JPH0996194A - Structure of support wall and construction method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily form a support wall, by which a high support effect can be obtained even for a rock cavern having a large section. SOLUTION: A support wall 10 comprises a first shotcrete layer 11, a lock anchor 15 placed toward the natural ground 1, a frame unit 16 built like a grid, a second shotcrete layer 12 formed in such a manner as to cover the frame unit 16, a third shotcrete layer 13, a fourth shotcrete layer 14 and a PS anchor 17 placed toward the natural ground 1, in which prestress is introduced. An anchor install member 22 is disposed in the intersection point of a longitudinal lattice girder 20 and a lateral lattice girder 21 for forming the frame unit 16 with the cylindrical part 22a thereof brought into contact with the first shotcrete layer 11. A PS anchor 17 is installed in the anchor install member 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to supporting walls such as large cavities such as underground power plants and underground storage bases, and tunnels (herein, wall is used in a broad sense including not only side walls but also ceiling walls). Structure and construction method.

[0002]

2. Description of the Related Art In general, NATM (New Aust) is used as a construction method for excavating and supporting underground cavities such as underground power plants and tunnels.
rian Tunneling Method) has been adopted. This NA
As a structure of a support wall of an underground cavity to which TM is applied, for example, Japanese Patent Publication No. 6-6878 discloses a polygonal lattice structure formed by reinforcing concrete and shotcrete on the excavated surface of the underground cavity, and the lattice structure. Has proposed a technique provided with a rock bolt driven in the ground. The structure of this supporting wall is to support the entire cavity by supporting it from inside using steel bars, shotcrete, etc., to support the entire cavity by fixing only the area near the excavation surface, and to prevent concentrated loads with a lattice structure. It suppresses the loosening of the rocks and disperses the ground stress.

However, as the cavity becomes larger in cross section,
The loosened area near the excavation surface caused by excavation spreads, and there is a limit in the lining structure of this supporting wall supported from the inside of the cavity. For this reason, a support wall structure that further strengthens the support for the expanded loosened area in the large cavity is necessary.

Therefore, in recent years, as shown in FIG. 10 (a), a large cavity such as an underground power plant or an underground storage station is formed by spraying on the excavated surface 2 of the cavity formed by excavating the natural ground 1. Fig. 10 (b) showing a plurality of sprayed concrete layers 3 and the sprayed concrete layers 3 directed toward the natural ground 1.
The structure of the supporting wall provided with a plurality of rock bolts 4 driven as shown in FIG. 2 and a PS anchor 5 having a long PC steel wire introduced with prestress is applied. The structure of this supporting wall is that the large cavity has a larger cross section than a tunnel such as a normal road and the extent of influence by excavation is large. Therefore, instead of supporting the cavity from the inside, the long PS anchor 5 is not supported. Fix the end part to the back of the natural ground 1 and PS anchor 5
It is intended to support the large cavity by the introduction force of.

[0005]

However, the structure of the supporting wall described above still has the following problems.
That is, the PC steel wire of the PS anchor 5 is 100 to 150.
It has a self-weight of kg / piece, and in the case of upward facing construction in particular, PS anchor 5 is used to prevent falling until it is fixed with cement-based filler and prestress is introduced.
Must be temporarily fixed.

Therefore, conventionally, for example, as shown in FIG. 11A, the base end portion 5b of the PC steel wire 5a is replaced with the base end portion 5b.
The lock bolt 6 for temporary fixing is hung by a wire W or the like for temporary fixing, and in this fixing work, the lock bolt 6 for temporary fixing, the wire W, and the like.
There was a problem that it took time and effort to install the. Further, a large-diameter disk-shaped bearing plate 7 is attached to the base end portion 5b as a pressure bearing plate for transmitting the introduction force of the PC steel wire 5a to the sprayed concrete layer 3, and the bearing plate 7 is attached to the weight. Since it is a thing, a great deal of labor was required for its mounting work.

As shown in FIG. 11 (b), a bearing plate 7 is attached to the base end portion 5b of the PC steel wire 5a, and a blocking pipe 8 is attached to the PC steel wire 5a as a temporary fixing device. And the bearing plate 7 is fixed to the sprayed concrete layer 3 and the blocking pipe 8 by bolts 9. In this case, the blocking pipe 8 had to be prepared for each PS anchor 5, and the work of forming a hole 8a for burying the blocking pipe 8 in the rock mass of the excavation surface 2 was required.

