JP5769239B2 - Ground improvement method for composite ground - Google Patents

Description

  The present invention relates to a ground improvement method for a composite ground in which a contaminated liquefied ground layer and an uncontaminated non-liquefied ground layer exist, and in particular, a pollutant contained in a contaminated liquefied ground layer. The present invention relates to a ground improvement method for a composite ground that prevents leakage from the ground surface easily.

  There is an uncontaminated non-liquefied ground layer below the ground surface, and there is a contaminated liquefied ground layer below it, in short, a contaminated liquefied ground layer and an uncontaminated non-liquefied ground layer, When improving the ground of each composite ground, there is a generally known compaction method. As this compaction method, for example, a casing pipe is inserted into the ground by a rotating device and a lifting device attached to the upper part, a sand-based water permeable material is introduced into the casing pipe, and a sand-based material is introduced from the tip of the casing pipe. By pulling out the casing pipe while discharging the water-permeable material, and further pushing it back, the sand-based water-permeable material is compacted while expanding the diameter in the ground. There is a SAVE composer method in which an improved sand pile that has been expanded to a larger diameter is compacted to compact the ground, and there is also a sand compaction pile method in which the rotating device is replaced with a vibration device.

  In the ground improvement by such compaction method, the improved sand pile constructed with water-permeable material reaches the ground surface from the contaminated liquefied ground layer through the uncontaminated non-liquefied ground layer. There was a risk that contaminants contained in the contaminated liquefied ground layer would leak to the ground surface through this improved sand pile.

  Therefore, conventionally, a method for purifying contaminated ground with combined ground reinforcement has been known. As a purification method of this soil strengthening combined contaminated ground, as disclosed in Japanese Patent No. 3714855, a number of improved sand piles by a compaction method for ground improvement are created to a predetermined depth, and groundwater is A pumping well for pumping is provided, and an air injection pipe for injecting compressed air is provided so as to reach the lower side of the contaminated liquefied ground layer. Next, the groundwater was pumped up by the pumping well and the groundwater level was lowered below the contaminated liquefied ground layer, and then compressed air was injected from the air injection pipe, and this injected compressed air was contaminated. By passing through the liquefied ground layer, pollutants contained in the liquefied ground layer are discharged together with compressed air to the ground through the improved sand pile, and the pollutants are collected on the ground. In addition to improving the ground, it was also designed to collect contaminants.

Japanese Patent No. 3714855

  In the case of performing such conventional soil strengthening combined purification method of contaminated ground, in addition to the construction of improved sand pile by compaction method, work such as pumping up groundwater by pumping well and injecting compressed air by air injection pipe is necessary. In some cases, these operations take time, and the construction period becomes longer, and the construction cost increases.

  On the other hand, in a complex ground where there is a contaminated liquefied ground layer and a non-contaminated non-liquefied ground layer, the contamination of the liquefied ground layer has a very low impact on the ground surface or contamination. In the case where the substance naturally decreases and disappears, instead of removing the pollutant contained in the liquefied ground layer by the purification method as described above, the pollutant is contained in the liquefied ground layer. There was also a method, but in the ground improvement by the conventional compaction method, it was difficult to contain the contaminants in the liquefied ground layer because the contaminants leaked to the ground surface through the improved sand pile as described above. There was a problem such as.

  Therefore, the present invention provides a pollutant contained in a contaminated liquefied ground layer when improving the composite ground in which a contaminated liquefied ground layer and an uncontaminated non-liquefied ground layer are respectively present. It is an object of the present invention to provide a ground improvement method for composite ground so that contaminants can be prevented from leaking to the ground surface by enclosing the liquefied ground in the liquefied ground layer.

