Excavating tool and steel pipe forepoling method

Abstract

An excavating tool capable preventing the natural ground from being loosened by excavated water and smoothly discharging excavated chips and a steel pipe forepoling method capable of securely providing earth reinforcing effects by using the excavating tool. The excavating tool (10) comprises a boring rod (12) rotatingly drivable around an axis (0), a tool body (11) fitted to the front of the boring rod (12) in the forward excavating direction, and a cylindrical steel pipe (13) having a specified clearance relative to the boring rod (12) with the boring rod (12) inserted therein. The excavating tool is characterized in that a flow passage (21) for supplying drilling water to the axial forward direction is formed in the tool body (11), and a fluid supply port (24) communicating with the flow passage (21) and jetting the drilling water is formed only at a position on the tool body opening to the inside of the steel pipe (13) toward the rear of the tool body (11) in the forward excavating direction.

Description

technical field [0001] The present invention relates to an excavating tool configured by inserting a digging rod with a tool body attached to its tip into a steel pipe (housing), and used for digging a steel pipe while forming an excavation hole in a mountain body with the tool body, and A steel pipe advance support method in which an injectant is injected after a hole-digging operation using the excavating tool to reinforce the mountain body. [0002] In addition, the present invention relates to an excavating tool in which a digging rod with a tool main body attached to its front end is inserted into a housing, the digging rod is inserted into the housing while forming an excavation hole on a mountain body with the tool main body, and the digging rod is sequentially inserted into the housing. It is used in the digging operation where the excavation hole of a predetermined depth is formed by connecting with the casing. Background technique [0003] Generally, in tunnel exc...

AI Technical Summary

Problems solved by technology

In order to avoid such a situation, it is necessary not to use the excavation water or to reduce the amount of excavation water used, and there is a problem that excavation debris accumulates in the gap between the steel pipe and the inner rod, which reduces the discharge performance of the excavation debris

In this way, it will be difficult to discharge the excavated debris, not only the speed of digging will become very slow, and the digging operation may not be continued.

In addition, even when only air is used to discharge excavated debris instead of boring water, sufficient discharge performance cannot be obtained.

[0008] In addition, in the case of a structure in which the check valve is pushed open by the internal pressure of the injection agent or the check valve is separated to open during the injection operation as in Patent Document 1, the outer side of the steel pipe is the hole wall of the excavated hole, It is possible that the check valve cannot be opened due to being blocked by the hole wall

In particular, due to the state of excavation, sand and soil may accumulate between the steel pipe and the excavation hole, and the pressure of the sand and soil may become an obstacle to the opening.

In this way, since the check valve becomes difficult to open, it is difficult to discharge the injection agent from the filter hole, and the effect of strengthening the mountain body cannot be obtained sufficiently.

[0009] In addition, in the above-mentioned steel pipe advance support method, when excavating a highly viscous and poorly fluid formation such as clay, excavation debris passing through the gap between the steel pipe 5 and the inner rod is accumulated in the gap and discharged. The problem of reduced efficiency

Moreover, it is possible that the excavation debris accumulated in this way is piled up one by one, making it difficult to discharge the excavation debris, thereby making it impossible to continue the digging operation.

In addition, in order to suppress the further softening of the mountain due to the excavation water when the ground is soft, or to suppress the impact on the buildings on the surface when the cover soil with the surface is shallow, it is necessary to reduce the amount of excavation water. amount of use, or air must be used instead of borehole water, in which case especially the accumulation of excavation debris becomes a problem

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