The present invention has been made in consideration of the above points, and has a structure of a supporting wall capable of easily forming a supporting wall which can obtain a high supporting effect even for an underground cavity having a large cross section. And to provide a construction method thereof.

[0009]

The present invention has the following features to attain the object mentioned above. That is, in the structure of the supporting wall according to claim 1, a first sprayed concrete layer formed by spraying concrete on the excavated surface, and a lock cast from the first sprayed concrete layer toward the ground. An anchor, a frame body composed of a steel structural material extending in one direction assembled in a lattice along the first sprayed concrete layer and fixed to the lock anchor, and a concrete body covering the frame body. The second sprayed concrete layer formed by spraying more than one layer, and the base end portion was positioned at the intersection of the steel structural material of the frame body, was placed toward the ground, and prestress was introduced. A long PS anchor,
At the intersection of the steel structural members of the frame body on which the anchors are placed, one end is brought into contact with the first sprayed concrete layer, and a tubular part is formed integrally with the tubular part. An anchor installation member including a flat plate portion arranged on a side of the material that is separated from the excavation surface is provided, and the PS anchor is installed on the anchor installation member. .

In the structure of the supporting wall according to claim 2, in the structure of the supporting wall according to claim 1, the anchor installing member is joined to the steel structural member of the frame body on the plate portion of the anchor installing member. It is characterized in that a joining plate for forming is formed.

In the structure of the supporting wall according to claim 3, in the structure of the supporting wall according to claim 1, the anchor installation member extends in a direction orthogonal to the PS anchor and the second sprayed concrete layer. It is characterized in that the reinforcing bars embedded in the are integrally provided.

According to a fourth aspect of the present invention, in the method of constructing a supporting wall, a first step of spraying concrete on an excavated surface to form a first sprayed concrete layer, and a surface of the first sprayed concrete layer to a natural ground. The second step of placing the lock anchors toward each other, and the steel structural materials assembled in a grid pattern, and the anchor installation members for installing the PS anchors at the intersections of these steel structural materials. The frame body is arranged along the surface of the first sprayed concrete layer with the tip of the tubular portion formed on the anchor installation member abutting the first sprayed concrete layer, and the frame body is locked. A third step of fixing to the anchor and a fourth step of spraying one or more concrete onto the first sprayed concrete layer to form a second sprayed concrete layer so as to cover the frame body. If, while pouring a PC steel long in the land mountains from the anchor installation member, after the base end portion of the PC steel was temporarily fixed to the anchor installation member, the P
A fifth step of placing a PS anchor by introducing prestress into the C steel material and fixing the base end portion is characterized.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of first and second embodiments of a structure of a supporting wall and a construction method thereof according to the present invention will be described below with reference to FIGS. 1 to 9. Here, a supporting wall and a method for constructing the supporting wall according to the present invention will be described with reference to an example of a case where the supporting wall is used to form a supporting wall forming an underground cavity having an ultra-large cross section.

[First Embodiment] As shown in FIGS. 1 and 2, the supporting wall 10 for lining the excavated surface 2 of the underground cavity formed by excavating the natural ground 1 is the first sprayed concrete layer ( First sprayed concrete layer) 11, second sprayed concrete layer (second sprayed concrete layer) 12, third sprayed concrete layer (second sprayed concrete layer) 13, fourth
Sprayed concrete layer (second sprayed concrete layer) 14
A rock anchor 15 placed on the ground 1, a second sprayed concrete layer 12, a third sprayed concrete layer 13,
Frame body 1 buried in the fourth sprayed concrete layer 14
6 and a long PS anchor 17 which is cast on the natural ground 1 and prestressed therein.

As shown in FIG. 2, the first sprayed concrete layer 11, the second sprayed concrete layer 12, the third sprayed concrete layer 13, and the fourth sprayed concrete layer 14 have concrete of a predetermined thickness on the excavated surface 2. It is formed by being sequentially sprayed. And the first sprayed concrete layer 11,
Between the second sprayed concrete layer 12 and the third sprayed concrete layer 13, welded wire mesh (not shown) is buried.

