JPH108874A - Water stop method at the time of inserting pipe into ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent underground water from springing up into an opencut hole easily and positively in case of inserting a pipe into the ground from the open-cut hole. SOLUTION: A part of an earth retaining wall is cut off, and the ground 13 on the inner side is manually dug by the specified depth in the horizontal direction to form a pre-excavated part 14. Freezing jigs 21 and drain pipes 22 are installed in the pre-excavated part 14. With the drain pipes 22 as escape paths of spring water, liquid nitrogen is led into freezing pipes 26 of the freezing jigs 21 to form a frozen area R around the freezing jigs 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for stopping water from flowing from a pipe starting portion when a pipe is inserted into a ground from an open hole, and particularly to a pipe insertion method in a pipe roof construction method. It is related to the water stopping method sometimes applied.

[0002]

2. Description of the Related Art The pipe roof method is a tunnel excavation method which is used when the earth covering is relatively small and the foundation of an existing structure is located above. In this method, as shown in FIGS. 6 and 7, pipe roof steel pipes 2, 2,... Are inserted horizontally from the open shaft 1 so as to form a roof along the upper part of the excavation area P, thereby preventing collapse of the ground. Then, the excavation area P is excavated.

[0003] When a pipe is inserted into a ground through an excavation hole as in such a pipe roof construction method, when the groundwater level L is high, the groundwater travels along the outer periphery of the pipe or a joint portion to start the pipe in the excavation hole. Spring water may be generated from for that reason,
2. Description of the Related Art Conventionally, countermeasures against water stoppage by soil improvement such as injection of chemicals or grout or formation of frozen soil have been taken. However, such ground improvement measures need to be performed quite extensively, resulting in delays in construction and increased costs. In addition, the effect cannot be expected much on the ground of mudstone layer or soft rock layer.

[0004] Therefore, there arises a technical problem to be solved in order to provide a simple and reliable method of stopping water when inserting a pipe into the ground, and the present invention solves the problem. With the goal.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been proposed to solve the above-mentioned problems, and has been proposed in the outer periphery of a starting portion of a pipe to be inserted into a ground through an open hole or a joint portion of a starting portion between adjacent pipes. A method of stopping water by piping a freezing pipe and a drain pipe, introducing a cryogen into the freezing pipe and forming a freezing area around the freezing pipe while using the drain pipe as an escape path for spring water. To provide.

[0006]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described in detail with reference to FIG. In FIG. 1, reference numeral 11 denotes an open hole, and reference numeral 12 denotes a retaining wall. In the pipe roof method, first, a part of the retaining wall 12 is cut off,
The ground 13 at the back (right side of the paper) is moved to a predetermined depth (1
(About 2 m) by hand digging to form the pre-dig portion 14. Then, the excavator 15 is loaded on the face of the excavation part 14.

On the surface of the retaining wall 12, a steel form 16 is installed along the entrance of the digging portion 14. A hole 17 is formed in the center of the steel form 16 so as to communicate with the excavated portion 14, and a sponge 18 is provided along the inner peripheral edge of the hole 17. . Thereafter, the mortar 19 is filled in the steel mold 16. Thus, the pipe roof steel pipe starting portion 20 is formed.

[0008] The mortar 19 also penetrates into the sponge 18. Sponge 18 thus cured
Serves as a stopper for preventing muddy water sent to the face during excavation of the pipe roof and grouting agent injected after the excavation ends from leaking into the opening 11. However, not sufficient shielding properties for low viscosity fluids such as groundwater, water pressure limit is about 0.3 kgf / cm ^2, to the water stopping groundwater to be the ten times more pressure Can not.

Therefore, in order to stop such groundwater, a pair of upper and lower freezing jigs 2 is attached to the pipe roof steel pipe starting portion 20.
1 and 21 are installed. Here, the sponge 18 is installed in the excavation portion 14 of the pipe roof steel pipe starting portion 20. However, the sponge 18 may be installed at the position of the sponge 18. Although not shown, the freezing jigs 21 and 21 installed in the excavation portion 14 are fixed to the ground 13 by anchors. Further, two drain pipes 22, 22 are provided on the lower side of the lower freezing jig 21 on the left and right sides (front side and back side).

FIG. 2 shows the freezing jigs 21, 21 and the drain pipes 22, 22. Freezing jigs 21
1 is formed in a substantially semi-annular shape having a radius of curvature slightly larger than the outer diameter of a pipe roof steel pipe to be described later. become. A flow resistance member 25 is provided on the peripheral surface of the steel plate 23. The flow resistance material 25 may be any material that can block the flow of groundwater.
It is formed of a highly water-absorbent fiber cloth or nonwoven fabric, glass wool, wire brush, steel material, or the like.

