JP6245741B2 - Construction method for buried structures - Google Patents

Description

  The present invention relates to a method for constructing a buried structure.

  Conventionally, as one of the techniques for embedding an embedded structure so as to cross from a contaminated section where soil contamination is recognized to an uncontaminated section where soil contamination is not recognized, for example, a soil cement wall which is an embedded structure A plurality of construction methods for crossing from a contaminated compartment to a non-contaminated compartment, which are part of the plurality of soil cement walls and are arranged near the boundary between the contaminated compartment and the non-contaminated compartment. The construction method which forms a part as a water-impervious part which has water-imperviousness is proposed (for example, refer patent document 1). This impermeable part is formed by replacing the soil in the vicinity of the boundary between the contaminated compartment and the non-contaminated compartment with fluidized soil (specifically, mud mortar) using the all casing method, for example. It arrange | positions so that a part of water part may overlap with a part of some soil cement wall.

JP 2013-174086 A

  However, in the conventional method described above, for example, a soil cement wall that is arranged so as to overlap with a part of the impermeable portion can be constructed until the fluidized soil embedded in the impermeable portion is compacted. Since it was not possible, the problem that construction time became long had arisen. In addition, when constructing a soil cement wall that is arranged so as to overlap with a part of the water-impervious part, if considering the formation of the water-impervious part using the all casing method, after forming the water-impervious part Since the soil cement wall arranged so that it overlaps will be constructed, there was a problem that the degree of freedom of construction became low.

  The present invention has been made in view of the above, and provides a method for constructing an embedded structure that enables the construction time to be shortened and the degree of freedom of construction to be improved. With the goal.

  In order to solve the above-described problems and achieve the object, the construction method of the buried structure according to claim 1 is a non-contaminated area where the soil is not contaminated and an area where the soil is contaminated. In a construction target area including a contaminated area, a method of constructing an embedded structure that is embedded so as to cross from the non-contaminated area to the contaminated area, the boundary between the contaminated area and the non-contaminated area A contamination diffusion prevention region to be formed, which is formed on the outer edge of the formation planned region where the formation of a contamination diffusion prevention region for preventing the soil of the contamination region from diffusing into the non-contamination region is formed. A partition wall burying step of burying a partition wall for partitioning the planned region from the outside, a removing step of removing soil in the planned formation region where the partition wall is embedded in the partition wall burying step, and the removing step Embedded in the formation planned region where the soil was removed in the formation step, forming the contamination diffusion prevention region, and embedded in the outer edge of the contamination diffusion prevention region formed in the formation step A removal step of removing the partition wall, and a buried structure burying step of burying the buried structure so that at least a part of the buried structure is disposed in the contamination diffusion prevention region.

  Moreover, the construction method of the embedded structure according to claim 2 is the construction method of the embedded structure according to claim 1, wherein a plurality of the embedded structure are arranged substantially along a direction from the non-contaminated region to the contaminated region. A ground improvement body in which a plurality of ground improvement bodies are arranged so that a part of each of the plurality of ground improvement bodies overlaps with a part of another adjacent ground improvement body. Including a body burying step, a part of the ground improvement body burying step is performed as the buried structure burying step, thereby burying a part of the plurality of ground improvement bodies as the buried structure.

  Moreover, the construction method of the buried structure according to claim 3 is the construction method of the buried structure according to claim 2, wherein the ground improvement body buried as the buried structure does not reach the contamination area. And a ground improvement body that is adjacent to the ground improvement body and is disposed in an area that reaches the contaminated area, and after removing the partition wall in the removal step In the buried structure burying step, after the ground improvement body arranged in the area not reaching the contaminated area is buried, the ground improvement body arranged in the area reaching the contaminated area is buried.

  Moreover, the construction method of the buried structure according to claim 4 is the construction method of the buried structure according to claim 2 or 3, wherein the plurality of ground improvement bodies in the ground improvement body burying step, Embedding sequentially from the non-contaminated area to the contaminated area.

  Moreover, the construction method of the embedded structure according to claim 5 is the construction method of the embedded structure according to any one of claims 1 to 4, wherein in the formation step, the ground surface of the planned formation region When the embedded structure is embedded in the embedded structure embedding step, the amount of soil necessary for embedding the healthy soil until the non-contaminated area and the ground surface of the contaminated area are substantially flush with each other. The amount of the healthy soil obtained by subtracting the amount of soil discharged is embedded in the planned formation area.

  According to the construction method of the buried structure according to claim 1, in the forming step, the pollution diffusion prevention region is formed by embedding healthy soil at the boundary between the non-contaminated region and the contaminated region, and the buried structure is buried. In the process, since the embedded structure is embedded so that at least a part of the embedded structure is disposed in the pollution diffusion prevention area, the embedded structure is embedded so as to cross from the non-contaminated area to the contaminated area. However, the contaminated soil in the contaminated area can be prevented from diffusing into the non-contaminated area. In particular, since the buried structure can be buried immediately after the contamination diffusion prevention region is formed, the construction time can be shortened as compared with the conventional method. Further, for example, the first embedded structure in which the embedded structure is disposed over the non-contaminated region and the contamination diffusion prevention region, the second embedded structure disposed only in the contamination diffusion prevention region, and the contamination diffusion prevention region. And the third embedded structure disposed over the contaminated area, the first embedded structure, the second embedded structure, and the third embedded structure are not made after the contamination diffusion prevention area is formed. Embed in order from the contaminated area to the contaminated area, or bury the second embedded structure after the contamination diffusion prevention area is formed, and then embed the first embedded structure and the third embedded structure Therefore, the degree of freedom in construction can be improved as compared with the conventional method.

  According to the construction method of the buried structure according to claim 2, a part of the ground improvement body is buried as a buried structure by performing a part of the ground improvement body burying process as a buried structure burying process. Therefore, even when a plurality of ground improvement bodies are embedded in the pollution diffusion prevention region, it is possible to prevent the soil contaminated with the contamination region from diffusing into the non-pollution region.

  According to the construction method of the buried structure according to claim 3, after removing the partition wall in the removal process, after burying the ground improvement body arranged in the area that does not reach the contaminated area in the buried structure burying process. Since the ground improvement body arranged in the area leading to the contaminated area is buried, among the plurality of ground improvement bodies, each of the ground improvement bodies embedded as buried structures is a part of the adjacent ground improvement body Even when the ground improvement body is buried so as to overlap with each other, it is possible to prevent the contaminated soil in the contaminated area from spreading beyond the boundary between the contaminated area and the non-contaminated area.