In the lock anchor 15, a steel rod or steel cable material 15a is inserted into a hole 18 having a predetermined depth, which is drilled in the ground 1 and filled with mortar, and its base end portion is the first shotcrete concrete. It is configured to be fixed by a fixing member 19 arranged on the layer 11.

The frame body 16 is arranged along the entire excavation surface 2 and is fixed to the base end portions of the lock anchors 15, 15, ..., The second sprayed concrete layer 12 and the third sprayed concrete layer. 13, fourth sprayed concrete layer 1
It is buried in 4.

As shown in FIG. 3, the frame body 16 includes a longitudinal lattice girder (steel structural material) 20 extending in the circumferential direction of the excavation surface 2 and a direction orthogonal to the lattice girder (steel structural material) 20, that is, a direction of excavation of an underground cavity. The lateral lattice girders (steel structural materials) 21 that extend are formed by combining them in a grid pattern.

The longitudinal lattice girder 20 and the lateral lattice girder 21 are truss-shaped reinforcing bar structural members, respectively.
It is formed of four main bars S arranged at the four corners of the cross section and extending parallel to each other, and a plurality of lattice members R connecting the main bars S to each other. Further, joint plates 20a, 21a located in a plane orthogonal to the extending direction are provided at both ends of each of the vertical lattice girder 20 and the horizontal lattice girder 21.

A plurality of such vertical lattice girders 20 are continuously arranged along the circumferential direction of the excavation surface 2, and their joint plates 20a are brought into contact with each other to be connected by a bolt (not shown). There is. The lateral lattice girder 21 is connected by a bolt (not shown) in a state where the joint plate 21a is in contact with the side surface of the intermediate portion of the longitudinal lattice girder 20.

The PS anchors 17 are installed via anchor installation members 22 at predetermined intersections between the longitudinal lattice girders 20 and the lateral lattice girders 21 of the frame body 16 thus formed in a lattice shape. ing.

As shown in FIG. 4, the anchor installation member 22
Is a metal cylinder 22a having a predetermined length and a cylinder 22a.
a plate portion 22b integrally provided on one end side of a and joint plates 22c, 22c integrally formed with the plate portion 22b for attaching the anchor installation member 22 to the frame body 16 (see FIG. 3). Has been formed.
The joining plates 22c, 22c are arranged to face each other with a predetermined distance therebetween with the tubular portion 22a interposed therebetween. Here, the distance between the inner surfaces of the joining plates 22c and 22c is as shown in FIG.
The width of the vertical lattice girder 20 shown in FIG. 2 and the joint plates 21a of the horizontal lattice girders 21 connected to both sides thereof,
It is set to be substantially the same as the dimension obtained by adding the thickness of 21a. Then, the bolt holes 23,
23 is formed. Further, as shown in FIG. 4, the plate portion 22b is provided with temporary fixing metal fitting mounting holes 24, 24 used for temporarily fixing the PS anchor 17 (see FIG. 2).

As shown in FIG. 2, in this anchor installation member 22, the plate portion 22b is brought into contact with the surface of the frame body 16 on the side separated from the excavation surface 2, and the end surface of the tubular portion 22a is made into the first sprayed concrete. It is arranged in contact with the layer 11. Then, the joint plates 22c, 22c are bolted to the vertical lattice girder 20 integrally with the joint plate 21a of the lateral lattice girder 21 through the bolt holes 23, 23 (see FIG. 4). The member 22 is integrally attached to the frame body 16.

The PS anchor 17 is a PC steel stranded wire 1
7a was drilled from the cylindrical portion 22a of the anchor installation member 22 to the natural ground 1 and inserted into a hole 25 of a predetermined depth filled with mortar (not shown), and a prestress of, for example, about 100 t was introduced into this hole. In this state, the base end portion is fixed to the plate portion 22b of the anchor installation member 22 by the fixing grip 26.

Next, the supporting wall 1 having the above-mentioned structure
The construction method No. 0 will be described. As shown in Figure 1,
When excavating an underground cavity, every time the natural ground 1 is excavated at a constant distance in a horizontal direction, a plurality of regions A, B, C ...
The following lining process is performed sequentially for N, and the lining is performed for each region from the top.

[Coupling of Upper Area A] First, the ground 1 is excavated to form an area A which is an upper area of the underground cavity.

