiment. FIG. 8 is an explanatory diagram showing the mouth pipe removal step S9 in the construction method for the earth retaining wall 100 according to the embodiment. FIG. 9 is an explanatory diagram showing the anchor fixing step S10 in the construction method for the earth retaining wall 100 according to the embodiment.

(Earth retaining wall)
The earth retaining wall 100 according to this embodiment can be applied, for example, to an earth retaining wall 100 for reinforcing a vertical shaft provided at the starting point or arrival point of a shield excavator (not shown) when constructing a tunnel or the like by a shield method. A part of the earth retaining wall 100 provided at the starting point or arrival point of the shield excavator, together with the anchor 20, is cut by the cutter of the shield excavator to form a through hole that constitutes a tunnel.

As shown in FIG. 9, the retaining wall 100 includes a diaphragm wall 10 having a core material 11 and soil cement 12 that fills the core material 11, and anchors 20 that reinforce the diaphragm wall 10.

In order to make the underground continuous wall 10 easier to cut with the cutter (not shown) of the shield excavator, multiple vertically extending core materials 11 made of a composite material, for example, of rigid urethane resin reinforced with glass fiber, are arranged at predetermined intervals, and these core materials 11 are wrapped and connected together and buried in soil cement 12 so as to form a surface along the cut end surface 100S of the shaft.
In addition, the underground diaphragm wall 10 is reinforced with anchors 20.

The anchor 20 has one end fixed to the ground G behind the earth retaining wall 100, and the other end supported by the earth retaining wall 100. The anchor 20 is, for example, a high-strength tensile material in the form of a string or rod. The anchor 20 has, for example, a fixing body 21 such as a packer fixed to the ground G via cement or the like at one end of the tensile material. As shown in FIG. 9, the anchor 20 has, for example, an anchor head 20h at the other end of the tensile material 20T, which penetrates the pressure plate 70 and the collar 22 and has a male thread on which the nut 23 can be screwed. The material of the anchor 20 is, for example, not steel but fiber-reinforced resin, like the core material 11, and is easily cut by the cutter of the shield excavator. Similarly, the material of the pressure plate 70 is, for example, not steel but fiber-reinforced resin, like the core material 11, and is easily cut by the cutter of the shield excavator. In this way, the core material 11, anchors 20, etc. that make up the earth retaining wall 100 are made of resin, not steel, making them easier to cut with the cutters of a shield excavator.

Here, the retaining wall 100 has a preliminary hole 20p formed in the soil cement 12 so as to be coaxial with the anchor pilot hole 20d that accommodates the anchor 20, and a resin guide tube 30 that fits into the preliminary hole 20p. The anchor 20 is inserted through the resin guide tube 30.
In this way, the retaining wall 100 has a resin guide pipe 30 that fits into the preliminary hole 20p or the anchor pilot hole 20d formed in the soil cement 12. This makes it easy to cut with the cutter of the shield excavator. Even if there is pressurized groundwater in the ground G where the preliminary hole 20p is drilled, the gap between the preliminary hole 20p and the resin guide pipe 30 is blocked, so that water can be prevented from flowing out from the gap between the resin guide pipe 30 and the cut end surface 100S until the anchor pilot hole 20d is drilled. Even if there is pressurized groundwater in the ground G where the anchor pilot hole 20d is drilled, the water that flows out from the drilling casing pipe C and the anchor pilot hole 20d can be guided to the water stop device 50 (see Figures 6 and 7). Even if there is unevenness in the cut end surface 100S (surface exposed to the shaft) of the soil cement 12, water can be prevented from flowing out from between the soil cement 12 and the resin guide pipe 30. Therefore, the adverse effects of pressurized groundwater during construction can be suppressed, and the retaining wall 100 can be easily cut by the cutters of a shield excavator.

(Resin guide tube 30)
Fig. 10 is a front view of the resin guide pipe 30 according to the embodiment. Fig. 11 is a cross-sectional view of the resin guide pipe 30 according to the embodiment. Fig. 12 is a detailed view of part B in Fig. 11 .
The resin guide tube 30 is made of a resin such as polyvinyl chloride. The resin guide tube 30 may be reinforced with fibers. This makes it easier to ensure the strength against the bearing pressure of the anchor 20.
As shown in FIGS. 10 to 12 , the resin guide pipe 30 includes a flanged pipe portion 31 and an O-ring 32 .
The resin guide tube 30 may be supported by anti-slip protrusions 60 attached to the core material 11. This makes it possible to restrict downward movement of the resin guide tube 30 due to the vertical component of the reaction force of the anchor 20.

