JP2007077739A - Jet grout type ground improvement construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ground improvement construction method with a high-quality high pressure injection agitating pile having a large diameter, by smoothly jetting sludge to the ground surface by solving the problem of blocking up a sludge passage in enlarging a ground improvement range in the viscous earth ground. <P>SOLUTION: When cutting the ground by injection pressure of 25 MPa or more and a delivery quantity of 100 l/min or more of a superhigh pressure hardening material, the sludge 10 is jetted to the ground surface by solving blocking-up of the sludge passage 9 by improving fluidity by melting a cut material of the viscous earth ground by adding a dispersant by the cement weight ratio of 0.1 to 0.45% to the cement-based superhigh pressure hardening material injected from a hardening material injection nozzle 7c of a hardening material injection pipe 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention uses high-pressure jet energy that is not easily affected by soil non-uniformity or soil boundary conditions in stable construction of water blocking walls, foundation ground, etc. The present invention relates to a jet grout type ground improvement method that improves the ground by mixing.

  Conventionally, as a jet grout type ground improvement method, for example, a swivel having a super high pressure hardener inlet and a compressed air inlet inserted into the hardener injection pipe from the ground surface to a target depth in the ground and assembled to the upper part of the hardener injection pipe. The high-pressure hardened material is injected from the ultrahigh-pressure hardened material inlet and the compressed air from the compressed air inlet, and the ultrahigh-pressure hardened material is supplied from the hardener injection nozzle of the monitor mechanism assembled to the lower part of the hardener injection pipe. The compressed air is continuously sprayed from the compressed air spray nozzle around the hardener injection nozzle in the radial direction of the pipe, and the hardener injection pipe is pulled up while being driven to rotate, thereby continuously spraying. Ground improvement work to improve the ground by cutting the surrounding ground with the swirling jet of the ultra-high pressure hardened material and the compressed air and hardening the cutting area Is (e.g., see Patent Document 1.).

Japanese Patent Laid-Open No. 6-306846

  In recent years, development of ultra-high pressure pumps has progressed, and it has been on the market with machines with large injection pressure and discharge volume. Along with this, the ground improvement range of the cylindrical solid body has increased. However, in the viscous ground, in order to increase the diameter of the high-pressure jet agitation pile, the viscous ground is formed with a high-pressure jet flow with an injection pressure of 25 MPa or more and a discharge rate of 100 l / min or more by the above ground improvement method. Even if it cuts, the part which the clay does not mix with a hardening material generate | occur | produces, and the mass of this cut clay increases, The blockage | blocks a mud passage, and has produced problems, such as ground uplift. Moreover, if it constructs without the lump being ejected on the ground surface, the quality of a high-pressure jet stirring pile will fall.

  The present invention has been made in order to solve such problems. The object of the present invention is the swirling jet of the super-high pressure curing material and the compressed air that are continuously injected as described above. In the jet grouting type ground improvement method that improves the ground by cutting the ground of the ground and hardening the cutting area, the extent of ground improvement is increased in the viscous ground by adding a dispersing agent to the ultra high pressure hardened material An object of the present invention is to provide a jet grouting type ground improvement method for high-pressure, high-pressure jet agitation piles that solves the problem that the mud passage is blocked and smoothly ejects mud to the ground surface and has a large diameter.

The present invention inserts a hardener injection pipe from the ground surface to a target depth in the ground, and from the ultrahigh pressure hardener inlet of a swivel having an ultrahigh pressure hardener inlet and a compressed air inlet assembled to the upper part of the hardener injection pipe. Cement-based ultra-high pressure hardened material is injected into the compressed air through the compressed air inlet, and the ultra-high pressure hardened material is injected from the hardener injection nozzle of the monitor mechanism assembled to the lower part of the hardener injection pipe. The ultra-high pressure cured material that is continuously ejected by continuously ejecting the compressed air from the compressed air spray nozzle around the nozzle in the pipe radial direction and pulling up the curing material injection tube while driving the swivel. In the jet grout type ground improvement method to improve the ground by cutting the surrounding ground with a swirling jet of compressed air and hardening the cutting area,
When cutting the ground with an injection pressure of 25 MPa or more and a discharge rate of 100 l / min or more of the ultra high pressure hardened material, 0.3 to 1.5% of the amount of the hardened material mixed with the dispersion material in the ultra high pressure hardened material by weight ratio. It is characterized by the addition.

  In this case, sodium polyacrylate can be used as the dispersing material.