A freezing tube 26 is provided on the outer peripheral surface of the steel plate 23. The freezing tube 26 is provided with the steel plate 23.
In order to cover the entire outer peripheral surface of the steel sheet 23, the steel sheet 23 is meandered in the axial direction while tracing the steel sheet 23 in the circumferential direction, and both ends thereof are drawn out from the left and right front edges of the steel sheet 23.

On the other hand, the drain pipes 22, 22 are installed such that the inlet ends thereof are near the inner edge of the lower freezing jig 21, and are drawn out toward the user. Then, as shown in FIG. 1, both the freezing pipe 26 and the drain pipe 22 extend from the pre-drilled portion 14 into the cutout hole 11 and then bend upward to reach the ground.

Further, as shown in FIG.
Is connected to a liquid nitrogen cylinder 28 through a heat insulating pipe 27. A solenoid valve 29 is provided in the heat insulating pipe 27.
The solenoid valve 29 is provided by the controller 30.
Is opened, liquid nitrogen is introduced from the liquid nitrogen cylinder 28 into the freezing tube 26 via the heat insulating pipe 27.

The liquid nitrogen cools and freezes the periphery of the freezing jig 21 while passing through the meandering portion of the freezing tube 26. Further, it is guided to the other end of the freezing tube 26 released to the ground and vaporized and released into the atmosphere. At the beginning of the introduction of the liquid nitrogen, the valve 31 provided near the outlet end of the drain pipe 22 is opened.

The reason that the other end of the freezing tube 26 is extended to the ground without being stopped in the drilling hole 11 and released is as follows.
This is because, if released inside the drill hole 11, the nitrogen concentration in the drill hole 11 becomes abnormally high, which is dangerous.

Further, a temperature sensor 32 is installed near the freezing jig 21 and its output is connected to the controller 30. A cooling temperature target value is set in the controller 30, and when the output reaches the target value,
The solenoid valve 29 is closed to stop the supply of liquid nitrogen.
Thereafter, when the temperature around the freezing jig 21 rises and the output exceeds the target value, the solenoid valve 2
Open 9 and recharge liquid nitrogen.

As described above, the temperature around the freezing jig 21 is controlled while the liquid nitrogen is intermittently supplied by the automatic control. In addition, when a large spring water suddenly occurs during the excavation of the pipe roof, the liquid nitrogen is continuously supplied without temperature control.

Thus, as shown in FIG.
A local frozen region R is formed around 1. Then, the groundwater in the ground 13 is transferred to the pipe roof steel pipe starting portion 20.
When it flows into the freezing region R, it is captured and frozen.

However, a large amount of energy is required to form the first ice from water that normally flows, and the flow rate is 1
It is said that ice does not easily take root if it exceeds 5 m / day. Therefore, when the liquid nitrogen is introduced, the spring water does not immediately stop, and the drain pipe 22 flows out as a main water path. Then, the water flow decreases near the freezing jig 21, and the flow velocity also decreases due to the action of the flow resistance member 25. In this way, ice is likely to be formed in the vicinity of the freezing jig 21, and the frozen region R grows rapidly.

When the frozen region R matures, the water is almost completely stopped except for the spring water from the drain pipe 22. Thereafter, the valve 31 is closed to cut off the escape route of the spring water. Thereby, the spring water from the pipe roof steel pipe starting section 20 is completely stopped.

The freezing region R only needs to be at a temperature at which water freezes, and has a sufficient water stopping function even in a relatively soft freezing state as long as the water flow is not so large. Therefore, it is not necessary to set the cooling temperature target value to an extremely low temperature, and liquid nitrogen can be saved. Further, there is no possibility that the excavator 15 is damaged.

Further, the drainage pipe 2 may be used in accordance with the magnitude of the amount of spring water.
It is advisable to adjust the tube diameter and number of tubes. Thus, the pipe roof steel pipe 33 is inserted into the pipe roof steel pipe starting portion 2 so as to penetrate the freezing region R and the pair of freezing jigs 21 and 21.
0 and the tip is connected to the excavator 15. Then, the excavator 15 is driven to start excavation. A digging jack (not shown) is provided behind the pipe roof steel pipe 33 to take the reaction force of digging. Thus, the pipe roof steel pipe 33 is pushed into the ground 13 in the horizontal depth direction together with the excavator 15.

Thus, the above-mentioned freeze-stopping measures are taken for the ground 1
3 is performed for each steel pipe 33 inserted into the pipe roof. And, as shown in FIG.
If the pipe roof 34 is formed by arranging 3, 33.
A freezing area R is provided on both upper and lower sides of the pipe roof 34 in the pipe roof steel pipe starting section 20.

