JP2012214980A - Construction method for underground wall and extraction method for core material of the underground wall - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for reducing the friction resistance force of a wall body against a core material to be extracted during extracting the core material embedded in the wall body from the wall body formed of a cement-based solidification material.SOLUTION: The construction method for an earth retaining wall 1 whose wall body 2 is formed of the cement-based solidification material and in which steel core materials 3 are embedded in the wall body 2, includes the steps of: connecting a negative electrode of a DC power supply 14 to the core material 3 to be extracted and a positive electrode of the DC power supply 14 to the other core material or a steel member 11 embedded in a ground; and using the DC power supply 14 for applying DC voltage between the core material 3 to be extracted and the other core material 3 or the steel member 11 before the cement-based solidification material is hardened.

Description

  The present invention relates to a method for constructing an underground wall in which a wall body is formed of a cement-based solidified material and a steel core material is embedded in the wall body, a method for extracting the core material of the underground wall, and the method for extracting The present invention relates to a method for forming a groundwater channel to be used and a method for opening a path of a shield machine.

  As a method of extracting multiple steel materials buried in the ground, connect the negative electrode of the DC power supply to the steel material to be extracted, connect the positive electrode of the DC power supply to the other steel material, apply a DC voltage to them, and then extract A method of drawing out a target steel material is known (for example, see Patent Document 1). In this steel material drawing method, an electroosmotic flow is generated between a pair of steel materials to which a DC voltage is applied, and moisture collects around the steel material to be drawn, thereby reducing the frictional resistance of the ground against the steel material drawing. This makes it easy to pull out the steel material.

Japanese Patent No. 3198598

  By the way, a core material may be pulled out from the underground wall constructed using the soil cement underground continuous wall construction method (hereinafter referred to as SMW construction method). In this case, when the above-described extraction method is applied, the negative electrode of the DC power source is connected to the core material to be extracted, and the positive electrode of the DC power source is applied to the steel material placed at a position away from the underground wall or the core material not to be extracted. And a DC voltage is applied to them. However, the wall body having a high water-stopping property formed of soil cement prevents the movement of moisture from the positive electrode to the negative electrode, so that the frictional resistance of the wall body against the drawing of the core material cannot be reduced.

  The present invention has been made in view of the above circumstances, and the friction of the wall body with respect to the extraction of the core material when the core material embedded in the wall body is extracted from the wall body formed of the cement-based solidified material. A method capable of reducing the resistance is provided.

  In order to solve the above problems, a method for constructing an underground wall is a method for constructing an underground wall in which a wall body is formed of a cement-based solidified material and a steel core material is embedded in the wall body. Before the cement-based solidified material is cured, the negative electrode of the DC power source is connected to the core material to be pulled out, and the positive electrode of the DC power source is connected to an electrode embedded in another core material or the ground, and the target to be pulled out by the DC power source. A step of applying a DC voltage between the other core material and the other core material or the electrode is carried out.

  Further, the method for extracting the core material of the underground wall is characterized in that the core material to be extracted is extracted from the underground wall constructed by using the underground wall construction method.

  In addition, the groundwater flow path is formed by extracting the core material of a part of the underground wall from the wall body using the method of extracting the core material of the underground wall, and the core of the underground wall. A groundwater flow path is formed in the underground wall by cutting out the wall body from which the material has been drawn.

  In addition, the method of opening the path of the shield machine uses the above-described method of pulling out the underground wall, the core material of a part of the underground wall constituting the wall of the start shaft of the shield tunnel is used for the start of the shield machine. The path is opened by pulling up from the path from the shaft.

  ADVANTAGE OF THE INVENTION According to this invention, when extracting the core material embed | buried under this wall body from the wall body formed with the cement-type solidification material, the frictional resistance force of the wall body with respect to extraction of a core material can be reduced.

It is an elevation view which shows the earth retaining wall constructed | assembled using the construction method of the underground wall which concerns on one Embodiment. It is a top view which shows a retaining wall. It is an elevation view which shows the state which has extracted the core material in the part for cutting of a retaining wall. It is an elevation view which shows the state which cut off the wall body of the part for cutting of a retaining wall. It is a top view for demonstrating the construction method of the underground wall which concerns on other embodiment. It is an elevation view which shows the earth retaining wall constructed | assembled using the construction method of the underground wall which concerns on other embodiment. It is an elevation view which shows the state which has pulled up the part to be excised of the earth retaining wall from the course of the shield machine. It is an elevation view which shows the state after extracting the core material of the part to be cut off of the retaining wall.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an elevation view showing a retaining wall 1 constructed using the underground wall construction method according to an embodiment, and FIG. 2 is a plan view showing the retaining wall 1. As shown in these drawings, the earth retaining wall 1 is constructed using the SMW method, and is a soil cement wall 2 formed by mixing and stirring cement milk as a cement-based solidifying material and soil. And a large number of steel cores 3 embedded in the wall 2.

