JP2013174086A - Method for constructing soil cement wall, and soil cement wall - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent contaminations from being diffused from a contaminated section to an uncontaminated section while suppressing increases in time and cost when constructing a soil cement wall in a site where the section whose soil contamination is recognized is present across the border between the contaminated section and uncontaminated section while leaving the contaminated section as it is.SOLUTION: There is provided a method of constructing a soil cement column array wall 10 across the border L between a contaminated section 102 and an uncontaminated section 104 in a site where the contaminated section 102 whose soil contamination is recognized is present, the method being a technique with no drilling agitation such as a chemical injection technique and characterized in constructing a water shield column 16 for enabling a part of the soil cement column array wall 10 to block water.

Description

  The present invention relates to a method for constructing a soil cement wall and a soil cement wall.

  When building a retaining wall on a site where there is a contaminated section where soil contamination is recognized by a survey based on the Soil Contamination Countermeasures Law, a soil cement column wall (for example, see Patent Document 1) is used as the retaining wall. In some cases, it is constructed so as to cross the boundary between the contaminated compartment and the non-contaminated compartment while leaving the contamination of the waste.

JP 2009-57682 A

  In the construction of the soil cement column wall, the soil is drilled and agitated, but if the soil is drilled and agitated at the boundary between the contaminated compartment and the non-contaminated compartment, the contamination is diffused from the contaminated compartment to the non-contaminated compartment. For this reason, it is necessary to replace the contaminated soil with healthy soil by the all-casing method, etc. prior to drilling and stirring the range in which the soil cement column wall is constructed in the contaminated section. It led to an increase.

  The present invention has been made in view of the above circumstances, and in a site where there is a contaminated section where soil contamination is recognized, the soil cement wall remains contaminated in the contaminated section and the contaminated section and the non-contaminated section. It is an object of the present invention to prevent the spread of contamination from a contaminated compartment to a non-contaminated compartment while suppressing an increase in time and cost.

  In the method for constructing a soil cement wall according to the present invention, the soil cement wall is disposed so as to cross the boundary between the contaminated compartment and the non-contaminated compartment where no soil contamination is found on the site where the contaminated compartment where soil contamination is found. It is a construction method, and at the boundary between the contaminated section and the non-contaminated section, a construction method in which a hole is not agitated or soil that has been agitated is not left, and a part of the soil cement wall is configured to be water-shielded. It is characterized by constructing a water shielding part.

  In the method for constructing the soil cement wall, the construction method may be a chemical solution injection method, and the water shielding portion may be constructed by spraying a water shielding chemical solution from a chemical solution injection pipe inserted into the non-contaminated section. .

  In the method for constructing the soil cement wall, the construction method may be an all-casing construction method, and the water shielding portion is formed by substituting the soil at a position overlapping the boundary between the contaminated compartment and the non-contaminated compartment with a water shielding material. May be built.

  In the method for constructing the soil cement wall, the construction method may be a sheet pile wall construction method, and the water shielding portion is constructed by driving a sheet pile across the boundary between the contaminated compartment and the non-contaminated compartment. May be.

  In addition, the soil cement wall according to the present invention is a soil cement constructed so as to cross the boundary between the contaminated compartment and the non-contaminated compartment where no soil contamination is found on the site where the contaminated compartment where the soil contamination is recognized. It is a wall, and is constructed by a construction method that does not leave a hole-stirred or left-stirred soil at the boundary between the contaminated section and the non-contaminated section, and is configured so that a part of the soil cement wall can be water-blocked It is characterized by comprising a water shielding part.

  According to the present invention, when the soil cement wall is constructed so as to cross the boundary between the contaminated compartment and the non-contaminated compartment while leaving the contaminated compartment in the site where the contaminated compartment where soil contamination is recognized exists. , It is possible to prevent the spread of contamination from the contaminated compartment to the non-contaminated compartment while suppressing an increase in time and cost.

