JP2012214979A - Extraction method for steel underground wall - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for effectively reducing the frictional resistance force of a ground against a steel underground wall to be extracted.SOLUTION: In the extraction method for a steel underground wall 1 embedded in a ground 3, a pair of steel members 11, 12 are embedded in the ground 3 so that one of the pair of steel members faces one wall face of the underground wall 1 and the other of the pair of steel members faces the other wall face of the underground wall 1, a positive electrode of a DC power supply 14 is connected to the pair of steel members 11, 12 and a negative electrode of the DC power supply 14 is connected to the underground wall 1, DC voltage is applied to the pair of steel members 11, 12 and the underground wall 1 by the DC power supply 14, and then the underground wall 1 is extracted from the ground 3.

Description

  The present invention relates to a steel underground wall drawing method, a groundwater flow path forming method using the method, and a shield machine path opening method.

  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, when pulling out the steel sheet pile constituting the underground wall using the above method, the steel material is placed at a position away from the steel sheet pile, the positive electrode of the DC power source is connected to this steel material, and the steel sheet pile is connected to the steel sheet pile. A negative electrode of a direct current power source is connected and a direct current voltage is applied to them. In this case, since the underground wall spreads in the horizontal direction and electroosmotic flow hardly occurs up to the surface on the opposite side of the negative electrode, the movement of moisture from the positive electrode to the negative electrode occurs only on one surface of the underground wall. That is, the frictional resistance of the ground against the drawing of the steel sheet pile cannot be effectively reduced.

  The present invention has been made in view of the above circumstances, and provides a method capable of effectively reducing the frictional resistance of the ground against drawing of a steel underground wall.

  In order to solve the above-mentioned problem, a method for extracting an underground wall is a method for extracting a steel underground wall embedded in the ground, wherein the first electrode faces one wall surface of the underground wall. Then, the second electrode is embedded in the ground so as to face the other wall surface of the underground wall, the positive electrode of the DC power supply is used as the first and second electrodes, and the negative electrode of the DC power supply is used as the underground It is connected to a wall, and after applying a DC voltage between the first and second electrodes and the underground wall by the DC power source, the underground wall is extracted from the ground.

  The underground wall may be pulled out of the ground after the DC voltage is applied between the first and second electrodes and the underground wall with a DC power source or may be applied.

  Further, the method for forming the groundwater flow path is to form the groundwater flow path in the underground wall by drawing a part of the underground wall from the ground using the method for extracting the underground wall. Features.

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

  ADVANTAGE OF THE INVENTION According to this invention, the frictional resistance force of the ground with respect to drawing of steel underground walls can be reduced effectively.

It is an elevation view which shows the earth retaining wall pulled out from the ground using the drawing method of the steel 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 is extracting the extraction object part of a retaining wall. It is an elevation view which shows the earth retaining wall pulled out from the ground using the drawing method of the steel underground wall which concerns on other embodiment. It is an elevation view which shows the state which has pulled up the extraction | drawer object part of a retaining wall from the course of a shield machine.

  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 that is pulled out from the ground 3 using a steel underground wall pulling method according to an embodiment, and FIG. 2 is a plan view showing the retaining wall 1. FIG. As shown in these drawings, the earth retaining wall 1 is a steel sheet pile wall constituted by a number of steel sheet piles (sheet piles) 2 placed on the ground 3.

  The steel sheet pile 2 is a U-shaped (hat type) steel sheet pile, and hook portions are formed at both ends, and the adjacent steel sheet piles 2 are connected in the lateral direction by engaging the hook portions with each other. ing. Further, the steel sheet pile 2 is driven up to the clay layer 4 of the ground 3 by a driving method such as a silent master (silent pile) method, and the retaining wall 1 and the clay in which the steel sheet pile 2 is connected in the horizontal direction. Layer 4 blocks the flow of groundwater.

  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 extracting a part of the steel sheet pile 2 from the ground 3, a groundwater flow path is formed in a part of the retaining wall 1. Then, the steel sheet pile 2 which comprises some retaining walls 1 is pulled out from the ground 3 using the method demonstrated below.

  First, a steel material 11 which is a long steel member is placed facing one wall surface of the retaining wall 1, and a steel material which is a long steel member facing the other wall surface of the retaining wall 1. 12 is placed. Further, the steel materials 11 and 12 are placed at predetermined positions from the drawing target portion 5 of the retaining wall 1 so as to extend to a depth at which the lower end of the retaining wall 1 is located. In addition, the steel materials 11 and 12 are placed so as to face each other across the center portion in the width direction (lateral direction) of the drawing target portion 5 of the retaining wall 1.