The flanged pipe 31 has a flat plate 311 having an opening 311q in the center, and a cylindrical portion 312 that communicates with the opening 311q. The end of the cylindrical portion 312 is joined to the opening 311q of the flat plate 311 in a watertight manner to form an integral part. The flat plate 311 and the cylindrical portion 312 are joined by, for example, fusion or welding. The central axis of the cylindrical portion 312 is appropriately inclined with respect to the central axis of the opening 311q of the flat plate 311 according to the angle of the anchor pilot hole 20d relative to the cutting end surface 100S. In this case, the shape of the opening 311q and the end face of the cylindrical portion 312 joined to the flat plate 311 are each elliptical.

The flat plate portion 311 has an annular groove 311g into which the O-ring 32 is fitted.
As shown in FIG. 12, the flat plate portion 311 is connected to the mouth pipe 40 by a bolt 33. In detail, the flat plate portion 311 has a female thread portion 311f for detachably attaching the mouth pipe 40 that guides the drilling casing pipe C. The flat plate portion 311 has, for example, 12 female thread portions 311f at equal pitches on a circle concentric with the central axis of the opening 311q. With this, the O-ring 32 is sandwiched between the flat plate portion 311 of the resin guide tube 30 and the mouth pipe 40, and the bolt 33 that penetrates the mouth pipe 40 and is screwed into the female thread 311f is tightened to ensure sealing between the resin guide tube 30 and the mouth pipe 40.

The outer diameter of the cylindrical portion 312 is set smaller than the preliminary hole 20p or the anchor pilot hole 20d. This allows the cylindrical portion 312 to be inserted and fitted into the preliminary hole 20p or the anchor pilot hole 20d. The inner diameter of the cylindrical portion 312 is set larger than the outer diameter of the casing pipe C for drilling holes. In other words, the inner diameter of the resin guide tube 30 is 100 mm or more and 500 mm or less. This allows the casing pipe C for drilling holes to be inserted inside the cylindrical portion 312 when drilling the anchor pilot hole 20d.

The O-ring 32 is an annular body with a circular cross section. The O-ring 32 fits into an annular groove 311g formed in the flat plate portion 311. When sandwiched between the resin guide tube 30 and the mouth tube 40, the O-ring 32 is restrained from deformation by the annular groove 311g, while maintaining a biasing force toward the flange of the mouth tube 40 due to elastic deformation, ensuring sealing. The cross-sectional diameter of the O-ring 32 is larger than the depth of the annular groove 311g. The O-ring 32 is made of, for example, acrylonitrile butadiene rubber (NBR).

(Opening pipe and water stop device)
Incidentally, as shown in Fig. 5, in the construction process of the earth retaining wall 100, in order to install the anchor 20, a mouth pipe 40 is installed on the exposed flat plate portion 311 of the resin guide pipe 30 inserted into the preliminary hole 20p formed in the cut end surface 100S (see Figs. 5 to 7). As shown in Figs. 6 and 7, the mouth pipe 40 has a water stop device 50 capable of sealing between the mouth pipe 40 and the casing pipe C for drilling. This allows water flowing out from the ground G to be guided to the water stop device 50 through the mouth pipe 40.

The mouth pipe 40 is made of, for example, steel. The mouth pipe 40 has a flange at its end that is connected to the plastic guide pipe 30 by a bolt 33. The surface of the flange is flat. The mouth pipe 40 is joined to the plastic guide pipe 30 by the bolt 33 with an O-ring 32 sandwiched between the plastic guide pipe 30 and the flange.

The water stop device 50 comprises a first pipe section 51 that is connected to the end of the mouth pipe 40 in a watertight manner, and a second pipe section 52 that is connected to the first pipe section 51.

One end of the first tube section 51 is connected to the mouth tube 40. The other end of the first tube section 51 is connected to the second tube section 52 via a shutter section 53 that can be opened and closed.