It is a top view which shows the site which constructs the soil cement pillar row wall concerning one embodiment. It is a top view which expands and shows a part of soil cement pillar row wall which concerns on one Embodiment. It is a top view which shows the construction procedure of the soil cement column wall which concerns on one Embodiment. It is a top view which shows the construction procedure of the soil cement column wall which concerns on one Embodiment. It is an elevation view which shows the construction procedure of the soil cement column wall which concerns on one Embodiment. It is a top view which shows the construction procedure of the soil cement column wall which concerns on one Embodiment. It is a top view which shows the construction procedure of the soil cement column wall which concerns on one Embodiment. It is a top view which expands and shows a part of soil cement pillar row wall which concerns on other embodiment. It is a top view which shows the construction procedure of the soil cement column wall which concerns on other embodiment. It is a top view which shows the construction procedure of the soil cement column wall which concerns on other embodiment. It is a top view which expands and shows a part of soil cement pillar row wall which concerns on other embodiment. It is a top view which shows the construction procedure of the soil cement column wall which concerns on other embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing a site 100 for constructing a soil cement column wall 10 according to an embodiment. As shown in this figure, the site 100 is a target site for soil contamination investigation based on the Soil Contamination Countermeasures Law, and the site 100 is divided into 10m grids to investigate the amount of soil elution and soil content of specific harmful substances. As a result, it has been confirmed that there are sections 102 in which soil contamination is recognized (hereinafter referred to as contaminated sections) and sections 104 in which soil contamination is not observed (hereinafter referred to as non-contaminated sections).

  The soil cement column wall 10 is constructed to traverse and traverse the contaminated compartment 102 and crosses the boundary between the contaminated compartment 102 and the non-contaminated compartment 104. The soil cement column wall 10 includes a plurality of soil cement columns 12 connected in a straight line. The distance between the centers of adjacent soil cement columns 12 is smaller than the diameter of the soil cement columns 12, and the adjacent soil cement columns 12 partially overlap each other. Further, H-shaped steel 14 (see FIG. 2) is embedded in every other soil cement column 12.

  FIG. 2 is an enlarged plan view showing a part of the soil cement column wall 10. As shown in this figure, the soil cement pillar 12 is not provided at the boundary L between the contaminated compartment 102 and the non-contaminated compartment 104, and between the soil cement pillars 12 on both sides of the boundary L, A cylindrical water-impervious column 16 made of a water-impervious material such as a water glass chemical constructed by a chemical injection method is provided. The impermeable columns 16 are integrated with the soil cement columns 12 on both sides thereof. In addition, the water-impervious pillar 16 is provided with water-imperviousness that can form a water-impervious wall together with the soil cement pillars 12 on both sides.

  3 to 7 are plan views or elevation views showing a construction procedure of the soil cement column wall 10. When the soil cement column wall 10 is constructed using a multiaxial ground improvement device, a plurality of soil cement columns 12 are constructed at a time as shown in FIGS.

  As shown in FIG. 5, in the process of constructing the soil cement column 12, the ground is excavated until the ground improvement device 1 reaches the support layer. At this time, in parallel with the excavation work, the ground improvement device 1 supplies cement milk into the excavation hole, whereby the excavated soil and the cement milk are agitated and mixed. And although illustration is abbreviate | omitted, the H-shaped steel 14 is built in the soil cement before hardening.

  Moreover, while excavating the ground while cutting the side portion of the soil cement pillar 12 that has already been constructed, a new construction is performed by injecting cement milk into the excavation hole and stirring and mixing the excavated soil and the cement milk. The soil cement pillar 12 and the already constructed soil cement pillar 12 on both sides thereof are integrated.

  Here, as shown in FIG. 6, in the construction of the soil cement column wall 10, the soil cement column 12 is not constructed at a position overlapping the boundary L. That is, at the boundary L between the contaminated compartment 102 and the non-contaminated compartment 104, the soil is not drilled and agitated to prevent the diffusion of contamination from the contaminated compartment 102 to the non-contaminated compartment 104.

