JP4438540B2 - Stress bearing material and construction method for underground continuous wall - Google Patents

Description

  The present invention relates to a stress bearing material disposed under an underground buried wall or the like in an underground continuous wall and a construction method for placing the stress bearing material under the underground buried object or the like.

  For example, when an underground soil retaining wall composed of soil cement piles with columnar underground continuous walls is constructed, as shown in FIG. 7, a defect portion may be generated in the retaining wall 1 due to the buried object A such as a water pipe. . Such a defect portion has been conventionally dealt with by ground improvement work. That is, in FIG. 7, the earth retaining wall 1 which consists of the soil cement pile which uses H-shaped steel as a core material is constructed in the both sides of the buried object A, and the outer side (opposite side of the main body structure) of the defect part. The ground improvement bodies 50 and 50 by a high-pressure jet system are constructed on the left and right sides under the buried object A. Further, when the main structure B side of the retaining wall 1 is excavated to the excavation bottom surface L having a predetermined depth, a sheet pile 51 made of a horizontal member such as a square steel pipe is provided inside the defect portion (the main structure side). It is done.

Further, there are Patent Document 1 and Non-Patent Document 1 as prior art documents related to the present invention. In Patent Document 1, a lower part of an underground object is excavated with a chain cutter, an area between the object and an embedded object is excavated with a high-pressure jet, a solidified material is injected into the excavated part, a wall body is constructed, It is disclosed that a filling with a filling material is performed between an embedded object and a buried object. In Non-Patent Document 1, under the underground buried object, etc., a special excavator is used to dig open, the reinforcing bar cage is installed under the underground buried object, etc., and then concrete is placed. It is disclosed that an underground continuous wall having the same specifications as that of a general part is constructed under an underground buried object.
JP 2002-131484 A "Encyclopedia of Civil Engineering Methodology Revision V (Document)", Industry Research Association Encyclopedia Publication Center, February 26, 2001, p. 133 (Underground continuous wall openwork method)

  In the conventional method for constructing the ground improvement body in the deficient portion of the retaining wall described above, there are problems such as that it takes time for construction, a lot of material costs and the like, and the total construction cost increases.

  The present invention has been made to solve the above-mentioned problems, and in the construction of the underground continuous wall, the steel material equivalent to the general part is used for the defect part under the underground buried object, etc. Without using special equipment to install the underground continuous wall wall, it is possible to easily and quickly build an underground continuous wall with the same strength as the general part, and to reduce the overall construction cost. It aims at providing a burden material and a construction method.

The invention of claim 1 of the present invention is a stress bearing material for an underground continuous wall built as a core material in a drilling hole, and is a vertical member (H-shaped steel, etc.) comprising flanges at both ends and a web connecting the flanges. Are arranged so that a plurality of webs are parallel to each other, and a cross member (steel material having a cross-sectional H shape or the like) composed of a flange connecting the flanges at both ends is inserted into the through hole of the web of the vertical member, A stress-bearing material for an underground continuous wall, characterized in that a core material panel is formed, and an opening for reducing resistance during installation is formed in the web of the cross member.

  In other words, it is possible to move horizontally with multiple vertical members when constructing a wall body with a core material under a buried underground structure or structure in a continuous underground wall such as a soil retaining wall of soil cement piles. After building a core panel consisting of multiple horizontal members next to the underground objects in the excavation trench, the horizontal members are pushed out horizontally and moved as stress bearing materials under the underground objects. A large opening is provided in a horizontal web perpendicular to the direction in which the cross member is built so that it can be easily built in soil cement (mortar) or the like. In this case, there is no vertical member under the underground object, etc., and a plurality of horizontal members are cantilevered by the vertical member on the side. Used. Further, since it is not necessary to move the vertical member horizontally, it is only necessary to provide a through-hole through which the horizontal member penetrates a normal web such as H-shaped steel. The cross member is constructed so that earth pressure can be borne by cantilever.

The invention of claim 2 of the present invention, the stress burden material according to claim 1, the cross-piece web is stress burden material underground continuous wall, characterized by being formed by truss.