  According to the construction method of the buried structure according to claim 4, since the plurality of ground improvement bodies are buried sequentially from the non-contaminated area toward the contaminated area, the case where they are sequentially embedded from the contaminated area toward the non-contaminated area. Compared with this, it is possible to prevent the contaminated soil in the contaminated area from diffusing into the non-contaminated area. Moreover, since it can embed efficiently compared with the case where a several ground improvement body is embed | buried in random order, it becomes possible to improve workability | operativity.

  According to the construction method of the buried structure according to claim 5, the buried structure to be arranged in the pollution diffusion prevention region is buried from the amount of soil necessary for flushing the formation scheduled region after the removal step. Since the amount of healthy soil subtracted from the amount of soil discharged in the process is embedded in the planned formation region, the amount of healthy soil embedded in the planned formation region in the formation process can be reduced. It becomes possible to reduce the work load for burying healthy soil in the process.

It is a top view which shows the outline | summary of the construction object area | region which concerns on this Embodiment. It is an enlarged view of the area | region A in FIG. It is a BB arrow sectional view of Drawing 2. It is a top view which shows the partition wall embedding process in the construction method of an embedded structure. It is CC sectional view taken on the line of FIG. It is a top view which shows the removal process in the construction method of a buried structure. It is DD sectional view taken on the line of FIG. It is a top view which shows the formation process in the construction method of a buried structure. It is EE arrow sectional drawing of FIG. It is a top view which shows the removal process in the construction method of a buried structure. It is FF arrow sectional drawing of FIG. It is a top view which shows the condition after the formation process and the removal process mentioned later are complete | finished. It is GG arrow sectional drawing of FIG. It is a top view which shows the ground improvement body embedding process of the construction method of an embedded structure. It is HH arrow sectional drawing of FIG. It is a top view which shows the ground improvement body embedding process of the construction method of an embedded structure. It is II sectional view taken on the line of FIG. It is a figure which shows the embedding procedure of the ground improvement bodies 40a-40l. It is a graph which shows the experimental result of experiment A, Comprising: The measurement result of pH of an improved body, the measurement result of pH of the surrounding soil located in the place 50 mm away from the improved body in the horizontal direction, and horizontal direction from an improved body It is a graph which shows the measurement result of pH of the surrounding soil located in the place 100 mm away along. It is a graph which shows the experimental result of Experiment B, Comprising: It is a graph which shows the measurement result of pH of improved soil, and the measurement result of pH of unmodified soil located just under improved soil.

  Hereinafter, an embodiment of a construction method for an embedded structure according to the present invention will be described in detail with reference to the drawings. However, the present invention is not limited by this embodiment.

(Basic concept of the present embodiment)
First, the basic concept of this embodiment will be described. The present embodiment is generally a method for constructing an embedded structure embedded in a construction target region including a non-contaminated region that is a region where soil is not contaminated and a contaminated region that is a region where soil is contaminated. It is about.

  Here, “contaminated” means a state where heavy metals, volatile organic compounds, pesticides and other harmful substances are contained in the soil to such an extent that they affect humans and ecosystems. The meaning may be changed to a different meaning depending on the situation, and the same applies to the meaning of “not contaminated” described later). In addition, “not contaminated” means that the above hazardous substances are contained in the soil to such an extent that they do not affect humans and ecosystems, or the above hazardous substances are not contained in the soil. Means state. Further, the “embedded structure” means a structure that is at least partially embedded in the ground. This “buried structure” is a concept including, for example, a ground improvement body, pipes such as water pipes and gas pipes, box culverts for tunnels, etc., but in this embodiment, it is for improving the strength of the soil. It will be described as a ground improvement body.

  In addition, the application target of the construction method of the buried structure is arbitrary, but in this embodiment, in order to take measures against liquefaction of the factory site where the commercial facility is scheduled to be built, The case where it applies to the construction which improves the ground by burying the improved body is explained. However, the present invention is not limited to this. For example, a box culvert may be installed on a site that includes a plant facility and a pipe that connects the plant facility and a facility adjacent to the plant facility or a farmland site where a predetermined amount or more of agricultural chemicals remain. The present invention may be applied to construction for constructing a tunnel by burying.

(Specific contents of this embodiment)
Next, specific contents of the present embodiment will be described.

(Configuration-construction target area)
Initially, the structure of the construction object area | region where the buried structure which concerns on this Embodiment is constructed is demonstrated. FIG. 1 is a plan view showing an outline of a construction target area according to the present embodiment. FIG. 2 is an enlarged view of region A in FIG. 3 is a cross-sectional view taken along line BB in FIG. In the following description, the X direction in FIG. 1 is the right direction of the construction target area, the X ′ direction in FIG. 1 is the left direction of the construction target area, the Y direction in FIG. The Y ′ direction is the forward direction of the construction target area, the Z direction of FIG. 3 is the upward direction of the construction target area, and the Z ′ direction of FIG. 3 is the downward direction of the construction target area. Here, in FIG. 1 to FIG. 3, the outer edge of each reference nonconforming section 20 (or the boundary between the reference conforming section 10 and the reference nonconforming section 20), which will be described later, is indicated by an imaginary line. The same applies to FIG. 17). 1 and 2, the contamination diffusion prevention region 30 described later is indicated by hatching (the same applies to FIGS. 12 to 16 described later).

  As shown in FIG. 1, the construction target area 1 is a factory site, and the construction target area 1 is surrounded by a temporary steel enclosure (not shown). The construction target area 1 includes a reference conforming section 10, a reference nonconforming section 20, and a contamination diffusion preventing area 30.

(Configuration-construction target area-standard conforming section and standard nonconforming section)
The reference conforming section 10 is a section provided in a non-contaminated area where the soil in the construction target area 1 is not contaminated. Moreover, the reference | standard nonconforming division 20 is a division provided in the contamination area | region where the soil in the construction object area | region 1 is contaminated. It is preferable that the nonconforming section 20 is provided with equipment for suppressing the soil contaminated with the nonconforming section 20 from diffusing to the outside. For example, the nonconforming section 20 has a watering facility, a temporary enclosure, and a floor. An iron plate or the like may be provided.