[First Spraying Concrete Layer Forming Step (First Step)] As shown in FIG. 2, after the leveling concrete is sprayed on the excavated surface 2 in the area A and smoothed to some extent,
Further, concrete is sprayed to form the first sprayed concrete layer 11 (in FIG. 5).

"Rock anchor placing step (second step)" A hole 18 having a predetermined depth is bored in the natural ground 1 through the first sprayed concrete layer 11 formed, and the hole 18 is filled with mortar. At the same time, the lock anchor 15 is inserted. Then, the fixing bracket 1 is attached to the base end of the lock anchor 15.
By attaching 9 and fixing it, excavation surface 2
Prevents local damage such as peeling of the rock surface in the vicinity (in Fig. 5). When the hole 18 is drilled, the hole 25 for placing the PS anchor 17 is also drilled at the same time.

"Frame body building step (third step)" Next, a welded wire net (not shown) is built along the surface of the first sprayed concrete layer 11, and then the frame body 16 is provided inside thereof. Assemble and build in the prescribed shape shown in (See Fig. 5). At this time, in the frame body 16, the anchor installation member 22 located at the intersection of the vertical lattice girder 20 and the horizontal lattice girder 21 is first drilled into the hole 2
5, the tubular portion 22a is brought into contact with the first sprayed concrete layer 11, and then fixed to the lock anchor 15. It should be noted that the frame body 16 is assembled by previously assembling the vertical lattice girder 20 and the horizontal lattice girder 21 into a predetermined size into a unit and further incorporating the anchor installation member 22 so that the assembling work can be performed. It can be done efficiently.

[Second to fourth sprayed concrete layer forming step (fourth step)] Next, concrete is sprayed so as to cover a part of the frame body 16 to form the second sprayed concrete layer 12. Then, along the surface of the second sprayed concrete layer 12, a welded wire mesh (not shown) is built only in a portion corresponding to the lattice space of the frame body 16.
At this time, the welded wire mesh (not shown) is attached to the lock anchor 1
5 is fixed via fixing metal fittings (not shown). And
After the welding wire net (not shown) is built, concrete is further sprayed to form the third sprayed concrete layer 13 having a predetermined thickness so as to cover the intermediate portion of the frame body 16. Subsequently, concrete is sprayed to cover the rest of the frame body 16 to form the fourth sprayed concrete layer 14 (in FIG. 5).

"PS anchor placing step (fifth step)"
After filling the mortar or the like in the hole 25 drilled in the ground 1, the PC steel strand 17a is inserted from the cylindrical portion 22a of the anchor installation member 22 into the hole 25 drilled in the ground 1 and the base thereof is inserted. The end portion is temporarily fixed to the anchor installation member 22.

At this time, for example, the following is used as a temporary fixing means for the PC steel stranded wire 17a to be cast upward. As shown in FIG. 6, a male screw M is formed on the base end portion of the PC steel strand 17a, and a temporary fixing nut 27 is screwed onto the male screw M. Further, a temporary fixing metal fitting 28 having a hole 28a smaller than the outer diameter of the temporary fixing nut 27 is formed in the central portion, and the PC steel stranded wire 17a is passed through the hole 28a, and this is attached to the plate portion 22b of the anchor installing member 22.
Bolts 29 in the temporary fixing metal mounting holes 24, 24 formed in
Fix at 29. As a result, the temporary fixing nut 27 is locked to the temporary fixing metal fitting 28, and the PC steel stranded wire 17a does not fall out.

After introducing the prestress into the PC steel stranded wire 17a after the temporary fixing, the temporary fixing metal fitting 28 and the tentative fixing nut 27 are removed, and the PC steel stranded wire 17a is tensioned by a prestress introducing means (not shown). In the state where a predetermined prestress (for example, 100 t) is introduced, as shown in FIG. 2, the grip 2 for fixing to the PC steel stranded wire 17 a
6 is attached and the PS anchor 17 is fixed (in FIG. 5). As a result, the supporting wall 10 is constructed on the excavated surface 2 in the area A shown in FIG.