The present invention provides a sand-based water-permeable material in a contaminated liquefied ground layer when improving the ground of a composite ground in which a contaminated liquefied ground layer and an uncontaminated non-liquefied ground layer are present. Is introduced into the casing pipe from the hopper of the construction machine , discharged from the tip of the casing pipe into the ground , pulled out while being discharged , then backed out, and repeated to improve the diameter and tighten. In addition to creating a sand pile, above the liquefied ground layer that created this improved sand pile , a sand permeable material is introduced and discharged when constructing the improved sand pile, with casing pipe, thus the same route of water permeable material sand system, by introducing into the casing pipe from a hopper construction caking material cementitious machine Discharged from the tip of the over single pipe in the ground, pull the casing pipe while discharging, and construct a predetermined by the height consolidation pile, the upper improvements sand pile was constructed Liquefaction ground layer at the consolidation pile This is a ground improvement method for a composite ground in which the contaminant contained in the contaminated liquefied ground layer is contained in the liquefied ground layer by closing.

  According to the present invention, the upper side of the improved sand pile formed on the contaminated liquefied ground layer is closed by the consolidated pile formed with cement-based consolidated material, so that it is included in the contaminated liquefied ground layer. In this liquefied ground layer, pollutants can be prevented from leaking to the ground surface.

  Moreover, without the conventional soil strengthening combined soil purification method, the liquefied ground layer was stabilized by creating an improved sand pile that was expanded and compacted to the contaminated liquefied ground layer. Since it can be improved to the ground and is performed by the same construction machine, the construction cost for the ground improvement work is reduced and the construction period is shortened.

It is explanatory drawing of the ground improvement construction method of the composite ground of this invention. It is process drawing of the ground improvement construction method of the composite ground of this invention. It is process drawing of the ground improvement construction method of the composite ground of this invention. It is process drawing of the ground improvement construction method of the composite ground of this invention. It is process drawing of another example of the ground improvement construction method of the composite ground of this invention. It is process drawing of another example of the ground improvement construction method of the composite ground of this invention. It is explanatory drawing of another example of the ground improvement construction method of the composite ground of this invention. It is process drawing of another example of the ground improvement construction method of the composite ground of this invention.

  An embodiment of the ground improvement method for composite ground according to the present invention will be described. As the composite ground in this case, as shown in FIG. 1, there is a non-contaminated non-liquefied ground layer A below the ground surface, and a contaminated liquefied ground layer B is present thereunder. It becomes a complex ground.

  As the construction machine 1 used for the ground improvement method of the composite ground, the casing pipe 2 penetrating the ground is arranged to be suspended by a construction machine main body (not shown), and the casing pipe 2 is rotated above the casing pipe 2. A rotating device 3 for moving up and down, a lifting device 4 for raising and lowering the casing pipe 2, and a hopper 5 for putting the material into the casing pipe 2 are respectively attached to the machine for the SAVE composer method. In addition, in this construction machine 1, the machine for the sand compaction pile method which attached the vibrator instead of the rotation apparatus 3 and the raising / lowering apparatus 4 may be used, and the machine for other construction methods may be sufficient.

  Next, the ground improvement method for composite ground according to the present invention will be described. Using the construction machine 1, the sand-based water permeable material 10 is introduced into the casing pipe 2 from the hopper 5, and after the introduction, FIG. ), The casing pipe 2 is penetrated to the lower end of the contaminated liquefied ground layer B by the rotating device 3 and the lifting device 4 attached to the upper portion of the casing pipe 2. After the penetration, as shown in FIG. 2 (b), the casing pipe 2 is pulled out while discharging the sand-based water permeable material 10 from the tip of the casing pipe 2, and then pulled out again as shown in FIG. 2 (c). By reversing the casing pipe 2, the improved sand pile 11 in which the sand-based water permeable material 10 expands in diameter on the liquefied ground layer B and is compacted is formed. As shown in FIGS. 3 (d) and 3 (e), by repeating this process upward, as shown in FIG. 3 (f), the improved sand pile 11 expanded and compacted was contaminated. The liquefied ground layer B is formed from the lower end to the upper end. By creating the improved sand pile 11 that has been expanded and compacted to the contaminated liquefied ground layer B in this way, the surrounding ground can be compacted together with the improved sand pile 11 that has been expanded and compacted. This can improve the liquefied ground layer B into a stable ground. The sand-based water-permeable material 10 is basically a sand material, but may be a material obtained by mixing an additive or the like with a sand material.

