JPH03448B2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The disclosed technology involves injecting powder such as cement into soft ground such as a layer of corroded soil, and stirring and mixing the powder and soil. It belongs to the field of technology that consolidates the ground by solidifying the ground.

<Summary of the gist> Therefore, this invention inserts an injection pipe into soft ground that contains a lot of corroded soil, excavates it with the excavation stirring part at its tip, and after reaching a predetermined depth, rotates it in the opposite direction and pulls it out. At the same time, the excavated soil is stirred, and at the same time, powder such as cement and other improving materials are injected into the agitated soil from the injection nozzle and mixed in the soil. This invention relates to a powder agitation ground improvement method, in particular, in which powder such as cement and other improving materials such as sand are separately transported in gas and ejected into the soil inside one excavation agitation blade. This invention relates to a ground improvement method using powder agitation to mix the powder with the soil.

<Prior art> Generally, when performing ground improvement on soft ground containing corroded soil such as in lakes and marshes, simply supplying powder such as cement into the soft ground and stirring and mixing it will cause the treated ground to deteriorate. Although it solidifies, it is extremely weak in strength, so other improving materials such as sand, which can be used as bulking materials, are supplied together with powder such as cement and mixed to increase the density of the ground. It is made to solidify with high strength.

As is well known, as shown in FIG. 1, when an injection pipe 2 is penetrated into soft ground 1 such as a lake or marsh containing a large amount of corroded soil, first, the tip excavation stirring blade 3 is attached to the base end of the injection pipe 2. Through the attached hydrostatic rotary drive device 4 and swivel joint 5, the bit 6
Rotary excavation is carried out by inserting the excavation into the soft ground 1 to crush the soil.

After drilling the hole to a predetermined depth, the injection pipe 2
Cement 8 and sand 9 mixed by a mixer 7 connected via a swivel joint 5 to the excavation stirring blade 3 via one transport passage in the injection pipe 2 by an air pump 10. The liquid is fed and ejected downward from a large number of nozzle holes of the ejection nozzle (not shown) of the excavation stirring blade 3.

The air ejected from each nozzle hole passes through the back surface of the rib on the side surface of the injection tube 2 and is discharged from the outlet 12 of the dust removal cover 11 provided on the ground.

A powder agitation ground improvement method has been developed and adopted, which improves the ground by repeating the steps described above.

<Problems to be Solved by the Invention> However, in the above-mentioned conventional powder stirring ground improvement method, the mixed powder of cement 8 and sand 9 fed through the transport passage of the injection pipe 2 is They may be separated during feeding, etc., and although they are mixed by the mixer 7, due to the difference in particle size, they are ejected into the soil in a separated state, and the soil There was a drawback in terms of accuracy in that the mixture was not uniformly mixed in the soil, which could cause unevenness on the improved ground.

In addition, various devices are required to synchronize the mixer 7 installed at the base of the injection pipe 2 on the ground side and the excavation stirring blade 3 at the bottom of the injection pipe 2. 2, the entire device had to be moved, which resulted in the disadvantage that the reset took a long time.

Another problem was that there was little freedom to quickly adjust the amount of sand in response to conditions such as the content of corroded soil in the improved ground.

<Purpose of the invention> The purpose of the invention is to solve the problems of the powder agitation ground improvement method based on the above-mentioned conventional technology as a technical problem, and to Provides an excellent powder stirring ground improvement method that is beneficial to the field of civil engineering technology in the construction industry by uniformly mixing and other improvement materials such as sand, and allowing flexibility in the mixing ratio. This is what I am trying to do.

<Means/effects for solving the problem> In order to solve the above-mentioned problem, the structure of the present invention, which is based on the above-mentioned claims, is to provide an injection pipe to soft ground containing a large amount of corroded soil. The injection pipe is rotated by the bit of the excavation stirring blade at the tip, inserted into the ground and excavated to a predetermined depth.Then, the injection pipe is pulled upward while rotating and A predetermined amount of powder such as cement and other improving materials such as sand are separately supplied to the rotation area of the excavation agitation blade from each injection nozzle provided inside one excavation agitation blade. A technical measure has been taken in which a predetermined ground improvement is carried out by ejecting and stirring and mixing with the soil through the excavation stirring blade, and the above-mentioned process is repeated.