[Layering of Regions B, C ... N] After the lining of the region A is completed in this way, the ground 1 below is excavated to a certain depth to form the next region B. Also in this region B, as in the region A, the above-mentioned first spraying concrete layer forming step, lock anchor placing step, frame body building step, second to fourth spraying concrete layer forming step, and PS anchor placing step. Depending on the process, lining will be performed. Further, after the lining of the region B is completed, the excavation is repeated in the same manner, and the lining is performed by each of the above steps up to the region N, which is the lowermost region. The wall 10 is built.

Next, the effect obtained by the structure of the supporting wall 10 and the construction method thereof will be described. The support wall 10 includes a first sprayed concrete layer 11, a lock anchor 15 placed toward the natural ground 1, a frame body 16 assembled in a lattice shape, and a second frame body 16 formed so as to cover the frame body 16. Sprayed concrete layer 12, third sprayed concrete layer 13, fourth sprayed concrete layer 14, and ground 1
It is composed of a PS anchor 17 which is driven toward and is prestressed. And the frame body 1
An anchor installation member 22 is provided at an intersection of the vertical lattice girder 20 and the horizontal lattice girder 21 constituting 6 with its tubular portion 22a abutting the first sprayed concrete layer 11. PS anchor 1
7 is installed. Further, such a supporting wall 10 is constructed by a first spraying concrete layer forming step, a lock anchor placing step, a frame body building step, second to fourth spraying concrete layer forming step, and a PS anchor placing step. It is configured to go. In such a supporting wall 10, the PS anchor 17 fixed to the natural ground 1 restrains the loose area of the excavation surface 2 caused by the prestress due to the prestress, and prevents the rock mass of the natural ground 1 from sliding. It is supposed to suppress. And the frame body 1
6, the first sprayed concrete layer 11, the second sprayed concrete layer 12, the third sprayed concrete layer 13, the fourth
The sprayed concrete layer 14, the lock anchor 15, and the PS anchor 17 are integrated. Furthermore, PS anchor 17
Is fixed to the intersections of the frame body 16, so a large introduction force of about 100t applied to the PS anchors 17 is dispersed and transmitted in four directions by the vertical lattice girders 20 and the lateral lattice girders 21 constituting the intersections. It is dispersed over the entire frame body 16, and the concentration of natural stress on the base end portion of the PS anchor 17 is suppressed. Therefore, in comparison with the conventional structure in which the rock mass only in the vicinity of the excavation surface 2 is simply fixed with the rock bolt, the supporting wall 10 constitutes a strong supporting structure by restraining the entire loose area of the underground cavity. be able to.

Further, since the anchor installation member 22 functions as a bearing plate for the PS anchor 17 and fixes it, a large bearing plate as in the conventional case is not required, and the anchor is compact and lightweight. Workability can be improved by the installation member 22.
Moreover, since the anchor installation member 22 is incorporated in the frame body 16 and embedded in the fourth sprayed concrete layer 14, the appearance of the support wall 10 can be improved. Furthermore, the PS anchor 1 is provided by the tubular portion 22a of the anchor installation member 22 during concrete spraying in the second to fourth spray concrete layer forming steps.
It is possible to secure a hole for driving 7 and improve workability. In addition, the joint plates 22c, 22 formed on the anchor installation member 22
Due to c, the anchor installation member 22 can be easily and reliably attached to the intersection of the longitudinal lattice girder 20 and the lateral lattice girder 21 that form the frame body 16.

Further, in the PS anchor setting process, P
The S anchor 17 is temporarily fixed to the anchor installation member 22 by a simple and lightweight member such as the temporary fixing metal fitting 28 described above. As a result, a lock anchor for temporary fixing becomes unnecessary, and work such as shaping the sprayed concrete surface or placing leveling mortar becomes unnecessary, so that the labor for construction can be saved and the cost can be suppressed. Further, in the second to third sprayed concrete layer forming steps, the frame body 16 built in the frame body building step can be used as a ruler, so that the second sprayed concrete layer 1
The appearance of the support wall 10 can be improved by making the finished shapes of the second, third sprayed concrete layer 13 and the fourth sprayed concrete layer 14 less uneven.

In addition, since the underground cavity is repeatedly excavated and lined for each region from the upper region A to the lower region N,
Since the upper part of the lining work area in the underground cavity is always supported, it is possible to form an underground cavity with a large cross section while ensuring work safety.

