JPH08199573A - Earth retaining method in excavation work - Google Patents

Abstract

PURPOSE: To prevent the collapse of an excavated ditch simply, safely and surely without using any heavy machine. CONSTITUTION: An air-bag 3a forming a semi-circular recessed groove 5 corresponding to a pipe 2 buried when it is expanded with pressure is placed to an excavated ditch 1 excavated from the ground to pressurize and expand, air-bags 3b, 3c are placed above the air-bag 3a to pressurize and expand, and bearing force against side walls of the excavated ditch 1 is ensured by inside pressure of air-bags 3a, 3b and 3c to maintain a channel shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth retaining method for excavation and civil engineering work in the case of laying pipes such as gas pipes and water and sewer pipes in the ground.

[0002]

2. Description of the Related Art When laying pipes such as gas pipes, oil pipes, water and sewer pipes, power transmission cables, and protective pipes for optical fiber cables for communication in the ground, a laying groove is made by cutting from the ground. A so-called excavation method is often employed in which the material is excavated, pipes are laid, joined, inspected, and anticorrosion work is performed, and then backfilled with backfill soil. During the construction period from this excavation to backfilling, in order to prevent the side wall of the excavation groove 1 from collapsing,
For example, as shown in the cross-sectional view of FIG. 7, a sheet pile 21 made of steel was driven along the side surface of the groove, and then the uprising 22 and the cut beam 23 were arranged at predetermined intervals.

When the pipes 2 to be buried are carried into the excavation groove 1 and arranged, the cut beams 23 are sequentially temporarily removed, the pipes 2 are carried in, and the cut beams 23 removed are re-installed. There is. After sequentially carrying in the pipe 2,
After carrying out a series of piping work such as positioning, attachment, joining, inspection, coating and the like of the pipe 2 which has been carried in, while the backfill groove 1 is backfilled with backfill soil, the cutting beam 23, the uprising 22, and the sheet pile 21. The work of sequentially removing such items has been performed using heavy machinery such as hoists and sheet pile pullers.

The use of these sheet piles 21 and the like was indispensable to secure the safety of the work inside the excavation groove 1, especially in the area of soil conditions where collapse is likely to occur.

As a substitute for driving the sheet pile 21, FIG.
It has also been practiced to use piles 24 or piles 24 and panels 25 as shown in the perspective view of FIG.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
When the sheet pile 21 is driven to prevent the collapse of the side wall of the building, a large-scale transport vehicle is required to transport the temporary material such as the sheet pile 21, the uprising 22, and the cut beam 23 to the site, and the capacity is increased. Required a large hoist (crane). Further, heavy machines such as a sheet pile driving machine for driving the sheet pile 21 and a sheet pile pulling machine for removing the sheet pile 21 have to be used. As described above, the capacity of the transporting device for transporting the temporary material and the mechanical devices used for placing and removing the temporary material are extremely large, and a space for temporarily placing these mechanical devices at a narrow construction site where the space is limited. It was difficult to secure the space.

Further, noise or vibration is generated when the sheet pile 21 is conveyed or placed, which causes pollution.

Further, when installing and removing the uprising 22 and the sill 23, the operator is often forced to enter the excavated groove 1, which is a very dangerous work.

Further, the supporting force required for the side wall of the groove for preventing the collapse of the excavation groove 1 changes according to the change of the water content of the soil, the change of the external pressure and the like. If it is desired to increase the bearing capacity of the side wall of the trench in response to changes in the water content of the soil, it is necessary to add sheet piles 21, uprisings 22, and beams 23. In some cases, it may not be possible to obtain the proper supporting force.

Also, when the piles 24 or the piles 24 and the panel 25 are used as a substitute for driving the sheet pile 21, it is indispensable to use a heavy machine when installing and removing them. It had similar disadvantages.

The present invention has been made in order to solve the above disadvantages, and provides a soil retaining method in excavation work which can prevent collapse of excavation grooves easily and surely without using heavy machinery. The purpose is to do.

[0012]

According to the earth retaining method in excavation work according to the present invention, an elastic material sheet having high mechanical strength and airtightness is formed into a bag shape in an excavation groove excavated from the ground, and internal pressure is applied. One or more gas bags that expand in a rectangular parallelepiped shape that is suitable for the excavation groove when placed under pressure are arranged, and the pressure determined by the soil, groundwater level, and depth of the excavation groove in the gas bag. It is characterized by enclosing the gas of.

Further, a gas bag having a semicircular concave groove having a diameter corresponding to the outer diameter of the pipe is arranged at the position where the pipe is laid when pressurized and expanded, and the gas bag is expanded by pressure, It is preferable to arrange a pipe to be buried in the concave groove of the formed gas bag.

It is preferable to have a partition wall which is embedded in the gas bag and which is divided in the axial direction of the tube.