  That is to say, a large number of large openings can be arranged in the web of the cross member to reduce the resistance at the time of erection, but a truss is formed by assembling reinforcing bars, etc., and a parallel flange made of flat steel or the like is formed on the truss. It is preferable to connect with a web. The cross section modulus of the cross member, the diameter of the reinforcing bar, etc. and the truss shape are determined so that the earth pressure can be borne by the cantilever.

Invention of Claim 3 of this invention is a construction method of the underground continuous wall which installs the stress bearing material as a core material under the underground buried object etc. (a structure etc. are included), Claim 1 or 2 After the core panel described in 1 is built to the side of the buried object in the drilling hole, the transverse member is moved horizontally to the buried object side, and the transverse member is placed directly under the buried object. It is the construction method of the underground continuous wall. A groove excavator can be used for horizontal movement of the cross member.

In the present invention having the above-described configuration, the stress burden is obtained by excavating the underground material with a trench excavator or the like (openworking), building the core panel, and then horizontally moving the cross member. It is possible to place multiple cross members as materials underneath the underground burial, etc. A wall body is constructed.

  Since the present invention is configured as described above, the following effects can be obtained.

(1) Multiple cross members as stress bearing materials can be easily placed under underground buried objects, etc., and are continuous to the left and right underground continuous walls in the missing part under the underground buried objects etc. A wall body having a core material having a required strength can be constructed.

(2) It is only necessary to use the steel material equivalent to the general part without constructing the ground improvement body as before, and the strength equivalent to that of the general part without using a special device for installing the steel material. It is possible to easily and quickly construct an underground continuous wall having a wall and to reduce the overall construction cost.

(3) By using a truss web in which reinforcing bars are assembled in the shape of a truss for the cross member web of the core panel, it is possible to easily secure the required strength while forming a large opening for reducing the movement resistance. be able to.

Hereinafter, the present invention will be described based on the illustrated embodiments. This embodiment is an example applied to an underground soil retaining wall made of soil cement piles, and is a case where a stress bearing material is installed under an underground buried object. FIG. 1 shows the configuration and construction procedure of the first embodiment of the method of horizontally moving the entire stress bearing material. FIG. 2 shows details of the stress bearing material of the first embodiment. FIG. 3 shows the configuration and construction procedure of the second embodiment of the method of horizontally moving only the cross member of the stress bearing material according to the present invention . 4 and 5 show details of the stress bearing material of the second embodiment. FIG. 6 shows an example of a trench excavator that excavates under a buried object.

<First Embodiment>
As shown in FIG. 1, a plurality of vertical members 10 having an H-shaped cross section (seven in the illustrated example) are arranged in parallel at a predetermined pitch, and each vertical member 10 is connected by a connecting member 11 such as a flat steel. A core material panel P1 that can be inserted into the excavation groove T is formed. After this core panel P1 is assembled on the ground, suspended by a crane and built so as to be located in the excavation groove T next to the underground object A, the inside of the excavation groove T is below the underground object A (defects) Part).

  The upper part of the vertical member 10 is cut out so that several (three in the illustrated example) of the vertical members 10 can be positioned below the underground object A. It is preferable that the several vertical members 10 of the missing portion are gradually shortened toward the underground object A. As shown in FIG. 1 (b), the other vertical members 10 (four in the illustrated example) are arranged vertically on the side of the underground object A. Although not shown, a core material made of a single H-section steel is built in a normal manner on the side of the underground object A on the opposite side.

  As shown in FIG. 2, the vertical members 10 having an H-shaped cross section are arranged so that the webs 10b are parallel to the wall thickness direction, and are arranged in the wall longitudinal direction so that the webs 10b are parallel to each other. The parallel flanges 10a and 10a are located inside and outside the retaining wall. By using T-shaped steel (cut tee) obtained by cutting H-section steel at the center of the web for the parallel flanges 10a and 10a, and connecting the pair of T-shaped steel flanges 10a with rebars 12 assembled in a truss, the horizontal movement direction ( The web 10b perpendicular to the wall longitudinal direction is formed with almost openings so as to facilitate horizontal movement in the soil cement (mortar). The reinforcing bar 12 is composed of an X-shaped diagonal member and a horizontal member, and a double warren truss is formed by joining the respective end portions to the inner protruding portion of the T-shaped steel flange 10a by welding. Not limited to this, other truss types may be used.

