JP6404063B2 - Crushed stone improvement object construction tool and crushed stone improvement object construction method - Google Patents

Description

  The present invention relates to an improved body construction tool and an improved body construction method for constructing an improved body using crushed stone, which is a natural material.

As a method for improving the ground, there is known a method for constructing a crushed stone improvement body in the ground by excavating a columnar hole in the ground, throwing crushed stones, and compacting them by applying pressure.
This crushed stone improvement body is used not only for ground improvement, but also for preventing liquefaction of the ground because the gap between crushed stones prevents and dissipates excessive pore water pressure during an earthquake.
This method of constructing a crushed stone improvement body is generally formed by excavating the ground with a screw auger to form a hole, throwing crushed stone into the formed hole, and pushing down the upper surface of the crushed stone introduced at the lower end of the screw auger to form a crushed stone. A crushed stone improvement body (crushed stone pile) is constructed by compacting by applying pressure and performing this several times in the height direction.
This method does not cause soil contamination or environmental destruction by using crushed stone, which is a natural material.

JP 2008-196249 A

However, the conventional method for constructing a crushed stone improvement body has the following problems.
(1) Crushed stone is laterally dispersed by the pressure applied to the upper surface of the crushed stone. For this reason, crushed stones may not be tightened in the case of highly viscous ground.
(2) When throwing crushed stone into the excavated hole, the wall surface of the hole collapses and soil is mixed into the crushed stone, which may not be a crushed stone improvement body.

  An object of this invention is to provide the crushed stone improvement object construction tool and the crushed stone improvement object construction method which can compact | solidify a crushed stone reliably and can build a strong crushed stone improvement object.

1st invention of this application made in order to achieve the said objective is the crushed stone improvement object construction tool for rolling a crushed stone in the ground, and constructing | assembling a columnar crushed stone improvement object, Comprising: A pressurizing body that can be inserted into the casing, and the pressurizing body includes a shaft and a disk-shaped pressurizing portion provided at a lower end of the shaft, and the outer diameter of the pressurizing body, The inner diameter of the casing is substantially the same, forming a stopper protruding from the inner periphery of the upper end of the casing, and forming a notch through which the stopper can be inserted in the outer periphery of the pressurizing part, A crushed stone improvement body construction tool is provided.
The second invention of the present application is a method for constructing a crushed stone improvement body using the crushed stone improvement body construction tool according to the first invention, wherein (a) the pressurizing portion of the pressurizing body interpolated in the casing is provided. The casing and the pressure body are inserted into the ground in a state where the casing and the pressure body are disposed at the lower end of the casing, and (b) the casing is placed in the ground and the pressure body is pulled up, and the stopper of the casing and the casing The notch of the pressurizing part is aligned and pulled out from the pressurizing body into the casing, (c) crushed stone is put into the casing to a predetermined height, and (d) the stopper of the casing and the pressurizing part again (E) rotating the shaft of the pressurizing body to engage the pressurizing portion with the stopper of the casing, and aligning the pressurizing body with the notch. Predetermined height pull The casing is also lifted at the same time, (f) the pressure body is pushed down to roll the crushed stone, and (g) the crushed stone improvement body is constructed by repeating (e) and (f). A method for constructing a crushed stone improvement body is provided.

The present invention can obtain at least one of the following effects by means for solving the above-described problems.
(1) Since the casing having the tip sealed with the pressurizing body penetrates the ground, the ground around the casing becomes dense. For this reason, even if pressure is applied to the crushed stone, the crushed stone does not spread in the surrounding ground, and it is surely compacted.
(2) Since the crushed stone is put into the casing, the crushed stone improved body is not mixed with soil.
(3) Since pressure is applied to the crushed stone in the casing, the pressure applied from the upper surface of the crushed stone is transmitted downward while compacting the entire crushed stone and acts on the exposed portion.
(4) Since the ground around the casing becomes dense and the crushed stone improvement body is compacted, the entire ground becomes solid and resistance increases in the event of an earthquake.
(5) The gap between crushed stones prevents and dissipates excessive pore water pressure during an earthquake.
(6) Since the lifting and re-pressurization can be performed by the vertical movement of only the pressurizing body, a process such as gripping the casing again is unnecessary, and the construction time is shortened.