  Further, the steel materials 11 and 12 are connected to the positive electrode of the DC power source 14, and the pull-out target portion 5 of the retaining wall 1 is connected to the negative electrode of the DC power source 14. Then, a DC voltage is applied between the steel material 11 and the extraction target portion 5 of the retaining wall 1 and between the steel material 12 and the extraction target portion 5 of the retaining wall 1 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 materials 11 and 12 connected to the positive electrode and the extraction target portion 5 of the retaining wall 1 connected to the negative electrode, the extraction target portion of the retaining wall 1 from the steel materials 11 and 12. The electroosmotic flow to 5 occurs, and moisture between the steel materials 11, 12 and the extraction target portion 5 of the retaining wall 1 collects in the extraction target portion 5 of the retaining wall 1.

  As a result, a soft soil layer having a much larger amount of water than the surroundings is formed at the boundary between the drawing target portion 5 of the earth retaining wall 1 and the ground 3. That is, the drawing target portion 5 of the retaining wall 1 is cut from the ground 3. Accordingly, the adhesion force between the extraction target portion 5 of the retaining wall 1 and the ground 3 is reduced, and the frictional resistance force of the ground 3 against the extraction of the extraction target portion 5 of the retaining wall 1 is decreased. The voltage value, the voltage application time, the distance between the steel material 11 and the retaining wall 1, the placement depth of the retaining wall 1, the width of the drawing target portion 5, the moisture content of the ground 3, and the electrolyte content of the ground 3 Set in consideration of the amount.

  FIG. 3 is an elevational view showing a state in which the extraction target portion 5 of the retaining wall 1 is being extracted. As shown in this figure, after applying a DC voltage between the steel materials 11 and 12 and the retaining wall 1, the steel sheet piles 2 included in the drawing target portion 5 are pulled out one by one. Thereby, a groundwater flow path is formed in the earth retaining wall 1. At this time, the steel sheet pile 2 is pulled out using a hydraulic press-fitting machine (silent pillar) or a crane. In addition, when pulling out the steel sheet pile 2 using a crane, it is necessary to make a hole for hooking the hook of the crane on the head of the steel sheet pile 2.

  Here, since the earth retaining wall 1 spreads in the lateral direction, when an electroosmotic flow from the steel material serving as the positive electrode to the earth retaining wall 1 is generated only on one side of the earth retaining wall 1, the earth retaining wall is used. It is difficult to generate an electroosmotic flow up to the opposite surface of 1, and water collects only on one side of the earth retaining wall 1. Therefore, in this embodiment, not only the steel material 11 serving as the positive electrode is placed on the ground 3 on one side of the retaining wall 1, but also the steel material 12 serving as the positive electrode is disposed on the ground 3 on the back surface side. The electroosmotic flow from the steel materials 11 and 12 to the retaining wall 1 was generated not only on one side of the retaining wall 1 but also on both sides of the retaining wall 1. Thereby, it will be in the state where not only the single side | surface of the earth retaining wall 1 but both surfaces were edge-cut from the ground 3. FIG. Therefore, compared with the case where a steel material serving as a positive electrode is placed only on one side of the retaining wall 1, and an electroosmotic flow from the steel material to the retaining wall 1 is generated only on one side of the retaining wall 1, The adhesion between the retaining wall 1 and the ground 3 can be reduced, and the frictional resistance of the ground 3 against the withdrawal of the retaining wall 1 can be reduced.

  Therefore, the operation | work which extracts the steel sheet pile 2 contained in the extraction object part 5 of the earth retaining wall 1 from the ground 3 can be facilitated. Moreover, the adhesion of soil, particularly viscous soil, to the steel sheet pile 2 to be pulled out can be suppressed, and as a result, the cavity remaining in the ground 3 after the steel sheet pile 2 is pulled out can be suppressed to a minimum. It is possible to suppress the occurrence of land subsidence due to the remaining cavity, or to eliminate the work of filling this cavity.

  FIG. 4 is an elevational view showing a retaining wall 101 that is pulled out from the ground 3 using a steel underground wall pulling method according to another embodiment. As shown in this figure, the retaining wall 101 is a steel sheet pile wall constituted by a number of steel sheet piles 2 and is a wall surface of a start shaft 6 of a shield machine (not shown) constructed by a shield tunnel construction. Configure. Here, a part of the earth retaining wall 101 blocks the course 7 of the shield machine, and in this embodiment, a part of the earth retaining wall 101 is lifted from the course 7 of the shield machine so that the path 7 of the shield machine is improved. Open.

  First, a steel material 111, which is a steel long member, is placed on the ground on the bottom side of the start shaft 6, and a steel material 112, which is a steel long member, faces the outer peripheral wall surface of the retaining wall 101. To cast. Further, the steel members 111 and 112 are placed at predetermined intervals from the drawing 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. In addition, the steel materials 111 and 112 are placed so as to face each other across the central portion in the width direction (lateral direction) of the drawing target portion of the retaining wall 101.