[0015]

In the present invention, a gas bag made of an elastic sheet is arranged in the excavation groove cut from the ground, a gas having a predetermined pressure is enclosed in the gas bag, and the inner pressure of the gas bag is applied to the side wall of the excavation groove. Secures the supporting force and maintains the groove shape.

Further, a gas bag forming a semi-circular concave groove corresponding to the pipe to be buried when pressurized and expanded is arranged in the excavation groove and pressurized and expanded to form a concave groove of the gas bag. A pipe to be buried is arranged inside, and the pipe to be buried is held and the shape of the groove is maintained so as to face earth pressure around the groove.

Further, the gas bag is divided by a partition wall provided inside to divide the gas bag in the axial direction so that the gas bag is held in a predetermined shape when expanded under pressure.

[0018]

1 is a sectional view showing an embodiment of the present invention. As shown in the figure, when the pipe 2 is buried by the excavation method, first, the excavation groove 1 is excavated from the ground surface to a predetermined depth.
To form. Next, in order to prevent the side wall of the excavation groove 1 from collapsing, earth retaining is performed using a plurality of gas bags 3a, 3b, 3c. The gas bags 3a, 3b, 3c are elastic sheet having high mechanical strength and airtightness, for example, synthetic rubber such as polyester urethane rubber, cloth or glass fiber coated with vinyl chloride resin, fluororesin, or the like, or It is formed of an ethylene-vinyl acetate copolymer, a synthetic resin such as a polyamide resin or polypropylene, or a polyvinyl formal fiber. As shown in the perspective views of FIGS. 2 and 3, the size and shape of the gas bags 3a, 3b, 3c have a width Wb adapted to the width W of the excavation groove 1 when the internal pressure is applied. The length Lb of the pipe 1 in the axial direction is formed so as to be easily handled, for example, to be expanded in a rectangular parallelepiped shape having a length of 1 m to 3 m, and the height Hb is the depth H of the cut groove 1. On the other hand, it is determined by how many divisions the gas bag is divided into. Further, one or a plurality of partition walls 4 are provided in the gas bags 3a, 3b, 3c, and the gas bags 3a, 3b, 3
When the internal pressure is applied to c to expand it, the rectangular parallelepiped shape is maintained and expanded. In addition, gas bag 3
When the lengths of a, 3b and 3c are short, the partition wall 4 may be omitted.

As shown in the perspective view of FIG. 2, the gas bag 3a installed in the lower portion of the pipe 2 to be laid has a pipe formed at the center of the upper surface of the rectangular parallelepiped formed when it is expanded by pressure. Has a semicircular concave groove 5 having a diameter corresponding to the outer diameter of the above, and has a gas injection port 6 on the upper surface. The gas bag 3b installed on the upper part of the gas bag 3a has a semicircular groove 5 having a diameter corresponding to the outer diameter of the pipe in the center of the lower surface of the rectangular parallelepiped formed when the gas bag 3a is expanded under pressure. It has a gas inlet 6.

Next, the work steps for earth retaining to prevent the side walls of the excavation groove 1 from collapsing by using the gas bags 3a, 3b, 3c configured as described above will be described.

First, the gas bag 3a is inserted into the excavation trench 1 and a general-purpose portable engine-driven air compressor for field construction is used. The accumulator (pressure 0.
(6 to 0.7 MPa) compressed air is reduced to a predetermined pressure by a pressure regulator, and air having a predetermined pressure is filled from an inlet 6 provided in the gas bag 3a to increase the internal pressure of the gas bag 3a to a predetermined pressure. The gas bag 3a is expanded into a predetermined shape as shown in FIG. 2, the side surface in the longitudinal direction of the gas bag 3a is brought into close contact with the side wall of the excavation groove 1, and then the inlet 6 is closed and sealed. The excavation work of this excavation groove 1 and the insertion of the gas bag 3a,
After performing the pressurizing and expanding operations for a predetermined length, the pipe 2 to be laid is placed in the semicircular groove 5 of the gas bag 3a. Next, the gas bag 3a is arranged on the gas bag 3a and the tube 2, and the gas bag 3b is pressurized and expanded. After that, the gas bag 3c that expands in a rectangular parallelepiped shape without grooves is arranged on the gas bag 3b, and the gas bag 3c is pressurized and expanded.

In this way, the gas bags 3a, 3b, 3c are sequentially arranged in the excavation groove 1, and the gas bags 3a, 3b, 3c are brought into close contact with the side walls of the excavation groove 1 by applying pressure and expansion.
The inner pressure of the gas bags 3a, 3b, 3c can secure a supporting force for the sidewall of the excavation groove 1, prevent the collapse of the sidewall of the excavation groove 1 while maintaining the groove shape of the excavation groove 1. Can be held in place.