  Here, although the method for determining the reference nonconforming section 20 is arbitrary, for example, the construction target region 1 is a grid of a size determined by laws and regulations by local surveying (specifically, a grid of 10 m in length and 10 m in width). Perform a known surface soil survey using the soil sampled from each grid (specifically, soil collected from at least one point in each grid). The method of certifying the lattice in which soil contamination is recognized from the result as the reference nonconforming section 20 is applicable.

(Configuration-Construction target area-Pollution diffusion prevention area)
The contamination diffusion prevention area 30 is an area for preventing the soil of the reference nonconforming section 20 from diffusing into the reference conforming section 10. The contamination diffusion prevention region 30 is formed at the boundary between the reference conforming section 10 and the reference nonconforming section 20. Here, “formed at the boundary between the reference conforming section 10 and the reference nonconforming section 20” means that the contamination diffusion prevention region 30 is formed in a peripheral region that crosses the boundary between the reference conforming section 10 and the reference nonconforming section 20. Or a contamination diffusion prevention region 30 is a peripheral region arranged closer to the reference nonconforming section 20 than the boundary, and a part of the contamination diffusion prevention region 30 is formed in a peripheral region adjacent to the boundary. In this embodiment, the former meaning will be described.

  Moreover, about the specific shape of this pollution diffusion prevention area | region 30, about the planar shape of the pollution diffusion prevention area | region 30, for example, it is set to a shape larger than the planar shape of the ground improvement body 40 mentioned later (or It may be set substantially the same as the planar shape of the ground improvement body 40 described later), specifically, it is set to a substantially circular shape with a diameter of about 1,200 m. Further, the depth of the contamination diffusion preventing region 30 is set to be substantially the same as the length in the vertical direction of the ground improvement body 40 described later, specifically, 11,000 mm to 16,000 mm.

  A method for forming the contamination diffusion prevention region 30 is arbitrary. For example, a method of forming the soil by embedding healthy soil after removing soil in the formation planned region 31 described later is employed. Here, “healthy soil” means soil that has not been contaminated. For example, washed soil that has been washed with a known soil washing machine or the like, soil in the standard-adapted section 10, or a mixture thereof. It is a concept that includes

(Configuration-ground improvement body)
Next, the configuration of the ground improvement body 40 will be described. As shown in FIG. 1, a plurality of ground improvement bodies 40 are embedded substantially along the left-right direction and embedded along the front-rear direction in the construction target region 1. Here, regarding the details of the configuration of the plurality of ground improvement bodies 40, the plurality of ground improvement bodies 40 are the same as each other, but in the following, the ground improvement bodies 40a to 40l in the plurality of ground improvement bodies 40 will be described. Then, explanation will be made by paying attention to the ground improvement bodies 40a to 40l shown in FIGS. 2 and 3 (in the case where the ground improvement bodies 40a to 40l do not need to be distinguished from each other, “the ground improvement body 40”). Generically).

  The ground improvement bodies 40a-40l are for raising the intensity | strength of the soil of the construction object area | region 1. As shown in FIG. For example, as shown in FIG. 2 and FIG. 3, the ground improvement bodies 40 a to 40 l are formed of substantially elongated columnar bodies, and left and right so as to cross from the reference conforming section 10 to the reference nonconforming section 20. They are juxtaposed along the direction. Specifically, the ground improvement bodies 40a to 40d are disposed in the reference conforming section 10, the ground improvement bodies 40e and 40f are disposed over the reference conforming section 10 and the pollution diffusion prevention area 30, and the ground improvement body 40g is disposed in the pollution diffusion prevention area. 30 and the reference nonconforming section 20, and the ground improvement bodies 40 h to 40 l are arranged in the reference nonconforming section 20. More specifically, a part of each of the ground improvement bodies 40a to 40l overlaps with a part of the adjacent ground improvement body 40 (more specifically, about 100 mm to 200 mm). Ii) The ground improvement bodies 40a to 40l are arranged.

  Here, the specific shape of the ground improvement body 40 is arbitrary. For example, the planar shape of the ground improvement body 40 may be set to a shape that provides the strength and stability of the ground improvement body 40. Specifically, it is set to a substantially circular shape with a diameter of 1,000 mm. Moreover, about the length of the vertical direction of the ground improvement body 40, when the ground improvement body 40 is embed | buried, the bottom layer of the said ground improvement body 40 and the stratum 2 (specifically thickness is difficult to osmose | permeate). Is preferably set so as to be able to come into contact with a semi-impervious layer having a water permeability coefficient of 1 μm or less per second, specifically 11,000 mm to 16,000 mm. Is set.

  The formation method of the ground improvement body 40 is arbitrary, but, for example, a stabilizer containing cement-based solidifying material or the like (hereinafter referred to as “stabilizer”) and local soil are stirred, and the stirring is performed. A method of forming by solidifying a material is employed. In addition, among the ground improvement bodies 40a-40l, the ground improvement bodies 40e-40g respond | correspond to the "buried structure" in a claim.

(Construction method for buried structures)
Next, the construction method of the buried structure according to the present embodiment will be described. FIG. 4 is a plan view showing a partition wall burying step in the construction method of the buried structure to be described later. 5 is a cross-sectional view taken along the line CC in FIG. FIG. 6 is a plan view showing a removal step in the construction method of the buried structure to be described later. 7 is a cross-sectional view taken along the line DD in FIG. FIG. 8 is a plan view showing a forming step in the construction method of the embedded structure to be described later. FIG. 9 is a cross-sectional view taken along the line E-E in FIG. 8. FIG. 10: is a top view which shows the removal process in the construction method of the embedded structure mentioned later. 11 is a cross-sectional view taken along line FF in FIG. FIG. 12 is a plan view showing a situation after a forming process and a removing process described later are completed. 13 is a cross-sectional view taken along the line GG in FIG. FIG. 14: is a top view which shows the ground improvement body embedding process of the construction method of the embedded structure mentioned later. 15 is a cross-sectional view taken along line HH in FIG. FIG. 16: is a top view which shows the ground improvement body embedding process of the construction method of the embedded structure mentioned later. 17 is a cross-sectional view taken along the line II in FIG. As shown in FIGS. 4 to 17, the embedded structure construction method according to the present embodiment includes a partition wall burying step, a removing step, a forming step, a removing step, and a ground improvement body burying step. It is out.