  And, as shown in FIG. 7, after the construction of the soil cement column row wall 10 lacking the soil cement column 12 at the position overlapping with the boundary L is completed, between the soil cement columns 12 on both sides sandwiching the boundary L, The water shielding column 16 is constructed by injecting a water shielding chemical such as a water glass chemical by a chemical injection method. Here, in the construction of the water-impervious column 16, the rod 2 provided with a nozzle at the tip is inserted into the ground, and the rod 2 is rotated, and a water-impervious chemical is ejected from the nozzle, whereby the water-impervious column is surrounded around the rod 2. At this time, the rod 2 is inserted into the non-contaminated section 104 and the water-impervious chemical liquid is ejected from the non-contaminated section 104.

  That is, the chemical liquid is jetted from the non-contaminated compartment 104 toward the contaminated compartment 102 to prevent the diffusion of the contamination from the contaminated compartment 102 to the non-contaminated compartment 104.

  As described above, according to the method for constructing the soil cement column wall 10 according to the present embodiment, the soil cement column wall 10 is traversed or longitudinally crossed the contaminated section 102 while leaving the contaminated section 102 contaminated. In the construction, the diffusion of contamination from the contaminated compartment 102 to the non-contaminated compartment 104 can be prevented without requiring time-consuming and costly work such as replacing the contaminated soil in the contaminated compartment 102 with healthy soil. it can.

  FIG. 8 is an enlarged plan view showing a part of a soil cement column wall 110 according to another embodiment. As shown in this figure, in the soil cement column wall 110, the soil cement column 12 is not provided at the boundary L between the contaminated section 102 and the non-contaminated section 104, and the soil cement on both sides sandwiching the boundary L is not provided. Between the columns 12, a cylindrical water-proof column 116 made of a water-blocking material such as fluidized soil (for example, mud mortar) constructed by the all casing method is provided. The impermeable columns 116 are integrated with the soil cement columns 12 on both sides. In addition, the water-impervious pillar 116 has water-imperviousness that can form a water-impervious wall together with the soil cement pillars 12 on both sides, and strength that can withstand earth pressure together with the soil cement pillars 12 on both sides.

  9 and 10 are plan views showing the construction procedure of the soil cement column wall 110. FIG. In the construction of the soil cement column wall 110, first, as shown in FIG. 9, the impermeable column 116 is constructed by the all casing method at a position overlapping the boundary L between the contaminated section 102 and the non-contaminated section 104. At this time, the casing tube 3 is pushed into the earth and sand at a position overlapping with the boundary L between the contaminated compartment 102 and the non-contaminated compartment 104, and the earth and sand inside thereof is excavated and discharged. Then, fluidized soil such as mud mortar is placed in the casing tube 3. Thereby, the earth and sand of the position which overlaps with the boundary L is substituted by fluidization processing soil, such as a mud mortar.

  Then, as shown in FIG. 10, the soil cement column wall 110 is constructed by constructing a plurality of soil cement columns 12 except for the position overlapping the boundary L and integrating them. Here, the construction method of the plurality of soil cement columns 12 is the same as that of the soil cement column wall 10 according to the above-described embodiment. However, when the soil cement columns 12 on both sides of the water shielding column 116 are constructed, mud soil The ground is excavated while cutting the side of the impermeable column 116 made of mortar, and the cemented milk is injected into the excavation hole, and the excavated soil and the cement milk are stirred and mixed. The cement pillar 12 is integrated. The construction of the impermeable columns 116 may be performed after the soil cement columns 12 on both sides thereof.

  As described above, according to the method for constructing the soil cement column wall 110 according to the present embodiment, the soil cement column wall 110 is traversed or longitudinally crossed the contaminated section 102 while leaving the contaminated section 102 contaminated. In the construction, the soil and sand only at the position overlapping the boundary L between the contaminated compartment 102 and the non-contaminated compartment 104 is replaced with a water-impervious material such as mud mortar. The diffusion of contamination can be prevented.

  FIG. 11 is an enlarged plan view showing a part of a soil cement column wall 210 according to another embodiment. As shown in this figure, in the soil cement column wall 210, the soil cement column 12 is not provided at the boundary L between the contaminated section 102 and the non-contaminated section 104, and the soil cement on both sides sandwiching the boundary L is provided. Steel sheet piles 212 are driven between the columns 12, and steel sheet piles 216 engaged with the steel sheet piles 212 are embedded in the soil cement columns 12 on both sides. Here, the engaging portion 218 between the steel sheet pile 212 and the steel sheet pile 216 is embedded in the soil cement column 12 in which the steel sheet pile 216 is embedded.

