JPH0776514B2 - Propulsion method in the spring formation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a propulsion method in a spring formation containing a large amount of groundwater.

<Prior Art> When a relatively large diameter propulsion pipe is laid in a gravel layer having a high water permeability, mud pressure is generally applied to prevent water from entering the propulsion pipe.

When the propulsion pipe has a small or medium diameter, other ground improvement methods such as chemical injection method are used together to prevent water from entering the propulsion tube.

<Problems to be Solved by the Present Invention> The conventional propulsion techniques described above have the following problems.

(B) The former water-stopping technology will require a large-scale muddy water treatment facility.

Therefore, the construction cost is high and it cannot be used at the site where it is difficult to secure a site for the muddy water treatment facility.

(B) In the latter case of water stoppage technology, the time and cost required for ground improvement are large.

<Object of the present invention> The present invention has been made in view of the above points, it is possible to reliably prevent water ingress into the propulsion pipe, it is possible to reduce the construction cost,
The purpose is to provide a propulsion method in a spring formation.

<Structure of the Present Invention> An embodiment of the present invention will be described below with reference to the drawings.

(A) Structure of excavation part Figures 1 and 2 show the excavation part provided at the tip of the laid pipe.

This excavation section comprises a front conduit 1, excavation means mounted on the front conduit 1, earth removing means, and direction correcting means.

Hereinafter, each part will be described.

(B) Leading Conduit The leading conduit 1 is a cylindrical body of which both ends are open, and accommodates the multi-drill 2 inside.

The leading conduit 1 is connected to the tip of a laying pipe 4 such as a fume pipe or a steel pipe through an intermediate cylinder 3, and a propulsion unit 5 installed in the starting shaft A.
It excavates in the ground by receiving two propulsion forces and rotation or swing.

[Drilling Means] The multi-drill 2 is provided with a plurality of down-the-hole drills 21 on its entire surface, and one end of a screw conveyor 6 for earth removal is connected to the other end.

The multi-drill 2 is accommodated in the destination conduit 1 so as to be rotatable and slidable along the axial direction by the movement of the screw conveyor 6.

Each down-the-hole drill 21 has a structure in which the down-hole drill 21 is hammered by compressed air sent through the shaft of the screw conveyor 6, but a well-known excavator other than the down-the-hole drill 21 can of course be adopted.

[Direction Correcting Means] A single or a plurality of direction correcting cylinders 7 are connected between the rear part of the front conduit 1 and the front part of the intermediate tube 3, and the front conduit 1 is expanded and contracted by the direction correcting cylinder 7. It is configured to control the direction of excavation.

It should be noted that in the present embodiment, a case will be described in which a direction correction function is provided, but a structure without a direction correction function may be used.

[Excavation Means] The screw conveyor 6 has its base end connected to the propulsion device 5,
By the rotation given from the propulsion unit 5, the earth is discharged to the starting shaft A side.

(C) Propulsion machine The propulsion machine 5 is installed in the starting shaft A, and the laying pipe 4 is given a thrust and an oscillating motion that repeats forward and reverse rotation, and the screw conveyor 6 is independently provided with a thrust and a rotational force advance. It is configured so that it can be given.

Due to the connection of the laying pipe 4 by welding, the propulsion device 5 is configured to be switchable between rotation and swing so as to give the laying pipe 4 a complete rotational movement.

<Operation> This method is performed in the following steps.

(A) Set of various equipment First, the propulsion unit 5 is installed in the starting shaft A.

The tail end of the intermediate cylinder 3 and the tail end of the screw conveyor 6 are connected to the respective drive parts of the propulsion unit 5.

(B) Start of excavation The operation of the propulsion device 5 is started, the multi-drill 2 is operated at the same time, and the excavation is started according to the planned line.

Further, the extension pipe 4 and the screw conveyor 6 are sequentially added to the tail ends of the intermediate cylinder 3 and the screw conveyor 6, respectively, and the excavation is continued.

[When excavating a non-spring layer] For example, when excavating a hard ground such as a rock and where groundwater does not exist, if the tip of the multi-drill 2 is projected forward from the front surface of the front conduit 1, the multi-drill 2 The original function of can be demonstrated to efficiently dig.

The ground material is discharged to the starting shaft A side via the screw conveyor 6.