[Second Embodiment] Next, a second embodiment of the structure of the supporting wall and the construction method thereof according to the present invention will be described. Here, the only difference between the support wall 40 of the second embodiment described below and the support wall 10 described in the first embodiment is the anchor installation member for installing the PS anchor 17. Since other structures and construction methods are the same, only the differences will be described, and description of common configurations will be omitted.

As shown in FIG. 7, the supporting wall 40 includes a first sprayed concrete layer 11, a lock anchor 15 cast toward the natural ground 1, a frame body 16 assembled in a lattice shape, and a frame. A second sprayed concrete layer 12, a third sprayed concrete layer 13, formed so as to cover the body 16;
It is composed of a fourth sprayed concrete layer 14 and a PS anchor 17 that is cast toward the natural ground 1 and introduced with prestress. Then, as shown in FIG. 8, the anchor installation member 41 is provided at the intersection of the vertical lattice girder 20 and the horizontal lattice girder 21 which form the frame body 16, and the PS anchor 1 is attached to the anchor installation member 41.
7 is installed.

As shown in FIG. 9, the anchor installation member 41
Is a tubular portion 41a made of metal and having a predetermined length, and a tubular portion 41a.
Rectangular plate portion 41b integrally provided on one end side of a
, Plate-shaped blade portions 41c, 41c, ... Radially extending from the tubular portion 41a toward the four corners of the plate portion 41b, and a reinforcing bar 41d integrally attached to these blade portions 41c,
41d, ... Reinforcing bars 41d, 41
d, ... Are provided at both end portions and the middle portion of the tubular portion 41a, respectively.
In the plane orthogonal to the PS anchor 17 shown in FIG. 7, the reinforcement is arranged so as to extend parallel to the main reinforcement S of the adjacent lattice lattices 20 in the vertical direction and the lattice lattice 21 in the horizontal direction. As shown in FIG. 9, the plate portion 41b has PS
Temporary fixing metal fitting mounting holes 24, 24 for mounting the temporary fixing metal fitting 28 (see FIG. 6) when temporarily fixing the anchor 17 (see FIG. 7) are formed.

In this anchor installation member 41, the plate portion 41b is brought into contact with the surface of the frame body 16 on the side separated from the excavation surface 2, and the end surface of the tubular portion 41a is brought into contact with the first sprayed concrete layer 11. And is integrated with the frame body 16 by welding or the like.

The construction method of the supporting wall 40 having such a structure is such that the frame body 16 is
Except that the anchor installation member 41 is previously attached to
The construction is exactly the same as the construction method of the supporting wall 10 described in the first embodiment.

According to the structure of the supporting wall 40 and the construction method thereof, the same effects as those of the structure of the supporting wall 10 and the construction method thereof shown in the first embodiment can be obtained. Further, the anchor installation member 41 is the frame body 16
The PS anchor 17 is provided at the intersection of the vertical lattice girder 20 and the horizontal lattice girder 21 that configure the above. Then, in the anchor installation member 41, reinforcing bars 41d, 41d, ... Which extend in a direction orthogonal to the PS anchor 17 are formed.
Is provided. As a result, the anchor installation member 41 that functions as a pressure support plate for the PS anchor 17 includes the reinforcing bars 41d, 41d, ... And the second sprayed concrete layer 1
By the concrete sprayed to form the second, third sprayed concrete layer 13 and the fourth sprayed concrete layer 14, a so-called reinforced concrete structure is formed, and the bearing pressure can be further increased.

In the first and second embodiments, the number of sprayed concrete layers forming the supporting walls 10 and 40 is not limited, and the lining thickness,
It may be set as appropriate according to the construction procedure. Further, the lock anchor 15 is not limited to the above-described form such as the material and the structure thereof, and in order to obtain the required performance or to facilitate the construction, for example, instead of the lock anchor 15, a cable is used. It is possible to adopt various things such as. The same applies to the PS anchor 17, and instead of the PC steel twisted wire 17a, a PC steel wire, a PC steel rod or the like may be adopted. In addition, regarding the shapes of the anchor installation members 22 and 41 for fixing the PS anchor 17,
Similarly, any shape may be used. further,
Regarding the tubular portions 22a and 41a of the anchor installation members 22 and 41, holes for placing the PS anchors 17 at the time of concrete spraying of the second sprayed concrete layer 12, the third sprayed concrete layer 13, and the fourth sprayed concrete layer 14. Any material other than metal may be used as long as it can ensure the above. Further, the frame body 16 is made of a lattice-shaped reinforcing bar structural material such as the longitudinal lattice girder 20 and the horizontal lattice girder 21, but for example, a truss-shaped reinforcing bar structural material or a steel frame structural material made of shaped steel such as H steel. Other steel structural materials may be used. Then, although the frame body 16 is constructed in the shape of a square lattice, it may be formed in a lattice shape of another shape. For example, a triangular lattice may be used.