  FIG. 12 is a plan view showing a construction procedure of the soil cement column wall 210. In the construction of the soil cement column wall 210, first, the soil cement column 12 is constructed except for the position overlapping the boundary L between the contaminated section 102 and the non-contaminated section 104, as shown in FIG.

  Before the soil cement is hardened, steel sheet piles 212 are built in the soil cement columns 12 on both sides of the boundary L, and the H-shaped steel 14 is built in the soil cement columns 12 on the outer side, and then straddles the boundary L. The steel sheet pile 216 is built in by vibro hammer construction or the like (see FIG. 11). At this time, the steel sheet piles 212 and 216 are installed so that the engaging portions 218 between the steel sheet piles 212 and the steel sheet piles 216 are embedded in the soil cement columns 12 on both sides of the boundary L. In addition, when performing the water stop process to the engaging part 218, it is not essential to embed the engaging part 218 in the soil cement pillar 12. Moreover, as a sheet pile, other sheet piles, such as a steel pipe sheet pile, are also applicable.

  As described above, according to the method for constructing the soil cement column wall 210 according to the present embodiment, the soil cement column wall 210 is traversed or longitudinally cut through the contaminated section 102 while leaving the contaminated section 102 contaminated. In the construction, the diffusion of the contamination from the contaminated compartment 102 to the non-contaminated compartment 104 can be prevented without requiring time-consuming and costly work such as replacing the contaminated soil with healthy soil.

  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 a soil cement column wall as an example, but the present invention can also be applied to other soil cement walls such as a continuous wall made of soil cement. In addition, the method of constructing a part of the wall located at the boundary between the contaminated compartment and the non-contaminated compartment is not limited to the above-described method, but other than the method of leaving the soil at the position overlapping with the boundary by stirring and drilling. If it can be adopted.

1 ground improvement device, 2 rod (chemical solution injection pipe), 3 casing tube, 10 soil cement column wall (soil cement wall), 12 soil cement column, 14 H type steel, 16 water shielding column (water shielding part), 100 site, 102 contaminated section, 104 non-contaminated section, 110 soil cement column wall (soil cement wall), 116 water blocking column (water blocking part), 210 soil cement column wall (soil cement wall), 212, 216 steel sheet pile (sheet pile) 218 Engagement part

Claims (5)

A method of constructing a soil cement wall so as to cross a boundary between the contaminated compartment and a non-contaminated compartment in which soil contamination is not found in a site where a contaminated compartment in which soil contamination is found,
At the boundary between the contaminated section and the non-contaminated section, a water-blocking part is constructed so that a part of the soil cement wall can be water-blocked by a construction method that does not leave the hole-stirred soil or leave the hole-stirred soil. A method for constructing a soil cement wall. The method is a chemical solution injection method,
The method for constructing a soil cement wall according to claim 1, wherein the water shielding portion is constructed by spraying a water shielding chemical solution from a chemical solution injection pipe inserted into the non-contaminated section. The construction method is an all casing construction method,
2. The method for constructing a soil cement wall according to claim 1, wherein the water shielding portion is constructed by replacing soil at a position overlapping with a boundary between the contaminated compartment and the non-contaminated compartment with a water shielding material. The construction method is a sheet pile wall construction method,
The method for constructing a soil cement wall according to claim 1, wherein the water shielding portion is constructed by placing a sheet pile across the boundary between the contaminated compartment and the non-contaminated compartment. A soil cement wall constructed to cross the boundary between the contaminated compartment and the non-contaminated compartment where no soil contamination was found on the site where the contaminated compartment where soil contamination was found,
Constructed by a construction method that does not leave the hole-stirred soil or the hole-stirred soil at the boundary between the contaminated section and the non-contaminated section, A soil cement wall characterized by comprising.