JP2905129B2 - Ground improvement method - Google Patents

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 In general, when a structure is to be built on soft ground in a landfill site, etc., construction to increase the strength of the ground in order to prevent liquefaction of the sand ground and increase the bearing capacity is required. Done in Although various construction methods have been put into practical use for performing such construction, there is a sand compaction pile method (SCP method) which is effective for both clayey soil and sand layer and is relatively inexpensive.

FIG. 8 is a diagram showing an outline of the SCP method.
As shown in FIG. 8, a steel guide pipe 103 having a vibratory hammer (not shown) mounted on the top is connected 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 introducing sand into the inside of the guide pipe 103 and giving vibration and vertical movement to the guide pipe 103. I do. Note that the door 105 is attached to the tip of the guide pipe 103 with a butterfly plate, and is opened when the guide pipe 103 is pulled out, drops sand in the guide pipe 103, and pushes the tip of the guide pipe 103 when the guide pipe 103 is pushed in. Is closed and the injected sand is pressurized.

[0004] However, when the SCP method is used, the following problems occur with respect to a nearby structure or site. Therefore, it is difficult to adopt the SCP method in an urban area. First,
The sand pile 107 expanded beyond the diameter of the guide pipe 103
As a result, the ground may be pushed out of the ground improvement area, deforming nearby premises and structures built there.

[0005] Second, a vibro hammer (not shown) is mounted on the top of the guide pipe 103, and
By vibrating 3, the driving of the guide pipe 103 and the compaction of the injected sand are performed, so that vibration is applied to a nearby site or a structure built there.

[0006]

For this reason, the following method is used to improve soft ground. (A) Without using SCP method, SMW (Soil Mixing Wa
ll) Use the construction method. In the SMW method, the ground is excavated with an auger, and cement milk is injected into the excavated portion and stirred. However, if a non-vibration system or non-expansive construction method such as the SCP method is used, the problem of vibration displacement is eliminated, but the cost is extremely increased and plant equipment for mortar preparation is required, and a work yard is required. Becomes

(B) As shown in FIG. 9, a buffer groove 111 is provided between a place where the SCP method is to be performed and an adjacent land 112.
In FIG. 9, 101 is the ground, and 109 is a sand compaction pile. As described above, the provision of the buffer groove 111 is inexpensive and is often used.
1 is less effective because it is difficult to make. In particular, when the improvement depth of the sand compaction pile 109 is deep, displacement and vibration are transmitted below the buffer groove 111 to the adjacent ground 112.

(C) As shown in FIG. 10, a buffer pipe 113 is provided between the place 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 formed by drilling the ground 101 with an auger or the like and loosening the ground 101. In this case, a loose ground is created between the place where the SCP method is performed and the adjacent ground 114, transmission of vibration and displacement is suppressed, and the buffer pipe 113 can be formed to a required depth, and the effect is large. . However, SCP
Since the loosened ground is compacted by the work of the construction method and the effect does not continue for a long time, the ground 101 is repeatedly used with an auger or the like.
Work is required to loosen.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a ground improvement method which is inexpensive and suppresses transmission of vibration and displacement to an adjacent land. It is in.

[0010]

Means for Solving the Problems In order to achieve the above object, a first aspect of the present invention is to provide a plurality of excavation holes around the ground for improving the ground, and set up a pipe above the excavation holes, A step of installing a rubber tube loaded with a liquid inside the borehole, a step of vibrating a sand pile in the ground for ground improvement, and discharging the liquid while pouring mortar into the rubber tube. And closing the excavation hole.

A second invention provides a step of providing a plurality of excavation holes around the ground for improving the ground and providing a cylindrical cushion material having a hole in the center in the inside of the excavation holes, In the process of building while vibrating the sand pile in, and inject mortar using the center hole of the cushion material,
And a step of closing the excavation hole.

[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 the first embodiment of the present invention. In FIG. 1, 1 is the ground, 3 is the groundwater table, 9 is the sand compaction pile, and a buffer band 5 is provided between the place where the SCP method is used and the adjacent land 4.
Is provided.

