JPH10102479A - Ground stabilization method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the structural weak point of a solidified body and obtain higher improving efficiency than in the construction of a pile-shaped improving body, in a method to prevent the liquefaction by improving the ground liable to liquefaction. SOLUTION: In the ground stabilization method, an agitating device 1 formed from a plurality of parallelly disposed rods 2, 2 and a box-shaped casing 5 supported on the outer peripheries of the rods 2, 2 is used, and excavated earth and solidifying agent are agitated and mixed and the mixture is formed into the shape of the casing 5 and hardened to continuously construct solidified bodies 10 having a rectangular cross section. In this case, the bodies 10 are arranged on a flat plane on square patterns in two directions or in an adjoining relationship in two directions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground stabilization method for stabilizing a liquefiable ground by improving the ground.

[0002]

2. Description of the Related Art When stabilizing a ground that may be liquefied by ground improvement and rebuilding it into a non-liquefied ground, Japanese Patent Publication No. 4-54004,
As in Japanese Patent Laid-Open No. Hei 4-20612, pile-shaped improvement bodies are arranged in a grid pattern, and their fluidity is cut off by restraining groundwater and sand, thereby ensuring the shear rigidity of the entire target ground. .

[0003] Since the pile-shaped improved body has a circular cross section, it must be wrapped and constructed as shown in Fig. 5- (b) in order to continue it. Since the strength is smaller than other parts and the structure is apt to be a weak point, there is a disadvantage that the shear strength is substantially determined by the part having a small width.

[0006] Further, in the form in which the circular cross section is wrapped as shown in FIG.
The efficiency of ground improvement is low because it is relatively low.

In view of the above background, the present invention proposes a liquefaction countermeasure method having no structural weakness and a high improvement efficiency.

[0006]

According to the present invention, a stirrer is continuously constructed using a stirrer including a plurality of rods arranged in parallel and having a rectangular casing surrounding all the rods. Thus, the structural weakness of the consolidated body is eliminated, and the improvement efficiency is improved as compared with the case where a pile-shaped improved body is constructed.

The casing is supported by the rod at a distance from the outer periphery of the rod and insulated from rotation of the rod.

[0008] The stirrer agitates and mixes the excavated soil excavated by the rod and the solidified material discharged into the ground through the interior of the rod, and then uniformly hardens the mixture into the shape of a casing to form a rectangular solid. Consolidation is established, and the consolidation is stabilized in two directions on a plane to stabilize the ground that may be liquefied.

The construction is completed, and the casing of the agitator is overlapped in the long side direction or the short side direction on the consolidated body before curing, and is continuously performed in two directions on a plane. The solid bodies having a rectangular cross section are arranged in a lattice pattern in two directions on a plane, or are arranged adjacent to each other in two directions. When arranged in a grid, groundwater and sand are constrained and fluidity is interrupted, as in Japanese Patent Publication No. 4-54004, and when adjacent in two directions, the entire ground is improved by liquefaction. Secures and stabilizes the shear stiffness.

[0010] Since the planar shape of the compact formed by a single operation using the stirrer is rectangular according to the shape of the casing, when the compacts are arranged in a lattice, the rectangular compact has the length. The ground in the direction that is continuous in the side direction is improved into a belt-like shape with a certain width, eliminating structural weakness such as when a pile-shaped improvement body wraps, and improving the area for a rectangular ground with a certain area. The efficiency of ground improvement is also improved because of the increase of 100%.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS. 2 and 3, the present invention provides a stirring device comprising a plurality of parallel rods 2, 2 and a box-shaped casing 5 supported on the outer periphery of the rods 2, 2. This is a method for improving and stabilizing the ground that has a possibility of liquefaction using the device 1.

A bit 3 for excavating the ground protrudes below each rod 2, and excavated soil is provided on the outer periphery above the bit 3.
A stirring blade 4 is provided to stir and mix the solidified material discharged through the inside of the rod 2. A stirring shaft 9 shown in FIGS. 1- (b) and (c) of the ground improvement machine is connected to the upper end of each rod 2, and the rod 2 is rotated by the stirring shaft 9 to excavate and stir the ground.

The discharge hole 6 from which the solidified material is discharged is formed in the rod 2, but when the solidified material is discharged only when the stirring device 1 penetrates, the discharge hole 6 is formed below the casing 5 as shown in FIG. In some cases, when the liquid is ejected, the ink is discharged to the lower position, the upper position, or the height range of the casing 5 with respect to the casing 5.

The casing 5 has a flat surface as shown in FIG.
Assembled in a rectangular shape, arranged at a distance from the outer periphery of the rods 2, 2, and connected to a support member 8 projecting from a bearing 7 surrounding each rod 2 so as to be insulated from rotation of the rod 2. It is supported by the rod 2.

