JP2014177796A - Ground improvement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground improvement method that enables construction to be inexpensively performed in a low-noise and low-vibration manner.SOLUTION: In a ground improvement method, an improvement body is constructed by consolidating the inside of the ground in a height direction, by carrying out a step (a) of bringing about penetration of the ground by a pressure implement, which has a tip provided with a pressure plate, while rotating the pressure implement, a step (b) of consolidating the ground below the pressure implement by pushing down the pressure implement without rotating it and a step (c) of pulling up the pressure implement in the ground while rotating it in a direction opposite to the direction in the step (a), and repeating the steps (b) and (c) more than once.

Description

  The present invention relates to a ground improvement method in a small-scale house.

In recent years, as a ground improvement in a small-scale house, a support pile is actively placed in a soft layer with poor location conditions.
As the support pile, a wooden pile, a steel pipe pile, a concrete pile or the like is used.

The conventional ground improvement methods using support piles have the following problems.
(1) Since wooden piles and steel pipe piles penetrate from the ground surface into the ground, noise and vibration during penetration are problematic.
(2) Since steel pipe piles and concrete piles are not natural materials, the burden on the environment is large and the value of the land is reduced.
(3) In any support pile, material costs and member costs are incurred.

  An object of this invention is to provide the ground improvement method which is low-noise and low-vibration and can be constructed at low cost.

  The first invention of the present application made to achieve the above object is as follows: (a) a step of penetrating a pressure tool having a pressure plate at the tip into the ground while rotating; and (b) rotating the pressure tool. (C) a step of pulling up the pressure tool in the ground while rotating in the opposite direction to (a), and (b) ) (C) is repeated a plurality of times to provide a ground improvement method for constructing an improved body by compacting the ground in the height direction.

The present invention can obtain at least one of the following effects by means for solving the above-described problems.
(1) Since the pressurizing tool is not given vibration or impact force, it can be constructed with low noise and low vibration.
(2) Since no steel pipe piles or concrete piles are used, the burden on the environment is small and the value of the land is not reduced.
(3) Since there is no material cost or material cost for piles, it can be constructed at low cost.

Explanatory drawing of the improvement body by the ground improvement method of this invention Explanatory drawing of pressurizing tool Explanatory drawing of ground improvement method

  Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings.

(1) Improvement body The ground improvement method of this invention performs ground improvement by constructing the improvement body 1 in the ground. (Figure 1)
The improved body 1 is constructed by compacting the ground a plurality of times at a predetermined interval depth in the ground.

(2) Pressurizing tool The pressurizing tool 2 includes a rotating shaft 21 and a pressing plate 22 provided at the lower end of the rotating shaft 21.
The rotating shaft 21 is a steel rod, and the upper end is configured to be attached to a conventionally used pile driving machine.
The pressure plate 22 is spiral and is attached so as to go around the rotating shaft 21. The pressure plate 22 has a radius of 50 cm when viewed in plan.

(3) Consolidation method Consolidation of the ground is performed by pressing down the entire pressure tool 2 by pushing the rotating shaft 21 downward with the pressure plate 22 of the pressure tool 2 disposed in the ground. As a result, the ground below and around the pressure plate 22 is consolidated.

(4) Construction method of improved body (4-1) Penetration of pressure tool While attaching the rotary shaft 21 of the pressure tool 2 to a pile driving machine (not shown) and rotating the rotary shaft 21 and the pressure plate 22, Penetration into the ground.
Since the pressure plate 22 is spiral, it proceeds in the depth direction in the ground and does not disturb the surrounding ground more than necessary.
The pressure plate 22 penetrates until it reaches a predetermined depth (2 to 4 m).

(4-2) Consolidation After the pressurizing tool 2 has been penetrated to a predetermined depth, the pressurizing plate 22 is pushed down together with the rotating shaft 21 to consolidate without rotating the pressurizing tool 2, and the lower end of the improved body 1 is constructed. .
The pressing force and pressurizing time vary depending on the quality of the ground on which the improved body 1 is to be constructed, but in the case of sand ground, 50 kN is the standard.
At this time, since no vibration or striking force is applied to the pressurizing tool 2, it can be constructed with low noise and low vibration.

(4-3) Pulling out and compacting When the compaction of the lower end is completed, the pressurizing tool 2 is pulled out while rotating in the direction opposite to the time of penetration, and the pressure plate 22 is pulled up in the ground.
Since the pressure plate 22 is arranged in a spiral shape, the surrounding ground is not disturbed more than necessary even when it is pulled out.
Then, the pressurizing tool 2 is pushed down again at the position where the depth is increased by 50 cm from the position where the previous pressurization is completed, and the pressure is consolidated.
Thereby, the lower part from the pressure plate 22 becomes the improved body 1.
And the improvement body 1 is constructed | assembled in the ground by repeating the compaction by drawing-out of the pressurizer 2, and pushing down.
In this way, since other members such as steel pipes and concrete are not used, the burden on the environment is small and the value of the land is not reduced. In addition, there is no material cost, no material cost, etc., and it can be constructed at low cost.
When the upper part of the improved body 1 is depressed from the other ground surface due to the compaction below, it is backfilled with soil generated in the field.

(4-4) Improvement of the ground Since the improved body 1 is pressed down and consolidated, not only the lower part of the pressure plate 22 but also the surrounding ground is consolidated.
Therefore, by constructing the improved bodies 1 in parallel at a predetermined interval, for example, a distance of 2 m, not only the portions of the improved bodies 1 but also the plurality of improved bodies 1 can be compacted.
Thereby, the whole ground can be improved.

DESCRIPTION OF SYMBOLS 1 Modified body 2 Pressurizing tool 21 Rotating shaft 22 Pressure plate

Claims (1)

(A) a step of penetrating a pressure tool having a pressure plate at the tip into the ground while rotating;
(B) a step of pressing down the ground in the ground without rotating the pressure tool to consolidate the ground below the pressure tool;
(C) pulling up the pressurizing tool in the ground while rotating in the opposite direction to (a);
By repeating the above (b) and (c) a plurality of times, the ground is consolidated in the height direction to construct an improved body.
Ground improvement method.

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