In the figure, reference numeral 33a denotes a pipe roof steel pipe inserted first.
Female joints 35 are protruded from both left and right outer surfaces of a in the pipe axis direction (perpendicular to the paper surface). On the other hand, the other pipe roof steel pipe 33 has a female joint 3
5 protrudes, and a male joint 36 protrudes from the opposite side. The female joint 35 and the male joint 36 project outward through the gap 24 between the pair of freezing jigs 21 and 21. The male joint 36 of the pipe roof steel pipe 33 to be newly installed is next to the female joint 35 of the adjacent pipe roof steel pipe 33 (33a) previously installed, one by one in the left and right directions centering on the pipe roof steel pipe 33a. Insert while fitting.

The female joint 35 is filled with styrofoam 37 in advance. This is because, when earth and sand enter the female joint 35 during insertion into the ground 13, it is difficult to fit the male joint 36 to the female joint 35 when inserting the next pipe roof steel pipe 33. This is to prevent such a situation. Then, the male joint 36 is fitted to the female joint 35 while crushing the styrene foam 37.

The joint structure composed of the female joint 35 and the male joint 36 has almost no water stopping function. Therefore, if another freezing jig 38 and a drain pipe 39 are installed in this joint portion,
The joint is also frozen, and the water stopping effect is further enhanced in combination with the operation of the freezing jig 21 and the drain pipe 22.

FIG. 5 shows the freezing jig 38 in which a U-shaped freezing tube 41 is provided on one side surface of a thin and thin steel plate 40. The freezing jig 38 is connected to the pipe roof steel pipe starting portion 2.
0 is inserted between each piece of the male joint 36.
On the other hand, the drain pipe 39 is connected to the pipe roof steel pipe starting portion 2.
0 at one corner of the female joint 35.

One end of both ends of the U-shaped freezing tube 41 is connected to a liquid nitrogen cylinder and the other end is released. Usually, temperature control is performed by a controller. It is the same as the case of the freezing jig 21 and the drain pipe 22 that the drainage pipe 39 is closed and the escape path is cut off when the frozen area has matured, as a spring escape route.

The pipe roof steel pipe 33 is connected to the ground 13
Is reached, the freezing jig 21 and the drain pipe 22 and the freezing jig 3
8 and a drain pipe 39 may be provided to form a frozen area. Thereby, spring water to the drilling hole on the arrival side can also be prevented.

Thus, the present invention can be variously modified without departing from the spirit of the present invention. For example, brine may be used as the freezing agent instead of liquid nitrogen.
(In that case, the frozen pipe is closed circuit, and the injected brine is collected, cooled and recirculated.) Not only the pipe roof method but also any method of inserting a tubular thing into the ground (shield, steel pipe stop, etc.) Water walls, etc.) can also be applied. And it goes without saying that the present invention extends to those.

[0031]

As described above, according to the present invention, a drainage pipe is formed by introducing a cryogen into the freezing pipe while forming a relief path for the spring water to reduce the water flow near the freezing pipe. The outer periphery and the joint are locally frozen. As a result, ice is formed and grows very easily near the freezing tube. Therefore, even if the flow velocity is large,
It is possible to reliably and quickly stop spring water into the drill hole.

Compared with conventional methods such as injection of a chemical solution or grout, the construction can be performed extremely easily, which not only contributes to shortening the construction period and the construction cost but also to the ground such as mudstone layer and soft rock layer. Is also very effective.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view of a freezing jig and a drain pipe in FIG.

FIG. 3 is an explanatory diagram showing the configuration of an automatic control system for intermittently supplying liquid nitrogen to control the temperature of a freezing region and a drain pipe.

FIG. 4 is a front sectional view of a pipe roof and a ground around the pipe roof, in which a pipe roof steel pipe starting portion is a cut surface.

FIG. 5 is a plan view of a freezing jig installed at a joint portion in FIG. 4;

FIG. 6 is an explanatory view of the pipe roof construction method, in which a side cross-sectional explanatory view after inserting a pipe roof steel pipe and before excavating an excavation area.

FIG. 7 is an explanatory front sectional view of the excavation area after excavation in FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Open hole 13 Ground 14 Excavation part 15 Excavator 20 Pipe roof steel pipe starting part 21, 38 Freezing jig 22, 39 Drain pipe 26 Freezing pipe 28 Liquid nitrogen cylinder 33 Pipe roof steel pipe 34 Pipe roof 41 U-shaped freezing pipe R Frozen area

Continued on the front page (72) Inventor Hiroshi Ito 1043 Ogikikubo, Tsukuba, Ibaraki Pref.

Claims (1)

[Claims] 1. A freezing pipe and a drainage pipe are piped around an outer periphery of a starting portion of a pipe inserted into a ground through an excavation hole or a starting portion joint portion between adjacent pipes, and the drainage pipe is used as an escape path for spring water. A method for stopping water when inserting a tube into the ground, wherein a freezing agent is introduced into the freezing tube to form a frozen region around the freezing tube.