JPS641609B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for improving soft ground, and more specifically, a kneading machine equipped with a stirring shaft and a discharge pipe is penetrated into soft ground, and blades are attached to the lower part of the stirring shaft. The present invention relates to a method for improving soft ground, in which the stirring part of the kneader is rotated to mix the caking agent discharged from the discharge pipe with the soft soil, thereby hardening the soft soil.

Conventional methods for improving this type of ground include: (1) discharging a caking agent and rotating the stirring section while penetrating the area to be improved with a kneader, and mixing the agent with the soft soil; (2) A method in which a kneading machine is inserted while only stirring the soft soil without discharging the caking agent, and the caking agent is discharged at the time of pulling out. A method of kneading soft soil with soft soil is known.

However, in the method (1) above, the caking agent and soft soil can be mixed in both the penetration and withdrawal processes, so the mixing is reliable; Due to the change in properties, the mechanical load increases significantly, especially during drawing, and the kneading machine therefore requires a high-output drive section.

In addition, if the caking agent is discharged above the above-mentioned stirring section, an unimproved portion where only stirring is performed and no caking agent is kneaded is left at the bottom layer of the improved area. It happens.

In the method (2) above, the caking agent is mixed with the soft soil when the kneading machine is pulled out, so it is not affected by the change in the soft soil properties in the case of (1) above. In order to ensure that the kneading is carried out reliably, it is necessary to provide a discharge tube orifice for the above-mentioned drug above the above-mentioned stirring section, and therefore, the above-mentioned drug is kneaded in the lowest layer of the part to be improved by only stirring. This will leave unimproved parts. Such unimproved areas cause subsidence of the improved ground, which is not desirable in terms of ground structure.

The present invention is intended to eliminate each of the drawbacks of the above two methods. After penetrating the soft ground to near the lower end of the part to be improved without discharging the consolidating agent, then While discharging the caking agent from below the stirring part formed at the bottom of the stirring shaft, the stirring part is rotated to knead the discharged chemical solution and the soft soil, while penetrating to the lower end of the area to be improved, and further solidifying. The device is designed so that the discharge of the chemical agent is switched to the upper part of the stirring section, and the mixing section is kneaded with the soft soil by the stirring section, while the kneading machine is pulled out, thereby improving the area to be improved from the bottom layer to the top layer. It is.

The drawings will be explained below.

In carrying out the present invention, a kneading machine a as shown in FIG.
Use. The kneading machine has a plurality of stirring shafts 1 hanging vertically from a drive section 3 via a reducer 4, and a plurality of blades 2 attached to the lower part of the stirring shaft to form a stirring section 5. has been done. A discharge pipe 7 is vertically installed between the stirring shafts in parallel with the stirring shaft, and the caking agent passes through the discharge pipe to the pipe opening 6 at the lower end of the discharge pipe.
It is installed so that it is discharged from.

The stirring shaft 1 is also hollow so that it also serves as a discharge pipe, and the lowest blade 2 is provided with a pipe opening 6', but it goes without saying that a separate discharge pipe that does not serve as such may also be provided. . In this way, the lower tube opening 6' is positioned below the stirring section 5, and the upper tube opening 6 is positioned above the stirring section.

The present invention is constructed as shown in FIG.

As shown in FIG. 1A, the kneader a is penetrated into the portion to be improved b near the lower end while rotating the stirring section and without ejecting the caking agent. From this position, while discharging the caking agent from the lower discharge pipe opening 6' and rotating the stirring section to mix the discharged chemical solution and the soft soil, the kneader is further moved to the top of the part to be improved. Penetrate by depth L′ of the lower layer. Next, as shown in FIGS. B and C, the discharging of the solidifying drug from the lower discharge pipe opening 6' is stopped, and while the solidifying medicine is being discharged from the upper discharge pipe opening 6, stirring is continued. While rotating the kneader, the kneader is pulled out as shown in Fig. D, and the soil is improved by kneading a consolidating agent into the soft soil to be improved from the bottom layer to the top layer. It is necessary to reliably improve the bottom layer, and it is desirable to move the stirring section and discharge pipe up and down several times to reliably mix the solidifying agent and soft soil in the bottom layer. .

As is clear from the above, in the present invention, the improvement of the lowest layer of the part to be improved is achieved by stirring using a kneader having a plurality of discharge pipes with pipe ports provided above and below the stirring section. The improvement can be carried out reliably and easily because the caking agent is discharged from the pipe opening at the bottom of the section, and the stirring section is rotated in the lowest layer to mix the soft soil in the lowest layer and the ground. ,
Therefore, the unimproved part that is only stirred and not mixed with chemicals as in the past does not remain at the bottom of the improved soil, and there is less risk of ground subsidence, and the upper layer is softer than the bottom layer. Soil improvement is carried out by discharging a caking agent from the pipe opening above the stirring section, rotating the stirring section to mix it, and then pulling out the kneading machine, so that changes in the properties of the soft soil that has been mixed with the agent can occur. The influence is extremely small, so the mechanical load can be reduced and the power of the kneading machine can also be reduced.

[Brief explanation of the drawing]

FIGS. 1A to 1D are schematic diagrams showing examples of the present invention in the order of construction, and FIG. 2 is a schematic diagram showing an example of a kneading machine used in the construction method of the present invention. a... Kneading machine, b... Area to be improved, b'... Bottom layer of the area to be improved, G... Soft ground, L... Length of stirring section, L'... Depth of the bottom layer of the area to be improved. S-l...
Total depth of the part to be improved, 1... Stirring shaft, 2... Vane, 3... Drive section, 4... Reducer, 5... Stirring part, 6, 6'... Discharge pipe mouth, 7... discharge pipe.

Claims (1)

[Claims] 1 A kneader equipped with a stirring shaft and a discharge pipe is penetrated into soft ground, and the stirring part formed by the bladed part at the bottom of the stirring shaft is rotated to soften the caking agent discharged from the discharge pipe. In the soft ground improvement method performed by mixing with soil, a plurality of the above discharge pipes are provided, and the mouths of some of the discharge pipes are located below the stirring section, and the mouths of the remaining discharge pipes are located above the stirring section. ,
The stirring part and the discharge pipe are rotated to penetrate the stirring part and the discharge pipe to near the lower end of the soft ground area to be improved without discharging the caking agent, and from this position, from the lower discharge pipe opening. While discharging the caking agent, the stirring section is rotated to knead the discharged chemical solution and the soft soil.The stirring section and the discharge pipe are penetrated to the lower end of the part to be improved, and then from the lower discharge pipe opening. At the same time as discharging is stopped, a caking agent is discharged from the upper discharge pipe opening, and the caking agent is kneaded with the soft soil while the kneading machine is pulled up, and the mixture is mixed from the bottom layer to the top layer of the area to be improved. This is a soft ground improvement method that is characterized by improving all areas.