The pressure of the air filled in the gas bags 3a, 3b, 3c in order to prevent the side walls of the excavation groove 1 from collapsing is empirically determined depending on the soil quality, the groundwater level, and the like. For example, a case where the groundwater level is relatively high and the soil is a sandy layer will be described with reference to the sectional view of FIG.

When the groundwater level 11 exists at a level (HL) from the ground surface as shown in FIG. 4, a liquid, for example water 13
According to a simulation experiment conducted on the collapse of the side wall of the excavation groove 1, even if the groundwater level 11 changes, the water level 13a in the liquid bag 12 is increased to a level above the groundwater level 11 by a certain level ΔH. It has been found that if kept, it is possible to prevent collapse of the excavation groove 1. That is, the hydraulic pressure distribution P due to the water level 13a which is a certain level ΔH above the groundwater level 11
If the side wall is supported by the pressure corresponding to (h), collapse of the cut groove 1 can be prevented. For example, when laying a pipe diameter of 400 A, if the depth H of the excavation groove 1 is 210 cm,
When the groundwater level 11 is extremely high, the pressure P required to prevent collapse of the side wall of the excavation groove 1 is, for example, (HL) = 30.
Even in the case of cm, P = ρgh = ρg (L + ΔH) = 1gf /
It can be said that cm ³ (180 + 20) = 200 gf / cm ³ = 0.02 MPa, that is, ΔH = 20 cm is sufficient. Here, ρ is the density of the water 13 injected into the liquid bag 12, and g is the gravitational acceleration. Therefore, 0.02 is added to each gas bag 3a, 3b, 3c.
By enclosing compressed air with a pressure of ~ 0.03 MPa,
The collapse of the excavation groove 1 could be sufficiently prevented.

In the above embodiment, the pipe 2 is provided in the lower part of the cut groove 1.
Two gas bags 3 having a semicircular groove 5 for holding
Although the case where a and 3b are installed has been described, as shown in FIG. 5, a gas bag 8a having a U-shaped groove 7 having a semicircular lower portion and an arc matching the outer diameter of the pipe 2 are provided at the lower portion. Even if the gas bag 8b fitted into the U groove 7 and the gas bags 8c and 8d that expands into a rectangular parallelepiped shape are used, the collapse of the excavation groove 1 can be prevented as in the above embodiment.

In the embodiment shown in FIG. 5, for example, the nominal pipe diameter 40
A specific example of burying a 0 A steel pipe in the ground by using the excavation method will be described. The groove depth H is determined by the sum of the soil cover S ₁ , the pipe diameter D and the lower clearance S ₂ . The soil cover S ₁ is a value determined by standards, rules, etc., and is 1500 mm for a pipe diameter of 400 A, for example. The lower clearance S ₂ of the pipe together with the clearance S _{3 on} the side surface of the pipe is the minimum value that can sufficiently fill the backfill soil at the time of backfilling. Here, the lower clearance S ₂ is 200 mm and the clearance S _{3 on} the side surface.
Is set to 300 mm. In this case, the depth H of the digging groove 1 is 2100
mm, the width W is 1000 mm. And the gas bag 8a-
The material of 8d is, for example, synthetic resin impregnated with a thickness of about 1.
When using a 5 mm cotton cloth, the width of the gas bag 8a is 1000 mm, which is the same as the width W of the cut groove 1, and the height is 800 m.
Assuming m and length of 1500 mm, the weight of the gas bag 9a is about 22.4 kg. The gas bag 8b has a width of 400 mm,
If the height is 200 mm and the length is 1500 mm, the weight is about 3 kg. If the gas bag 8c is 1000 mm in width, 800 mm in height and 1500 mm in length, the weight is about 10.5 kg, and the gas bag 8d is 1000 mm in width, 500 mm in height and long. If it is 1500 mm, the weight will be about 8.5 kg. Therefore, the gas bag 8
The a to 8d can be easily transported and can be installed in the excavation trench 1 without using heavy machinery such as a hoist.

In the above embodiment, the independence of the ground is relatively high,
The case where there is time to hang the pipe 2 after excavating the excavation groove 1 has been explained, but when the excavation groove 1 has to be excavated immediately after the excavation groove 1 is excavated, or when the excavation groove is excavated, An example in which it takes time from the excavation of the pipe 1 to the installation of the pipe 2 will be described.

In this case, after the excavation groove 1 is excavated, as shown in the sectional view of FIG. 6, a gas bag having a semicircular concave groove 5 for holding the pipe 2 on one surface is formed in the same manner as the gas bags 3a and 3b. 9a and 9b are installed opposite to each other in the excavation groove 1, and the gas bags 9a and 9b are pressurized and expanded to clamp the lower part of the excavation groove 1. After that, gas bags 9c and 9d having no groove are sequentially installed and pressurized and expanded to carry out mountain retaining. After repeating this work one after another, when excavation of the specified span and mountain retaining are completed,
The tube 2 is horizontally drawn into the hole formed by the semicircular groove 5 of the gas bags 9a and 9b. In this way the digging groove 1
After excavating, the mountain can be clamped immediately and the pipe 2 can be installed safely.

