JPS5949375B2 - Deep mixing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a deep mixing method for creating a large number of mixed piles in which quicklime and soft cohesive soil are mixed by mixing coarse quicklime into soft cohesive soil.

The biggest problem with this conventional construction method is that the mixture of soft clay soil and quicklime causes a high degree of shibosilane reaction.

For this purpose, it is necessary to uniformly mix quicklime with a fine viscosity into the clay soil.

However, currently used construction machines use a feeder with a screw inside a hollow tube to discharge quicklime evenly into the ground, so to prevent clogging, a somewhat coarser particle size is used. I have no choice but to do it.

Therefore, there was a problem that the soft cohesive soil and quicklime were not sufficiently mixed.

As a result, the strength in on-site construction was 1 in the indoor test strength. Differences such as ``A'' and ``A'' occur.

That is, in on-site construction, the digestion reaction occurs quickly, but the pozzolanic reaction is insufficient in comparison.

Furthermore, there is a construction machine described in Japanese Patent Application Laid-open No. 19317/1983 as a construction machine for uniformly mixing quicklime into soft and viscous soil.

This known construction machine has an upper stirring blade, a lower stirring blade, and a screw feeder equipped with a tip valve that can be opened and closed, but the upper and lower stirring blades are located below the quicklime outlet.

For this reason, after the construction machine penetrates into the ground, the tip valve is opened and the quicklime is discharged into the ground while the construction machine is pulled up; stirring with stirring blades is necessary, so it is not possible to mix the lime in one time. Not enough effect.

Therefore, after the construction machine is pulled up while discharging the quicklime, it is necessary to further penetrate the construction machine and stir and mix, which poses a problem of poor construction efficiency.

Although the present invention uses a construction machine similar to the above-mentioned known construction machine consisting of an upper stage stirring blade, a lower stage stirring blade, and a feeder equipped with a tip valve that can be opened and closed, we have researched its construction method and developed a construction machine. This is an improved method in which a tip valve is provided between the upper stage stirring blade and the lower stage stirring blade, so that the stirring action can be fully utilized.

That is, the present invention improves the above-mentioned known construction machine and has a structure in which the tip valve for discharging quicklime is located between the upper and lower stirring blades, and the tip valve is opened to discharge coarse particles from the lower end of the feeder. While discharging quicklime, the upper stirring blade and lower stirring blade are rotated to penetrate into the soft and slightly viscous soil, and when the lime is descending, the coarse quicklime is stirred and mixed into the ground by the upper stirring blade. After the machine reaches a predetermined depth, the tip valve is closed and quicklime for the next pouring is put into the feeder if necessary.Then, after waiting for the digestion reaction of the coarse quicklime stirred into the ground, the machine is turned off. While drawing the lime, the quicklime and the soft and slightly viscous soil are mixed again using the upper and lower stirring blades, thereby sufficiently stirring and mixing the quicklime and causing a sufficient pozzolanic reaction.

Next, to explain the details with reference to the drawings, A in the drawing is a construction machine, and there is a drive device 1 such as a hydraulic motor at the upper end, and a feeder B in which a screw 3 is fitted in a hollow tube 2 is in the center of the lower part. On both sides thereof, a pair of stirring shafts 6 having upper stirring blades 4 and lower stirring blades 5 are provided at the lower ends.

Further, a quicklime charging hopper I is provided at the upper side of the hollow tube 2, and a tip valve 8 is provided at the lower end.

The construction machine A as described above is hoisted up by a crane or the like (not shown) and installed at the desired construction site, and while the stirring shaft 6 is rotated by the drive device 1, the soft and slightly viscous soil is ground as shown in FIGS. 2 and 3. It penetrates into 9.

During this penetration, the tip valve 8 is opened, and the feeder B is
The coarse-grained quicklime that was input into the ground is discharged, and as the construction machine A penetrates into the ground 9, the upper stage stirring blade 4 stirs and mixes the soft and slightly viscous soil and quicklime.

In this way, when the construction machine A reaches a predetermined depth, a mixed pile 10 of quicklime and soft cohesive soil is formed.

Next, the tip valve 8 is closed, the stirring shaft 6 is stopped, and quicklime for the next pouring is charged into the feeder B from the hopper 7 as required.

During the previous process, that is, the time required for the penetration of the construction machine A, the discharge of quicklime into the ground 8, stirring and mixing, and the introduction of quicklime into the feeder B for the next pouring, the amount of quicklime discharged into the ground 8 was The digestion reaction of quicklime proceeds rapidly, and after the reaction, the quicklime disintegrates into a lump of powdered slaked lime.

The grains of quicklime are hard and do not break easily, but when external force is applied again from the stirring blade, the lumps of slaked lime are easily dispersed and become fine granules.

Therefore, after the quicklime for next pouring has been put into the feeder B, if the tip valve 8 is closed and the stirring shaft 6 is rotated again as shown in Fig. 4, the stirring blades of the upper and lower stages will be pulled out. 4.5 is the improved ground 11 where slaked lime is crushed and thoroughly stirred and mixed with the soft cohesive soil, and when the construction machine A is completely pulled out as shown in Fig. 5, the pozzolanic reaction is sufficiently carried out.
is obtained.

As described above, the present invention uses a construction machine consisting of a feeder equipped with a tip valve that can be opened and closed between the upper stage stirring blade and the lower stage stirring blade. The quicklime is mixed with the blades, and then the construction machine is pulled out and the upper and lower stirring blades are used to further stir the already mixed quicklime coarse particles and soft viscous soil, thereby stirring the quicklime to a sufficient degree of soft and viscous activity. Mixing and dispersion is possible, and excellent ground improvement is achieved through sufficient pozzolanic reaction.

In addition, the quicklime used in the method of the present invention is a coarse grain with good feeding efficiency, and the process only requires one penetration and extraction, and when the penetration is completed, quicklime for the next charge is poured into the feeder, so it is easy to feed. Since the required time can be used as the time required for the digestion reaction of quicklime, there is no waste of time required for the digestion reaction, and the pulling speed of the construction machine can be at the same level as the conventional construction method, so it is effective in almost the same time as the conventional construction method. This is a useful invention that allows deep mixing processing to be performed.

[Brief explanation of drawings]

FIGS. 1 to 5 are partial longitudinal sectional side views of each step showing an embodiment of the construction method of the present invention. A...Construction machine, B...Feeder, 4.
... Upper stage stirring blade, 5 ... Lower stage stirring blade, 9
...Soft viscous land board, 10...Mixed pile.

Claims (1)

[Claims] 1. In a construction method in which quicklime is mixed into soft and slightly viscous soil and stirred using a construction machine consisting of an upper stirring blade, a lower stirring blade, and a feeder equipped with a tip valve that can be opened and closed, the tip valve for discharging quicklime from the construction machine is The structure is placed between the upper and lower stirring blades, and the tip valve is opened to discharge coarse quicklime from one end of the tweeter while the upper and lower stirring blades are rotated and mixed into soft and slightly viscous soil. By penetrating, coarse-grained quicklime is stirred into the ground by the upper stage stirring blade when descending, and after the construction machine reaches a predetermined depth, the tip valve is closed and quicklime for next pouring is poured into the feeder as needed. put it in 1
Next, after waiting for the digestion reaction of the coarse quicklime stirred into the ground, the construction machine is pulled out and the quicklime and the soft and viscous soil are mixed again using upper and lower stirring blades.