JPH11172667A - High-pressure injection ground-improvement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-pressure injection ground-improvement method, in which an obstruction layer can be drilled easily even when there is the obstruction layer such as a hard layer, a riprap layer, etc., in a ground to be improved and by which the term of works can be made remarkably shorter than conventional technique. SOLUTION: A down-the-hole-hammer 5 is installed to a monitor 4 for injecting a hardener liquid mounted at the lower end section of a shaft body 1a in an injection rod used for the high-pressure injection soil-improvement method, by which the hardener liquid is injected into a ground to be improved at high pressure from an injection nozzle set up at the lower end section of the shaft body while rotating and vertically moving the shaft body and the ground is improved, and an obstruction layer D such as a riprap layer, a hard layer, etc., in the ground to be improved is drilled by striking by the down-the- hole-hammer 5 and drilled up to specified depth. The hardener liquid B is injected at high pressure from the monitor 4 for injecting the hardener liquid while turning and pulling up the injection rod 1, and an improved body G is prepared.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving a high-pressure injection ground, and more particularly, to forming an improved body in a ground to be improved, wherein an obstacle layer such as a rubble layer or a hard layer exists in the ground to be improved. The present invention relates to a high-pressure injection ground improvement method suitable for construction in cases or underwater construction.

[0002]

2. Description of the Related Art Conventionally, a high-pressure injection ground improvement method has been widely used in which a hardened material liquid is injected at high pressure from an injection nozzle into a ground to be improved while an injection rod is rotated and moved up and down to form an improved body and improve the ground. Have been done. This high-pressure injection ground improvement method, when there is an obstacle layer such as a rubble layer or a hard layer above the ground to be improved or in the ground, make advance drilling using a rotary percussion drill etc. It is customary to lay an injection rod in the borehole.

[0003]

However, the above conventional method has the following problems. That is, in the conventional method,
Various steps such as pre-drilling, inner tube pulling, filling of the injection rod, casing pulling, and hardening liquid injection forming are required, which requires a great deal of labor and time.

[0004] In construction where the ground to be improved is underwater, the location of the preceding excavation hole is below the water surface, so that protection and position confirmation of the preceding excavation hole are complicated and difficult.

[0005]

SUMMARY OF THE INVENTION The present invention has the following configuration to solve the above-mentioned problem. While rotating the shaft body up and down, high-pressure injection of the hardening material liquid into the improvement target ground from the injection nozzle provided at the lower end of the shaft body, the injection rod used in the high-pressure injection ground improvement method for improving the ground, A down-the-hole hammer is attached to the hardening material liquid injection monitor provided at the lower end of the shaft body, and the down-the-hole hammer strikes and drills an obstacle layer such as a rubble layer, a hard layer in the ground to be improved to a predetermined depth. After drilling holes, a high-pressure injection ground improvement method is used in which a hardening material liquid is injected at high pressure from a hardening material liquid injection monitor while the injection rod is rotated and pulled up to form an improved body.

According to the construction method of the present invention, a down-the-hole hammer provided at the end of a monitor for injecting a hardening material liquid on an injection rod strikes and drills to a predetermined depth, and then the hardening material liquid is supplied from an injection nozzle while rotating and pulling up the injection rod. As the improved body is created in the ground to be improved while injecting at the same time, the pre-drilling, inner pipe extraction, and injection rod building required when the ground including the conventional obstacle layer was improved by the high-pressure injection method It is possible to create an improved body in the ground to be improved with only two steps of drilling and hardening liquid injection, which are the standard high-pressure injection process. It is.

As described above, since the method of the present invention is a method including two steps of drilling holes and injection of a hardening material liquid, it is possible to shorten the period of work and to save the time and labor required for construction. It is economical. Further, even in the case of underwater construction where the ground to be improved is underwater, the drilling and injection forming steps can be performed continuously, so that there is no need to protect and position the preceding excavation hole as in the conventional construction method.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the high-pressure injection ground improvement method of the present invention will be described below with reference to the drawings.
FIG. 1 is an enlarged schematic cross-sectional view of a main part of an injection rod of the present invention, and FIG. 2 is an explanatory view showing a construction procedure of the present invention. As shown in FIG. 1, an injection rod 1 used in the method of the present invention includes an outer tube 2 forming an air flow path 2a inside a shaft 1a supported by a driving device (not shown); The inner pipe 3 forming the flow path 3a is formed in a double pipe structure.
Further, a hardening material liquid ejecting monitor 4 is attached to the lower end of the shaft body 1a of the injection rod 1 by a screw joint 7.

