JPS6272810A - Ground improvement work - Google Patents

Abstract

PURPOSE:To concurrently perform the formation of an improved soil pile and the improvement of the ground between the piles by a method in which a grout of a high solidifying strength is injected from a jet nozzle in the lower end of an injection tube toward the lower side and at the same time from the tip of a stirring blade toward the side. CONSTITUTION:An injection tube 1 penetrated into a ground is pulled up, during which period a grout of high solidifying strength is injected downwards from a jet nozzle in the lower end of the tube 1 to form an improved soil pile 12. At the same time, the grout is injected sidewards from a jet nozzle in the tip of a stirring blade 3 to improve the surrounding ground 13 of the pile 12. Many improved soil piles 12 can thus be formed for reinforcing the ground by performing the operations on changed places and the water-stopping effect of the ground between the piles 12 can also be raised.

Description

[Detailed Description of the Invention] "Field of Application of the Invention" This invention is directed to soft #l! This relates to a ground improvement method using grout for the purpose of strengthening the deck and stopping water.

``Conventional technology'' Conventional ground improvement methods using grout for soft ground can be broadly divided into the following methods.

b) A method of creating improved consolidated upper piles by forcibly stirring and mixing the ground soil and grout.

口) A method in which grout is infiltrated into the gaps between soil particles or injected in veins without changing the arrangement of soil particles in the ground.

Methods b) include the jet grout method, which adds jet energy to the grout and physically mixes it with the ground soil, and the mechanical stirring method, which forcibly stirs the soil and grout mechanically using stirring χ, etc. has been put into practical use.

This method involves injecting grout into the ground and is generally called the ground injection method.In the case of sandy soil, grout (e.g., water glass type) that has gel time between soil particles is infiltrated and solidified to reduce the viscosity. This is a method of improving the ground by injecting it into the soil in veins, and among these methods, the method that uses a chemical solution (water glass) for grout is called the chemical injection method.

``Problem to be solved by the invention'' In method (a) above, the mechanical stirring method uses the rotation of stirring blades to uniformly drill holes in a certain area regardless of the relative density of the target ground (hardness and softness of the ground). By stirring and mixing with soil, an improved soil layer with a constant diameter can be obtained, uniform consolidation strength can be obtained even if the amount of grout (including hardening agent) added is small compared to the amount of improved soil, and there is also less waste during construction. The amount of soil is low,
Equipment used, grout! It has the advantage of low construction costs due to soil disposal, etc.

However, since an improved soil layer with a fixed diameter is created, it is technically extremely difficult to reliably connect and integrate adjacent piles when they are constructed continuously, and as a result, as shown in Figure 6. However, there is a drawback that solidification of the ground and water stoppage cannot be expected in the gaps between the piles, and when the purpose is to stop water during actual construction, a chemical solution is injected between each pile to compensate for the water stoppage effect. The current situation is that construction must be carried out.

On the other hand, the jet grouting method applies ultra-high pressure jet energy to the grout to excavate the ground, and also stirs and mixes the soil and grout to create an improved soil layer. Even if the joint between the piles is incomplete, some of the grout is press-fitted into the ground outside of the six piles, and the same improvement effect as the ground injection method can be obtained between the piles, resulting in 41! The advantage of this method is that water can be expected to flow without injecting chemicals between the piles, unlike the mechanical agitation method.

However, since the jet pressure is always constant, there is a drawback that the improved soil pile diameter is greatly affected by the relative density of the ground. That is, as shown in Figure 8, the pile diameter becomes smaller in hard soil layers, and conversely, the pile diameter becomes larger in soft soil layers.
As a result, upper piles of uniform diameter cannot be obtained, and the improvement range cannot be clearly identified.

In addition, since jet energy is used, the equipment used is expensive, and since the amount of improved soil requires a very large amount of grout, the disposal cost of soil removal (muddy water mixed with grout and soil) is high, making construction costs relatively high. be.