  Among these, the “partition wall burying step” is a step of burying a partition wall 50 to be described later in the formation planned region 31. Here, the “formation scheduled region 31” means a region in the construction target region 1 where the contamination diffusion prevention region 30 is scheduled to be formed. In the present embodiment, the planned formation region 31 is formed in a peripheral region across the boundary between the reference conforming section 10 and the reference nonconforming section 20 in the construction target region 1 before the contamination diffusion preventing region 30 is formed. Yes. In addition, the specific shape of the planned formation region 31 is set, for example, in substantially the same shape as the shape of the contamination diffusion prevention region 30. Specifically, the planar shape of the planned formation region 31 is The length of the formation region 31 in the vertical direction is set to 11,000 mm to 16,000 mm. Further, the “removal step” is a step of removing the soil in the formation planned region 31. The “forming step” is a step of forming the contamination diffusion prevention region 30. Further, the “removal step” is a step of removing a partition wall 50 described later. The “ground improvement body burying step” is a step of burying a plurality of ground improvement bodies 40. Below, among the several ground improvement bodies 40, the detail of each process in the case of embedding the ground improvement bodies 40a-40l shown in FIG.

(Construction method for buried structure-partition wall burying process)
First, the partition wall embedding process will be described. As shown in FIGS. 4 and 5, in the partition wall embedding step, the partition wall 50 is embedded at the outer edge of the formation planned region 31.

  Here, the “partition wall 50” is a wall body for partitioning the formation region 31 from the outside in order to prevent the contaminated soil in the formation region 31 from diffusing into the reference conforming region 10. For example, it is a concept including a substantially tubular casing. The specific shape of the partition wall 50 is arbitrary, but the planar shape of the partition wall 50 is set to be substantially the same as the outer edge shape of the contamination diffusion prevention region 30, for example. The inner diameter of the wall 50 is set to 1,180 mm, and the outer diameter of the partition wall 50 is set to a substantially annular shape of 1,200 mm. The vertical length of the partition wall 50 is set to be substantially the same as the vertical length of the contamination diffusion prevention region 30, for example, specifically, 11,000 mm to 16,000 mm. . The material of the partition wall 50 is arbitrary. For example, when the partition wall 50 is buried, it is possible to prevent the contaminated soil or groundwater in the partition wall 50 from diffusing outside. A material having a water barrier property is desirable, for example, a steel material.

  The partition wall 50 may be embedded in any method. For example, after installing a known rocking press (not shown) on which the partition wall 50 is set in the vicinity of the formation planned region 31, this known rocking press is installed. A method of embedding the partition wall 50 by oscillating press-fitting (for example, rotary press-fitting or the like) with respect to the outer edge of the planned formation region 31 by a dynamic press-fitting machine is employed.

(Embedded structure construction method-removal process)
Next, the removal process will be described. As shown in FIGS. 6 and 7, in the removing step, the soil of the formation scheduled region 31 in which the partition wall 50 is embedded in the partition wall burying step is removed. Specifically, the soil in the partition wall 50 is excavated by a known excavator (not shown) to a predetermined depth (for example, a depth substantially equal to the vertical length of the ground improvement body 40). The excavated soil is discharged to the outside. In addition, when the soil discharged to the outside can be separated into the soil discharged from the standard conforming section 10 and the soil discharged from the standard nonconforming section 20, for example, the soil discharged from the standard conforming section 10 is discharged. The soil is used as healthy soil used in the formation process, and the soil discharged from the non-standard-conforming section 20 is transported to a predetermined contamination treatment facility by a vehicle or the like and then purified at the predetermined contamination treatment facility. It is desirable to be processed. On the other hand, when the soil discharged to the outside cannot be separated into the soil discharged from the standard conforming section 10 and the soil discharged from the standard nonconforming section 20, the soil discharged to the outside is It is desirable that after being transported to a predetermined contamination treatment facility by a vehicle or the like, the purification treatment is performed in the predetermined contamination treatment facility.

  Here, the method for excavating the soil in the partition wall 50 is arbitrary. For example, when the soil excavation depth in the partition wall 50 is lower than the groundwater level, a known pump (not shown) It is desirable to adopt a method of excavating the soil in the partition wall 50 after lowering the groundwater level by pumping up the groundwater existing in the planned formation region 31 and its surrounding region using The same applies to the operation of penetrating the pair of stirring shaft lower piles 60 in the ground improvement body burying step described later). By this method, it becomes possible to prevent the contaminated soil in the nonconforming section 20 from diffusing due to groundwater. In this method, groundwater pumped by a known pump is discharged into the sewer, etc., for example, when it is confirmed that it conforms to the sewage exclusion standard. When confirmed, it is desirable that after being transported to a predetermined contamination treatment facility by a vehicle or the like, the purification treatment is performed at the predetermined contamination treatment facility.

(Construction method for buried structures-formation process, removal process)
Then, a formation process and a removal process are demonstrated. As shown in FIGS. 8, 9, 12, and 13, in the formation process, the contamination diffusion prevention region 30 is formed by burying healthy soil in the formation planned region 31 from which the soil has been removed in the removal step. Is done. Then, as shown in FIGS. 10 to 13, in the removal process, the partition wall 50 embedded in the outer edge of the contamination diffusion prevention region 30 formed in the formation process is pulled out, so that the partition wall 50 is removed. The

  Specifically, when the embedding depth of the partition wall 50 is relatively deep as in the present embodiment, it is desirable that the formation process and the removal process are alternately performed as described below. That is, first, as shown in FIGS. 8 and 9, a predetermined amount of healthy soil (for example, the amount of healthy soil in which the ground surface of the formation planned region 31 is increased by about 1,000 mm) is input into the partition wall 50. The filled soil is buried by being compacted by watering or the like. Next, as shown in FIGS. 10 and 11, the partition wall 50 has a height (e.g., about 800 mm to 900 mm) to the extent that only the lower end portion of the partition wall 50 covers the embedded healthy soil. It is pulled up by the above-mentioned known rocking press-fitting machine (in addition, healthy soil is embedded in the gap generated by pulling up the partition wall 50). Subsequently, a predetermined amount of healthy soil is further introduced into the partition wall 50 above the compacted healthy soil, and after the filled healthy soil is compacted, the partition wall 50 is It is raised to a height that covers the above-mentioned healthy soil. 12 and 13, the ground surface of the planned formation region 31 is substantially flush with the ground surfaces of the reference conforming section 10 and the reference nonconforming section 20, and the partition wall 50 Repeat until is completely pulled out.