The shutter section 53 is a plate-like body that has enough rigidity to stand on its own without significant deflection under its own weight and is provided so that it can slide freely in a direction perpendicular to the axial direction of the anchor pilot hole 20d. This allows the shutter section 53 to be closed before inserting the casing pipe C for drilling, thereby sealing off the outflow of pressurized water from the ground G through the preliminary hole 20p, and then the shutter section 53 can be opened when the casing pipe C for drilling is to be inserted.

The first pipe section 51 also has a drain valve 55 that can be switched between a closed state to seal the water inside the water stop device 50 and an open state to allow the water to be drained.

One end of the second pipe 52 is connected to the first pipe 51 via the shutter 53. The other end of the second pipe 52 has a seal 54 made of a flexible material such as rubber. The seal 54 may be a rubber plate having a predetermined thickness and a central opening with a diameter smaller than the outer diameter of the casing pipe C for drilling holes. In this way, since the water stop device 50 has the seal 54, when drilling the anchor pilot hole 20d, the inner surface of the seal 54 comes into close contact with the outer surface of the casing pipe C for drilling holes, and water flowing out of the ground G passing between the casing pipe C for drilling holes and the inner surface of the water stop device 50 can be sealed.

(Construction method of earth retaining wall)
The construction method of the earth retaining wall 100 according to this embodiment will be described in detail below.
First, as shown in Fig. 1, a diaphragm wall 10 including a core material 11 and soil cement 12 is constructed on the ground G. Then, an earth retaining wall 100 is constructed with the side surface of the diaphragm wall 10 exposed as a cut end surface 100S of a shaft.

(1) Next, a preliminary hole 20p is drilled using a drill D having a bit with an outer diameter larger than the outer diameter of the bit placed at the tip of the drilling casing pipe C (preparatory hole drilling step S1). The direction of the preliminary hole 20p is the same as the axial direction of the anchor pilot hole 20d. The inner diameter of the preliminary hole 20p is made larger than the maximum outer dimension when the mouth packer 34 (see Figure 2) is wrapped around it. The length of the preliminary hole 20p is made longer than the length of the cylindrical portion 312 of the resin guide tube 30.

(2) Next, as shown in Fig. 2, the resin guide pipe 30 is inserted into the preliminary hole 20p (resin guide pipe installation step S2). This completes the construction of the retaining wall 100 with the resin guide pipe 30 embedded in the soil cement 12.
In detail, a resin guide tube 30 with a mouth packer 34 attached thereto in advance is prepared. The mouth packer 34 is an annular container that can be filled with a fluid filler. The mouth packer 34 is, for example, a resin or cloth bag that is thin and flat when not filled with a filler and has a circular cross section when filled with a filler. The mouth packer 34 is wound around the cylindrical portion 312 in advance in a deflated state with a small volume without being filled with a filler. The mouth packer 34 communicates with a filler supply pipe (not shown). The supply port of the supply pipe is exposed from the cut end surface 100S.
Then, the cylindrical portion 312 of the resin guide tube 30 with the mouth packer 34 attached is fitted inside the preliminary hole 20p, and the flat portion 311 of the resin guide tube 30 is placed against the cut end surface 100S.
In addition, without using the mouth packer 34, the gap between the flat plate portion 311 of the resin guide pipe 30 and the soil cement may be filled with putty or the like.

(3) Next, as shown in FIG. 3, the mouth packer 34 is filled with the filler through the supply pipe (gap sealing process S3). The filler may be in a fluid state when supplied. Then, the mouth packer 34 expands and increases in volume, and fits into the gap between the preliminary hole 20p and the resin guide tube 30 and adheres tightly to it. In this way, the gap m between the preliminary hole 20p, which has a flat inner surface all around, and the resin guide tube 30, which has a flat outer surface all around, is blocked by the mouth packer 34. Therefore, even if the cut end surface 100S is uneven and the gap e between the flat plate portion 311 and the cut end surface 100S is not aligned, the outflow of pressurized water from the ground G through the preliminary hole 20p or the anchor pilot hole 20d can be sealed.

