JPS5812419B2 - Improvement method for soft ground - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a construction method for improving soft ground using a liquid solidifying agent.

Conventionally, the structure was such that liquid solidification agent was released from the lower end of a vertical hollow shaft, and the soil was stirred and mixed using a device with multi-stage cutting and mixing blades, while the solidification agent was mixed. There is a method in which a liquid solidification agent is discharged from the lower end of the excavation auger, and the soil and solidified soil are stirred and mixed using an auger with an expanded hole provided at the lower end for stirring.

The disadvantage of these conventional methods is that the liquid solidifying agent is supplied from the lower end of the hollow tube, and the soil is agitated and mixed using an agitating blade slightly above it, so it is necessary to stir and mix the soil while the device is being penetrated or pulled out. The efficiency is poor, and since the stirring blade is a rod-shaped or plate-shaped object protruding from the rotating shaft, in reality, the solidifying agent is filled into the voids created after the stirring blade rotates, making it impossible to achieve complete mixing. It is not.

In view of the above-mentioned problems with the conventional construction method, the present invention uses a special stirring blade to thoroughly stir and mix a solidifying agent into the soil, and the details thereof are as follows.

In Figures 1 to 3, reference numeral 1 denotes a vertical hollow rotating shaft that can penetrate into the ground and is rotated by an appropriate drive device and penetration device, and the shaft 1 has a lower end that can be easily penetrated into the ground. The end fitting 2 is fixed and closed.

A is a stirring blade fixed to this rotating shaft 1, and a pair of belt-shaped bodies 3,
It consists of 4.

These strips 3 and 4 are alternately twisted in opposite directions and bent in a wave shape, and are fixed to both sides of the shaft 1.
4 form a continuous stirring blade A having an elliptical shape as a whole as shown in FIG.

That is, in FIG. 1, the strip 3 in front of the shaft 1 is at the right end a.
1, the furthest away from axis 1 and parallel to axis 1,
From this a1, it twists 90 degrees and curves downward to the left, becomes perpendicular to axis 1, and is fixed to the outside of axis 1, and then turns to the left, twists in the same direction, and curves downwards, twisting 90 degrees. , it becomes a3, which is the farthest from axis 1, and from there it further twists in the same direction and curves to the lower right, and the point where it twists 90 degrees and becomes perpendicular to axis 1 becomes a4, and then from a1 to a
It is the same as 3.

Also, the strip 4 after the shaft 1 is bL opposite to the strip 3 described above.
It is twisted and curved as b2, b3, and b4.

In Figure 1, the strips 3 and 4 appear to be spiral, but as is clear in Figures 2 and 3, they are not spiral.
The stirring blade A is nearly flat.

Further, the connecting portion between the shaft 1 and the strips 3 and 4 is reinforced with a reinforcing material 5.

Also, the upper end portions a1 and b1 of each strip 3 and 4 and the shaft 1'
A linear end plate 6 is fixed between them.

Furthermore, a plurality of holes 7 are formed at appropriate intervals in the rotating shaft 1, and a supply pipe for a liquid solidifying agent is connected to the upper end of the shaft 1 via a swivel joint or the like (not shown) as required. Accordingly, the structure is such that a solidifying agent can be injected into the shaft 1 and supplied into the soil from each hole 7.

For construction using the above-mentioned stirring device, first
Set vertically on the ground 8 to be improved as shown in
It penetrates into the ground 8 as shown in H, but at this time, the shaft 1 may or may not be rotated, and no solidifying agent is supplied.

When the soil reaches a predetermined depth as shown in (2), the solidifying agent is supplied into the shaft 1 while in this position, and the solidifying agent is injected into the soil from each hole 7 while the rotary shaft 1 is rotated. Stir and mix.

When a certain amount of liquid solidifying agent is injected and the stirring and mixing is completed by the specified rotation speed of the rotating shaft 1, the rotating shaft 1 is pulled out as shown in ■ and ■. At this time, the rotating shaft 1 may be rotated or not. There are cases.

Next, the rotary shaft 1 is moved to the next construction site on the ground and the same construction is performed.

However, since the stirring blade A in the present invention consists of a pair of twisted and curved strips 3 and 4 as shown in FIGS. 1 to 3, stirring and mixing by the strips 3 in FIG.
1. Near a1 of the part surrounded by a2 and axis 1, the strip 3 is vertical and parallel to the vertical axis of rotation 1, so the soil on the surface of the strip 3 is at the innermost part of the rotation radius. As the soil is pushed, a tangential flow from the rotating blade A and a radial flow from the axis 1 occur, and in the vicinity of a1 to a2, the belt 3 gradually tilts horizontally due to the torsion angle of the belt 3. This pushes the soil diagonally downward or upward, creating an axial flow and preventing stagnation.

Each part of the other band-shaped body 4 is stirred and mixed in the opposite direction of the directional flow by the band-shaped body 3, and the blade as a whole is continuously stirred and mixed for each part, so that mixing can be performed throughout the stirring blade A without any stagnation. I can do it.

Therefore, by rotating the stirring device at a predetermined position and supplying the liquid assimilate agent, stirring and mixing is performed over the entire length, so that stirring and mixing can be carried out sufficiently and efficiency is also good.

Therefore, there is no need to mix the solidifying agent without raising or lowering the stirring device.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway front view of the stirring device used in the construction method of the present invention, Fig. 2 is a plan view of the same as above, Fig. 3 is a side view of the same, and Fig. 4
The figure is a cross-sectional view of each process in the construction state. A... Stirring device, 1... Rotating shaft, 3, 4... Band-shaped body, 7
...hole.

Claims (1)

[Scope of Claims] 1. It is bent in a wave-like manner on both sides of the rotating shaft driven by an appropriate drive device, and is oriented parallel to the rotating shaft at the bent portions on both sides, and perpendicular to the rotating shaft at the portion near the rotating shaft. A stirring device is used in which a pair of twisted strips are shaped like an elliptical continuous body when viewed from the front, and the sides are fixed so that they are nearly flat and serve as stirring blades. There is a process of penetrating the rotating shaft into the ground, a process of mixing a fixed amount of liquid solidification agent into the soil while rotating the stirring device that reaches a predetermined depth, and a process of stirring the stirring device without injecting the solidification agent. A method for improving soft ground that includes a pulling process. 2. The method for improving soft ground according to claim 1, wherein the stirring device is rotated when it penetrates into the ground and when it is pulled out from the ground.