  Thus, since the contamination diffusion prevention area 30 is formed by burying healthy soil in the formation planned area 31, the ground improvement bodies 40e to 40g can be embedded immediately after the contamination diffusion prevention area 30 is formed. The construction time can be shortened as compared with the conventional method. Further, by alternately performing the formation process and the removal process, the partition wall 50 and the partition wall 50 are embedded when the partition wall 50 is pulled up, compared to the case where the removal process is performed after the formation process. It is possible to prevent the buried healthy soil from rising together by the frictional force generated between the soil and the healthy soil.

(Construction method of buried structure-ground improvement body burying process)
Subsequently, the ground improvement body burying step will be described. As shown in FIGS. 2, 3, and 14 to 17, in the ground improvement body embedding process, after the partition wall 50 is removed in the removal process, the ground improvement body 40 a that is arranged substantially along the left-right direction. The ground improvement bodies 40a to 40l are arranged so that a part of each of the ground improvement bodies 40a to 40l overlaps with a part of the other adjacent ground improvement bodies 40. .

  Specifically, in the present embodiment, ground improvement bodies 40a to 40l are embedded according to the following procedure. FIG. 18 is a diagram illustrating a procedure for burying the ground improvement bodies 40a to 40l. As shown in FIG. 18, first, a pair of stirring shaft lower piles 60 mounted on a known ground improvement processing device are respectively installed at positions where two adjacent ground improvement bodies 40 in the construction target region 1 are arranged. (See FIG. 18A). Next, while each of the pair of stirring shaft lower piles 60 is agitated between the stabilizer injected from the outside and the soil where the corresponding ground improvement body 40 is disposed, the pair of stirring shaft lower piles 60 Are penetrated (see FIG. 18B). Next, when each of the pair of stirring shaft lower piles 60 is penetrated to a predetermined depth, the known ground improvement processing device causes the pair of stirring shaft lower piles 60 to face the ground surface facing the tip portions of the pair of stirring shaft lower piles 60. The tip processing is performed (see FIG. 18C). Here, the “tip treatment” is a treatment for increasing the strength of the ground surface facing the tip portion of each of the pair of stirring shaft lower piles 60. For example, cement milk is applied to the ground surface. The process etc. which inject are applicable. Next, the pair of stirring shaft lower piles 60 are respectively pulled out while the stabilizer and the soil at the position where the corresponding ground improvement body 40 is disposed are stirred by the pair of stirring shaft lower piles 60 ( (Refer FIG.18 (d)). Then, the two ground improvement bodies 40 are embed | buried when this stirred thing solidifies. Subsequently, after this known ground improvement processing device is installed in the vicinity of the position where the other two adjacent ground improvement bodies 40 are arranged in the construction target area 1 (see FIG. 18 (e)), as described above. In addition, operations such as penetration of the pair of stirring shaft lower piles 60, the tip treatment, and extraction of the pair of stirring shaft lower piles 60 are performed. In this case, for example, when the work is performed at a position where at least one of the other two adjacent ground improvement bodies 40 overlaps with a part of the existing ground improvement body 40, the pair of The stirring shaft lower pile 60 on the existing ground improvement body 40 side is penetrated while cutting the side part of the existing ground improvement body 40. Next, after the above-described tip treatment is performed, the stabilizer, the soil at the position where the corresponding ground improvement body 40 is disposed, and the cut pieces of the existing ground improvement body 40 are stirred, The pair of stirring shaft lower piles 60 are pulled out. Thereafter, the agitated material is solidified, whereby the other two adjacent ground improvement bodies 40 are embedded, and of the other adjacent two ground improvement bodies 40, the existing ground improvement body 40 The ground improvement body 40 which overlaps with a part and the existing ground improvement body 40 are integrated. And a series of work mentioned above is repeatedly performed until all the ground improvement bodies 40a-40l are embed | buried as shown in FIG. 2, FIG.

  Here, as to the embedding order of the ground improvement bodies 40a to 40l, a part of each of the ground improvement bodies 40a to 40l overlaps with a part of the adjacent ground improvement body 40 as in the present embodiment. In addition, even when the ground improvement bodies 40a to 40l are buried, they are buried in an order that can prevent the contaminated soil of the reference nonconforming section 20 from spreading beyond the boundary between the reference conforming section 10 and the reference nonconforming section 20. Is done. For example, as shown in FIG. 14 to FIG. 17, the ground non-conformity section 20 is reached in the ground improvement bodies 40 e to 40 g (embedded structure) embedded at a position at least partially overlapping with the pollution diffusion prevention region 30. When the ground improvement body 40f arrange | positioned in the area | region which does not exist, and the ground improvement body 40g which is the ground improvement body 40g adjacent to the said ground improvement body 40f, and is arrange | positioned to the area | region which reaches | attains the reference | standard nonconformity division 20 are included. The ground improvement bodies 40a to 40l are embedded in the order in which the ground improvement body 40g is embedded after the ground improvement body 40f is embedded. Here, the “region that does not reach the reference nonconforming section 20” corresponds to, for example, the contamination diffusion prevention region 30, the region extending over the contamination diffusion prevention region 30 and the reference conformation section 10, or the like. Further, the “region reaching the reference nonconforming section 20” corresponds to, for example, an area extending over the contamination diffusion preventing area 30 and the reference nonconforming section 20.