  The vertical member 10 in which such a T-shaped steel flange 10a is connected by the truss web 10b has a shape having the same section modulus as that of the core H-shaped steel to be entered when there is no embedded object. Specifically, a necessary section modulus is obtained by the shape in which the pair of T-shaped steel flanges 10a and 10a are cut and arranged. The shearing force is borne by the rebar 12 assembled in a truss shape.

  The connecting material 11 is determined so as to be able to support its own weight when the whole is lifted by a crane, and a flat bar is attached to the outer surface of the T-shaped steel flange 10a of the vertical member 10 and fixed by welding or the like. The connecting material 11 is an X-shaped diagonal material and a horizontal material, and is arranged in a plurality of stages on the upper part from the excavation bottom L after the earth retaining wall is constructed.

  In addition, to give a numerical example of the earth retaining wall to be constructed, in a normal design (original design) that does not consider the buried object, the cross-sectional force is 1 m, for example, bending moment is Mmax = 691 kNm and shearing force is Smax = 395 kN In the case of the retaining wall under the buried object, when the pitch of the vertical members 10 is 0.6 m, Mmax = 415 kNm and Smax = 237 kN. Based on this, the required cross-section and truss-like reinforcing bars are determined.

<Second Embodiment>
As shown in FIG. 3, a plurality of vertical members 20 made of H-shaped steel (four in the illustrated example) are arranged in parallel at a predetermined pitch, and are arranged at a predetermined pitch up and down with respect to the web of each vertical member 20. The core material panel P2 that can be inserted into the excavation groove T is formed by inserting a plurality (21 in the illustrated example) of the cross members 21 having an H-shaped cross section. The core panel P2 is assembled on the ground, and the cross member 21 is protruded to the opposite side of the underground object A, and is hung by a crane so as to be positioned beside the underground object A in the excavation groove T. After being pushed in, all the cross members 21 are pushed and moved horizontally under the underground object A (defect portion). For the extrusion of the cross member 21, a groove excavator can be used.

  As shown in FIG. 3 (b), a plurality of cross members 21 are parallel to the bottom of the underground object A in a state where the vertical members 20 are vertically arranged on the side of the underground object A. Arranged. The length of the cross member 21 is set to a length that protrudes by a predetermined length while being cantilevered by all the plurality of vertical members 20. It is preferable to use several pieces (three in the illustrated example) on the upper side of the cross member 21 that gradually become shorter toward the underground object A. As shown in FIG. 4, a core material 30 made of a single H-section steel is built in a normal manner on the side of the underground object A opposite to the core material panel P <b> 2. The cross members 21 are arranged at the same pitch as the pitch of the vertical members 20, for example, in the upper part from the excavation bottom L after the earth retaining wall is constructed.

  As shown in FIG. 4, since the H-shaped steel vertical member 20 does not need to move horizontally, a normal H-shaped steel is used, and the web 20 b is disposed so as to be parallel to the wall thickness direction. The webs 20b are arranged in the wall longitudinal direction so as to be parallel, and the parallel flanges 20a and 20a are located on the inner side and the outer side of the earth retaining wall. As shown in FIG. 5A, the web 20b has a through hole (opening) 22 through which the cross member 21 passes. The opening size of the through hole 22 is the same as the cross section of the cross member 21 having an H-shaped cross section, and the cross member 21 is slidably supported.

  The cross members 21 having an H-shaped cross section are arranged in the vertical direction with the web 21b lying horizontally so that the parallel flanges 21a and 21a are positioned inside and outside the retaining wall. As shown in FIG. 5 (b), flat steel is used for the parallel flanges 21a and 21a, and this pair of flat steel is connected by a reinforcing bar 23 assembled to a truss, so that the web 21b perpendicular to the erection direction is almost open. It is formed so that resistance is reduced when it is built in soil cement (mortar). The reinforcing bar 23 is composed of a chord material joined to the inner surface of the flat steel flange 21a, an X-shaped diagonal material, and a horizontal material, and each of them is joined to the inner surface of the flat steel flange 21a by welding. Forming a truss. Not limited to this, other truss types may be used.