[When excavating the spring layer] For example, when excavating a soft spring layer in the gravel area, if the multi-drill 2 as described above is to be excavated from the front surface of the front conduit 1, Submerge in.

Therefore, when excavating such a spring layer, contrary to the case described above, when the excavation is performed with the tip of the multi-drill 2 retracted from the front surface of the front conduit 1, the ingress of water into the front conduit 1 is prevented. You can dig in.

This is because there is a difference in the hydraulic conductivity of the earth and sand located inside and outside the front conduit 1.

That is, as shown in FIG. 2, when the front conduit 1 is pushed in the excavation direction, the front conduit 1 penetrates into the ground and the earth and sand is taken into the front conduit 1.

The earth and sand taken into the front conduit 1 is impacted by the multi-drill 2 to be consolidated, and its hydraulic conductivity changes to a small value.

Therefore, even if the groundwater tries to enter the front conduit 1, infiltration of the groundwater is blocked by the soil in the front conduit 1, and the groundwater is pushed out of the front conduit 1 as shown by the arrow in FIG.

The multi-drill 2 efficiently excavates the soil compacted in the leading conduit 1.

Further, even if the operation is interrupted at the time of connecting the laying pipe 4 and the screw conveyor 6, the difference in the hydraulic conductivity between the soil inside and outside the leading conduit 1 does not significantly change, so that there is no risk of water ingress into the leading conduit 1.

(C) Completion of laying When the leading conduit 1 reaches the reaching shaft B, the leading conduit 1 and the screw conveyor 6 are removed, and the laying of the laying pipe 4 is completed.

<Other Embodiments> It is also possible to carry out construction using the leading conduit 1a as shown in FIG.

The tip conduit 1a is a cylindrical body having a tip with a different wall thickness and an eccentric cross section in which the center line of the inner circumference is deviated from the center line of the outer circumference.

The multi-drill 2 is accommodated in the tip conduit 1a in a deflected state,
When a deviation in the excavation direction occurs, the excavation direction can be corrected by the difference in the wall thickness of the tip of the leading conduit 1a.

Then, if the spring layer is dug in a state where the front surface of the front conduit 1a is located in front of the tip of the multi-drill 2, it is possible to prevent water from entering the front conduit 1a, as in the above-described embodiment.

According to the present embodiment, the impact of the multi-drill 2 not only compacts the soil in the front conduit 1a, but also the front conduit 1a is penetrated into the ground while swinging due to the difference in wall thickness of the front surface of the front conduit 1a. Since the soil in 1a is consolidated, there is an advantage that the inundation prevention effect is further improved.

In this embodiment, there is a slight structural difference in the front conduit 1a, and other points are the same as the above-mentioned embodiment, and therefore, the same members are designated by the same reference numerals and their description is omitted. Is omitted.

<Effects of the Present Invention> Since the present invention is as described above, the following effects can be expected.

(B) Unlike conventional mud pressure method and chemical injection method,
The water can easily be prevented from entering the front conduit by simply digging the front surface of the front conduit forward of the tip of the multi-drill.

Therefore, it is not necessary to use a large-scale muddy water treatment facility and a chemical injection facility as in the past.

(B) The status of water stoppage in the front conduit can be easily determined by the presence or absence of runoff water on the starting shaft side, and if there is runoff water, it is sufficient to simply penetrate the front conduit until the water stops flowing out.

Therefore, the still water management is easy.

(C) Since the ground on the face side is compacted and there is no disturbance,
A reaction force when correcting the excavation direction of the leading conduit can be reliably obtained, and stable direction correction can be performed.

[Brief description of drawings]

 1 is an explanatory view of an embodiment according to the present invention. FIG. 2 is a vertical sectional view of a leading conduit. FIG. 3 is an explanatory view of an embodiment using another leading conduit.

Claims (1)

[Claims] 1. A leading conduit is connected to the tip of a laying pipe, a multi-drill is housed in the leading conduit so as to be rotatable and axially slidable, and a screw conveyor for earth removal is connected to the multi-drill, In the propulsion method of propelling the laying pipe while digging the multi-drill, advance the tip pipe from the tip of the multi-drill, hit the soil taken in the tip pipe with the multi-drill, consolidate, and the hydraulic conductivity of the sand around the tip pipe. A method of propulsion in a spring formation that excavates while reducing the hydraulic conductivity of sediment in the preceding conduit.