Explanatory drawing of the crushed stone improvement body construction tool of this invention Explanatory drawing of the combination of casing and pressurized body Explanatory drawing of the crushed stone improvement body construction method of this invention

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[1] Configuration <1> Overall configuration.
The crushed stone improvement body construction tool of this invention consists of the cylindrical casing 1 and the pressurization body 2 which can be inserted in the casing 1 (FIG. 1).
Each component will be described below.

<2> Casing.
The casing 1 is made of a steel pipe whose inner diameter is substantially the same as the diameter of the crushed stone improvement body to be constructed.
The length of the casing 1 is longer than the crushed stone improvement object to be constructed.
A stopper 11 is provided on the inner periphery of the upper end of the casing 1.
The stopper 11 is for engaging the pressurizing body 2 described later.
The stopper 11 is provided with a plurality of symmetrical central axes of the casing 1.

<3> Pressurized body.
The pressurizing body 2 is a member inserted into the casing 1.
The pressing body 2 includes a shaft 21 and a pressing portion 22 provided at the lower end of the shaft 21.
The shaft 21 is a rod-like member that is longer than the length of the casing 1.
The pressurizing unit 22 is a disk-shaped member whose outer diameter is slightly smaller than the inner diameter of the casing 1.
A notch 221 through which the stopper 11 of the casing 1 can pass is formed on the outer periphery of the pressure unit 22.
The notch 221 is provided at a position corresponding to the stopper 11 of the casing 1.

<4> A combination of a casing and a pressurized body.
The pressurizing part 22 of the pressurizing body 2 has a slightly smaller diameter than the inner diameter of the casing 1, and has a notch 221 corresponding to the stopper 11. Therefore, by aligning the positions of the notch 221 and the stopper 11 (FIG. 2 a), it can be inserted into the casing 1 from above the casing 1.
Then, the shaft 21 is rotated after the insertion to shift the positions of the stopper 11 and the notch 221 so that the pressurizing portion 22 does not come out of the casing 1 (FIG. 2b).

  Next, the crushed stone improvement object construction method using the crushed stone improvement object construction tool concerning the present invention, and its operation and effect are explained.

[2] Usage mode <1> Insertion of pressure body.
On the ground, the pressurizing body 2 is inserted into the casing 1.
The pressurizing part 22 is arrange | positioned at the lower end of the casing 1 (FIG. 3a).
Since the pressurizing part 22 has a slightly smaller diameter than the inner diameter of the casing 1, the lower end of the casing 1 is almost sealed by the pressurizing part 22.
A shaft 21 of the pressurizing body 2 extends from the upper end of the casing 1.

<2> Penetration work.
Next, the casing 1 and the shaft 21 of the pressurizing body 2 extending from the casing 1 are gripped by a pile driving machine (not shown) and penetrated into the ground A by press-fitting or rotary press-fitting (FIG. 3b).
Since the lower end of the casing 1 is sealed by the pressurizing part 22, the soil of the ground A does not enter the casing 1 during penetration.
And the ground A around the casing 1 and the pressurization part 22 becomes dense by penetrating the casing 1 and the pressurization part 22.
The casing 1 and the pressurizing body 2 penetrate until the lower end of the casing 1 and the pressurizing part 22 reach the depth of the lower end of the crushed stone improvement body to be constructed.
Since the casing 1 is longer than the crushed stone improvement body, the upper end of the casing 1 protrudes from the ground A.

<3> Input of crushed stone.
After penetrating the casing 1 to a predetermined depth, only the shaft 21 of the pressure body 2 is gripped by the pile driving machine, and only the pressure body 2 is pulled up.
Then, the position of the stopper 11 of the casing 1 and the position of the notch 221 of the pressurizing unit 22 are matched, and the pressurizing body 2 is pulled out from the casing 1.
In the ground A, only the hollow casing 1 is inserted.
And the crushed stone 3 is thrown in from the upper part of the casing 1 (FIG. 3c).
Natural crushed stone (No. 4, 5, 6) or reclaimed crushed stone (RC-40, RC-30 and RM-30) is used.
The space into which the crushed stone 3 is charged is isolated from the ground A by the casing 1. Therefore, no soil is mixed during the charging.
The height of the crushed stone 3 is lower than the lower end of the stopper 11 of the casing 1.