  The core material 3 is H-shaped steel, and a large number of core materials 3 are arranged in the horizontal direction at predetermined intervals. The wall body 2 and the core material 3 extend to the clay layer 5 of the ground 4, and the flow of groundwater is blocked by the wall body 2 and the clay layer 5 which are water blocking walls.

  Here, when the groundwater level at the downstream side of the groundwater flow from the retaining wall 1 is lower than the groundwater level at the upstream side of the groundwater flow from the retaining wall 1, there is a well on the downstream side. Therefore, it is necessary to keep the groundwater level on the downstream side above a certain level. For this reason, for example, when the earth retaining wall 1 is constructed over a long distance, such as when the earth retaining wall 1 is constructed along a subway line or the like, the earth retaining wall is provided after the construction of the metro line or the like is completed. By excising a part of 1, a groundwater flow path is formed in a part of the earth retaining wall 1. Therefore, the retaining wall 1 is constructed using the method described below for the purpose of improving the workability of the step of cutting a part of the retaining wall 1.

  First, a wall 2 made of soil cement is formed in the ground using a method such as an in-situ stirring method, a replacement method, or a stable liquid solidification method, and the core material 3 is attached to the wall 2 before the soil cement is hardened. insert. And the following processes are implemented before hardening of soil cement.

  In this process, first, a steel material 11 having a hat-shaped cross section, which is a long steel member, is placed at a predetermined distance from the excision target portion 6 of the retaining wall 1 and the depth at which the lower end of the retaining wall 1 is located. It will be placed so that it will extend. Further, the steel material 11 is placed so as to face the central portion in the width direction of the portion 6 to be cut of the retaining wall 1.

  Further, steel rods 12 are attached to the upper ends of the plurality of core members 3 included in the excision target portion 6 of the retaining wall 1, and the plurality of core members 3 are electrically connected by the rod members 12. Moreover, the positive electrode of the DC power source 14 is connected to the steel material 11, and the negative electrode of the DC power source 14 is connected to the plurality of core members 3 included in the portion to be cut 6 of the retaining wall 1. Then, a DC voltage is applied between the steel material 11 and the plurality of core materials 3 included in the excision target portion 6 by the DC power source 14.

  Here, the normal ground contains a considerable amount of moisture and a considerable amount of electrolyte. For this reason, when a DC voltage is applied between the steel material 11 connected to the positive electrode and the plurality of core members 3 in the excision target portion 6 connected to the negative electrode, the plurality of core materials in the excision target portion 6 from the steel material 11 3 is generated, and moisture between the steel material 11 and the excision target portion 6 gathers around the core material 3 in the excision target portion 6.

  As a result, a moisture layer is formed at the boundary between the core member 3 and the wall body 2 in the excision target portion 6. That is, after the soil cement of the wall body 2 is hardened and the construction of the retaining wall 1 is completed, the core material 3 in the excision target portion 6 is cut from the wall body 2. Thereafter, one side of the retaining wall 1 is excavated to perform a predetermined foundation work, then the soil is backfilled, and finally the core material 3 of the portion 6 to be cut is pulled out. At that time, the adhesive force between the core material 3 and the wall body 2 in the excision target portion 6 is reduced, and the frictional resistance force of the wall body 2 against the extraction of the core material 3 in the excision target portion 6 is reduced. The voltage value, the voltage application time, the distance between the steel material 11 and the retaining wall 1, the depth of the retaining wall 1, the width of the portion 6 to be excised, the soil cement, the moisture content of the ground and the inclusion of electrolyte Set in consideration of the amount. Here, the time until the soil cement is hardened and the degree of electroosmotic flow are obtained in advance by experiments, and the voltage value, voltage application time, etc. are set according to the experimental results.

  FIG. 3 is an elevational view showing a state in which the core member 3 in the excision target portion 6 of the retaining wall 1 is pulled out. As shown in this figure, the core material 3 included in the excision target portion 6 is pulled out one by one from the wall body 2 in a state where the soil cement is cured. At this time, the core material 3 is pulled out using a hydraulic press (silent pillar) not shown, a crane not shown, or the like. In addition, when pulling out the core material 3 using a crane, it is necessary to make a hole for hooking the crane hook on the head of the core material 3.