In each of the above embodiments, the case where the pressurized air to be enclosed in the gas bag is supplied by using the general-purpose portable engine-driven air compressor for on-site construction has been described. When the pressurized gas is supplied using the enclosed pressure vessel, noise during construction can be significantly reduced.

In each of the above embodiments, the case where the pressurized gas is enclosed in the gas bag has been described. However, if there is water leaking from the periphery of the excavation groove 1 and there is intruding water in the excavation groove 1, the gas bag is filled with the gas bag. If buoyancy acts and the gas bag may float, it is possible to prevent the gas bag from rising by enclosing water with the pressurized gas in the gas bag at the same level as the water level of the intruding water. it can.

[0031]

As described above, according to the present invention, the gas bag made of the elastic sheet is arranged in the excavation groove cut from the ground, and the gas having a predetermined pressure is sealed in the gas bag. Since the support force against the side wall of the excavation groove is secured by the internal pressure and the groove shape is maintained, it is possible to securely clamp the excavation groove without the use of temporary materials such as sheet pile, uprising, and cut beams. . Therefore, it is not necessary to use large vehicles such as sheet piles and heavy machinery such as hoists to carry temporary materials, so the storage space for heavy machinery can be eliminated and noise and vibration during construction can be eliminated. Can be reduced.

Further, a gas bag forming a semi-circular concave groove corresponding to the pipe to be buried when pressurized and expanded is arranged in the excavation groove and pressurized and expanded to form a concave groove of the gas bag. Since the pipe to be buried is arranged inside, the pipe to be buried can be reliably held and the groove shape can be held so as to face the earth pressure around the groove.

Further, since the gas bag is divided with respect to the axial direction of the pipe to be embedded by the partition wall provided inside and is held in a predetermined shape when the gas bag is expanded under pressure, the shape of the gas bag is excavated. It can be held according to the shape of the groove, and the collapse of the open-cut groove can be reliably prevented.

Further, since the gas bag has a small weight and can be folded before enclosing the gas, the volume can be made extremely small, and the bag can be easily transported without requiring a storage space at the construction site. OK.

Further, since the gas bags may be transported and arranged in accordance with the progress of the trench digging work and the pressurized gas may be enclosed therein,
No special heavy machinery or equipment is required, and the work can be done easily by manpower.
It can be shortened to 50 or less.

Furthermore, since the surface of the open-cut groove is covered with a gas bag, it is possible to prevent the operator from falling into the groove and the work tools from falling, which improves the safety of the work and damages the pipe. Can be prevented.

Further, since the side wall supporting force can be easily adjusted by adjusting the pressure of the gas filled in the gas bag, the soil acting on the side wall of the excavation groove due to the change of the groundwater level, the fluidization of the sediment due to rainfall, etc. It is possible to easily respond to changes in pressure.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a gas bag of the above embodiment.

FIG. 3 is a perspective view showing another gas bag of the above embodiment.

FIG. 4 is a cross-sectional view showing the operating principle of the above embodiment.

FIG. 5 is a sectional view showing a second embodiment of the present invention.

FIG. 6 is a sectional view showing a third embodiment of the present invention.

FIG. 7 is a perspective view showing a conventional example.

FIG. 8 is a perspective view showing another conventional example.

[Explanation of symbols]

 1 Open-cut grooves 2 Pipes 3a, 3b, 3c Gas bag 4 Partition walls 5 Recessed grooves 7a, 7b, 7c, 7d Gas bag 9a, 9b, 9c, 9d Gas bag

Continuation of the front page (72) Inventor Yasuhiro Matsuo 122-6, Shimotsuko, Atsugi, Kanagawa

Claims (3)

[Claims] 1. A rectangular parallelepiped which is formed in a bag shape in an excavation groove excavated from the ground by an elastic sheet having high mechanical strength and airtightness and adapted to the excavation groove when an internal pressure is applied. A soil retaining method in excavation work, characterized in that one or a plurality of expanding gas bags are arranged, and a gas having a pressure determined by the soil quality of the excavation portion, the groundwater level, and the depth of the excavation groove is enclosed in the gas bag. 2. A gas bag having a semicircular concave groove having a diameter corresponding to the outer diameter of the pipe at the position where the pipe is laid when pressurized and expanded is placed in the excavation groove and expanded under pressure. The earth retaining method for excavation work according to claim 1, wherein a pipe to be buried is arranged in the formed groove of the gas bag. 3. The earth retaining method for excavation work according to claim 1 or 2, further comprising a partition wall which is embedded in the gas bag and which is divided in a pipe axis direction.