  Specifically, in the present embodiment, as described above, since the two ground improvement bodies 40 are buried at the same time by the pair of stirring shaft lower piles 60, the ground improvement bodies 40a to 40l are adapted to the standard. Two sections are embedded sequentially from the section 10 toward the reference nonconforming section 20 (more specifically, as shown in FIGS. 14 and 15, after the ground improvement bodies 40e and 40f are embedded, FIG. As shown in FIG. 17, the ground improvement bodies 40g and 40h are buried, etc.). By embedding the ground improvement bodies 40a to 40l in this order, the contaminated soil in the reference nonconforming section 20 is compared with the reference conforming section 10 as compared to the case of sequentially embedding from the standard nonconforming section 20 toward the reference conforming section 10. Can be prevented from diffusing. Moreover, since the ground improvement bodies 40a-40l can be embedded efficiently compared with the case where it embeds in random order, it becomes possible to improve workability. In addition, among such ground improvement body embedding processes, the process of embedding the ground improvement bodies 40e to 40g corresponds to the “buried structure embedding process” in the claims. Thus, the construction method for the buried structure is completed.

(Experimental result)
Next, experimental results of a pH measurement test related to the ground improvement body 40 will be described. Here, the “pH measurement test” is a test for measuring the pH of the ground improvement body 40 and its surrounding area after a predetermined period. In the following, two experiments (hereinafter referred to as “Experiment A” and “Experiment B”) shown in non-patent literature (“Ground improvement manual using cement-based solidification material”, (Cement Corporation), p. 58) ) Will be described.

  First, the experimental result of “Experiment A” will be described. FIG. 19 is a graph showing the experimental results of Experiment A, the measurement results of the pH of the improved body (corresponding to the ground improved body 40 of the present invention), and a position 50 mm away from the improved body in the horizontal direction. It is a graph which shows the measurement result of pH of the surrounding soil to be measured, and the measurement result of pH of the surrounding soil located 100 mm away from the improved body in the horizontal direction, the horizontal axis is the age of the improved body, the vertical axis Indicates a measured pH value. This experiment A is an experiment in which the secular change (specifically, the secular change from 0 years to 10 years of age of the improved body) of the pH measurement values regarding the improved body and the surrounding soil is investigated. As shown in FIG. 19, from the experimental results of Experiment A, even when the age of the improved body has passed 10 years, the fluctuations of the pH measurement values in the various surrounding soils are small and almost neutral. all right.

  Next, the experimental result of Experiment B will be described. FIG. 20 is a graph showing the experimental results of Experiment B. The measurement results of the pH of the improved soil (corresponding to the ground improvement body 40 of the present invention) and the measurement of the pH of the unmodified soil located directly under the improved soil. FIG. 20 is a graph showing the results, in which the horizontal axis represents the measured value of pH, and the vertical axis represents the measured value of depth and pH (shown as “pH” in FIG. 20). This experiment B is an experiment in which the measured values of pH regarding the improved soil after 2 years and 9 months of age and the unmodified soil were investigated. As shown in FIG. 20, when the age of the improved body is 2 years and 9 months from the experimental result of Experiment B, the measured value of the pH suddenly increases in the range from -30 mm to -40 mm in the unmodified soil. It turns out that it is falling. Moreover, it turned out that it is almost neutral in the range from -40 mm to -90 mm in the unmodified soil.

  As described above, the reason why the above experimental results of Experiment A and Experiment B were obtained is that the alkaline component is leached from the surface of the improved body (or improved soil) due to carbonation by the carbon dioxide gas in the air, rainfall, or the like. Even in this case, it can be said that the diffusion of the alkali component is suppressed by the buffering action of the soil around the improved body (or improved soil). From this, for example, among the ground improvement bodies 40a to 40l according to the present invention, the ground improvement body 40f embedded as an embedded structure, and the ground improvement body 40f disposed in the region reaching the reference nonconforming section 20 is provided. When buried, even if the harmful substances contained in the ground improvement body 40f leak to the outside due to the leaching of the alkaline component of the ground improvement body 40f, the buffering action of the soil around the ground improvement body 40f works. Therefore, it is considered that the diffusion of the harmful substance is suppressed.

(effect)
As described above, according to the present embodiment, in the formation process, the contamination diffusion prevention region 30 is formed by embedding healthy soil at the boundary between the standard conforming section 10 and the standard nonconforming section 20, and the embedded structure embedding process. , Since the ground improvement bodies 40e to 40g are embedded so that at least a part of the ground improvement bodies 40e to 40g is arranged in the pollution diffusion prevention region 30, the ground improvement bodies 10e to 40g are crossed from the reference conforming section 10 to the reference nonconforming section 20. Thus, even when the ground improvement bodies 40e to 40g are embedded, it is possible to prevent the contaminated soil in the reference nonconforming section 20 from diffusing into the reference conforming section 10. In particular, since the ground improvement bodies 40e to 40g can be embedded immediately after the contamination diffusion prevention region 30 is formed, the construction time can be shortened as compared with the conventional method.

  Moreover, since the ground improvement bodies 40e-40g are embed | buried as a buried structure among the ground improvement bodies 40a-40l by performing a part of ground improvement body burying process as a buried structure burying process, the ground improvement bodies 40e-40g. Even when the soil is buried in the pollution diffusion prevention region 30, it is possible to prevent the contaminated soil in the reference nonconforming section 20 from diffusing into the reference conforming section 10.

  In addition, after removing the partition wall 50 in the removal process, after burying the ground improvement bodies 40e and 40f arranged in the area not reaching the reference nonconforming section 20 in the buried structure burying process, the ground improvement bodies 40e and 40f Since the adjacent ground improvement bodies 40g and 40h are embedded, among the ground improvement bodies 40a to 40l, a part of each of the ground improvement bodies 40e to 40g embedded as an embedded structure is a part of the adjacent ground improvement body 40. Even when the ground improvement bodies 40e to 40g are buried so as to overlap with each other, the contaminated soil of the reference nonconforming section 20 is diffused beyond the boundary between the reference nonconforming section 20 and the reference conforming section 10. Can be prevented.

  Further, in the ground improvement body embedding process, the ground improvement bodies 40a to 40l are sequentially embedded from the standard conforming section 10 toward the standard nonconforming section 20, so that they are sequentially embedded from the standard nonconforming section 20 to the standard conforming section 10. Compared to the case, it is possible to prevent the contaminated soil in the nonconforming section 20 from diffusing into the conforming section 10. Moreover, since the ground improvement bodies 40a-40l can be embedded efficiently compared with the case where it embeds in random order, it becomes possible to improve workability.

[Modifications to Embodiment]
Although the embodiments of the present invention have been described above, the specific configuration and means of the present invention can be arbitrarily modified and improved within the scope of the technical idea of each invention described in the claims. Can do. Hereinafter, such a modification will be described.

