JPH0336331A - Friction reducing method for underground structure - Google Patents

Abstract

PURPOSE:To surely display a friction force reducing effect with simplified execution by setting up a pipe-shaped member, in which many fine holes are drilled, in a place positioned in the external surface side of an underground structure and injecting a lubricant after the structure is constructed. CONSTITUTION:A reinforcing steel bar cage 12 is inserted into a groove hole excavated in the ground, thereafter a panel wall is formed by casting concrete, and in the sideward of this panel wall, by connection-forming successively the other panel walls, an underground structure is constituted. In the case of this method of construction, a pipe-shaped member 28, in which many fine holes 30, 30 faced to a surface direction of the structure are drilled, is left as set up in a place positioned in an external surface side of the structure. Next, after the structure is constructed, a lubricant is supplied to the pipe-shaped member 28 and jetted from the fine holes 30, 30, and negative friction force of the structure is reduced by forming a film of the thin lubricant in the periphery of the structure.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for reducing friction in underground structures, and in particular,
This paper relates to a friction reduction method for underground structures constructed using the continuous underground wall construction method.

(Prior art) As is well known, the continuous underground wall construction method involves excavating a trench in the ground, inserting a reinforcing cage into the trench, and then pouring concrete to form a panel wall. This is a construction method in which a panel wall is formed, and other panel walls are successively connected to the side of this panel wall, and is used as an earth retaining wall of an underground structure or a main wall of an underground tank.

By the way, when constructing an underground structure on soft ground,
It is known that a negative frictional force that tries to pull the structure downwards acts on the outer circumference of the structure due to consolidation settlement of the soft ground, and if measures are not taken to reduce this force, it will have a negative impact on the underground structure. give.

Therefore, methods for reducing friction in underground structures have been proposed, as seen in, for example, Japanese Patent Laid-Open No. 53-56806 and Japanese Patent Publication No. 58-58495.

The former reduction method involves drilling a guide hole near the outer periphery of the constructed underground structure, inserting an injection pipe equipped with an injection nozzle into the guide hole, and discharging asphalt emulsion from the nozzle while pulling up the injection pipe. In this method, high-speed water, air, etc. are injected to form an emulsion film on the outer periphery of the structure to reduce frictional force.

On the other hand, the latter reduction method involves preparing multiple plates coated with a friction reducing agent such as asphalt, movably attaching these plates to a reinforcing cage, and using the pressure of the poured concrete to excavate the plates. This is a method in which the friction force reducing agent is placed on the outer surface of the structure by pressing it against the wall of the hole.

However, such a method of reducing frictional force requires, in particular,
The application to underground structures constructed using the continuous underground wall construction method is explained below. There were technical issues.

(Problem to be Solved by the Invention) In other words, in the former method, a large number of guide holes must be drilled along the outer periphery of the structure.
When an underground structure is constructed at a great depth using the continuous underground wall construction method, construction takes time and the construction period becomes longer.

In addition, in the latter method, when concrete is poured to form the panel wall, the concrete enters and intervenes between the wall of the excavation hole and the friction force reducing agent, so that the effect of reducing friction force is not sufficient. It is not demonstrated.

This invention was made in view of these conventional problems, and its purpose is to provide an underground structure that is easy to construct and that reliably exhibits the effect of reducing frictional force. The object of the present invention is to provide a method for reducing friction.

(Means for Solving the Problems) In order to achieve the above objects, the present invention involves excavating a trench in the ground, inserting a reinforcing bar cage into the trench, and then pouring concrete to create a panel wall. In an underground structure constructed using a continuous underground wall construction method in which a panel wall is formed and other panel walls are sequentially connected and formed on the side of the panel wall, a wall of the structure is located on the outside of the structure. A tubular member having a large number of pores oriented in a plane direction is installed, and after the structure is constructed, a lubricant is supplied to the tubular member, and the lubricant is injected from the pores. shall be.

(Operations and Effects of the Invention) According to the method for reducing frictional force configured as described above, when forming a panel wall using the continuous underground wall construction method, a tubular member is installed at a location located on the outside surface of the structure, and the structure is By injecting the lubricant from the tubular member after constructing the object, a thin film of lubricant is formed around the outer periphery of the structure, thereby reducing the negative frictional force of the structure.

The formation of this lubricant film of ε is much simpler than the conventional method of drilling guide holes, since it is only necessary to install a tubular member at a predetermined location.

Furthermore, since the lubricant film that reduces frictional force is formed after the construction of the structure, it can be reliably formed without being affected by the construction of the structure.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure N41 and Figure 2 show an embodiment of the method for reducing friction in underground structures according to the present invention.

In the friction reduction method shown in the figure, first, an underground structure is constructed in soft ground using the continuous underground wall construction method.

