JPS593603B2 - Soft ground improvement method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a soft ground improvement method.

Since Japan's ground is often soft, consisting of alluvial estuarine deposits, volcanic ash layers, etc., it is necessary to perform some kind of ground improvement when carrying out civil engineering work on this ground.

For this purpose, various construction methods have been proposed.

For example, a soil improvement device attached to a wetland crawler crane is pushed into the ground, and through its stirring shaft, cement, slurry, and other input materials are ejected from the stirring blade at the tip, and the stirring blade in the ground is moved up and down to improve the soil. There is a method of mixing input materials and solidifying this into a columnar shape.

However, due to the nature of the ground, the mixing of the ground and input materials is not sufficient, and especially in humid ground, mixing cannot be expected at all.

There is also a method of stirring the ground and input materials using a device that has stirring blades at the lower ends of two parallel shafts, but the parts where the stirring blades overlap are well agitated, but the areas around them are well stirred. As in the case of the above-mentioned construction method, there remain drawbacks such as the inability to obtain homogeneous improved ground.

The present invention is characterized in that excavating blades and stirring blades having rotary blades arranged radially at predetermined intervals around a rotation axis are arranged vertically and facing each other, and these upper and lower layers are arranged opposite to each other. By using two rotating rotary blades, we can dramatically improve the mixing of the ground and input materials, and create homogeneous column-shaped or wall-shaped structures for use in improving soft ground. It provides a construction method for the purpose.

Embodiments of the present invention will be described below with reference to the drawings.

First, the equipment used in the construction method of the present invention has the following configuration.

A hollow shaft 2 is rotatably supported on the machine frame 1, a crown gear 3 is fixed to the upper part of the hollow shaft 2, and a digging blade 4 is fixed to the lower end thereof.

A gear 5 is fixed to the upper end of the hollow shaft 2, and the gear 5 is connected to a motor 6 attached to the machine frame 1 via a suitable transmission mechanism.

Further, there is a rotary outer part 8 disposed concentrically with respect to the hollow shaft 2 which is rotatably supported in the machine frame 1 via a bearing 7, and an annular gear 9 is provided on the upper edge of this outer cylinder 8. , and a stirring blade 10 is fixed to its lower end.

As shown in FIG. 2, the digging blade 4 and the stirring blade 10 each have rotary blades 4a and 10a extending radially from the center of rotation and arranged at a predetermined interval from each other, These blades 4a.

The outermost end of 10a is located at A on substantially the same circumference.

Pinions IL11, which engage the crown gear 3 and the annular gear 9 of the outer cylinder 8, respectively, are rotatably pivoted to the machine frame 1.

A pipe 12 for feeding input materials is connected to the upper opening of the hollow shaft 2.

Further, the input material entering the hollow shaft 2 from the pipe 12 is discharged from a discharge hole 2' at the lower end of the hollow shaft 2.

Note that the hollow shaft 2 and the outer cylinder 8 may be provided so that they are individually driven to rotate.

Since the device used in the construction method of the present invention has the above-mentioned configuration, this device is held vertically with an appropriate device,
Lower it gradually.

At the same time, the motor 6 is driven once, thereby first rotating the hollow shaft 2 and also rotating the outer cylinder 8 via the pinion 11 in the opposite direction to the hollow shaft 2.

As a result, the excavating blade 4 and the stirring blade 10 are rotated in opposite directions.

Both stir and excavate the ground to an appropriate depth.

After excavating to an appropriate depth, while rotating the excavating blade 4 and stirring blade 10 and pulling them upward or repeating vertical movements,
Input materials (cement silk, water glass, cement slurry, etc.) are injected through the pipe 12 and the hollow shaft 2.

Further, pressurized water and compressed gas may be mixed as appropriate depending on the geological conditions.

As a result, a mixed stratum of the ground and the input material is created in the agitated and excavated ground, and as the input material hardens, a columnar structure consisting of the ground and the input material is created.

In the above embodiment, the diameter of the outer cylinder 8 is shown to be larger than that of the hollow shaft 2, but this is for explanation only, and the outer diameter of the hollow shaft and the inner diameter of the outer cylinder 8 are shown to be in contact establish.

As described above, in the present invention, the input material is injected while rotating the excavating blade 4 and the stirring blade 10 located in two layers in opposite directions, so that the excavated soil is not pinched by the excavating blade or the stirring blade. Therefore, the "tomomawari" phenomenon in which the excavated soil rotates with the blade does not occur, and as a result, the soil and input materials are well mixed, resulting in homogeneous improved soil without being affected by the soil. It is something that can be done.

In addition, the excavating blade and stirring blade each have rotating blades that extend radially from the center of rotation at intervals from each other, so the excavated soil is moved from the center of rotation toward the outer periphery in response to the longitudinal force of the rotary blades. It will flow, thus ensuring that the excavated soil in the radial direction of the borehole is mixed.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view showing the construction method of the present invention, and Figure 2 is the same as Figure 1.
It is a cross-sectional view along the -■ line. 2...Hollow shaft, 8...Outer cylinder, 4...
...Drilling blade, 10...Stirring blade.

Claims (1)

[Claims] 1. An excavating blade and an agitating blade having rotary blades arranged radially at a predetermined distance from each other around a rotating shaft are arranged in a vertical relationship and facing each other, and these excavating blades and an agitating blade are
The blades are advanced into the ground while rotating in opposite directions to stir and excavate the native ground without discharging the excavated soil, and then retreated while maintaining the mutual rotation of the two blades while injecting input material. A soft ground improvement method that is characterized by repeatedly moving forward and backward to ensure mixing of the existing ground and input materials.