(About problems to be solved and effects of the invention)
First, the problems to be solved by the invention and the effects of the invention are not limited to the above contents, and may vary depending on the implementation environment and details of the configuration of the invention. May be solved, or only some of the effects described above may be achieved. For example, in the buried structure burying process, even if it is not possible to embed the buried structure more accurately than in the past so that at least a part of the buried structure is disposed in the pollution diffusion prevention region 30, In the case where the burying of the embedded structure can be achieved in the same manner as before by a technique different from the conventional technique, the problem of the present invention has been solved.

(About the planar shape of the pollution diffusion prevention area)
In the above embodiment, the planar shape of the contamination diffusion prevention region 30 has been described as being formed in a substantially circular shape, but is not limited to this, for example, a substantially triangular shape, a substantially rectangular shape, a substantially pentagonal shape, or the like. It may be formed in a square shape. Further, when the contamination diffusion prevention region 30 is a peripheral region closer to the reference nonconforming section 20 than the boundary, and a part of the contamination diffusion prevention region 30 is formed in a peripheral region adjacent to the boundary, It may be formed in a substantially square shape or a substantially semicircular shape. In this case, the planar shape of the partition wall 50 is formed in a shape corresponding to the planar shape of the contamination diffusion prevention region 30. For example, when the planar shape of the contamination diffusion prevention region 30 is a substantially square shape, It is formed in a square ring shape.

(Regional wall)
In the said embodiment, although the division wall 50 demonstrated that it was a substantially cylindrical casing, it is not restricted to this, For example, with the earth retaining wall etc. which were formed by arranging several steel sheet piles in parallel without a gap There may be. In this case, the method for embedding the partition wall 50 is arbitrary. For example, after a known pile driving machine in which the partition wall 50 is set is installed in the vicinity of the formation planned region 31, by this known pile driver, For example, a method of embedding the partition wall 50 by driving it into the outer edge of the region 31 to be formed may be employed.

(About ground improvement)
In the said embodiment, although it demonstrated that the number of the ground improvement bodies 40 embed | buried as a buried structure was plural (specifically, ground improvement bodies 40e-40g correspond), it is not restricted to this, A buried structure The number of ground improvement bodies 40 to be embedded as an object may be singular.

  In the above embodiment, the planar shape of the ground improvement body 40 has been described as being formed in a substantially circular shape, but is not limited thereto, and is, for example, a rectangular shape such as a substantially triangular shape or a substantially rectangular shape. Alternatively, it may be substantially elliptical or substantially fan-shaped.

(About construction method of buried structure)
In the above-described embodiment, it has been described that the partition wall burying step, the removing step, the forming step, the removing step, and the ground improvement body burying step are sequentially performed, but the present invention is not limited thereto. For example, when there are a plurality of boundaries between the reference conforming section 10 and the reference nonconforming section 20 in the construction target region 1, a partition wall embedding process, a removing process, a forming process, and a removing process are performed at the plurality of boundaries. By being performed, after the pollution diffusion prevention area 30 is formed in advance on all of the plurality of boundaries, the ground improvement body 40 is embedded by performing the ground improvement body embedding process at the plurality of boundaries. Also good.

(About formation process and removal process)
In the said embodiment, although demonstrated that the formation process and the removal process were performed alternately, it is not restricted to this. For example, when the embedding depth of the partition wall 50 is relatively shallow, the removal process may be performed after the formation process is performed.

  In the above embodiment, in the forming step, the healthy soil is embedded in the partition wall 50 until the ground surface in the partition wall 50 is substantially flush with the ground surfaces of the reference conforming section 10 and the reference nonconforming section 20. However, the present invention is not limited to this. For example, from the amount of soil necessary to bury healthy soil until the ground surface of the planned formation region 31 is substantially flush with the ground surfaces of the standard conforming section 10 and the standard nonconforming section 20, the embedded structure is embedded in the embedded structure embedding process. The amount of healthy soil obtained by subtracting the amount of soil discharged when at least a part of the ground improvement bodies 40e to 40g to be embedded as objects may be embedded may be embedded in the formation planned region 31. Here, “the soil discharged when at least a part of the ground improvement bodies 40e to 40g is buried” means, for example, when at least a part of the ground improvement bodies 40e to 40g is buried. When the stabilizer and the soil at the position where the corresponding ground improvement body 40 is arranged are stirred by each of the stirring shaft lower piles 60, the soil has a soil amount corresponding to the amount of the stabilizer. Applicable to soil discharged outside. In this way, when the amount of healthy soil subtracted in the formation step (that is, the amount of healthy soil in which the amount of soil corresponding to the amount of the stabilizer is subtracted in advance) is embedded in the formation planned region 31. By using the soil discharged when at least a part of the ground improvement bodies 40e to 40g is buried in the buried structure burying step, by filling the recess formed in the pollution diffusion prevention region 30 after the forming step, It is possible to make the ground surface of the pollution diffusion prevention region 30 substantially flush with the ground surfaces of the reference conforming section 10 and the reference nonconforming section 20. Thereby, since the amount of the soil of the healthy soil embedded in the formation planned region 31 in the formation process can be reduced, for example, it becomes possible to reduce the work load for the embedding of the healthy soil in the formation process. As described above, when there are a plurality of boundaries between the reference conforming section 10 and the reference nonconforming section 20 in the construction target region 1, the contamination diffusion preventing region 30 is formed in advance on all of the plurality of boundaries. In that case, in order to ensure safety, it is desirable that a temporary enclosure such as an iron fence be provided on the outer edge of the pollution diffusion prevention region 30 where the ground improvement body burying process has not yet been performed.

(About ground improvement body burial process)
In the above embodiment, in the ground improvement body burying step, the ground improvement bodies 40e to 40g (buried structure) at least partially embedded in the position overlapping with the pollution diffusion prevention region 30 are not compliant with the standard conformity section 10. Although it described that it was embed | buried sequentially toward the division 20, it is not restricted to this. For example, the ground improvement bodies 40e and 40g may be embedded after the ground improvement body 40f is embedded. In this case, the ground improvement bodies 40e to 40g are buried one by one by the known ground improvement processing equipment to which one stirring shaft lower pile 60 is attached. Thus, since the embedding order of the ground improvement bodies 40e-40g can be changed according to a condition, it can be said that the freedom degree of construction can be improved compared with the conventional method.