  FIG. 4 is an elevational view showing a state in which the wall body 2 of the portion 6 to be cut of the retaining wall 1 has been cut. As shown in this figure, the portion of the wall body 2 from which the core material 3 has been drawn is excavated by a mechanical excavation method or the like and excised. Thereby, a groundwater flow path is formed in the earth retaining wall 1.

  Here, in this embodiment, when the earth retaining wall 1 is constructed, before the soil cement of the wall body 2 is hardened, the core in the excision target portion 6 from the steel material 11 placed in the vicinity of the excision target portion 6 is used. An electroosmotic flow to the material 3 was generated. Thereby, the process of pulling out the core material 3 in the portion 6 to be excised from the wall body 2 in a state where the soil cement is hardened, the adhesion between the core material 3 and the wall body 2 is reduced, and the core material 3 is pulled out. It can implement in the state by which the frictional resistance of the wall body 2 with respect to was reduced. Therefore, the operation | work which pulls out the core material 3 contained in the part 6 to be excised of the retaining wall 1 from the wall body 2 can be facilitated.

  Moreover, the process of cutting out a part of the earth retaining wall 1 can be performed in a state where only the soil cement exists without the core material 3 in the cut part of the wall body 2, and in this process, the soil cement is excavated. Thus, it is sufficient to cut and the work of cutting the core material 3 can be made unnecessary. Therefore, the operation | work which cuts off a part of earth retaining wall 1 can be facilitated.

  FIG. 5 is a plan view for explaining the underground wall construction method according to another embodiment. As shown in this figure, in the construction method of the retaining wall 1 according to the present embodiment, the following steps are performed before the cement of the wall body 2 is hardened.

  In this process, first, steel bars 12 are attached to the upper ends of a plurality of cores 3 included in the portion 6 to be cut of the retaining wall 1, and the cores 3 are electrically connected by the bars 12. To do. Further, the negative electrode of the DC power source 14 is connected to the plurality of core members 3 included in the portion 6 to be cut of the retaining wall 1, and the positive electrode of the DC power source 14 is connected to the core member 3 outside the portion to be cut 6 of the retaining wall 1. Connect. Then, by applying a DC voltage between the core material 3 outside the excision target portion 6 and the plurality of core materials 3 included in the excision target portion 6 by the DC power source 14, the excision target portion The electroosmotic flow from the outer core material 3 to the plurality of core materials 3 in the excision target portion 6 is generated.

  Thereby, it will be in the state where the some core material 3 in the part 6 to be excised is edge-cut from the wall body 2. FIG. After that, when the soil cement of the wall 2 is hardened and the construction of the retaining wall 1 is completed, one side of the retaining wall 1 is excavated to perform a predetermined foundation work, and then the soil is backfilled. Then, the core material 3 of the portion 6 to be excised is pulled out. At that time, the adhesion force between the core material 3 and the wall body 2 is reduced in the excision target portion 6, and the frictional resistance force of the wall body 2 against the core material 3 is pulled out.

  FIG. 6 is an elevation view showing the earth retaining wall 101 constructed using the underground wall construction method according to another embodiment. As shown in this figure, the earth retaining wall 101 is composed of a soil cement wall body 2 and a number of steel core members 3 embedded in the wall body 2, and is constructed by shield tunnel construction. The wall surface of the start shaft 7 of the shield machine (not shown) to be formed is configured. Here, a part of the core material of the retaining wall 101 blocks the path 8 of the shield machine. In this embodiment, the path 8 of the shield machine is opened by cutting a part of the retaining wall 101. . Therefore, for the purpose of improving the workability of the process of cutting off a part of the retaining wall 101, the following process is performed when the retaining wall 101 is constructed and before the soil cement of the wall body 2 is hardened. To implement.

  First, a steel material 111 that is a long steel member is placed facing the outer peripheral wall surface of the earth retaining wall 101. Further, the steel material 111 is placed at a predetermined distance from the pull-up target portion of the retaining wall 101 so as to extend to a depth at which the lower end of the retaining wall 101 is located. Further, the steel material 111 is placed so as to face the center in the width direction (lateral direction) of the portion to be pulled up of the retaining wall 101.

  Further, the positive electrode of the DC power supply 14 is connected to the steel material 111, and the negative electrode of the DC power supply 14 is connected to the core material 3 in the pull-up target portion of the retaining wall 101. Then, by applying a DC voltage between the steel material 111 and the core material 3 inserted in the lifting target portion of the retaining wall 101 by the DC power source 14, the steel material 111 moves to the lifting target portion of the retaining wall 101. An electroosmotic flow to the inserted core material 3 is generated.