The hardening material liquid ejecting monitor 4 is provided with a hardening material liquid flow path 3 in a shaft 1a of the injection rod 1 having a double pipe structure.
and a hardening material liquid injection nozzle 6 having a hardening material liquid flow path 4b communicating with the hardening material liquid B and spraying the hardening material liquid B supplied from the flow path 4b.
And an air flow path 4a communicating with the air flow path 2a of the shaft body 1a.

A down-the-hole hammer 5 is attached to a lower part of the monitor 4 for ejecting the hardening material liquid constructed as described above.
The down-the-hole hammer 5 is operated by the compressed air A from the air flow path 4a of the monitor 4 for injecting the hardening material liquid.

The injection rod constructed as described above is set at a predetermined drilling position on the ground to be improved, and drilling is performed. As shown in FIG. In the course of drilling, when it comes into contact with an obstacle layer D such as a hard layer below the top soil C of the ground to be improved, the down-the-hole hammer 5 provided at the tip of the injection monitor 4 hits the obstacle such as the hard layer. The material layer D is hit and drilled.

Next, the injection rod 1 penetrates the soil layer (E) to be improved to a predetermined depth while discharging only the compressed air A from the air flow path 4a of the hardening material liquid ejection monitor 4 from the tip of the down-the-hole hammer 5 (FIG. 2 (b)). After the penetration to the predetermined depth is completed, as shown in FIG. 2 (c), further excavation (F) is performed.

After drilling to a predetermined depth, the hardening material liquid B is injected from the injection nozzle 6 of the injection monitor 4 as shown in FIG. 2C, and injected as shown in FIG. The improved body G is formed while the rod 1 is rotated and pulled up. When the hardening material liquid B is jetted to a predetermined depth and the formation of the improved body G is completed, the jetting of the hardening material liquid B is stopped as shown in FIG. The improved body G of is produced.

[0014]

As a result of implementing the method of the present invention, even if there is an obstacle layer such as a hard layer or a rubble layer in the ground to be improved, the obstacle layer can be easily drilled. The construction period was greatly shortened compared to the technology, and a great economic effect was obtained.

[0015] In addition, even if the result of underwater construction is performed, it is possible to easily drill an obstacle layer such as a rubble layer on the sea floor, and it is not necessary to protect the excavation hole and to confirm the position. The same effect as was obtained.

[Brief description of the drawings]

FIG. 1 is an enlarged schematic sectional view of a main part of an injection rod of the present invention.

FIG. 2 is an explanatory view showing a construction procedure of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Injection rod 2 Outer pipe 2a Air flow path 3 Inner pipe 3a Hardened material liquid flow path 4 Hardened material liquid ejection monitor 4a Air flow path 4b Hardened material liquid flow path 5 Down-the-hole hammer 6 Injection nozzle 7 Screw joint A Compressed air B Hardening Material C Surface soil on the ground to be improved D Obstacle layer E Improved ground layer F Excavation G Improved body

Claims (1)

[Claims] 1. A high-pressure injection ground improvement method for improving a ground by rotating a shaft body up and down while injecting a high-pressure hardening material liquid into an improvement target ground from an injection nozzle provided at a lower end portion of the shaft body. A down-the-hole hammer is attached to a hardening material liquid ejection monitor provided at the lower end of the shaft body of the injection rod to be used, and the down-the-hole hammer strikes and drills an obstacle layer such as a rubble layer or a hard layer in the ground to be improved. A high-pressure injection ground improvement method, wherein a hardened material liquid is injected at a high pressure from a monitor for injection of a hardened material while rotating and lifting up an injection rod to form an improved body.