  Moreover, although the said embodiment demonstrated that the ground improvement body 40a-40l was embed | buried in the ground improvement body embedding process after the contamination spreading | diffusion prevention area | region 30 was formed, it is not restricted to this. For example, when the ground improvement body 40f is located closer to the reference conforming section 10 than the boundary between the reference conforming section 10 and the reference nonconforming section 20, and located near the boundary, the ground improving bodies 40a to 40f are provided. After being buried, a contamination diffusion prevention region 30 is formed (in this case, the contamination diffusion prevention region 30 is a region in the reference nonconforming section 20, and a part of the contamination diffusion prevention region 30 is adjacent to the boundary. Then, ground improvement bodies 40g to 40l may be embedded. In this case, the size of the contamination diffusion prevention region 30 is set to a size that can prevent the contaminated soil in the contamination region from diffusing beyond the boundary between the contamination region and the non-contamination region. The ground improvement body 40g is set to a size that allows the ground improvement body 40g to be completely accommodated in the contamination diffusion prevention region 30. In this case, the ground improvement body 40g is embed | buried by the said well-known ground improvement processing apparatus with which one stirring shaft lower pile 60 was mounted | worn, for example. Or it is not restricted to the said magnitude | size, For example, you may set to the magnitude | size which can fully accommodate the ground improvement bodies 40g and 40h in the said pollution diffusion prevention area | region 30. FIG. In this case, for example, the ground improvement bodies 40g and 40h are embedded by the above-described known ground improvement processing equipment to which the two stirring shaft lower piles 60 are attached. Thus, since the order in which the contamination diffusion prevention regions 30 are formed can be changed according to the situation, it can be said that the degree of freedom in construction can be improved as compared with the conventional method. In this case, the planar shape of the contamination diffusion prevention region 30 is arbitrary. For example, one side of the contamination diffusion prevention region 30 is a boundary between the reference conforming section 10 and the reference nonconforming section 20 so that the contamination diffusion preventing region 30 can be easily formed. You may form in the substantially rectangular shape which adjoins.

  Moreover, although the said embodiment demonstrated that the ground improvement bodies 40a-40l were embed | buried in the ground improvement body embedding process after the partition wall 50 was removed in the removal process, it is not restricted to this. For example, after the ground improvement bodies 40a to 40d and 40i to 40l are buried in the ground improvement body embedding process, the partition wall 50 is removed in the removal process, and then the ground improvement bodies 40e to 40h are buried in the ground improvement body embedding process. May be.

  In the above-described embodiment, the ground improvement bodies 40a to 40l have been described as being embedded two by two from the reference conforming section 10 toward the reference nonconforming section 20, but the present invention is not limited thereto. For example, after the ground improvement bodies 40a to 40d and 40i to 40l are embedded in order from the reference conforming section 10 toward the reference nonconforming section 20, the ground improvement bodies 40e to 40h are changed from the reference conforming section 10 to the reference nonconforming section. Two of them may be buried sequentially toward 20. Or after the ground improvement bodies 40a-40d and 40i-40l are embed | buried sequentially 2 each toward the reference | standard conformity division 10 from the reference | standard nonconformity division 20, the ground improvement bodies 40e-40h are reference noncompliance division 10 Two of them may be buried sequentially toward 20.

DESCRIPTION OF SYMBOLS 1 Construction object area | region 2 The stratum which groundwater does not osmose | permeate 10 Standard conformity division 20 Standard nonconformity division 30 Contamination diffusion prevention area 31 Planned formation area 40, 40a-40l Ground improvement body 50 Compartment wall 60 Pile under stirring axis

Claims (5)

In a construction target area including a non-contaminated area that is an area in which the soil is not contaminated and a contaminated area that is an area in which the soil is contaminated, embedding is performed so as to cross from the non-contaminated area to the contaminated area A method of constructing a structure,
Contamination diffusion prevention region formed at the boundary between the contamination region and the non-contamination region, and the formation of a contamination diffusion prevention region for preventing the soil of the contamination region from diffusing into the non-contamination region is scheduled A partition wall burying step of burying a partition wall for partitioning the formation planned region from the outside at the outer edge of the planned formation region;
A removal step of removing soil in the planned formation area in which the partition wall is embedded in the partition wall burying step;
A formation step of forming the contamination diffusion prevention region by embedding healthy soil in the formation planned region where the soil has been removed in the removal step;
A removal step of removing the partition wall embedded in the outer edge of the contamination diffusion prevention region formed in the formation step;
A buried structure burying step of burying the buried structure so that at least a part of the buried structure is disposed in the contamination diffusion prevention region;
Construction method of buried structure including A plurality of ground improvement bodies arranged approximately along the direction from the non-contaminated area toward the contaminated area, and a part of each of the plurality of ground improvement bodies adjacent to each other. Including a ground improvement body burying step of burying a plurality of ground improvement bodies arranged so as to overlap with each other,
By performing a part of the ground improvement body burying process as the embedded structure burying process, a part of the plurality of ground improvement bodies is embedded as the embedded structure,
The construction method of the buried structure according to claim 1. The ground improvement body to be buried as the buried structure is a ground improvement body arranged in a region not reaching the contaminated area, and a ground improvement body adjacent to the ground improvement body and arranged in a region reaching the contaminated area. Including a ground improvement body,
After the partition wall is removed in the removal step, in the buried structure embedding step, the ground improvement body disposed in a region that does not reach the contaminated region is embedded and then disposed in a region that reaches the contaminated region. Bury the ground improvement body,
The construction method of the buried structure according to claim 2. In the ground improvement body burying process,
The plurality of ground improvement bodies are sequentially embedded from the non-contaminated area toward the contaminated area.
The construction method of the buried structure according to claim 2 or 3. In the forming step,
From the amount of soil necessary to bury the healthy soil until the ground surface of the planned formation region is substantially flush with the ground surface of the non-contaminated region and the contaminated region, the embedded structure is embedded in the embedded structure embedding step. The amount of the healthy soil obtained by subtracting the amount of soil discharged when the object is embedded is embedded in the formation planned area.
The construction method of the embedded structure as described in any one of Claim 1 to 4.

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