JPS59213899A - Method of lining concrete placing construction in method of shielding construction - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The shield propulsion method is generally employed in underground tunnel construction methods for sewerage work and electrical facility management construction work. In this construction method, the tunnel is cut once using a Shield 9 excavator, steel segments or concrete segments are assembled, and this is used as a reaction force to dig, and after the tunnel has been penetrated, the segment body is lined with concrete to complete the tunnel. .

In the construction of the above-mentioned Hime Econch IJ-1-, when concrete is poured using steel segments as the outer peripheral formwork,
The steel segments act as a restraint against the stress deformation of the poured concrete, which causes cracks to occur in the hardened concrete. Measures have been taken to prevent this cracking, such as using low-heating cement, lowering the temperature of the concrete during pouring, and preventing ventilation and drying of the chamber that maintains the atmosphere inside the tunnel, but these measures have not been sufficiently effective. The reality is that we are not getting it.

The present invention was proposed in order to solve these problems, and consists of a wire mesh stretched between the wire meshes protruding from the segment main body, and a copper wire mesh with a gap formed between the wire mesh and the main body. This relates to a lining concrete casting method in the Shield 9 construction method, which is characterized in that the segment is used as an outer formwork and lining concrete is cast on the inner circumferential side thereof.

The causes of cracks and fissures in concrete can be roughly divided into those caused by temperature stress due to heat generated during concrete hardening, and those caused by drying shrinkage, but in underground tunnel 2, it is thought that the former is the main cause.

Therefore, the temperature stress of concrete is generally expressed by the following equation.

σt−ΔT・α・E, −R・・・・・・・・・・・・・
...(1) i1 σt : Temperature stress (kglc
τ2) 7T: Temperature drop CC) α: Linear expansion coefficient of concrete? r) Ec: Effective elastic modulus of concrete (kg/cm') R2 If the degree of constraint σ7 exceeds the tensile strength of concrete after hardening, cracks will occur.

Now ΔT=20U, α-1.0X10 E, E, = 1
．． 4×105kg/Crn2. Assuming R-1, (1)
From the formula, σt=20x1.0x10xl, 4x10xl-
20kg/cm" roar.

Cracks due to temperature occur during the hardening period of concrete, and generally occur within 3 to 7 days. The tensile strength of concrete is approximately 1 I of its compressive strength. Therefore, after about 6 to 7 days of curing, only a tensile strength of 7 to 10 kg/c7n2 can be expected, and from the above calculation, cracks will naturally occur.

Therefore, in equation (1), stress due to temperature can be reduced by artificial manipulation. It lowers ΔT￥. R
The point is to make it smaller.

Therefore, reducing ΔT is only moderately effective, and hardly any effect can be expected in the summer. Therefore, in order to prevent cracks in the concrete lining, the intended purpose cannot be achieved unless the degree of restraint R is reduced.

Accordingly, in the present invention, as described above, a wire mesh is stretched between the lips protruding from the segment main body, and the steel segment with a gap formed between the wire mesh and the main body is used as an outer formwork. Since the lining concrete is placed on the inner circumference side, a gap is formed between the steel segment and the lining concrete, and the edge between the two is cut by the gap, and the degree of restraint R is increased. This reduces the number of cracks in the concrete lining and prevents the occurrence of cracks, and furthermore, the wire mesh suppresses the occurrence of cracks in the concrete lining.

The present invention will be described below with reference to the illustrated embodiments.

(1,) is a steel segment, a lip (1h) is provided protruding from the arcuate main body (1a), and an injection D (IC) for injection material is missing in the same (1h).

Then, the lip (of the steel segment (1) n1 erected on the circumferential surface of the tunnel excavated by the seal l-''1 bending machine)
A wire mesh (2) is stretched for 1 hour) before concrete pouring.

Next, the segment (1) is used as an outer formwork to form a wire mesh (2).
Pour concrete lining (3) on the outside of the concrete lining. At this time, the injection pipe (
4) is buried. Note that (5) in the figure is the segment connecting bolt.

When the lining concrete (3) is placed as described above, the steel segment (1) and the lining concrete 1 are separated by the wire mesh (2).
．． A gap (6) will be formed between the first and second parts (3).

When the internal temperature of the poured concrete becomes close to the surrounding temperature of the concrete, the steel segment (11
The injection material (force) is injected into the gap (6) between the concrete lining (3) and the concrete lining (3) through the injection pipe (4).

At this time, the injection material (7) is applied to the lip (1) of the segment (1).
b) Each segment via the injection port (IC) provided in
(1) and lining conch! The gap (6) between J −
2) is integrated with the lining concrete (3), and the same injection material (7) provides a water-stopping effect.

Although the present invention has been described above with reference to embodiments, the present invention is, of course, not limited to such embodiments, and can be modified in various ways without departing from the spirit of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a vertical side view of a tunnel constructed by the method of the present invention, FIG. 2 is a vertical front view thereof, and FIG. 6 is a partial slope view of a steel segment. (1)...Steel segment, (1α)...Segment body. (1h)...Reply, (2)...Wire mesh, (3)...
Lining concrete. Agent: Patent attorney: Shige Okamoto, 3 other people

Claims (1)

[Claims] A wire mesh is stretched between the wires that protrude from the segment body,
A gap t("l") is formed between the wire mesh and the main body.
A heating concrete pouring method in the shield method, which is characterized by using the Id segment as an outer formwork and pouring agricultural concrete on the inner periphery thereof.