JPH021960B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a method for constructing a tunnel, and more particularly, to a method for introducing stress into lining concrete.

[Conventional technology]

Conventionally, when attempting to introduce stress into the concrete lining of a tunnel, a construction method commonly known as the "post-tension method" has often been adopted.
In this construction method, tension members are placed in advance in the circumferential direction of the tunnel during formwork assembly, and stress is introduced by waiting for the concrete to harden and tying up the tunnel with the tension members.

[Problems to be solved by the present invention]

In the "post-tension method," it is necessary to install the jacks to tighten the tendons at a predetermined position within the formwork, and a recess (width x 7s x 7s ≒ 300mm x 700mm x
200mm), the work of filling the recesses with concrete after removing the formwork, and the need to bury expensive fasteners were pointed out.

[Means for solving problems]

The present invention is a construction method created to improve such problems. The present invention is a "pretension construction method" in which annular tension members are placed between the formwork and the ground, and then a plurality of jacks are placed inside the formwork in a radial direction from the center of the tunnel. This method involves expanding the ring diameter, waiting for the concrete to harden, loosening the jacks, and introducing stress.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view of the concrete lining according to the present invention, and FIG. 2 is a detailed view of the A--A cross section in FIG. 1.

In FIG. 1, a formwork 2 installed within a tunnel cross section is held by shoring 5.

Further, tensioning screw jacks 3 are screwed onto the circumferential surface of the formwork 2 at approximately 30 degree intervals in a radial direction from the center of the tunnel.

A receiver 6 is attached to the tip of the tensioning screw jack 3 and holds the tensioning material 1.

Before pouring concrete, screw in the tensioning screw jack 3, spread the tension material 1, cast concrete 4, wait for it to harden, and screw in the tensioning screw jack 3.
loosens and introduces stress into the concrete.

〔Effect of the invention〕

The effects brought about by the present invention are as follows.

a It is possible to introduce uniform stress.

b. Stress introduction work is easy. c There are few dead parts.

d) Filling after demolding the formwork is easy and the finished surface is smooth.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the tunnel structure according to the present invention, and FIG. 2 is a detailed view of the A--A cross section in FIG. 1: tension material, 2: formwork, 3: tension jack,
4: Concrete, 5: Shoring, 6: Receiver.

Claims (1)

[Claims] 1. In a method of lining a tunnel using the "prestressed construction method," a ring-shaped tendon is fitted between the formwork and the ground as viewed from the tunnel cross direction, and the tension material is placed in advance around the formwork. After tensioning the tension material in the radial direction of the tunnel using a plurality of jacks attached to the surface in a radial direction from the center of the tunnel, concrete is poured, and the jacks are loosened after waiting for the concrete to harden. A construction method that creates stress in the concrete lining. 2. A construction method for producing stress in lining concrete according to claim 1, characterized in that a semicircular receiver is provided in the pressure-bearing portion of the jack to hold the tension material.