Further, in each of the above-mentioned embodiments, the case where the present invention is applied to the lining wall of the underground cavity has been described, but the present invention is not limited to this, and other supporting walls such as supporting walls for tunnels and It can also be applied to a continuous earth wall cliff wall, etc.

[0047]

As described above, according to the structure of the supporting wall according to the first aspect, the first shotcrete concrete layer, the lock anchor cast toward the natural ground, and the steel anchor extending in one direction. A frame body formed by assembling structural members in a lattice shape and fixed to a lock anchor, a second sprayed concrete layer formed so as to cover the frame body, and a long PS anchor into which prestress is introduced. And, an anchor installation member comprising a tubular part that is brought into contact with the first sprayed concrete layer and a flat plate part is arranged at the intersection of the steel structural members of the frame body, and the anchor installation member is The PS anchor was installed. In such a support wall structure, the loosened area of the excavation surface is constrained by the PS anchor that is driven into the ground and introduced with prestress. The frame body can integrate the first sprayed concrete layer, the second sprayed concrete layer, the lock anchor, and the PS anchor. Also, P
Since the S anchor is fixed to the intersection of the steel structural members, the introduction force is dispersed and transmitted to the surroundings by the steel structural members forming the intersection. As a result, the entire supporting wall is integrated and restrains the entire loose area of the underground cavity, disperses the ground stress and suppresses concentrated load and partial displacement, while the steel structural material itself is the supporting effect. Since it is improved, a strong supporting structure can be obtained even in an underground cavity with a large cross section. Also, since the anchor installation member functions as a bearing plate for the PS anchor and fixes it, a large bearing plate is no longer required as in the conventional case, and the PS installation can be made smaller and lighter by the anchor installation member.
The anchor can be fixed, and the workability and safety can be improved. In addition, the tubular portion of the anchor installation member can secure a hole for placing the PS anchor when spraying concrete to form the second sprayed concrete layer, thereby improving workability. be able to.

According to the structure of the supporting wall of the second aspect of the present invention, the joint plate for joining to the steel structural material of the frame body is formed on the plate portion of the anchor installation member. Accordingly, the anchor installation member can be easily and surely attached to the intersection of the steel structural members of the frame body.

According to the structure of the supporting wall of the third aspect, the anchor installing member is integrally provided with the reinforcing bar extending in the direction orthogonal to the PS anchor. As a result, PS
The anchor installation member functioning as a pressure bearing plate for the anchor is, so to speak, a reinforced concrete structure made up of the reinforcing bars and the concrete sprayed to form the second sprayed concrete layer, and the supporting pressure is further increased to the claim 1. This effect can be made more prominent.

According to the method of constructing the supporting wall according to claim 4, the supporting wall is formed by the first spraying concrete layer forming step, the lock anchor placing step, the frame body installing step and the second spraying concrete layer forming step. , And PS anchor construction process. Then, in the frame body building process, the lattice-shaped frame body is
The anchor installation member incorporated at the intersection was built with the tip of the tubular portion in contact with the first sprayed concrete layer. Thereby, when concrete is sprayed in the second sprayed concrete layer forming step, a hole for driving the PS anchor can be secured by the tubular portion of the anchor installation member, and the workability can be improved. Further, in the second sprayed concrete layer forming step, the grid-shaped frame body can be used as a ruler, and the finished shape of the sprayed concrete can be improved to reduce irregularities. Further, in the PS anchor placing step, since the base end of the PS anchor is temporarily fixed to the anchor installation member, it becomes possible to perform temporary fixing with a simple member and no special member such as a lock bolt for temporary fixing is required. In addition, the work of shaping the surface of the sprayed concrete layer becomes unnecessary, and the efficiency of temporary fixing work and the reduction of construction cost can be achieved.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing one form of a support wall structure according to the present invention.