In the drawing, when there are two rods 2 (biaxial type)
In this case, the casing 5 is provided as shown in FIG.
As shown in (1), two pile-shaped improvements having a circular cross section are assembled into a rectangle having a size circumscribing two adjacent shapes. Although not shown, there are cases where three rods 2 are arranged side by side (three-axis type), in which case the three pile-shaped improved bodies are assembled to a size that circumscribes adjacent shapes.

The stirrer 1 stirs and mixes the excavated soil excavated by the rod 2 and the solidified material discharged into the ground from the discharge hole 6 through the inside of the rod 2, and mixes the mixture as shown in FIG. To form a consolidated body 10 having a rectangular cross section.

FIGS. 1 (a) to 1 (e) show a once-performing procedure using the stirrer 1. FIG. (a) shows a state in which the stirrer 1 is positioned, and (b) shows a state in which the ground is excavated with the bit 3 and at the same time, the solidified material is discharged from the rod 2 and the excavated soil and the solidified material are stirred and mixed by the stirring blade 4. The state in which the stirrer 1 is penetrating into the ground is shown in (c).
The state which formed the lower end part is shown. (d) shows the stirring device 1 with the rotation of the rod 2 stopped or with the rod 2 rotated.
And (e) shows a state in which one construction is completed. The solidified material may be discharged at least when the stirring device 1 penetrates, but is also performed at the time of pulling out for careful mixing.

FIGS. 4A and 4B show an example of the arrangement of the compact 10. (a) is a plan view, when the solidified bodies 10 having a rectangular cross section are continuous in two directions and arranged in a lattice form, (d)
This is a case where they are constructed adjacent to each other in the direction. (a) consolidated body 10
When the distance between the parallel compacts 10 is smaller than the length of the long side of the casing 5 of the stirring device 1 shown in FIGS. A single-shaft type agitator 11 is used.

FIG. 5A shows a cross section of the compact 10 completed by the agitating device 1 of the present invention, and FIG. 5B shows a cross section of the improved pile for comparison. FIG. 6 shows a state where (a) and (b) of FIG. 5 are combined.

In the case of the present invention, as shown in FIG. 6, the consolidated body 10 can be constructed without waste on a rectangular ground, and the area ratio is improved by 21% compared with the case of the pile-shaped improved body. Regarding the shearing force applied to the consolidated body 10, in the case of the pile-shaped improved body, the resistance to the shearing force is substantially determined by the width of the hatched portion in FIG. Since the consolidated body 10 of the present invention is continuous at a constant width in the long side direction, the resistance (the short side) is determined by the width (short side). Since the substantial width of the body is 0.8 m, if the material strength is equal to that of the pile-like improvement, the strength of the completed consolidated body 10 is increased by 25% as compared with the case of the pile-like improvement.

[0021]

According to the present invention, the flat shape of a compact formed by a single operation of the stirrer is rectangular according to the shape of the casing, and when the compacts are arranged in a lattice, the rectangular compact has the length. Since the ground in the direction that is continuous in the side direction is improved into a band shape having a certain width, there is no structural weak point as in the case where the pile-shaped improved body is wrapped.

Further, since the area of improvement for a rectangular ground having a fixed area is 100%, the efficiency of improvement is improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a construction procedure using a stirring device.

FIG. 2 is an elevation view showing a stirring device.

FIG. 3 is a plan view of FIG. 2;

FIG. 4 is a perspective view showing an example of constructing a consolidated body.

FIG. 5 (a) is a plan view showing a compact according to the present invention,
(b) is a plan view showing the improved pile.

FIG. 6 is a plan view showing a comparison between a cross section of the consolidated body of the present invention and a cross section of the pile-shaped improved body.

FIG. 7 is an elevation view showing a single-shaft stirring device.

[Explanation of symbols]

1 stirrer, 2 rod, 3 bit, 4
Stirring blade, 5 Casing, 6 Discharge hole, 7 Bearing, 8 Support member, 9 Stirring shaft, 10 Solid body, 11
…… Stirring device.

Claims (1)

[Claims] 1. A plurality of parallel rods each having a stirring blade protruding from the outer periphery thereof, and supported by the rods at a distance from the outer periphery of the rods in a state insulated from rotation of the rods.
Using a stirrer composed of a rectangular casing, the excavated soil excavated by the rod and the solidified material discharged into the ground through the rod are agitated and mixed, and the mixture is evenly shaped into the shape of the casing. Is a method of stabilizing the ground that may be liquefied by building a solidified body with a rectangular cross-section and attaching the casing of the stirring device to the solidified body before hardening. It is constructed continuously in two directions on a plane while overlapping in the direction or the short side direction, and the solidified body with a rectangular cross section is arranged in a grid on the plane in two directions, or arranged in a state adjacent to two directions Ground stabilization method to be performed.