JP2678659B2 - Liquefaction countermeasures - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a liquefaction countermeasure method for preventing liquefaction of ground.

[Problems to be Solved by Conventional Techniques and Inventions] As a liquefaction countermeasure work for the ground, a compaction method by vibration or the like and a solidification method by chemical injection have been put into practical use. However, in these methods, a structure has already been built. There is a problem that it is difficult to use it as a liquefaction countermeasure against the existing place, for example, the ground of a factory site.

The present invention can be used as a countermeasure against the liquefaction of the ground in a place where a structure is already built (for example, a construction site) in this way, and the liquefaction countermeasure work by the conventional method can be applied to the ground due to, for example, the influence of vibration or chemical injection It was made for the purpose of being able to use it in places where it is difficult to take it due to the influence.

[Means for Solving the Problem] The gist of the present invention is that a mesh cylinder having a gap for preventing the inflow of sand is further inserted, and if necessary, inside cylinder pipes with slits for internally supporting the mesh cylinder are inserted. And, after inserting a cylinder hole with slits provided with a number of holes through which excess pore water pressure is provided with a bottom lid at the bottom into the liquefied ground, inside the cylinder pile with slits provided, a hollow with a slit on the surface A large number of water pressure removing balls consisting of small spheres are filled, and excess pore water pressure around the cylinder pile with slits installed in this ground is guided into the cylinder pile, and this is applied between the water pressure removing spheres filled in the cylinder pile. This is related to the liquefaction countermeasure construction method in which water is allowed to flow out from the upper part of the cylinder pile through the space of, and if necessary, water in the cylinder pile is removed in advance through a drain pipe that penetrates into the cylinder pile. It is a collection.

[Operation] In the tubular pile with a slit used in the present invention, not only excess pore water pressure flows through the slit, but also sand flows in with the excess pore water pressure. Therefore, in order to prevent this, the inflow of sand is blocked inside the tubular pile. Although a mesh cylinder having a gap is provided, the mesh cylinder is preferably made of stainless steel in order to make it a permanent structure.

The inside cylinder tube with slit, which is inserted into the slit cylinder pile of the present invention as necessary, is a support for the above mesh cylinder and prevents the mesh cylinder from being deformed inward by water pressure. For this purpose, for example, a vinyl chloride resin slit cylinder is used.

Further, the water pressure removing spheres to be filled in the slit-equipped cylinder piles are hollow spheres like vinyl chloride resin ping-pong spheres, for example, and a slit is provided on the surface to prevent clogging. .

If these water pressure removing balls are packed in a slitted pile, the space inside the pile will be almost the same, and excess pore water that has penetrated into the pile can be discharged to the upper part through this space. It is possible to prevent deformation of the inside tube. Therefore, it is possible to release the excess pore water pressure around the cylinder pile at a stretch, and it is also equipped with the deformation of the surrounding ground.

Needless to say, the use of the above-mentioned inside tube can be omitted if these water pressure removing balls can be completely filled in the tube pile.

Furthermore, if a highly rigid tube such as a slit steel tube is used as the slitted tubular tube, it can be expected to increase the horizontal resistance of the pile in addition to preventing the liquefaction.

[Example] The basic structure of the tubular pile with slits used in the present invention is the first
As shown in the figure, it consists of a cylindrical pile with slits (1), a stainless steel mesh tube (2), a vinyl chloride resin drain tube (3), and a lower lid (4). Is provided with a large number of holes through which excess pore water passes. The mesh tube (2) is provided with a gap so that the sand does not flow into the pile (1) together with the pore water. The inside cylinder tube (3) prevents the mesh cylinder (2) from being deformed inward.

The slitted pile with the above structure is pushed into a hole previously drilled in the liquefied ground with an earth auger, etc. until its upper end is flush with the ground, and then a slit is made on the surface with vinyl chloride resin hollow globules. A large number of the water pressure removing spheres (5) are filled in the inside cylindrical pipe (3).

FIG. 2 shows an example in which the drainage pipe (6) is inserted into the inside cylinder pipe (3) in advance. In this case, the lower lid (4) also has the slit cylinder hole (1) and the mesh cylinder (2). )
However, in this case, the pile (1) and the mesh tube (2) may have an integrated structure with a bottom.

As described above, the excess gap (7) around the pile installed on the liquefaction ground enters the pile through the slit of the pile (1) and the mesh of the mesh tube (2), and the space between the water pressure removal balls (5) is formed. It rises and flows out from the upper part of the pile, and the excess pore water pressure in the liquefied ground can be effectively released.

[Effects of the Invention] According to the present invention, since the mesh cylinder is inserted inside the slit-equipped cylinder pile, there is no risk of clogging due to sand or the like, and it is also advantageous in terms of replacement of the slit cylinder.

Also, since the pile is filled with water pressure removing balls, there is a lot of space inside the pile, and excess pore water that has entered the pile can be immediately drained to the top of the pile, which is advantageous in terms of construction efficiency as a liquefaction countermeasure.

[Brief description of the drawings]

1 (A) and (B) are a longitudinal sectional view and an AA sectional view showing an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing another example of the present invention. 1 …… Slit cylinder pile 2 …… Mesh cylinder 3 …… Inside cylinder tube 4 …… Lower lid 5 …… Water pressure removal ball 6 …… Drainage pipe 7 …… Excessive pore water.

Claims (3)

(57) [Claims] 1. Liquefaction is expected in a slitted cylinder pile in which a mesh cylinder having a gap for preventing the inflow of sand is inserted and a large number of holes for allowing excess pore water pressure to pass through are provided with a bottom lower lid. After inserting it into the ground, the inside of the slitted pile is filled with a large number of water pressure removing balls consisting of hollow small spheres with slits on the surface, and excess space around the slitted pile installed in this ground is filled. A liquefaction countermeasure method characterized in that water is guided into the tubular pile, and the water is allowed to flow out from the upper portion of the tubular pile through the space between the water pressure removal balls filled in the tubular pile. 2. The method according to claim 1, wherein an inside cylinder tube with a slit for supporting the mesh cylinder from the inside is provided in the mesh cylinder. 3. The method according to claim 1, wherein a water drain pipe is inserted into the tubular pile, and water in the tubular pile is drained through the drain pipe.