FIG. 2 is an enlarged cross-sectional view showing a main part of a first form of the structure of the support wall.

FIG. 3 is an elevational view showing a lattice-shaped frame body forming the support wall.

FIG. 4 is a perspective view showing an example of an anchor installation member incorporated in the frame body.

FIG. 5 is a perspective view for explaining a construction procedure in one mode of the construction method of the supporting wall according to the present invention.

FIG. 6 is a cross-sectional view showing a temporary fixing structure of a PS anchor with the anchor installation member.

FIG. 7 is an enlarged cross-sectional view showing a main part of a second form of the structure of the support wall.

FIG. 8 is an elevational view showing a lattice-shaped frame body forming the support wall.

FIG. 9 is a perspective view showing an example of an anchor installation member incorporated in the frame body.

FIG. 10 is a schematic cross-sectional view showing a structure of a conventional supporting wall and a placement layout drawing of PC anchors and lock bolts.

FIG. 11 is a cross-sectional view showing a temporary fixing structure of a conventional PC anchor.

[Explanation of symbols]

1 rock mass 2 excavated surface 10, 40 support wall 11 first sprayed concrete layer (first sprayed concrete layer) 12 second sprayed concrete layer (second sprayed concrete layer) 13 third sprayed concrete layer (second sprayed concrete layer) Concrete layer) 14 Fourth sprayed concrete layer (second sprayed concrete layer) 15 Lock anchor 16 Frame body 17 PS anchor 20 Longitudinal direction lattice girder (steel structural material) 21 Lateral direction lattice girder (steel structural material) 22, 41 Anchor installation member 22a, 41a Cylinder part 22b, 41b Plate part 22c Joining plate 41d Reinforcing bar

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kosuke Kakimi 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Makoto Hasegawa 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Masahiro Masaya 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Akira Fujino 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. ( 72) Inventor Eigo Kojima 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd.

Claims (4)

[Claims] 1. A first sprayed concrete layer formed by spraying concrete on an excavated surface, a lock anchor cast from the first sprayed concrete layer toward the ground, and a steel extending in one direction. A frame body having a structure in which the structural material is assembled in a lattice shape along the first sprayed concrete layer and fixed to the lock anchor; and one or more concrete sprayed so as to cover the frame body. And a second sprayed concrete layer, and a long PS anchor having a base end located at the intersection of the steel structural members of the frame body, which is placed toward the natural ground and prestressed. At the intersection of the steel structural members of the frame body on which the PS anchor is placed, one end is brought into contact with the first sprayed concrete layer, and the tubular part is formed integrally with the tubular part. And an anchor installation member provided with a flat plate-shaped plate portion arranged on a side of the steel structural member separated from the excavation surface, and the PS anchor is installed on the anchor installation member. The structure of the supporting wall, which is characterized by being 2. The structure of the supporting wall according to claim 1,
A supporting wall structure, wherein a joining plate for joining the anchor installing member to the steel structural material of the frame body is formed in the plate portion of the anchor installing member. 3. The support wall structure according to claim 1, wherein:
A structure of a supporting wall, wherein the anchor installation member is integrally provided with a reinforcing bar that extends in a direction orthogonal to the PS anchor and is embedded in the second sprayed concrete layer. 4. A first step of spraying concrete on an excavated surface to form a first sprayed concrete layer, and a second step of placing a lock anchor from the surface of the first sprayed concrete layer toward the ground. And the anchor installation member for installing the PS anchor at the intersection of these steel structural members, which is composed of steel structural members assembled in a grid pattern, is formed on the anchor installation member. In a state in which the tip of the formed tubular portion is in contact with the first sprayed concrete layer, the third step of arranging along the surface of the first sprayed concrete layer and fixing to the lock anchor, A fourth step of spraying one or more concrete onto the first sprayed concrete layer to form a second sprayed concrete layer so as to cover the frame body; By placing a long PC steel material therein, temporarily fixing the base end portion of the PC steel material to the anchor installation member, and then introducing prestress to the PC steel material to fix the base end portion. And a fifth step of placing a PS anchor.