JPS6268917A - Improvement for weak ground - Google Patents

Abstract

PURPOSE:To prevent earth from being increased in volume and from filling or the like, by injecting soil hardener into weak ground to be mixed with each other, and by eliminating the undisturbed soil of a quantity corresponding to the working quantity of the hardener. CONSTITUTION:Stirring wings 7 are saliently arranged at the lower ends of rotary shafts 6 extending downward from a driving section 5 suspended with a wire W, and on the outer periphery of the rotary shafts 6, screws 8 for sludge withdrawal are fitted to form a soil improvement device. The rotary shafts 6 are rotated and positioned in weak ground, and a ground hardener is jetted from the lower sections of the rotary shafts 6, and the soil and the hardener are mixed with each other by the stirring wings 7. Then, the rotational frequency of the rotary shafts 6 are regulated, so that a soil discharging quantity on ground with the screws 8 is equal to the injected quantity of the hardener. As a result, the volume of earth is not increased, and earth is prevented from filling.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field to which the Invention Pertains) The present invention relates to a method of hardening soft ground by stirring and mixing a ground hardening material (cement, cement milk, etc.) in the form of powder or slurry.

(Problem to be solved by the invention and its characteristics) One problem when hardening soft ground by stirring and mixing a ground hardening material is that, depending on the properties of the original ground, a large amount of material, which can reach several tens of inches in volume ratio to the ground soil, The mixing of soil hardening materials causes the ground to swell and spread laterally, which has a negative impact on existing structures in the surrounding area.

The present invention aims to solve the above-mentioned problems, and its structural features are as described in the claims.

That is, the present invention enables the addition and mixing of the ground hardening agent by removing an amount of the original ground soil corresponding to the amount of the ground hardening agent used when hardening the soft ground by stirring and mixing the soil hardening agent. This is to prevent the volume of the treated ground from increasing due to

The present invention generally covers a type of soft ground improvement method in which soft ground is hardened by stirring and mixing a ground hardening material.
It can be applied regardless of the stirring/mixing means, processing mode, etc., and for example, a stirring blade at the lower end. When forming pile-shaped hardened portions at a predetermined pitch by raising and lowering an attached rotating shaft, is there a stirring and mixing means? When the entire ground is hardened by moving it in the horizontal direction, various cases can be considered, such as changing the amount of ground hardening material mixed depending on the properties of the original ground at each point. Soil may be removed in any manner suitable for each of these cases.

(Detailed explanation of the invention with drawings) Figures 1 to 3 show three examples of ground improvement made by the present invention.
Although these two cases are similar, the present invention is not limited thereto.

In the case of Fig. 1, a large number of pile-shaped or wall-shaped stirring and mixing treatment sections 1 are constructed in the ground in area A at a predetermined pitch.
Ground improvement is carried out in area A in such a way that a stirring and mixing treatment section 1 and a non-treatment section 2 coexist.

In this case, the amount Q1 of the soil hardening material mixed into the stirring and mixing processing section 1 is constant in the two depth directions, and correspondingly, the amount Q2 of ground soil removed is also constant in the two depth directions. .

In the case of FIG. 2, the lower layer 2 of area A is treated in the same manner as in FIG. 1, but the upper layer 3 is entirely stirred and mixed. In this case, the amount of ground hardening material mixed in Q1 is larger in the upper layer 3 and smaller in the lower layer 2, so correspondingly, the amount of ground soil removed Q2 is also φ larger in the upper layer 3 and smaller in the lower layer. It is less in part 2.

In the case of Fig. 3, the entire area A is stirred and mixed, but at that time, the amount of soil hardening material mixed in is changed to Q+ according to the change in the original ground strength S in the depth Z direction, and the area A The ground within the building is made to have uniform improved strength. Therefore, in this case, the removed amount Q2 of the ground soil is changed in accordance with the change in the mixed amount Q1 of the soil hardening material.

Next, an apparatus for carrying out the present invention will be explained with reference to FIGS. 4 to 8.

In the apparatus shown in FIG. 4, a rotating shaft 6 extends downward from a drive unit 5 suspended by a wire 4 from a construction machine body (not shown).
A stirring blade 7 is protruded from the lower end, and a soil removal screw 8 is attached to the outer periphery of the rotating shaft 6, and when the device is lowered, a soil hardening material determined by the design is removed by the soil removal screw 8. An amount of soil corresponding to the mixed amount is removed, and when the device is raised, the ground hardening material and the ground soil are stirred and mixed by the stirring blades 7 through the internal space of the rotating shaft 6.

In general, the amount of soil removed by a screw auger Q is the effective soil removal area of the screw k 1% pitch? If p1 is the rotational speed per unit time and n1 is the operating time, then Q=aXpXnXt, so P% ”%
When any one of t is changed, Q changes.

The apparatus shown in FIG. 5 differs from the apparatus shown in FIG. 4 in that a soil hardening material supply pipe 9 is provided separately.

The device shown in FIG. 6 differs from the device shown in FIG. 5 in that the soil removal screw 8 is attached to the outer periphery of the soil hardening material supply pipe.

The device shown in FIG. 7 can be moved horizontally to a predetermined depth. It is a type that stirs and mixes at once,
An earth removal means [2 is provided in front of the rotating shaft 11 in the direction of movement of the rotary shaft 11 on which the stirring blades 10 are protruded in multiple stages.

The soil removal means shown in FIG. 8 is for partially changing the soil discharge amount, and the screw 13 is inserted into the entire pipe 15 through a rotating shaft 14 with a screw 13 attached to the outer periphery of the tip. It is inserted so that it protrudes by a predetermined length, and the amount of soil removed can be changed by changing the rotation speed of the rotary shaft 14. The air rises inside the pipe 15 with the help of the air.

(Effects of the Invention) The present invention is as described above, and the volume of the ground increases due to the mixing of a ground hardening material. Since this can be completely prevented, even if there is an existing structure on the adjacent land, ground improvement can be carried out by using a soil hardening material without considering the effect on the existing structure.

[Brief explanation of the drawings] Figures 1 to 3 are explanatory diagrams of ground improvement according to the present invention;
7 to 7 are explanatory diagrams of the apparatus for implementing the present invention, and FIG. 8 is a diagram of another example of the earth removal means. DESCRIPTION OF SYMBOLS 1... Stirring and mixing processing section, 6... Rotating shaft, 7... Stirring blade, 8... Soil removal screw,...

Claims (1)

[Claims] A soft ground improvement method in which soft ground is hardened by stirring and mixing a ground hardening material, and the method is characterized by removing an amount of original soil corresponding to the amount of the ground hardening material used.