(4) Next, as shown in FIG. 4, the anti-slip protrusion 60 is installed (anti-slip protrusion installation step S4). The anti-slip protrusion 60 is fixed to the diaphragm wall 10 in a state where it protrudes from the cut end surface 100S toward the shaft directly below the resin guide pipe 30. The anti-slip protrusion 60 is fixed to the core material 11 or the soil cement 12 by, for example, an anchor bolt. The anti-slip protrusion 60 is formed of, for example, a resin material that can be cut by the cutter of the shield excavator. The anti-slip protrusion 60 is fixed to the diaphragm wall 10 in a state where it protrudes from the cut end surface 100S toward the shaft directly below the resin guide pipe 30, so that when the anchor 20 installed obliquely to the cut end surface 100S is tensioned in a later process, the resin guide pipe 30 receives a vertical downward component force acting on the resin guide pipe 30 via the anchor 20, and the resin guide pipe 30 does not move downward.
It is also possible to hold the resin guide tube 30 in a suspended state from above without using the anti-slip protrusions 60.

(5) Next, as shown in FIG. 5, an O-ring 32 is attached to the resin guide tube 30. Then, with the O-ring 32 sandwiched between the resin guide tube 30 and the mouth tube 40, the mouth tube 40 is attached to the resin guide tube 30 using a bolt 33 (mouth tube joining process S5). Note that the O-ring 32 and the bolt 33 are each made of a material that can be cut by the cutter of the shield excavation machine, for example, a resin material.

(6) Next, as shown in Fig. 6, a water stop device 50 is attached to the mouth pipe 40 (water stop device attachment step S6). In detail, the water stop device 50 capable of sealing between the resin guide pipe 30 and the drilling casing pipe C is joined to the resin guide pipe 30 via the mouth pipe 40.
Then, the casing pipe C for drilling holes is inserted from the opening at the end of the water stop device 50, and the end of the casing pipe C for drilling holes is made to reach the bottom of the preliminary hole 20p through the mouth pipe 40 and the resin guide pipe 30. From there, the drilling is further advanced with the bit arranged at the tip of the casing pipe C for drilling holes to form the anchor pilot hole 20d in the ground G (anchor pilot hole drilling step S7). That is, the casing pipe C for drilling holes is drilled through the resin guide pipe 30, the mouth pipe 40, and the water stop device 50 to drill the anchor pilot hole 20d. At this time, the mouth pipe 40, the water stop device 50, and the seal part 54 provided on the water stop device 50 can seal the water flowing out through the gap k between the casing pipe C for drilling holes and the resin guide pipe 30. Therefore, the adverse effects of pressurized groundwater during construction can be suppressed.

(7) Next, as shown in FIG. 7, an anchor 20 with a packer or other fixing body 21 attached to its tip is passed inside the drilling casing pipe C, and the tip of the anchor 20 is allowed to reach the bottom of the anchor pilot hole 20d. The drilling casing pipe C is then removed from the anchor pilot hole 20d, and the fixing body 21 is expanded. Alternatively, the tip of the anchor 20 is fixed to the ground G by filling the tip of the anchor 20 with cement paste or the like and allowing it to harden (anchor insertion step S8).

(8) Next, as shown in FIG. 8, the bolt 33 is removed to disconnect the nozzle pipe 40 from the plastic guide pipe 30, and the nozzle pipe 40 and the water stop device 50 are removed from the plastic guide pipe 30 (mouth pipe removal process S9).

(9) Next, as shown in FIG. 9, in a state where the pressure plate 70 and the collar 22 are passed through the anchor head 20h, the anchor head 20h is appropriately gripped with a hydraulic jack (not shown) or the like to tension the tension member 20T of the anchor 20 (anchor fixing step S10). The end surface of the collar 22 that contacts the pressure plate 70 is inclined with respect to the support surface that supports the nut 23 according to the axial direction of the anchor pilot hole 20d. At this time, since there is the anti-slip protrusion 60, the downward movement of the pressure plate 70 can be restricted even if the pressure plate 70 is not fixed to the resin guide tube 30. Then, the nut 23 is screwed into the male thread formed on the anchor head 20h. As a result, the underground continuous wall 10 is reinforced by the anchor 20. Therefore, the anchor 20 is supported via the pressure plate 70, and the resin guide tube 30 is arranged on the back side of the pressure plate 70. This makes it easier to seal off water from flowing out from the ground G, and also allows the drilling casing pipe C to be guided. Furthermore, the load of the anchor 20 can be received via the pressure plate 70.
In this way, the retaining wall 100, which is made of a material that can be cut by the cutter of a shield excavator and is composed of the diaphragm wall 10 reinforced with anchors 20, can be constructed while sealing off the outflow of pressurized water during construction. This makes it possible to provide an earth retaining wall 100 and a construction method for an earth retaining wall that can be easily cut by the cutter of a shield excavator and that can suppress the adverse effects of pressurized groundwater during construction.