<Example> Next, an example of the present invention will be described below with reference to the drawings from FIG. 2 onwards.

Note that the same parts as those in the embodiment shown in FIG. 1 will be explained using the same reference numerals.

As shown in Figures 1, 2, 3, and 4, when penetrating the injection pipe 2 into the soft ground 1, first, the excavation stirring blade 3' at the tip thereof is rotated by a static pressure rotary drive device similar to Figure 1. , the tip bit 6' is used to excavate and insert into the soft ground 1 to crush the soil.

After excavating to a predetermined depth, cement 8 as a powder and sand 9 as another improvement material are inserted into the injection pipe 2 using transport pipes 11 and 12, respectively, using a feeding device on the ground. Transported by air.

The pumped cement 8 and sand 9 are then laterally moved along the excavation stirring blades 3', 3', which have a C-shaped cross section and are integrally fixed to the tip of the injection pipe 2 in the diametrical direction and extended laterally. The injection pipe 2 is separately injected into the water-containing crushed soil from the nozzle holes 15, 15... and the nozzle holes 16, 16... of the injection nozzles 13, 14 provided, and at the same time, the injection pipe 2 is rotated while being pulled upward. The crushed soil is stirred by each excavation stirring blade 3', and the cement 8 and sand 9 are sufficiently and uniformly mixed in the soil.

And nozzle holes 15, 15..., 16, 16...
The air blown out from the tube passes through the back of a rib-shaped spill (not shown) on the side of the tube and is discharged to the ground.

During the above process, cement 8 is pumped into the ground 1
The mixing ratio of sand 9 and sand 9 is determined in a predetermined design according to the content of corroded soil, and the transport pipe 1
1 and 12 continuously.

In this way, the soft ground 1 is improved by repeating drilling and injection stirring and mixing at a predetermined pitch.

It should be noted that the embodiments of the present invention are of course not limited to the above-mentioned embodiments; for example, in addition to cement and sand, other improvement materials may also be ejected by changing the relative vertical positions. Various aspects can be adopted, such as the following.

<Effects of the Invention> As described above, according to the present invention, the powder and the improving material are separately fed into the injection pipe by gas transport prior to injection, without the need to mix the powder and the improving material in advance. There is no need for a mixing device because the amount can be set in advance, and there is no separation effect during feeding compared to a type that is mixed in advance, making it possible to reliably feed a predetermined amount at a time. , it has an excellent effect of improving construction accuracy without unevenness.

In addition, there is no need to install a mixing device on the ground, and it is sufficient to simply equip the excavation agitation blade with a normal soil stirring function and a mixing agitation blade for powder and improvement material. There is no need for synchronization, the time required between each process can be shortened, and the excellent effect of not only significantly shortening the construction period but also realizing a significant reduction in cost is achieved.

Furthermore, since the powder and the improvement material are fed separately by gas transport, the amount of feeding can be set arbitrarily, which not only makes it possible to quickly respond to the moisture content of the ground, but also allows the amount of improvement material to be easily changed. Therefore, it is possible to fully demonstrate its effects, especially in ground improvement methods containing corroded soil.

In addition, ground improvement work can be carried out reliably, so
It does not interfere with the next stage of construction on the improved ground, and has the advantage of reducing costs because there is no need for repair work.

[Brief explanation of the drawing]

Figure 1 is a schematic partial cross-sectional view of the entire injection pipe, Figure 2-
Figure 4 shows one embodiment of this invention,
Figure 2 is a partial sectional view of the tip of the injection tube, Figure 3 is
FIG. 2 is a side view, and FIG. 4 is a bottom view of FIG. 1... Soft ground, 8... Powder, 9... Improved material.

Claims (1)

[Claims] 1 In a powder agitation ground improvement method that improves the ground by injecting powder and other improving materials into soft ground and mixing them with crushed soil, the powder and other improving materials are mixed with the crushed soil. A ground improvement method using powder agitation, characterized in that each gas is separately transported into crushed soil, injected inside one excavation stirring blade, and then stirred and mixed with the crushed soil.