  Then, after the improved sand pile 11 is formed on the contaminated liquefied ground layer B, the cement-based consolidated material 20 is introduced into the casing pipe 2 from the hopper 5 using the same construction machine 1, and the casing pipe By pulling out the casing pipe 2 while discharging the cement-based consolidated material 20 from the tip of 2, as shown in FIG. 4 (g), the consolidated pile 21 is formed on the non-contaminated non-liquefied ground layer A. Create. The consolidated pile 21 is formed at a predetermined height, for example, 2 to 3 m. In this cement-based consolidated material 20, a solid pile 21 is formed at a predetermined height on the non-liquefied ground layer A above the liquefied ground layer B on which the improved sand pile 11 is formed. The upper side of the improved sand pile 11 created in the liquefied ground layer B is closed by the created consolidated pile 21. The cement-based caking material 20 is a mixture of gravel or crushed stone with cement milk, but other materials may be used as long as they are similar materials.

  In addition, after the consolidated pile 21 is formed on the non-contaminated non-liquefied ground layer A, the surface of the casing pipe 2 is moved to the surface that is the upper end of the non-liquefied ground layer A as shown in FIG. The sand-based water-permeable material 10 may be discharged from the tip, and the sand-based water-permeable material 10 may be filled therein, or surrounding sand or the like may be filled.

  In this way, the upper side of the improved sand pile 11 formed on the liquefied ground layer B is covered with the consolidated pile 21 formed with the cement-based consolidated material 20 and included in the contaminated liquefied ground layer B. The contaminated material can be contained in the liquefied ground layer B, and the contaminant can be prevented from leaking to the ground surface.

  Moreover, according to the soil quality of the contaminated liquefied ground layer B and the non-contaminated non-liquefied ground layer A, the consolidated pile 21 formed in the non-liquefied ground layer A may be expanded. . As shown in FIG. 5 (a), the casing pipe 2 is pulled out while discharging the cement-based consolidated material 20 from the lower end of the casing pipe 2, and then pulled out again as shown in FIG. 5 (b). By returning the casing pipe 2 and repeating this, the cement-based consolidated material 20 is expanded in diameter in the non-liquefied ground layer A, and the expanded consolidated pile 21 is formed. At this time, the expanded piled pile 21 may have the same pile diameter as the improved sand pile 11 formed on the liquefied ground layer B or a pile diameter larger than that. As a result, the pollutant contained in the contaminated liquefied ground layer B is reliably contained in the consolidated pile 21.

  Furthermore, there is a place where the boundary between the contaminated liquefied ground layer B and the uncontaminated non-liquefied ground layer A is not clear. In such a place, the contaminated liquefied ground layer B is formed. As shown in FIGS. 6A and 6B, the consolidated pile 21 that closes the upper side of the improved sand pile 11 has the same pile diameter as that of the improved sand pile 11 or a pile diameter larger than that. Then, the consolidated pile 21 is formed so as to extend to the liquefied ground layer B. Thereby, even in a place where the boundary is not clear, the pollutant contained in the contaminated liquefied ground layer B can be reliably contained by the consolidated pile 21.

  Further, another embodiment of the ground improvement method for composite ground according to the present invention will be described. This is a composite ground in which a plurality of contaminated liquefied ground layers and non-contaminated non-liquefied ground layers are overlapped. Specifically, as shown in FIG. There is a non-contaminated non-liquefied ground layer A, a contaminated liquefied ground layer B is present below it, and a non-contaminated non-liquefied ground layer C and a contaminated liquefied material thereunder. This is a case where the ground layer D exists.