  As a result, the core material 3 is cut off from the wall 2 at the portion to be pulled up of the earth retaining wall 101. Then, when the construction of the retaining wall 101 is completed by hardening the soil cement of the wall body 2, the inside of the retaining wall 101 is excavated to construct the start shaft 7, and then the core material of the lifting target portion 6 Pull 3 out. At that time, the adhesion force between the core material 3 and the wall body 2 is reduced in the portion to be pulled up of the earth retaining wall 101, and the frictional resistance force of the wall body 2 against the core material 3 being pulled out is reduced.

  FIG. 7 is an elevational view showing a state where the portion to be cut of the retaining wall 101 is pulled up from the path 8 of the shield machine. As shown in this figure, the core members 3 in the portion to be pulled up of the retaining wall 101 are pulled up one by one from the path 8 of the shield machine. At this time, the core material 3 is pulled up using a hydraulic press-fitting machine (silent pillar), a crane, or the like.

  FIG. 8 is an elevation view showing a state after the core material 3 of the part to be cut out of the retaining wall 101 is pulled out. As shown in this figure, when the core material 3 in the wall 2 is pulled out, the path 8 of the shield machine is opened, and excavation by the shield machine is started.

  Here, in the present embodiment, when the earth retaining wall 101 is constructed, before the soil cement of the wall body 2 is hardened, the steel material 111 embedded in the vicinity of the pulling target portion is changed to the core material 3 in the cutting target portion. Of electroosmotic flow. As a result, the step of pulling up the core material 3 in the portion to be pulled up from the wall body 2 in a state where the soil cement is hardened, the adhesion between the core material 3 and the wall body 2 is reduced, and the core material 3 is pulled out. It can implement in the state in which the frictional resistance of the wall 2 was reduced. Therefore, the work of pulling up the core member 3 included in the pull-up target portion of the retaining wall 101 from the course 8 of the shield machine can be facilitated.

  Further, the step of cutting a part of the earth retaining wall 101 can be performed in a state where only the soil cement is present in the cut portion of the wall body 2 without the core material 3, and in this step, the soil cement is shielded. Only excavating and excising with a machine is sufficient, and the work of cutting the core 3 can be made unnecessary. Therefore, it is possible to facilitate the work of excising a part of the earth retaining wall 101.

  In addition, the above-mentioned embodiment is for making an understanding of this invention easy, and does not limit this invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof. For example, in the above-described embodiment, the present invention has been described by taking the earth retaining walls 1 and 101 having a configuration in which the core 3 made of H-shaped steel is embedded in the wall body 2 formed of soil cement as an example. What is necessary is just to select suitably the composition of the cement-type solidification material which forms the body 2, and the shape of the steel core material 3 and the steel material 11. FIG. Moreover, in the above-mentioned embodiment, although steel materials were used as an electrode, you may use the member formed with materials, such as another metal and carbon, as an electrode. Furthermore, in the above-described embodiment, the steel material is cast to the depth of the underground wall, but the steel material may be shallower than the depth of the underground wall.

DESCRIPTION OF SYMBOLS 1 Earth retaining wall, 2 wall body, 3 core material, 4 ground, 5 clay layer, 6 part to be excised, 7 start shaft, 8 course, 11 steel material (electrode), 12 bar, 14 DC power supply, 101 earth retaining wall , 111 Steel (electrode)

Claims (4)

A method of constructing an underground wall in which a wall body is formed of a cement-based solidified material and a steel core material is embedded in the wall body,
Before the cement-based solidified material is cured, a negative electrode of a DC power source is connected to a core material to be pulled out, and a positive electrode of a DC power source is connected to another core material or an electrode embedded in the ground. A method for constructing an underground wall, comprising performing a step of applying a DC voltage between a core material and the other core material or the electrode.   A method for extracting a core material of an underground wall, wherein the core material to be extracted is pulled out from the underground wall constructed using the method for constructing an underground wall according to claim 1.   Using the method for extracting the core material of the underground wall according to claim 2, the core material of a part of the underground wall is extracted from the wall body, and the core material of the underground wall is extracted. A method for forming a groundwater flow path, wherein a groundwater flow path is formed in the underground wall by excising the wall body.   Using the underground wall drawing method according to claim 2, the core material of a part of the underground wall constituting the wall surface of the start shaft of the shield tunnel is pulled up from the course from the start shaft of the shield machine. The method of opening the route of the shield machine, characterized in that the route is opened.

Images