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, the flat plate portion 311 constituting the flanged pipe portion 31 of the resin guide pipe 30 may completely block the opening at one end of the cylindrical portion 312 without forming an opening 311q in the center. This allows water flowing out from the ground G through the preliminary hole 20p to the cut end surface 100S to be sealed off until the anchor pilot hole 20d is drilled with the casing pipe C for drilling, and when the anchor pilot hole 20d is drilled, the flat plate portion 311 can be easily broken with the casing pipe C for drilling. Note that a valve for draining water flowing out from the ground G may be provided in the center of the flat plate portion 311 that blocks the opening at one end of the cylindrical portion 312.

In addition, the components in the above embodiment may be replaced with well-known components as appropriate without departing from the spirit of the present invention, and the above-mentioned modifications may be combined as appropriate.

10 Diaphragm wall 11 Core material 12 Soil cement 20 Anchor 20d Anchor pilot hole 20h Anchor head 20p Spare hole 20T Tensile material 21 Fixing body 22 Collar 23 Nut 30 Resin guide tube 31 Flanged tube section 32 O-ring 33 Bolt 34 Mouth packer 40 Mouth pipe 50 Water stop device 51 First tube section 52 Second tube section 53 Shutter section 54 Seal section 55 Drain valve 60 Anti-slip protrusion section 70 Pressure plate 100 Earth retaining wall 100S Cut end surface 311 Flat plate section 311f Female thread section 311g Annular groove 311q Opening 312 Cylindrical section C Casing pipe for drilling D Drill e, k, m Gap G Ground

Claims (8)

A retaining wall comprising a diaphragm wall having a core material and soil cement burying the core material, and an anchor reinforcing the diaphragm wall,
A preliminary hole is formed in the soil cement so as to be coaxial with an anchor pilot hole for accommodating the anchor, and a resin guide tube is fitted into the preliminary hole,
The anchor is inserted into the resin guide tube ,
The resin guide tube has a flat plate portion at an end thereof,
The flat plate portion is connected by a bolt to a mouth pipe that guides a casing pipe for drilling,
The mouth pipe has a water-stopping device capable of sealing between the mouth pipe and the drilling casing pipe.
An earth retaining wall characterized by: A retaining wall comprising a diaphragm wall having a core material and soil cement burying the core material, and an anchor reinforcing the diaphragm wall,
A preliminary hole is formed in the soil cement so as to be coaxial with an anchor pilot hole for accommodating the anchor, and a resin guide tube is fitted into the preliminary hole,
The anchor is inserted into the resin guide tube ,
The resin guide tube is supported by anti-slip protrusions attached to the core material.
An earth retaining wall characterized by: The resin guide tube has a flat plate portion at an end thereof,
The retaining wall according to claim 2 , characterized in that the flat plate portion is connected by bolts to a mouth pipe that guides a casing pipe for drilling. The retaining wall according to claim 3, characterized in that the mouth pipe has a water-stopping device capable of sealing between the mouth pipe and the drilling casing pipe. The anchor is supported via a pressure plate,
The retaining wall according to claim 2, characterized in that the resin guide pipe is arranged on the back side of the pressure plate. The retaining wall according to any one of claims 1 to 5 , characterized in that the inner diameter of the resin guide pipe is 100 mm or more and 500 mm or less. The retaining wall according to any one of claims 1 to 6 , characterized in that the resin guide pipe is reinforced with fiber. A step of constructing an earth retaining wall with a resin guide pipe embedded in soil cement;
a step of joining a water-stopping device capable of sealing between the resin guide pipe and a casing pipe for drilling to the resin guide pipe via a mouth pipe;
and a step of passing the drilling casing pipe through the plastic guide pipe, the mouth pipe and the water-stopping device to drill pilot holes for anchors.

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