In constructing a structure, as shown in FIG. 1(A), a rectangular excavation hole 10 is formed in the ground while being filled with muddy water, and a reinforcing bar cage 12 is built inside the excavation hole 10.

As shown in detail in FIG. 2, the reinforcing bar cage 12 used at this time has vertical bars 14 and horizontal bars 16 that are combined vertically and horizontally, and a box joint 18 is integrally attached to the end. There is.

The box joint 18 includes a pair of inner and outer plates 20 and 22 disposed inside and outside the structure, and a partition plate 2 through which the horizontal stripes 16 are penetrated.
4 and a pull-out plate 26, and has a square shape with an open upper end.

A tubular member 28 extending over the entire length of the outer plate 22 located on the outer side of the structure is installed.

In this embodiment, the tubular member 20 is fixed at a position offset from the center of the outer plate 22 toward the partition plate 24, and has a large number of pores 30 bored along its longitudinal axis.

The pores 30 are provided on both sides of the tubular member 28,
Each direction is oriented toward the plane of the structure.

Furthermore, it is desirable that the size of each pore 30 is large enough to prevent concrete from entering.

When the reinforcing bar cage 12 with the above configuration is set in a predetermined position,
Concrete is placed on the inner side of the partition plate 24 to form the preceding panel wall 32.

Next, as shown in FIG. 1(B), an excavation hole 10a is drilled on the side of the box joint 18, and a reinforcing bar cage 12a is installed inside this excavation hole 10a with a box joint 18a installed in the same manner as above. is constructed, concrete is poured, and the trailing panel wall 32a is constructed.
is formed.

Once the trailing panel wall 32a is formed, the pull-out plate 26.26a of the box joint 18.18a is
are respectively removed, and connecting reinforcing bars 34 are superimposed and installed between the horizontal bars 16 and 16a.

Thereafter, as shown in FIG. 1(D), the box joint 18.1
The connection of the leading and trailing panel walls 32, 32a is performed by pouring concrete in 8a.

Thereafter, by repeating the above operations, underground structures such as earth retaining walls and tank side walls are constructed.

Once construction of the structure is complete, each tubular member 28 is provided with a lubricant.

The lubricant used here is, for example, a liquid lubricant made by suspending bentonite in water or bubbles made by foaming a surfactant. Sprayed in the direction of the surface.

The injected lubricant extends along the gap between the wall of the structure and the soft ground, and as a result, a thin film of lubricant is formed around the outer periphery of the structure, reducing the negative frictional force of the structure. reduced.

Formation of the lubricant film at this time is much easier than the conventional method of drilling guide holes, as it is only necessary to install the tubular member 28 on the side plate 22 of the box joint 18. Become.

In addition, since the lubricant film that reduces frictional force is formed after the structure is constructed, it can be reliably formed without being affected by poured concrete or the like when constructing the structure.

FIG. 3 shows another embodiment of the present invention, in which the present invention is applied to a case where a continuous underground wall is constructed without using the box joint 18.

In this embodiment, the excavated hole 10 is formed into a rectangular shape by, for example, a hydrophrase excavator, and a reinforcing bar cage 12' is built inside the excavated hole 10.

The reinforcing bar basket 12' has vertical bars 14 and horizontal bars 1 as in the above embodiment.
6, and a reinforcing frame 36 is installed between these reinforcing bars 14 and 16 arranged at predetermined intervals.

Then, on the end side of the reinforcing frame 36, there are
A tubular member 28 having the same pores 30 as in the above embodiment is attached via a channel material 38.

In this embodiment as well, lubricant is supplied to the tubular member 28 after the structure is constructed, and the lubricant is injected from the pores 30 to form a lubricant film on the outer surface of the structure. Similar effects can be obtained.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of the friction reduction method for underground structures according to the present invention in the order of steps, FIG. 2 is a perspective view of the main parts of a reinforcing bar cage used in the method, and FIG. FIG. 7 is a plan view of a main part of a reinforcing bar basket used in another embodiment. 10.10a... Excavation hole 12.12a... Rebar cage 28... Tubular member 30...
・・・・・・・・・・・・Pore 34.34a・・・Panel wall

Claims (1)

[Claims] A continuous site in which a trench is excavated in the ground, a reinforcing cage is inserted into the trench, concrete is poured, a panel wall is formed, and other panel walls are successively connected to the sides of this panel wall. In an underground structure constructed by the inner wall construction method, a tubular member having a large number of pores oriented in the surface direction of the structure is installed at a location on the outer surface of the structure, A method for reducing friction in an underground structure, comprising supplying a lubricant to the tubular member after constructing the structure, and injecting the lubricant from the pores.