On the other hand, the method (1) has the advantage of being able to strengthen the entire ground easily with relatively simple equipment and can also be expected to have a water-stopping effect, but it is also possible to pressurize the grout and pressurize it without stirring the ground. Since it is a method of

As mentioned above, each of the above-mentioned construction methods has advantages and disadvantages, and each has the disadvantage that its purpose of use is limited.

``Means for Solving the Problems'' In order to solve the above-mentioned conventional problems, the present invention aims to strengthen the ground, which is the main improvement, by using grout with high consolidation strength, which has no effect on the relative density of the ground. The mechanical agitation method is used to obtain a uniform pile diameter, and jet grouting or ground injection methods are used to improve the intermediate area between the piles, which is expected to have a water-stopping effect, and these processes can be performed simultaneously or sequentially. By doing so, we propose a rational ground improvement method that can simultaneously obtain the advantages of ground reinforcement and water-stopping effects.

"Embodiments" Below, embodiments of the present invention shown in the drawings will be described.
FIG. 1 shows an example of an injection pipe used in the present invention, and the injection pipe 1 has three grout passages 2a, 2b,
It consists of a triple tube with 2c or a triple tube in which three small diameter tubes are loaded into a large diameter tube, and a plurality of stirring blades 3 are provided on the outer periphery of the tip.

At the tip of the stirring blade 3, any two of the channels 2a,
Inner and outer grout introduction channels 4 that communicate independently with 2b
Large tip discharge ports 5°6, such as double nozzle pipes, which are independently connected to a and 4b are installed.

The blade tip discharge ports 5 and 6 do not necessarily have to be double nozzles, and may be installed in parallel or at an angle so that their jet directions intersect with each other. In addition, the blade tip discharge ports do not necessarily have to be two, and as shown in Fig. 2, the two-component grout (liquid A, liquid B) introduced independently through the introduction channels 4a and 4b can be mixed. After mixing in the chamber 7, this mixed liquid may be discharged from one blade tip discharge port 8.

A tube end discharge port 9 communicating with the other flow path 2c is installed near the stirring blade 3, such as at the tip of the injection tube 1 or its outer periphery. When provided at the pipe end discharge port 9, for example at the tip opening of the injection pipe 1, a check valve 10 is installed between it and the flow path 2C.

In addition, by attaching, for example, pins 11, 11 to the tip of the injection pipe 1 and the lower surface of the stirring blade 3, or attaching a drilling tool such as an earth auger, it is possible to drill into the ground while rotating the injection pipe 1. There is.

The construction of the improved pile is carried out using the injection pipe 1 as follows.

First, in the first method shown in FIG. 3, grout with high solidification strength is discharged from the outlet 9 at the end of the tube while rotating the injection tube 1 and drilling the ground with the bit 11, and then the grout is The grout and soil are stirred and the improvement pile 12 is constructed 1 to a predetermined depth.

Next, for this improvement, before hardening the pile 12, while pulling up the injection tube 1 with or without rotation, the two blade tip discharge ports 5.6 or 8 at the tip of the agitating blade 3 are connected at regular intervals, for example, with a short gel time. Grout such as water glass grout is injected and mixed with soil by injection into the surrounding ground or by gent energy to create surrounding improved soil 13.

In this method, grout is injected while drilling with or without water, so in sandy soil where the hole wall is prone to collapse, the grout acts as an adhesive like bentonite, The adhesive effect can prevent soil from collapsing. Therefore, construction can be carried out without using any special anti-collapse agent on the bentonite ring, and the material's W
It is possible to reduce the amount of J and simplify the construction process, and it is also possible to achieve high strength by preventing a decrease in the consolidation strength of the grout due to the combined use of bentonite.

Next, in the second method shown in FIG. 4, the injection pipe 1 is rotated and a hole is drilled into the ground to a predetermined depth using the bit 11. While creating the improved consolidated pile 12 by discharging high-strength grout and stirring and mixing it with the soil using the stirring blade 3, at the same time, grout with a short gel time is discharged from the blade tip discharge port 5.6 or 8 at the tip of the stirring blade 3. A grout such as water glass grout is injected into the surrounding ground or mixed with soil using jet energy to create a surrounding improvement of ±13.