  In the case of this second embodiment, there is no vertical member in the portion of 2 m, for example, directly under the buried object (defect portion), so that the vertical member 20 having a width of 2.1 m, for example, is present in this range. About the four vertical members 20, it is set as the H-section steel which has a section modulus twice as large as a section modulus required when there is no buried object. For the cross member 21, a cross section and a truss-like reinforcing bar necessary for cantilevering against earth pressure are determined.

  In addition, to give a numerical example of the earth retaining wall to be constructed, in a normal design (original design) that does not consider the buried object, the cross-sectional force is 1 m, for example, bending moment is Mmax = 691 kNm and shearing force is Smax = 395 kN In the case of the earth retaining wall under the buried object, when the pitch of the vertical members 20 is 0.6 m, Mmax = 415 kNm and Smax = 237 kN, so that Mmax is doubled to bear the missing part. = 830 kNm and Smax = 474 kN. Based on this, the required cross-section and truss-like reinforcing bars are determined. Since the earth pressure near the bottom of excavation is 179 kN / m, the cross member 21 has a cross section and a truss-like reinforcing bar that can bear this earth pressure by cantilever.

  For example, a trench excavator 40 shown in FIG. 6 can be used as the trench excavator for excavating the underground buried object A. Under the underground buried object A is excavated (openworked) by a chain cutter 41 supported by taking a reaction force on the casing in the vertical shaft. Further, the cross member 21 can be pushed and moved by using the groove excavator 40. Not only this but other groove excavators can also be used.

  In addition, although the above demonstrated the earth retaining wall by a soil cement pile, it is applicable not only to this but another underground continuous wall.

It is a front view which shows the structure and construction procedure of 1st Embodiment of the system which moves the whole stress bearing material horizontally, (a) is at the time of installation, (b) shows after horizontal movement. The details of the stress bearing member of the first embodiment of FIG. 1 are shown, (a) is a front view, (b) is a horizontal cross-sectional view of a longitudinal member, and (c) is a side view of the longitudinal member. It is a front view which shows the structure and construction procedure of 2nd Embodiment of the system which moves only the crosspiece of the stress bearing material of this invention horizontally, (a) is at the time of construction, (b) is after horizontal movement of a crosspiece. Show. It is a front view which shows the detail of the stress bearing material of 2nd Embodiment of FIG. Fig. 4 shows the vertical and horizontal members, where (a) is a horizontal cross-sectional view of the vertical member, (b) is a side view of the vertical member, (c) is a vertical cross-sectional view of the cross member, and (d) is a cross-sectional view of the cross member. It is a top view. It is a front view which shows an example of the groove excavator which excavates under a buried object. It shows how to deal with the missing part under the underground soil retaining wall of soil cement piles. (A) is a horizontal sectional view and (b) is a front view.

Explanation of symbols

1 …… Underground continuous wall (ground soil retaining wall of soil cement pile)
10 …… Vertical material 10a… Flange (T-shaped steel flange)
10b ... Web (truss web)
DESCRIPTION OF SYMBOLS 11 ... Connecting material 12 ... Reinforcing bar 20 ... Vertical member 20a ... Flange 20b ... Web 21 ... Cross member 21a ... Flange (flat steel flange)
21b ... Web (truss web)
22 …… Through hole (opening)
23 ... Reinforcing bar 30 ... Core material 40 ... Groove excavator 41 ... Chain cutter A ... Underground object B ... Body structure T ... Excavation groove P1 ... Core material panel P2 ... Core material panel

Claims (3)

It is a stress bearing material for the underground continuous wall built as a core material in the drilling hole, and a plurality of vertical members consisting of flanges on both ends and webs connecting between the flanges are arranged so that the webs are parallel to each other. A core panel is formed by inserting a cross member composed of a web connecting between the flange and the web into a through hole of the vertical web, and the cross member web has an opening for reducing resistance during installation. A stress bearing material for underground continuous walls, characterized by being formed. 2. The stress bearing member according to claim 1 , wherein the cross member web is formed of a truss. It is a construction method of an underground continuous wall in which a stress bearing material as a core material is installed under a buried object etc. in the ground, and the core material panel according to claim 1 or 2 is lateral to the buried object in a drilling hole. A construction method for a continuous underground wall characterized in that, after being built in, a horizontal member is horizontally moved to the side of the buried object, and the transverse member is arranged directly under the buried object.

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