  According to the present invention, when the viscous ground is cut with a high-pressure jet with an injection pressure of 25 MPa or more and a discharge amount of 100 l / min or more, a hardened portion where clay does not mix with the ultra-high pressure hardening material is generated. Fluidity can be promoted by dissolving the solidified portion with a dispersing agent (0.3 to 1.5% of the amount of kneaded material by weight) added to the high-pressure curing material. If the added amount of the dispersing agent is less than 0.3% of the hardened material kneading amount, the effect of dissolving the hardened portion is thin. On the other hand, if it exceeds 1.5%, the curing time of the cement-based ultrahigh pressure curing material takes a long time, It tends to lose ground improvement effect when diluted with groundwater. The clay is only slightly melted around the periphery of the clay to increase the fluidity, and the mud passage is ejected to the ground without being blocked.

  Since the ground is cut at an injection pressure of 25 MPa or higher and a discharge rate of 100 l / min or higher, the ground cutting range is widened and the ground cutting capacity is increased. As described above, in the viscous ground, there are many hard portions that are not mixed with the hardener and the mud passage is blocked. However, according to the present invention, the injection pressure of the ultrahigh pressure hardener is 25 MPa or more and the discharge amount is 100 l / l. When cutting the ground at min or more, the dispersion is added to the ultra high pressure hardened material in an amount of 0.3 to 1.5% of the amount of the hardened material, so that the hardened portion of the cut clay is melted. Therefore, it was possible to eliminate the blockage of the mud drainage passage, and to provide a ground improvement method for high-pressure, high-pressure jet agitation piles with a large diameter.

  A preferred embodiment of the present invention will be described with reference to the drawings. 1 (a) to 1 (f) are explanatory views showing the order of work steps by the jet grout type ground improvement method of the present invention, and FIG. 2 is a connection structure of a hardener injection pipe used in the jet grout type ground improvement method of the present invention. (A) is an exploded view showing a mode of connecting a swivel, a hardener injection pipe, a coupling, and a monitor mechanism, (b) is a longitudinal sectional view of the monitor mechanism, and (c) is a diagram of FIG. It is CC sectional view taken on the line in FIG.

  An embodiment of the jet grout type ground improvement method of the present invention will be described below with reference to FIGS. (A) of FIG. 1 is a drilling process diagram using a front conduit, (b) a process diagram for installing a hardened material injection pipe, (c) is an injection test process diagram with water, and (d) is a process for creating a high-pressure injection stirring pile. FIG. 5E is a drawing process diagram of the hardener injection tube, and FIG. 9F is a cleaning / filling process diagram of the hardener injection tube. Hereinafter, it demonstrates in order of a process.

(1) Drilling process by the leading conduit As shown in FIG. 1 (a), a boring machine M is installed on the ground, and the drilling by the leading conduit 1 is performed to the target drilling depth while circulating water or mud water. That is, water or circulating mud is supplied to the inlet 2a of the swivel 2 connected to the upper end of the leading conduit 1, and the water or mud is discharged from the lower leading conduit 1a to which the metal crown 3 of the leading conduit 1 is attached. By lowering the conduit 1 while turning it and drilling holes with the metal crown 3, the leading conduit 1 is inserted to a predetermined depth in the ground.

(2) Step of Erecting Curing Material Injection Pipe Next, as shown in FIG. 1 (b), a predetermined amount of the curing material injection tube 4 is built into the leading conduit 1 and the leading conduit 1 is pulled out.
The hardener injection tube 4 used here is composed of a double tube rod, and as shown in FIG. 2A, a swivel 5 having an ultrahigh pressure hardener inlet 5a and a compressed air inlet 5b is connected to the upper end thereof. The monitor mechanism 7 is connected to the lower end portion via the coupling 6. As shown in FIGS. 2B and 2C, the monitor mechanism 7 has a double pipe structure having a jet passage 7a and a compressed air passage 7b, and the upper end of the jet passage 7a is an ultra-high pressure curing of the swivel 5. The material inlet 5a and the upper end of the compressed air passage 7b are in communication with the compressed air inlet 5b of the swivel 5, respectively, and a hardener injection nozzle 7c is provided at the lower end of the jet passage 7a, and the lower end of the compressed air passage 7b. Each is provided with a compressed air injection nozzle 7d. The hardener injection nozzle 7c is opened radially outwardly at a part of the outer peripheral surface of the monitor mechanism 7, and the compressed air injection nozzle 7d jets compressed air A radially outward from the periphery of the hardener injection nozzle 7c. Is formed.

(3) Injection test process with water After the installation of the hardener injection tube 4, as shown in FIG. 1 (c), ultrahigh pressure water is applied to the ultrahigh pressure hardener inlet 5a of the swivel 5 of the hardener injection tube 4. Compressed air is respectively injected into the compressed air inlet 5b, and super high pressure water W is continuously injected from the hardened material injection nozzle 7c of the monitor mechanism 7 in the pipe radial direction, and a compressed air injection nozzle around the hardened material injection nozzle 7c. While the compressed air A (see FIG. 2B) is injected from 7d, the hardening material injection tube 4 is driven to rotate and an injection test is performed. If there is no abnormality in the injection test, switch the ultra-high pressure water to a cement-based ultra-high pressure hardener and start the process of creating a high-pressure injection stirring pile.