In this method, the ground is clayey soil such as silt or clay,
This method is mainly used when the hole wall can be maintained even if the hole is drilled with or without drilling water.Since both grouts are discharged at the same time, it has better workability and is technically more efficient than the first method. Excellent.

Furthermore, in the third method shown in FIG. 5, after rotating the injection pipe 1 and drilling a hole in the ground to a predetermined depth using the bits tt and tt, while pulling up the injection pipe 1, the consolidation strength is measured from the discharge lower part of the pipe end. While discharging high grout, the improved consolidated pile 12 is constructed by stirring and mixing with the soil using the stirring ff3 until a certain stage, and once the rotation is stopped, the blade tip discharge ports 5 and 6 provided at the tip of the stirring blade 3 Or short gel time from 8,
For example, after injecting grout such as water glass grout and mixing it with the soil by pressurizing it into the surrounding ground or using jet energy to create the surrounding area 13, the same construction is carried out at regular stages while pulling up the injection pipe 1. Repeat.

This method is similar to the second method above, but because the injection into the surrounding ground is performed intermittently, the effect of creating consolidated piles is mainly achieved by stirring the soil and grout, which has a high consolidation strength. , injection into the surrounding ground is used when only a water stop effect is expected.

Each of the above steps is performed continuously on the adjacent ground, and as shown in Figure 6, the areas between the improvement piles 12.12 constructed adjacent to each other are filled with grout injected from the blade tip outlets 5 and 6.8. Create an integrated surrounding area improvement of ±13.

In addition, in the first to third methods described above, the grout with high consolidation strength may be injected instead of the grout with a short gel time that is injected from the blade tip discharge port 5, 6 or 8 at the tip of the stirring blade 3. Further, in the second and third methods, when excavating with the injection pipe 1, excavation may be performed while discharging excavation water using any of the discharge ports 5, 6, 8, 9, Further, excavation may be carried out without using excavation water.

□ The one-component grout with high consolidation strength used in this invention is a grout using a normal cement-based or slag-based hardener, and it goes without saying that other additives can be added as necessary. .

In addition, water glass grout used as a grout with a short gel time is a two-component instant-setting grout with a gel time of 10 to 30 seconds or less, which is made of water glass (liquid A) as the main ingredient and a gelling agent (liquid B) added thereto. Alternatively, a two-component instant grout that gels instantaneously (gelling time: 0 seconds) is used when a gelling agent such as kelsulam chloride is added to water glass.

The reason for using grout with such a short gel time is that
After the soil and high-strength grout are stirred and mixed by the stirring blade 3 as described above, the grout injected from the blade tip discharge ports 5, 6.7 of the stirring blade 3 is press-fitted into the surrounding unimproved ground. This is because the liquid flows backward, so it is necessary to solidify it in as short a time as possible. In particular, instant setting grout is desirable when injecting in fixed steps without rotating the injection tube 1.

On the other hand, if the soil to be improved is very soft and active, the relative density of the ground and grout will not change that much.
Even if a grout with a long gel time and high consolidation strength is used, backflow does not occur much, and such grout can also be used.

In addition, the above-mentioned two-component grout with short gel time (A,
In the case of flash setting grout, liquid B) is mixed together in the mixing chamber 7 and then injected from one blade tip discharge port 8, or
Either method may be used, in which liquids A and B are injected separately from the two blade tip discharge ports 5.6 and mixed in the ground.In the case of instant grouting, the latter two liquids may be mixed in the ground. This is done by mixing.

