JPH07206503A - Back-filling material and shield process using the same - Google Patents

Abstract

PURPOSE:To obtain a back-filling material having high water-stopping performance by mixing a slurry liquid consisting of a mixture of cement, slag and a strength developing material such as lime with another liquid having a function to absorb the water in the above slurry liquid and increase the viscosity of the mixture to develop a plastic strength. CONSTITUTION:A slurry liquid A is prepared by mixing a cement incorporated with an alkali metal or an alkaline earth metal, slag, a strength-developing material such as lime and bentonite to water. Separately, a liquid B is prepared by treating an acrylic acid-vinyl alcohol copolymer with a strong acid and mixing the obtained highly water-absorbing resin particles to a bentonite slurry. The liquid A is mixed with the liquid B at a prescribed volume ratio to obtain a back-filling material which increases the viscosity of the liquid A to a plastic strength by the absorption of water. The liquid A is transferred from the pipe 14 of a shield machine 10 with a pump, the liquid B is mixed to the liquid A by a liquid B mixing apparatus 15 and the back- filling material 16 consisting of the uniformly mixed liquid A and liquid B is supplied from the rear end in the shield machine 10 and filled in a tail void formed by the excavation to prevent the ground subsidence. The filled material is hardened after a prescribed period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backfill material used in a shield construction method and a shield construction method in which the backfill material is filled between a lining formed by assembling segments and a ground.

[0002]

2. Description of the Related Art Generally, in a shield construction method, as shown in FIG. 5, a shield machine 1 is excavated by a certain length, and a ring 3 having segments 2, 2 ... The lining 4 is formed, and a reaction force is applied to the lining 4 to propel the shield machine 1.

A backfilling material 5 having fluidity is injected into a gap (tail void) between the outer peripheral surface of the lining 4 and the ground to fill the gap. As the backfill material 5, conventionally, a two-liquid type in which the liquid A and the liquid B are mixed near the injection port is widely used.

At present, the two-liquid material which is the mainstream of the backfill material is the high-concentration slurry liquid A mixed with strength-enhancing materials such as cement, slag and lime, and liquid B mainly composed of sodium silicate. Is a mixture of. This material is in a plastic state within a few seconds after mixing the liquids A and B (the material itself loses fluidity, but it easily flows when pressed. Generally, the compressive strength is 0.1 kgf / cm ² or less. ), And is injected between the lining and the ground while maintaining the plastic state. After the injection, it becomes a solidified state in about 30 minutes to 1 hour.

[0005]

Generally, the effect of the backfill material is to prevent ground subsidence by filling the tail voids and prevent groundwater from penetrating into the shield. It is clear that the infiltration of groundwater occurs from the joint part of the segment, and the water blocking of this part is performed by the backfill material, the packing attached to the segment joint part, and the secondary lining concrete. However, with recent shields,
It is not uncommon to omit the secondary lining, and in that case, the waterproofness of the backfill material is even more important. When it is expected that the backfill material is waterproof, it is a major premise that no cracks occur in the segment joints.

It is said that the deformation of the segment joint portion due to the excavation reaction force of the shield machine is transmitted to the rear by about 20 rings (about 20 m), and the construction time is about one day. Therefore, a large deformation occurs in the segment joint portion for about one day. However, the above-mentioned two-component backfill material, which is currently the mainstream, uses the B liquid mainly composed of sodium silicate, so that the reactivity with the cement is fast and the time until the solidification is reached. The maximum is 1 hour. Therefore,
There is a risk of cracks occurring in the segment joints due to the deformation of the shield due to the recoil force.When cracks occur at this location, it is impossible to expect the backfill material to be effective as a waterproof material. There is a problem of becoming.

In view of such a conventional problem, the present invention is a two-component type backing material that requires a plasticity holding time (for example, about one day) and is long, and finally exhibits a strength equivalent to that of a natural rock. The purpose of the present invention is to provide a filling material, and a shield construction method using the same, in which cracks are less likely to occur in backfilling and which is more excellent in waterproofness.