FIG. 2 is a longitudinal sectional view of the buffer 7, FIG. 3 is a sectional view taken along the line AA of FIG. 2, and FIG. 4 is a sectional view taken along the line BB of FIG. When constructing the buffer 7, first, the inside of the ground 1 is drilled with an auger or the like, and an excavation hole 11 is provided. A pipe 13 is erected on the top of the borehole 11, and a rubber tube 15 loaded with water 14 is installed inside the pipe 13 and the borehole 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 so as to be pressed by water pressure. Note that a liquid other than the water 14 may be loaded into the rubber tube 15.

In FIG. 1, for example, when the SCP method is performed, a required number of buffers 7 are constructed between the adjacent land 4 and
After that, the sand compaction pile 9 is constructed and SCP
Perform the construction method. When the SCP method is performed, collapse of the wall surface of the excavation hole 11 is prevented by the water pressure in the rubber tube 15. In addition, the deformation of the rubber tube 15 prevents the ground deformation by the SCP method from being transmitted to the adjacent ground 4, and the water 14 in the rubber tube 15 absorbs the vibration, thereby preventing the vibration from being transmitted to the adjacent ground 4. Is done.

When the SCP is completed, the water 14 is drained while the mortar is poured into the rubber tube 15, and the borehole 11 is closed. As described above, according to the first embodiment, even if the SCP method is used, the displacement of the ground and the transmission of vibration to the adjacent ground 4 can be prevented. For this reason, ground improvement can be performed even in an urban area using an 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 groundwater table, 9
Is a sand compaction pile, in which a buffer band 19 is provided between a place where the SCP method is used and an adjacent land 18, and a buffer 21 is provided in the buffer band 19.

FIG. 6 is a longitudinal sectional view of the buffer 21 and 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 an excavation hole 23 is provided. A cylindrical cushion material 25 having a hole 27 at the center is set in the excavation hole 23. The cushion material 25 has a certain degree of rigidity and can prevent the inflow of soil around the excavation hole 23. The cushion material 25 is formed by welding and shaping a material obtained by curling a synthetic resin fiber (such as Hetimaron (trade name)). For example, the outer peripheral portion is covered with a sheet.

In FIG. 5, for example, when the SCP method is performed, the required number of buffers 21 are built between the ground 18 and the adjacent land 18, and then the sand compaction pile 9 is built to form
Perform the 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 time. By installing the required number of buffers 21 in the ground 1, deformation of the ground and transmission of vibration to the adjacent ground 18 by the SCP method can be reduced.

After the completion of the construction, as shown in FIG. 6, a grout hose 29 is inserted into a hole 27 provided at the center of the cushion material 25, mortar is injected from the grout hose 29, and the excavation hole 23 is closed. I do. According to the second embodiment, similarly to the first embodiment, even if the SCP method is used, the displacement of the ground and the transmission of vibration to the adjacent ground 18 can be prevented.

[0021]

As described above in detail, according to the present invention, it is possible to provide a ground improvement method which is inexpensive and suppresses transmission of vibration and displacement to an adjacent land.

[Brief description of the drawings]

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

FIG. 2 is a longitudinal sectional view of a buffer body 7;

FIG. 3 is a sectional view along AA in FIG. 2;

FIG. 4 is a sectional view taken along line BB of FIG. 2;

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

FIG. 6 is a longitudinal sectional view of the buffer 21.

FIG. 7 is a sectional view taken along the line CC of FIG. 6;

Fig. 8 Schematic diagram of SCP method

FIG. 9 is a schematic diagram of a case where an SCP method is performed by providing a buffer groove 111;

FIG. 10 is a schematic diagram of a case where an SCP method is performed by providing a buffer pipe 113;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ground 7 ... Buffer body 9 ... Sand compaction pile 11 ... Drilling hole 13 ... Pipe 14 ... Water 15 ... Rubber tube 21 ... Buffer body 25 ... Cushioning material

Claims (2)

(57) [Claims] 1. A plurality of excavation holes are provided around the ground on which ground improvement is to be performed , and a pipe is erected above the excavation holes.
A step of placing a rubber tube loaded with liquid inside micro該掘boring, a step of constructing while vibrating the Sunakui in soil to perform ground improvement, while pouring mortar into the rubber tube, the liquid
Discharging the body and closing the excavation hole . 2. A step of providing a plurality of excavation holes around the ground for which the ground improvement is to be performed, and providing a cylindrical cushion material having a hole at a central portion inside the excavation hole; Building a sand pile inside while vibrating, and injecting mortar using the center hole of the cushion material
And closing the excavation hole .