``Effects of the Invention'' As described above, according to the present invention, the reinforcement of the ground, which is the main focus of improvement, is achieved by using grout with high consolidation strength and using a mechanical stirring method that allows a uniform pile diameter to be obtained without affecting the relative density of the ground. In addition to constructing piles for improvement, improvements to the intermediate area between the piles, where a water-stopping effect is expected, can be performed using jet grouting or ground injection methods, and these processes can be performed simultaneously or sequentially. By doing so, it is possible to perform ground improvement that simultaneously strengthens the entire ground and ensures a water-stopping effect.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing an outline of the main parts of the injection pipe used in the construction method of the present invention, and FIG. 2 is a partial vertical cross-sectional view showing another aspect of the blade tip discharge port of the injection pipe. Figures 3 (a), (b), Figures 4 (a), (b), and Figures 5 (a), (b), and (C) are longitudinal sectional views showing the steps of the construction method of the present invention. FIG. 6 is a cross-sectional view showing the state of ground improvement according to the present invention, and FIGS. 7 and 8 are longitudinal sectional views showing the state of ground improvement using the conventional construction method. 1. Injection pipe, 2a, 2b, 2c flow passage, 3.
・Agitation type, 5, 6.8...Blade tip outlet, 9...Pipe end outlet, 12...Improved upper pile, 13...Surrounding improved soil. Patent applicant: Fuku Co., Ltd. 1) Kumisanki Shoji Co., Ltd. Shimoda Technology Research Institute Co., Ltd. Representative: Fujii Sanete L-)
6 Q11E1 YoG Shigeru) IO month 14, 1985 Mr. Akio Kuroda, Commissioner of the Japan Patent Office ・、;、 41,319 indications 1985 Patent Application No. 110006 2 Name of the invention Ground improvement method 3 Person making the amendment! Relationship with 19 cases Patent applicant Fuku Co., Ltd. 1) Gumi rln Kisho Co., Ltd. 11 Shimota Technology Research Institute Co., Ltd. 4 Agent 301 Sakamachi Building, 13 Sakamachi, Shinjuku-ku, Tokyo 35
No. 9-3489;, - (8139) Patent attorney Minoru Fujii 5 Date of amendment order September 3, 1986 6 Brief explanation of the drawings of the specification subject to amendment 1. /

Claims (1)

[Scope of Claims] 1) A stirring blade is provided on the outer periphery of the tip of a tube having three grout channels, and a blade tip discharge is provided at the tip of the stirring blade to communicate with each of the two channels of the grout channel. An injection pipe provided with an outlet and a pipe end discharge port communicating with another flow path at the tip of the pipe body is rotated, and the consolidation strength is measured from the pipe end discharge port while drilling the ground. After injecting grout with a high level of water and stirring and mixing the ground soil and the grout with the stirring blade to create an improved consolidated pile to a predetermined depth, the injection pipe is pulled up at regular intervals with or without rotation. A ground improvement method characterized in that grout is injected from the blade tip outlet and mixed with or press-fitted with soil in the surrounding ground. 2) A stirring blade is provided on the outer periphery of the tip of a tube having three grout channels, and a blade tip discharge port is provided at the tip of the stirring blade that communicates with each of the two channels of the grout channel, and the pipe has three grout channels. After drilling a hole to a predetermined depth while rotating an injection tube provided with an outlet at the end of the tube that communicates with another channel at the distal end of the body, the injection tube is pulled up with or without rotation. A ground improvement method characterized by injecting grout with high consolidation strength from the end discharge port and at the same time injecting grout from the blade tip discharge port to stir and mix the soil in the surrounding ground and each of the grouts. 3) A stirring blade is provided on the outer periphery of the tip of the pipe body having three grout channels, and a blade tip discharge port is provided at the tip of the stirring blade that communicates with each of the two channels of the grout channel, and After drilling the injection tube to a predetermined depth while rotating the injection tube, which has an outlet at the end of the tube that communicates with another flow path at the distal end of the body, the injection tube is rotated and pulled up until a certain step. Grout with high consolidation strength is injected from the blade tip outlet to create an improved consolidated pile of a certain stage, and at the pulling position, rotation is stopped and grout is injected from the blade tip outlet to mix with the surrounding soil. Or, a ground improvement method characterized by press-fitting, and then repeating the same process while pulling up the injection pipe at regular intervals.