[0008]

The features of the backfill material according to the present invention for solving the above-mentioned conventional problems and achieving the intended purpose are that a strength-developing material such as cement, slag, or lime is used. The mixed slurry A liquid is mixed with the liquid B having a function of thickening the liquid A to a plastic strength by absorbing water in the liquid A. Secondly, By containing an alkali metal component or an alkaline earth metal component in the solution A and reacting with the alkali metal or alkaline earth metal in the solution A, which does not absorb and swell with normal water in the solution B, Thirdly, by including the water-absorbent particles having the property of initiating water-absorption swelling, the liquid B is formed by mixing the water-absorbent particles with bentonite mud to prevent sedimentation of the water-absorbent particles. According to claim 2, Located in the back-filling material.

The characteristics of the shield construction method according to the present invention are:
The backfill material is injected between the lining and the ground to fill the tail void.

As the water-absorbent particles, for example, those obtained by treating a vinyl acrylate vinyl alcohol copolymer (superabsorbent resin) with a strong acid such as hydrochloric acid, sulfuric acid or nitric acid can be used.

[0011]

In the backfill material of the present invention, by mixing the liquid A with the liquid B, the liquid B absorbs the water in the liquid A and is thickened to a plastic strength, and finally the liquid A itself is added. It is hardened by a hydration-hardening strength developing material such as cement contained. Liquid A can be stored as a highly fluid slurry to enable long-distance transportation by piping, and the curing speed of the strength-developing material can be adjusted to 1 to several days by adjusting additives such as a retarder. It can be adjusted to the required length. And this A
By mixing the liquid B with the liquid, the water of the liquid A is absorbed,
The viscosity is increased to the plastic strength, and the amount of water for curing is adjusted by this, and it is cured in the previously assumed curing time of the liquid A.

In addition, the solution A contains an alkali metal or an alkaline earth metal (for example, Ca ions in cement), and the solution B uses water-absorbing particles which absorb and swell by reacting with these metals. The liquid can be made into a fluid one using water, and by mixing bentonite with this, precipitation of water-absorbing particles is prevented and transportability by piping is improved, and water-absorbing property for liquid A is absorbed. It becomes easy to make the mixing distribution of the particles more uniform.

Further, by using such a backfill material in a shield construction method in which a lining in which segments are assembled is sequentially formed and a reaction force is applied to the lining, a joint is formed by a reaction force when the shield machine is propelled. The backing material can be maintained in a plastic strength state for 1 to several days until the excavation time for a length of about 20 rings in which the deformation of the joint portion occurs and even if the joint portion deforms. The filled backing material does not crack.

[0014]

EXAMPLES First, the backing material according to the present invention will be described based on examples.

[0015]Example  Liquid B (thickener) in liquid A (fly ash mortar)
Mix at a mixing ratio of 100: 1.

[Compounding] Liquid A (in 1 m ³ ) Cement 250 kg Bentonite 50 kg Fly ash 880 kg Water 500 kg Retarder 3 kg B liquid (in 0.01 m ³ ) Water-absorbing particles 5 kg Bentonite 1 kg Water 6 kg However, it is high as water-absorbing particles. Particles of vinyl acrylate alcohol copolymer, which is a water-absorbent resin, are treated with hydrochloric acid.

Comparative Example As a comparative example, a backfill material having the following composition which was conventionally used was used.

[Compound] Liquid A (1 m³Medium) Slag hardener 250 kg Bentonite 90 kg Water 872 kg Stabilizer 1 kg B liquid Special silica 0.1 m³ Comparison of strength characteristics  1 and 2 show the comparison of strength. Plasticity retention time (compression
Strength is 0.1 kgf / cm²Time to reach
By comparison, the embodiment of the present invention described above as shown in FIG.
1 is about 1 day, which is very long.
Is very short, about 30 minutes. Also, on the 28th
As shown in Fig. 2, the strength of both materials is higher than that of natural ground.
(Compressive strength 20 kgf / cm²Degree)
I understand.