<4> Pulling up the casing.
The position of the stopper 11 of the casing 1 and the position of the notch 221 of the pressure unit 22 are aligned, and the pressure unit 22 is inserted into the casing 1.
When the pressurizing body 2 is arranged between the upper end of the crushed stone 3 and the lower end of the stopper 11 and the pressurizing body 2 is rotated around the shaft 21, the stopper 11 of the casing 1 and the notch 221 of the pressurizing portion 22 correspond to each other. The stopper 11 and the pressurizing unit 22 are engaged with each other with a deviation from the position.
And the axis | shaft 21 of the pressurization body 2 is hold | gripped with a pile driving machine, and the pressurization body 2 is pulled up. Then, the stopper 11 of the casing 1 comes into contact with the upper surface of the pressurizing portion 22, and the casing 1 can be pulled up simultaneously with the pressurizing body 2.
The pressurizing body 2 and the casing 1 are pulled up by about 1 m (FIG. 3d).
By pulling up the casing 1, about 1 m from the bottom of the crushed stone 3 introduced into the ground A is exposed from the casing 1 into the ground A.
And the crushed stone 3 spreads by the thickness of the steel pipe which comprises the casing 1, and the exposed part 31 is formed.

<5> Pressurization.
The shaft 21 of the pressurizing body 2 is pulled down only by pressing the pressurizing body 2 while being gripped by the pile driving machine.
And the crushed stone 3 is pressurized with the pressurization part 22 lower surface of the pressurization body 2 (FIG. 3e).
Since the crushed stone 3 is located inside the casing 1 above 1 m from the bottom, the pressure applied from the upper surface of the crushed stone 3 is transmitted downward while compacting the entire crushed stone 3 and acts on the exposed portion 31.
Since the surrounding ground is dense due to the penetration of the casing 1 and the pressurizing body 2 in the exposed portion 31, the exposed portion 31 is compacted without the crushed stone 3 spreading in the surrounding ground. For this reason, even if the viscosity of the ground A is high, the crushed stone 3 can be reliably compacted.

<6> Pulling up and repressurization.
After pressurizing and compacting the crushed stone 3, the pressurizing body 2 is pulled up, the casing 1 is pulled up in the same manner as in <4> above, and pressurization is performed in the same manner as in <5> above.
By repeating this process, a crushed stone improvement body is constructed in the ground A (FIG. 3f).
Since the crushed stone improvement body is constructed by compacting the crushed stone 3, there are voids between the crushed stones 3. This void prevents and dissipates excessive pore water pressure during an earthquake.
By pressing in multiple steps, the crushed stone 3 can be reliably compacted from the lower end.
Moreover, since the ground around the casing 1 becomes dense and the crushed stone improvement body is constructed by compacting the crushed stone 3, the entire ground becomes solid, and resistance increases during an earthquake or the like.
Since the pulling and re-pressurization can be performed by the vertical movement of only the pressurizing body 2, a process such as gripping the casing 1 again is unnecessary, and the construction time is shortened.

DESCRIPTION OF SYMBOLS 1 Casing 11 Stopper 2 Pressurizing body 21 Shaft 22 Pressurizing part 221 Notch 3 Crushed stone 31 Exposed part

Claims (2)

A crushed stone improvement body construction tool for rolling a crushed stone in the ground to construct a columnar crushed stone improvement body,
A cylindrical casing, and a pressurizing body that can be inserted into the casing,
The pressurizing body comprises a shaft and a disk-shaped pressurizing portion provided at the lower end of the shaft,
The outer diameter of the pressurizing body and the inner diameter of the casing are substantially the same,
Forming a stopper projecting from the inner periphery of the upper end of the casing;
A crushed stone improvement object construction tool, wherein a notch through which the stopper can be inserted is formed on the outer periphery of the pressurizing portion. A crushed stone improvement body construction method using the crushed stone improvement body construction tool according to claim 1,
(A) In a state where the pressurizing portion of the pressurizing body inserted in the casing is disposed at the lower end of the casing, the casing and the pressurizing body penetrate into the ground,
(B) Pulling up the pressure body while the casing is placed in the ground, aligning the stopper of the casing and the notch of the pressure portion, and pulling out the casing from the pressure body,
(C) throwing crushed stone into the casing to a predetermined height;
(D) Again, the stopper of the casing and the notch of the pressure part are aligned, and the pressure part is inserted into the casing.
(E) rotating the shaft of the pressurizing body to engage the pressurizing portion with the stopper of the casing, and simultaneously pulling up the casing by pulling up the pressurizing body to a predetermined height;
(F) pressing down the pressure body to roll the crushed stone,
(G) A method for constructing a crushed stone improvement body, wherein the crushed stone improvement body is constructed by repeating the steps (e) and (f).

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