  After the sand-based water permeable material 10 is put into the casing pipe 2, the casing pipe 2 is moved to the bottom by the rotating device 3 and the lifting device 4 attached to the upper portion of the casing pipe 2 as shown in FIG. It penetrates to the lower end of the contaminated liquefied ground layer D. After the penetration, as described above, the improved sand is expanded and compacted into the liquefied ground layer D by pulling out the casing pipe 2 while discharging the sand-based water-permeable material 10 from the tip of the casing pipe 2 and driving it back. The pile 11 is created, this is repeated, and the improved sand pile 11 which is expanded and compacted is created from the lower end to the upper end of the bottom contaminated liquefied ground layer D.

  Then, after the improved sand pile 11 is formed on the bottom contaminated liquefied ground layer D, the cement-based consolidated material 20 is introduced into the casing pipe 2 as described above, and from the tip of the casing pipe 2. By pulling out the casing pipe 2 while discharging the cement-based consolidated material 20, as shown in FIG. 8 (b), the consolidated pile 21 is placed at a predetermined height on the non-contaminated non-liquefied ground layer C. Just build up and close the upper side of the improved sand pile 11. Thereafter, the sand-based water-permeable material 10 is discharged and filled from the tip of the casing pipe 2 to the upper end of the non-liquefied ground layer C.

  Next, in the upper contaminated liquefied ground layer B, the casing pipe 2 is pulled out from the lower end of the casing pipe 2 while discharging the sand-based water-permeable material 10 from the front end of the casing pipe 2 and driven back. Then, the improved sand pile 11 expanded to the liquefied ground layer B and compacted was formed, and this was repeated to expand the compacted sand pile 11 that had been expanded and compacted into the contaminated liquefied ground layer B on the upper side. From bottom to top.

  Then, after the improved sand pile 11 is formed on the contaminated liquefied ground layer B on the upper side, the cement-based consolidated material 20 is put into the casing pipe 2 as described above, and the cement-based material is introduced from the tip of the casing pipe 2. By pulling out the casing pipe 2 while discharging the consolidated material 20, the consolidated pile 21 is formed to a predetermined height on the upper non-contaminated non-liquefied ground layer A, and the upper side of the improved sand pile 11. Block. Thereafter, as shown in FIG. 8C, the sand-based water-permeable material 10 is discharged and filled from the tip of the casing pipe 2 to the surface that is the upper end of the non-liquefied ground layer A.

  Thus, even in the case of a composite ground in which the contaminated liquefied ground layers B and D and the uncontaminated non-liquefied ground layers A and C overlap each other, each contaminated liquefied ground layer B , D can be contained in the respective liquefied ground layers B, D.

  In the case of a composite ground in which a plurality of contaminated liquefied ground layers and non-contaminated non-liquefied ground layers are overlapped, the pollutants are liquefied by repeating the same process as described above. It can be contained in the ground layer.

  DESCRIPTION OF SYMBOLS 1 ... Construction machine, 2 ... Casing pipe, 3 ... Rotating device, 4 ... Lifting device, 5 ... Hopper, 10 ... Sand-based water-permeable material, 11 ... Improved sand pile, 20 ... Cement-based consolidated material, 21 ... Consolidated pile

Claims (1)

When refining a composite ground where a contaminated liquefied ground layer and an uncontaminated non-liquefied ground layer exist,
In the contaminated liquefied ground layer , sand-based water permeable material is put into the casing pipe from the hopper of the construction machine , discharged from the tip of the casing pipe into the ground , pulled out while discharging, and then returned to the ground. By repeating this process, we created an improved sand pile that was expanded and compacted.
Above the liquefied ground layer that created this improved sand pile , using the hopper and casing pipe of the construction machine, which will insert and discharge sand-based water permeable material when constructing the improved sand pile, as the same route of water permeable material sand system was discharged from the tip of the casing pipe in the ground and put into the casing pipe from a hopper construction caking material cementitious machine, while discharging Included in the contaminated liquefied ground layer by pulling out the casing pipe, creating a consolidated pile with a predetermined height, and closing the upper side of the improved sand pile formed on the liquefied ground layer with this consolidated pile A ground improvement method for composite ground, which is designed to contain contaminated contaminants in a liquefied ground layer .

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