(4) Formation process of high-pressure jet stirring pile As shown in FIG. 1 (d), in the formation process, the hardener injection pipe 4 is pulled up while being swiveled, and simultaneously shown in FIGS. 2 (b) and 2 (c). As described above, the super high pressure hardened material G is continuously jetted from the hardener jet nozzle 7c, the compressed air A is jetted from the compressed air jet nozzle 7d, and the surrounding ground (viscous soil) is cut by the swirling jet, A high-pressure jet stirring pile 8 is created in the cutting area. At this time, in order to widen the ground cutting range and increase the ground cutting capacity, the viscous ground is cut with a high-pressure jet having an injection pressure of 25 MPa or more and a discharge amount of 100 l / min or more.
Here, it should be noted that even if a hardened portion where clay does not mix with the hardened material is generated by cutting the viscous ground, the hardened portion is melted to improve fluidity, and the mud passage 9 is blocked. In addition, a dispersion liquid such as polyacrylic acid soda is added in advance to the cured material to be ejected from the cured material spray nozzle 7c so that the mud 10 is ejected to the ground surface. Since the dispersion material dissolves the solidified portion to improve fluidity, the mud 10 is smoothly ejected to the ground surface without the mud passage 9 being blocked by the mud.

  If the amount of the dispersing agent added is less than 0.3% of the amount of the hardened material kneaded by weight, the effect of dissolving the hardened portion is thin. On the other hand, if it exceeds 1.5%, the setting time of the cement-based ultrahigh pressure hardener is long. Since it is diluted with groundwater and easily loses the ground improvement effect, it is 0.3 to 1.5%, preferably 0.5 to 1.0%, more preferably 0.8 to the amount of the hardened material kneaded by weight. %.

(5) Drawing process of hardener injection tube After completion of the formation, as shown in FIG. 1 (e), the supply of the ultra-high pressure hardener and compressed air is stopped, and the hardener injection pipe 4 is pulled out to the ground.

(6) Cleaning and filling process of hardener injection pipe After the hardener injection pipe 4 is pulled out, the inside of the pipe 4 is washed with fresh water and moved to the next formation point. As shown in FIG. 1 (f), the hole 11 generated above the high-pressure jet stirring pile 8 by pulling out the hardener injection tube 4 is filled with mud or mortar.

  Although the embodiments of the present invention have been described above, a plurality of injection nozzles (hardening material injection nozzles 7c and compressed air injection nozzles 7d) may be provided in the monitor mechanism 7. There is no problem even if there is no compressed air injection nozzle and only the curing material injection nozzle.

(A)-(f) is explanatory drawing which shows the order of the work process by the jet grout type ground improvement construction method of this invention. The connection structure of the hardening | curing material injection pipe used for the jet grout type ground improvement construction method of this invention is shown, The figure (a) is an exploded view which shows the aspect which connects a swivel, a hardening | curing material injection pipe, a coupling, and a monitor mechanism, FIG. 4B is a longitudinal sectional view of the monitor mechanism, and FIG. 4C is a sectional view taken along the line CC in FIG.

Explanation of symbols

4 Curing Material Injection Pipe 5 Swivel 5a Ultra High Pressure Curing Material Inlet 5b Compressed Air Inlet 7 Monitor Mechanism 7c Curing Material Injection Nozzle 7d Compressed Air Injection Nozzle

Claims (1)

Insert the hardener injection pipe from the ground surface to the target depth in the ground, and insert the superhigh pressure hardener inlet of the swivel with the ultrahigh pressure hardener inlet and the compressed air inlet assembled on the upper part of the hardener injection pipe from the cementitious super Pressurize the high-pressure hardened material from the compressed air inlet, respectively, and insert the ultrahigh-pressure hardened material from the hardener injection nozzle of the monitor mechanism assembled to the lower part of the hardener injection pipe around the hardener injection nozzle. The compressed air is continuously jetted from the compressed air jet nozzle in the radial direction of the pipe, and the hardened material injection pipe is driven to pull up while being driven to rotate, thereby continuously injecting the ultrahigh pressure hardened material and the compressed air. In the jet grout type ground improvement method to improve the ground by cutting the surrounding ground with the swirling jet of and hardening the cutting area,
When cutting the ground with an injection pressure of 25 MPa or more and a discharge rate of 100 l / min or more of the ultra high pressure hardened material, 0.3 to 1.5% of the amount of the hardened material mixed with the dispersion material in the ultra high pressure hardened material by weight ratio. A jet grout type ground improvement method characterized by adding.

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