JPS6044451B2 - Ground improvement method - 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,
A method for improving soft ground in which the stirring part of a kneading machine, which has blades attached to the lower part of the stirring shaft, is rotated to mix the caking agent discharged from the discharge pipe with the soft soil, thereby hardening the soft soil. Regarding.

Conventional methods for improving this type of ground include (1) discharging a caking agent and rotating the stirring part while penetrating the area to be improved with a kneader, and mixing the agent with a soft soil mixer; (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 withdrawal. A method of kneading soft soil with soft soil is known.

However, in the method (1) above, the caking agent and the soft soil can be mixed in both the steps of penetration and extraction, so the mixing is reliable, but the mixing of the caking agent and the soft soil 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, the unimproved portion, which has only been stirred and has not been kneaded with the caking agent, is placed in the lowest layer of the improved portion. I will leave it behind.

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, and includes a discharge pipe that is movable up and down relative to the stirring shaft, a pipe opening at the lower end of the discharge pipe located above the stirring section, and While stirring the soft soil by rotating the stirring part without discharging the caking agent, the kneader is penetrated into the soft soil until the stirring part reaches the bottom layer of the area to be improved, and at the penetration position, the mixing machine is stirred. After stopping the rotation of the stirring part and lowering the pipe opening until it reaches the lower part of the stirring part, raising the pipe opening to the upper part of the stirring part while discharging the caking agent, and then rotating the stirring part. Then, the soft soil at the lowest layer of the soft ground where the stirring section is located is kneaded with the caking agent, and then the caking agent is continuously discharged from the upper position of the stirring section, and the stirring section is rotated, Opening the kneading machine while kneading the ejected chemical and soft soil,
This is provided so that the portion to be improved can be improved down to the lowest layer.

The drawings will be explained below.

In carrying out the present invention, a kneader a as shown in FIG. 2 is used.

The kneading machine has a plurality of stirring shafts 1 suspended from a drive section 3 via a reducer 4, and a plurality of blades 2 attached to the lower part of the stirring section 5. is formed. Between the stirring shafts. A discharge pipe 7 is provided vertically in parallel with the stirring shaft, and the solidifying agent is discharged from the pipe opening 6 at the lower end of the discharge pipe through the discharge pipe. The discharge pipe 7 is designed to be able to move up and down with respect to the stirring shaft, and the pipe opening 6 can move up and down within the length L of the stirring section 5. It is. Incidentally, in order to perform a construction method different from that of the present invention, the stirring shaft 1 may be made hollow to also serve as the second discharge pipe, and the lowest blade 2 may be provided with a second pipe opening 6''. Construct as shown in Figure 1.

As shown in Fig. 1A, the pipe port 6 at the lower end of the discharge pipe is positioned above the stirring section, and the lower part of the kneading machine a is placed in the improved part b of the soft ground G while the stirring shaft is rotated. The soil is penetrated to the lowest layer of the area to be improved while stirring the soft soil by rotating the stirring section without ejecting the caking agent. At the penetration position, stop the rotation of the stirring part and insert the pipe port 6 under the stirring part in Fig. 1B.
The tube opening 6 is moved to the upper part of the stirring section as shown in D while the solidifying agent is discharged as shown in C in the same figure. Next, by rotating the stirring part, the above-mentioned chemical agent and soft soil are kneaded, and the bottom layer b of the improved part is mixed.
'' process is completed. Next, with the discharge pipe port 6 positioned above the stirring section, the chemical solution is discharged, and the stirring section is rotated to mix the discharged chemical and the soft soil. and others,
Raise the kneading machine as shown in Figure 1E and improve the ground from the bottom layer to the top layer of the improved area. As is clear from the above, in the present invention, the kneading machine stirs the soft soil by rotating the stirring part without discharging the caking agent until the stirring part reaches the bottom layer of the improved part. is penetrated into the soft ground, and while discharging the consolidating agent at the penetration position, the outlet of the discharge pipe is moved from the bottom to the top of the stirring section, and the soft soil at the lowest layer of the soft ground is moved by the rotation of the stirring section. and a caking agent, and then the caking agent is continuously discharged from the upper position of the stirring section, and the stirring section is rotated to knead the discharged agent and the soft soil, while the kneading machine is lifted up. This improves everything from the bottom layer to the top layer of the area to be improved, which has been stirred in advance, so that the unimproved area, which has only been stirred and not kneaded with chemicals, remains at the bottom of the improved ground. This will not cause ground subsidence, and the discharge pipe can be moved up and down relative to the stirring shaft.
When the stirring section is rotating, the outlet of the discharge pipe is always located at the top of the stirring section, and when moving up and down between the stirring sections,
Since the rotation of the stirring section is stopped, there is no fear that the blades 2 of the stirring section will hit the discharge pipe during rotation, and stirring and kneading with the caking agent can be performed reliably.

Furthermore, improvement of the soft soil layer above the bottom layer is carried out by discharging the caking agent from the pipe port moved above the stirring section, and pulling out the kneading machine while rotating the stirring section to mix it. The effect of changes in the properties of the soft soil mixed with chemicals is extremely small, and therefore the mechanical load can be reduced and the power of the kneader can also be reduced.

[Brief explanation of the drawing]

The upper part of FIG. 1A is a schematic diagram showing an example 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 present invention. a... Kneading machine, b... Part to be improved, b
″...Lowest layer of the area to be improved, G...Soft ground, L...Length of stirring section, 1...
Stirring shaft, 2... impeller, 3... drive unit,
4... Speed reducer, 5... Stirring part, 6,
6...Discharge pipe port, 7...Discharge pipe.

Claims (1)

[Claims] 1 A kneading machine 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, and the caking agent is discharged from the mouth of the discharge pipe. In the soft ground improvement method carried out by kneading and soft soil, the discharge pipe is provided so as to be movable up and down with respect to the stirring shaft, and the pipe opening at the lower end of the discharge pipe is located at the upper part of the stirring part, and While stirring the soft soil by rotating the stirring part without discharging the caking agent, the kneader is penetrated into the soft soil until the stirring part reaches the bottom layer of the area to be improved, and at the penetration position, the mixing machine is stirred. After stopping the rotation of the stirring section and lowering the tube opening to the lower part of the stirring section, raising the tube opening to the upper part of the stirring section while discharging the caking agent, and then rotating the stirring section, The soft soil at the lowest layer of the soft ground where the stirring section is located is kneaded with the caking agent, and then the caking agent is continuously discharged from the upper position of the stirring section and the stirring section is rotated to mix the caking agent. This soil improvement method is characterized in that the mixer is mixed with soft soil and the kneading machine is pulled up to improve the entire area from the bottom layer to the top layer of the pre-mixed area to be improved.