JPH09125359A - Soil improving technique - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent soil from being extruded or vibration from being transmitted to the outside in a soil improvement area by providing multiple drilled holes around the ground for which a soil improvement is performed and also providing water-filled rubber tubes and cushion material-filled cushion bodies. SOLUTION: Multiple cushion bodies 7 are built between a ground 1 to which a sand compaction SCP method is applied and its adjacent lands. Also drilled holes 11 are provided in the cushion bodies 7 by drilling the ground 1. A pile 13 is erected at the upper part of the drilled holes 11, and a rubber tube 15 filled with water 14 is set inside the pile 13 and the drilled holes 11. Also a water level in the rubber tube 15 is set higher than the ground level so that the inner surfaces of the drilled holes 11 are pressed by a hydraulic pressure. When the SCP work method is applied, the wall surfaces are prevented from being collapsed by the hydraulic pressure inside the rubber tube 15. Thus the rubber tube 15 is defomed so as to prevent the deformation and vibration of the ground on the adjacent lands.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving soft ground in a landfill or the like.

[0002]

2. Description of the Related Art Generally, when constructing a structure on a soft ground such as a landfill site, it is necessary to carry out a construction to increase the strength of the ground in advance in order to prevent liquefaction of the sand ground and increase the bearing capacity. To be done. Although various construction methods have been put into practical use for performing such construction, the sand compaction pile construction method (SCP construction method) is effective for both cohesive soil and sand layers and is a relatively inexpensive construction method.

FIG. 8 is a diagram showing an outline of the SCP construction method.
As shown in FIG. 8, a steel guide pipe 103 having a vibro hammer (not shown) mounted on the top is attached to the ground 101.
The sand pile 107 having a diameter larger than the diameter of the guide pipe 103 is constructed inside the ground 101 by penetrating the inside and introducing sand into the guide pipe 103 to give vibration and vertical movement to the guide pipe 103. To do. The door 105 is attached to the tip of the guide pipe 103 by a butterfly plate, and is opened when the guide pipe 103 is pulled out to drop sand in the guide pipe 103, and when the guide pipe 103 is pushed in, the tip of the guide pipe 103 is pushed. The sand is closed and the sand added is pressurized.

However, when the SCP method is used, the following problems occur with respect to structures and sites that are close to each other, so that it is difficult to adopt the SCP method in urban areas. First,
In addition, the sand pile 107 that is enlarged to the diameter of the guide pipe 103 or more
As the ground is being built, the ground may be pushed out to the outside of the ground improvement portion, which may deform the adjacent site or the structure built there.

Secondly, a vibro hammer (not shown) is attached to the top of the guide pipe 103, and the guide pipe 10
By vibrating 3, the guide pipe 103 is driven in and the sand that has been injected is compacted, so that vibration is applied to the adjacent site and the structure built there.

[0006]

Therefore, in the case of improving the soft ground, the following method is adopted. (A) SMW (Soil Mixing Wafer) without adopting the SCP method
ll) Adopt the construction method. In the SMW method, the ground is excavated with an auger, cement milk is injected into the excavated portion, and the mixture is stirred. However, if a non-vibration system, non-expansion method such as the SCP method is adopted, the problem of vibration displacement will disappear, but the cost will rise significantly and plant equipment for mortar preparation will be required, and a work yard will be required. Becomes

(B) As shown in FIG. 9, a buffer groove 111 is provided between the place where the SCP method is performed and the adjacent place 112.
In FIG. 9, 101 is the ground, and 109 is a sand compaction pile. As described above, providing the buffer groove 111 is inexpensive and often used, but the deep buffer groove 11 is provided.
1 is difficult to make, so it has little effect. Especially, when the improvement depth of the sand compaction pile 109 is deep, the displacement and vibration are transmitted to the adjacent ground 112 below the buffer groove 111.

(C) As shown in FIG. 10, a buffer pipe 113 is provided between the location where the SCP method is performed and the adjacent land 114. In FIG. 10, 101 is the ground and 109 is a sand compaction pile. The buffer pipe 113 is obtained by boring the ground 101 with an auger or the like and loosening the ground 101. In this case, a loose ground is created between the location where the SCP construction method is performed and the adjacent land 114, transmission of vibration and displacement is suppressed, and it is possible to build the buffer pipe 113 to a required depth, and the effect is also great. . However, SCP
Since the loose ground is compacted by the work of the construction method and the effect does not last long, use the auger etc. many times to ground 101
Work to loosen is required.

The present invention has been made in view of the above problems, and an object thereof is to provide a ground improvement method in which the cost is low and the transmission of vibrations and displacements to an adjacent ground is suppressed. It is in.

[0010]

In order to achieve the above-mentioned object, a first aspect of the present invention is to provide a rubber tube in which a plurality of excavation holes are provided in the periphery of the ground for soil improvement, and a liquid is loaded inside the excavation holes. The ground improvement method is characterized by including a step of installing and a step of constructing a sand pile while vibrating the ground while vibrating the ground. According to the first aspect of the present invention, a plurality of excavation holes are provided around the ground to be improved, a rubber tube filled with a liquid is installed inside the excavation holes, and a sand compaction pile method is applied to the ground to be improved.