  Further, the steel materials 111 and 112 are connected to the positive electrode of the DC power supply 14, and the negative electrode of the DC power supply 14 is connected to the drawing target portion of the retaining wall 101. Then, by applying a DC voltage between the steel material 111 and the portion to be pulled out of the retaining wall 101 and between the steel material 112 and the portion to be pulled out of the retaining wall 101 by the DC power source 14, the steel material 111. , 112 is caused to generate an electroosmotic flow from the retaining wall 101 to the drawing target portion.

  Thereby, it becomes the state by which the extraction object part of the earth retaining wall 101 was edge-cut from the ground. Therefore, the adhesion force between the extraction target portion of the retaining wall 101 and the ground is reduced, and the frictional resistance force of the ground against the extraction of the extraction target portion of the retaining wall 101 is reduced.

  FIG. 5 is an elevational view showing a state in which the part to be pulled out of the retaining wall 101 is pulled up from the path 7 of the shield machine. As shown in this figure, after applying a DC voltage between the steel materials 111, 112 and the retaining wall 101, the steel sheet piles 2 included in the portion to be pulled out of the retaining wall 101 are moved one by one to the path 7 of the shield machine. Pull up from. At this time, the steel sheet pile 2 is pulled up using a hydraulic press machine (silent pillar), a crane, or the like. Thereby, the course 7 of the shield machine is opened.

  Here, in the present embodiment, not only the steel material 112 serving as the positive electrode is placed on the ground on the outer peripheral side of the start shaft 6, but also the steel material 111 serving as the positive electrode is disposed on the ground on the bottom side of the start shaft 6. The electroosmotic flow from the steel materials 111 and 112 to the retaining wall 101 was generated not only on one side of the retaining wall 101 but also on both sides of the retaining wall 101. As a result, not only one side of the earth retaining wall 101 but also both sides are cut from the ground. Therefore, as compared with the case where a steel material serving as a positive electrode is placed only on one side of the retaining wall 101 and an electroosmotic flow from the steel material to the retaining wall 101 is generated only on one side of the retaining wall 101, The adhesion force between the earth retaining wall 101 and the ground can be reduced, and the frictional resistance of the ground against the withdrawal of the earth retaining wall 101 can be reduced.

  Therefore, the operation | work which pulls up the steel sheet pile 2 contained in the extraction object part of the earth retaining wall 101 from the course 7 of a shield machine can be facilitated. Further, it is possible to suppress the adhesion of soil, particularly viscous soil, to the steel sheet pile 2 to be pulled up, and as a result, it is possible to minimize the cavities remaining in the ground after the steel sheet pile 2 is pulled out, so that it remains on the ground. It is possible to suppress the occurrence of land subsidence due to the cavities, and to eliminate the need to fill the cavities.

  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 configured by the steel sheet pile 2 as an example. The present invention can be applied.

  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. Moreover, in the above-mentioned embodiment, after applying a DC voltage between the pair of steel materials and the retaining wall, the steel sheet pile of the retaining wall was pulled out, but the DC voltage between the pair of steel materials and the retaining wall. The steel sheet pile of the retaining wall may be pulled out while applying. Furthermore, in the above-described embodiment, the pair of steel materials are cast to the depth of the underground wall, but the depth of the pair of steel materials may be shallower than the depth of the underground wall.

DESCRIPTION OF SYMBOLS 1 Earth retaining wall (underground wall), 2 Steel sheet pile, 3 Ground, 4 Clay layer, 5 Drawing object part, 6 Starting shaft, 7 way, 11 Steel materials (1st electrode), 12 Steel materials (2nd electrode) , 14 DC power supply, 101 earth retaining wall (underground wall), 111 steel material (first electrode), 112 steel material (second electrode)

Claims (3)

A method of pulling out a steel underground wall buried in the ground,
The first electrode faces one wall surface of the underground wall, and the second electrode is embedded in the ground so as to face the other wall surface of the underground wall,
Connecting a positive electrode of a direct current power source to the first and second electrodes, and a negative electrode of the direct current power source to the underground wall;
After applying a DC voltage between the first and second electrodes and the underground wall by the DC power source,
A method of extracting the underground wall, wherein the underground wall is extracted from the ground.   A groundwater flow path, wherein a groundwater flow path is formed in the underground wall by extracting a part of the underground wall from the ground using the underground wall drawing method according to claim 1. Forming method.   By pulling up a part of the underground wall constituting the wall of the start tunnel of the shield tunnel from the course from the start shaft of the shield machine by using the underground wall drawing method according to claim 1, A method for opening a route of a shield machine, characterized by opening the route.

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