Next, the shield construction method according to the present invention will be described based on examples.

3 and 4 show the main parts of the method of the present invention. In the figures, 10 is a shield machine, and 11 is a segment ring 13, 13 ... It is a lining that has been extended in sequence. The liquid A having a high fluidity is transported by a pump from the pipe 14 in this tunnel, and the liquid B is mixed and mixed with the liquid B by the liquid mixing device 15, and the tail void is generated from the rear end of the shield machine 10 by the excavation. Is filled as a backfill material 16 of AB liquid mixture. The B liquid mixing device 15 is connected to the A liquid flow path to connect the Y-shaped tube 17 and forcibly add the B liquid from the injection pipe 18 by a feeder. A uniform mixing tube 19 is connected to the rear of the Y-shaped tube 17 so that the liquids A and B are uniformly mixed.

In the backfill material thus filled every time when excavation is performed, the water content in the AB mixed solution is sucked into the water-absorbing particles to make it highly viscous after injection, and fills the tail voids to prevent ground subsidence and prevent water stoppage. After exhibiting a preset curing time, it is completely cured and high strength is exhibited.

[0022]

As described above, the backfill material of the present invention is AB
By mixing the liquids, it becomes highly viscous, and since the liquid A itself is hardened by the strength-improving material that has been adjusted in advance, the load-bearing capacity and water-stopping capacity as the back-filling material are exhibited after the back-filling material is injected, and The plastic state can be maintained for a long time, and when used as a backfill material for a portion that is easily deformed after filling, it can be cured without causing cracks.

Further, in the shield construction method of the present invention, the backfill material having a length of up to about 20 rings, which is influenced by the reaction force when the shield machine is propelled, can maintain a high viscosity in a plastic state and cracks occur. It is suitable for backfilling a waterproof segment lining which is not subjected to a secondary lining.

[Brief description of drawings]

FIG. 1 is a backfill material of an example of the present invention and a comparative example (conventional product).
It is a graph which shows an initial state among the compressive strength test results.

FIG. 2 is a graph showing a condition up to 28 days of the above material age.

FIG. 3 is a cross-sectional view of a main part of an example of a shield construction method according to the present invention.

FIG. 4 is a sectional view of a portion of the above-mentioned B liquid mixing device.

FIG. 5 is a cross-sectional view showing a conventional shield construction method.

[Explanation of symbols]

 10 shield machine 11 lining 12 segment 13 cement ring 14 piping 15 B liquid mixing device 16 backfill material 17 Y-shaped pipe 18 injection pipe 19 uniform mixing pipe

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Claims (5)

[Claims] 1. A liquid A in the form of a slurry in which a strength-developing material such as cement, slag, or lime is mixed, and a liquid B having a function of thickening the liquid A to a plastic strength by absorbing water in the liquid A. Backfill material obtained by mixing liquids. 2. The solution A contains an alkali metal component or an alkaline earth metal component, and the solution B does not absorb and swell with normal water, but is mixed with the alkali metal or the alkaline earth metal in the solution A. The backfill material according to claim 1, wherein the backfill material comprises water-absorbing particles having a property of starting to swell by absorbing water by reacting. 3. The backfill material according to claim 2, wherein the liquid B is formed by mixing water absorbing particles with bentonite muddy water. 4. A shield construction method in which a lining is formed by assembling segments rearward, and the lining is provided with a reaction force to propel a shield machine, and cement and slag are provided in a gap between the lining and the ground. It is obtained by mixing a slurry-like liquid A mixed with a strength-developing material such as lime and liquid B having a function of thickening the liquid A to a plastic strength by absorbing water in the liquid A. A shield construction method characterized by injecting and filling backfill material. 5. The solution A contains an alkali metal component or an alkaline earth metal component, and the solution B does not absorb and swell with normal water, but is mixed with the alkali metal or the alkaline earth metal in the solution A. The shield construction method according to claim 4, which comprises water-absorbing particles having a characteristic of starting water absorption and swelling by reacting.