A second aspect of the invention is to construct a plurality of excavation holes in the periphery of the ground to be improved and to provide a cushion material inside the excavation holes, and to oscillate sand piles in the ground to be improved. The ground improvement method is characterized by including the step of: In the second aspect of the invention, a plurality of excavation holes are provided in the periphery of the soil to be improved, a cushion material is provided inside the excavation holes, and a sand compaction pile method is performed in the soil to be improved.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic diagram of a ground improvement method according to a first embodiment of the present invention. In FIG. 1, 1 is the ground, 3 is the water table, and 9 is a sand compaction pile. A buffer zone 5 is provided between the location where the SCP method is used and the adjacent land 4, and a buffer body 7 is provided in the buffer zone 5.
Is provided.

FIG. 2 is a vertical sectional view of the buffer member 7, FIG. 3 is a sectional view taken along line AA of FIG. 2, and FIG. 4 is a sectional view taken along line BB of FIG. When constructing the buffer body 7, first, the inside of the ground 1 is drilled with an auger or the like to provide the excavation hole 11. A pipe 13 is erected above the excavation hole 11, and a rubber tube 15 filled with water 14 is installed inside the pipe 13 and the excavation hole 11.
The water level in the rubber tube 15 is set higher than the surface of the ground 1, and the inner surface of the excavation hole 11 is controlled by water pressure. A liquid other than water 14 may be loaded in the rubber tube 15.

In FIG. 1, for example, when the SCP method is used, a required number of buffer bodies 7 are built between the adjacent land 4,
Then build Sand Compaction Pile 9 and SCP
Perform construction method. When the SCP method is performed, the wall pressure of the excavation hole 11 is prevented from collapsing due to the water pressure inside the rubber tube 15. Further, the deformation of the ground by the SCP method is prevented from being transmitted to the adjacent ground 4 by the deformation of the rubber tube 15, and the water 14 in the rubber tube 15 absorbs the vibration, so that the transmission of the vibration to the adjacent ground 4 is prevented. To be done.

When the SCP construction is completed, the mortar is poured into the rubber tube 15 to drain the water 14 and close the excavation hole 11. As described above, according to the first embodiment, it is possible to prevent the displacement of the ground and the transmission of vibration to the adjacent ground 4 even if the SCP method is used. Therefore, even in urban areas, the ground can be improved by using the inexpensive SCP method.

Next, a second embodiment will be described. FIG. 5 is a schematic diagram of the ground improvement method according to the second embodiment. In FIG. 2, 1 is the ground, 3 is the water table, and 9 is
Is a sand compaction pile, and a buffer band 19 is provided between a place where the SCP method is used and the adjacent ground 18, and a buffer body 21 is provided in the buffer band 19.

FIG. 6 is a vertical sectional view of the buffer 21, and FIG. 7 is FIG.
It is sectional drawing by CC of FIG. When constructing the buffer 21, first, the inside of the ground 1 is drilled with an auger or the like, and the excavation hole 23 is provided. A cylindrical cushion material 25 having a hole 27 in the center is set up in the excavation hole 23. The cushioning material 25 has a certain degree of rigidity and can prevent the inflow of soil around the excavation hole 23, and is formed by curling synthetic resin fibers by welding and shaping (Hetimalon (trademark) or the like). For example, the outer periphery is covered with a sheet.

In FIG. 5, when the SCP method is used, for example, the required number of buffer bodies 21 are built between the adjacent land 18, and then the sand compaction pile 9 is constructed to construct the S
Perform CP method.

When the SCP method is performed, the cushion material 25 behaves elastically and the soil around the excavation hole 23 does not fall, so that the behavior as an elastic material can be maintained for a long period of time. By installing the required number of buffers 21 in the ground 1, it is possible to reduce the deformation of the ground and the transmission of vibration to the adjacent ground 18 by the SCP method.

After the construction is completed, as shown in FIG. 6, the grout hose 29 is inserted into the hole 27 provided in the central portion of the cushion member 25, and the mortar is injected from the grout hose 29 to close the excavation hole 23. To do. According to the second embodiment, similarly to the first embodiment, even if the SCP construction method is used, it is possible to prevent displacement of the ground and transmission of vibration to the adjacent ground 18.

[0021]

As described above in detail, according to the present invention, it is possible to provide a ground improvement method in which the cost is low and the transmission of vibration and displacement to the adjacent ground is suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a ground improvement method according to the first embodiment.

FIG. 2 is a vertical sectional view of a buffer body 7.

FIG. 3 is a sectional view taken along line AA of FIG.

FIG. 4 is a sectional view taken along line BB of FIG.

FIG. 5 is a schematic diagram of a ground improvement method according to the second embodiment.

FIG. 6 is a vertical sectional view of the buffer body 21.

7 is a sectional view taken along the line CC of FIG.

FIG. 8 Schematic diagram of SCP method

FIG. 9 is a schematic diagram when the SCP method is performed with the buffer groove 111 provided.

FIG. 10 is a schematic diagram of a case where a buffer pipe 113 is provided to perform the SCP construction method.

[Explanation of symbols]

 1 ... Ground 7 ... Buffer 9 ... Sand compaction pile 11 ... Drill hole 13 ... Pipe 14 ... Water 15 ... Rubber tube 21 ... Buffer 25 ... Cushion material

Claims (2)

[Claims] 1. A process of providing a plurality of excavation holes in the periphery of the ground to be improved and installing a liquid-filled rubber tube inside the excavation holes, and vibrating sand piles in the ground to be improved. A ground improvement method comprising the steps of constructing. 2. A step of providing a plurality of excavation holes in the periphery of the ground to be improved and providing a cushioning material inside the excavation holes, and a step of constructing sand piles in the ground to be improved while vibrating the ground. A ground improvement method characterized by comprising: