JP2005163526A - Filler for rear face cavity of mountain tunnel and filling method for rear face cavity for mountain tunnel using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that although a filler has been conventionally injected by an air mortal construction method, a foaming urethane construction method, a plastic grout construction method, etc. because the rear face cavity of a tunnel may cause a reason of loose natural ground but lightweight, injection property, handlability, and low costs are requested. <P>SOLUTION: A specified volume of mountain tonnel rear face cavity filling material containing at least water, hydraulic cement, and lightweight aggregate is injected into the rear face cavity 10 by a rear face cavity filler injection device 12. The injection is carried out as well known by an injection nozzle 13. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a mountain tunnel back cavity filling material and a mountain tunnel back cavity filling method using the same, and more specifically, it is lightweight, excellent in injectability and handling properties, and can reduce construction costs. The present invention relates to a mountain tunnel back cavity filling material and a mountain tunnel back cavity filling method using the same.

  The rear cavities of railway, road, and waterway tunnels constructed by the mountain tunnel method are structurally disadvantageous because the ground reaction force cannot be expected from the back of the lining when the tunnel is subjected to plastic pressure or partial pressure. In addition, it can be a factor causing loosening of natural ground.

The backfill injection method applied to the back cavity of the mountain tunnel is shown below.
(1) Air mortar method: A mortar mixed with air is used as a backfill injection material, and injected into the back cavity. The air mortar method is generally inexpensive, but has high fluidity, so cracks in the ground, cracking of the lining, deviation from the joints, etc. occur, and the flow does not stop at the place to be filled (crown, etc.) Problems such as material separation caused by spring water have been pointed out. Moreover, there is a drawback that limited injection is difficult.

  (2) Urethane foam method: Urethane or silica resin is injected into the back cavity as an injection material. The urethane foam method has the characteristics that the resin curing time is short and the construction equipment is small, but the injection material is expensive, so backfill injection under spring water or small-scale backfill injection Stays on. In addition, since the curing time of the resin is short, there is a drawback that the number of injection holes must be increased.

  (3) Plastic grout method: A cement-based material having plasticity (the injection material itself has no fluidity but easily flows under pressure) is injected into the back cavity. The plastic grout method can be used for limited injection because there are few cracks in the ground and deviation from the gap outside the predetermined surface of the lining surface. Materials used for the plastic grout method can be classified into a one-component non-air system and a two-component air system.

-One-component (non-air) materials Materials containing cement, bentonite and water-absorbing polymers, and materials containing mortar and special thickeners are known. The one-component material can reduce the construction equipment, but the specific gravity is about 1.3 to 1.5, which is slightly larger than the one using the following two-component (air-based) material. .
-Two-component (air-based) material The material is pumped in two systems, mixed at the tip of the pumping tube to make an injection material, and injected into the back cavity. According to this construction method, the quality of the injection material is generally good even if long-distance pumping is performed, but at least two mixers and a pump are required, and the construction equipment becomes larger than the construction method using the one-component material, Cost increases.

In addition, about a mountain Tonell construction method, it describes in the following nonpatent literature 1, for example.
How to make a subway-mountain tunnel method, [online], [October 23, 2003 search], Internet <URL: http://www.city.kyoto.jp/kotsu/kensetu/tunnel>

  Accordingly, an object of the present invention is to provide a mountain tunnel back cavity filling material that is lightweight, excellent in injectability and handling properties, and capable of reducing construction costs, and a mountain tunnel back cavity filling method using the same. It is.

The present invention provides a mountain tunnel back cavity filler characterized by containing water, hydraulic cement, and lightweight aggregate.
The present invention also provides the above-mentioned mountain tunnel back cavity filler, which further contains a polycarboxylic acid-based water reducing agent.
The present invention also provides the mountain tunnel back cavity filling material, wherein the lightweight aggregate is pearlite and / or foam beads.
Moreover, this invention provides the mountain tunnel back surface cavity filling method which has the process of inject | pouring the said mountain tunnel back surface cavity filler into the back surface cavity of the tunnel formed in the mountain.

  ADVANTAGE OF THE INVENTION According to this invention, the mountain tunnel back surface cavity filling method using this and a mountain tunnel back surface cavity filling method which is lightweight, is excellent in injectability | operativity and handleability, and can also reduce construction cost are provided.

(Hydraulic cement)
The hydraulic cement used in the present invention is not particularly limited as long as it is an inorganic substance exhibiting hydraulic properties. For example, mixed cement such as fly ash cement, early strong Portland cement, very early strong Portland cement, ultra finely ground cement (Colloid cement), alumina cement and the like. Further, the specific surface area of the brane specified in JIS R 5201 is preferably 2500 to 5000 cm ² / g.

(Lightweight aggregate)
The lightweight aggregate used in the present invention is not particularly limited and can be appropriately selected, but perlite, expanded beads (expanded polystyrene) or a mixture thereof is preferable.
The specific gravity of the lightweight aggregate is preferably less than 1.0, and more preferably 0.01 to 0.5.

  In the present invention, the water / binder ratio is preferably 70 to 150% (mass basis). In addition, the binder as used in the field of this invention means the material containing hydraulic cement, a lightweight aggregate, the following thickener, and a hardening accelerator.

The mountain tunnel back cavity filler of the present invention preferably further contains a polycarboxylic acid-based water reducing agent. Specific examples of this polycarboxylic acid-based water reducing agent include composites (calcium-based) whose main component is a polycarboxylic acid ether. Commercially available products can also be suitably used, and examples thereof include trade name Core Flow NF-100 manufactured by Taiheiyo Cement Co., Ltd., trade name SP-8HE manufactured by NMB, Kao Corporation Mighty 2000TH, and the like. The blending ratio of the polycarboxylic acid water reducing agent is preferably, for example, 0.3 to 2.4 kg / m ³ .

Various additives such as a thickener and a curing accelerator can be blended with the mountain tunnel back cavity filler of the present invention, if necessary.
As the thickener, a known cellulose-based thickener can be used, and the blending ratio thereof is preferably, for example, 1.0 to 9.0 kg / m ³ .
As a hardening accelerator, an alkali metal salt, calcium aluminate, etc. are mentioned, for example, As for the mixture ratio, 1.0-50 kg / m < ³ > is preferable, for example.

Next, the mountain tunnel back cavity filling method of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram for explaining the mountain tunnel backside cavity filling method of the present invention. When the back cavity 10 is present in the tunnel 1 constructed by the mountain tunnel method, the mountain tunnel back cavity filler of the present invention containing at least water, hydraulic cement, and lightweight aggregate is used as a one-component material. It can be injected into the cavity 10. The mountain tunnel back cavity filling material of the present invention is lighter than the conventional one, so that the load acting on the tunnel lining can be reduced and the burden on the tunnel can be reduced. Moreover, since it is 1 liquid property, it is excellent in handleability and can also reduce construction cost. According to the construction method of the present invention, as shown in FIG. 1, materials other than water are transported to the vicinity of the back cavity 10, and water and necessary power are supplied from the external supply device 11. At the time of construction, a predetermined amount of filler is injected into the back cavity 10 by the back cavity filler injection device 12 installed in the tunnel 1. The injection may be performed by the injection nozzle 13 as is well known. The injection amount of the filler may be an amount that satisfies the volume of the back cavity.

  FIG. 2 is a plan view of the injection device 12. The injection device 12 includes a mixer 21 that mixes materials such as water, hydraulic cement, and lightweight aggregate, a receiving port 22 that receives the material mixed by the mixer 21, and a predetermined amount of the mixed material to the injection nozzle 13. The metering pump 23 is capable of being sent out. The material mixed by the mixer 21 is introduced into the metering pump 23 from the material input port 25 through the pipe 24. With this injection device 12, a desired amount of filler that fills the volume of the back cavity can be injected into the back cavity 10.

Hereinafter, the present invention will be further described by way of examples.
Ordinary Portland cement (manufactured by Taiheiyo Cement) as the cement, foam beads (specific gravity 0.016) and fine pearlite (specific gravity 0.4) as the lightweight aggregate, and polycarboxylic acid-based water reducing agent (product) Name core flow NF-100 (manufactured by Taiheiyo Cement Co., Ltd.), thickener (trade name Metroze 90SH-10000, manufactured by Shin-Etsu Chemical Co., Ltd.) and curing accelerator (calcium aluminate), The mountain tunnel back cavity filling material of the present invention was prepared.
The obtained filler was subjected to a flow test (JHS A313-1992, diameter φ80 mm × height H80 mm cylinder). The results are shown in Table 2.

From the results in Table 2, it can be seen that the mountain tunnel back cavity filler of the present invention has almost no flow-down in 3 hours after mixing, and therefore can maintain high injectability when pumped by a pump. Moreover, the mountain tunnel back cavity filling material of the present invention is lightweight, and since it is one-component, it is excellent in handleability and can reduce the construction cost.
From the results in Table 2, it can be seen that the backfill of the mountain tunnel according to the present invention has a small effect of the temperature during mixing on the flow value. Furthermore, they are within the range of general plastic material flow management shown in Table 3 below. Therefore, the mountain tunnel back cavity filling material of the present invention can be used in summer and winter.

Using the same lightweight aggregate and admixture as in Example 1, using the same lightweight aggregate and admixture as in Example 1, using ordinary Portland cement (manufactured by Taiheiyo Cement) and fly ash in a mass ratio of 4: 3. According to the ratio, the mountain tunnel back cavity filling material of the present invention was adjusted.
The obtained filler was subjected to a flow test (JHS A313-1992, diameter φ80 mm × height H80 mm cylinder). The results are shown in Table 5.

注）軽量骨材の内訳は、発泡ビーズ１．３ｋｇ／ｍ^３、パーライト１６１．３ｋｇ／ｍ^３である。
混和剤の内訳は、ポリカルボン酸系減水剤０．５ｋｇ／ｍ^３、増粘剤２．３ｋｇ／ｍ^３、硬化促進剤４６．２ｋｇ／ｍ^３である。

Note) The breakdown of lightweight aggregate is foam beads 1.3kg / m ³ and pearlite 161.3kg / m ³ .
Breakdown of admixtures, polycarboxylic acid-based water reducing agent 0.5 kg / ^{m 3,} thickener 2.3 kg / ^{m 3,} a curing accelerator 46.2kg / ^{m 3.}

From the results in Table 5, it can be seen that the mountain tunnel back cavity filling material of the present invention has a small flow down in 2 hours after kneading, and therefore can maintain high injectability when pumped by a pump. Moreover, the mountain tunnel back cavity filling material of the present invention is lightweight, and since it is one-component, it is excellent in handleability and can reduce the construction cost.
In addition, from the results in Table 5, the mountain tunnel back cavity filling material of the present invention is the flow standard for the back cavity filling material described in Japan Road Public Corporation “Back sheet cavity injection method design and construction guidelines”. It satisfies the standard values of the following Table 6 regarding the properties.

It is a figure for demonstrating the mountain tunnel back surface cavity filling method of this invention. It is a top view of an injection device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Tunnel, 10 ... Back cavity, 11 ... External supply device, 12 ... Back cavity filling material injection device, 13 ... Injection nozzle, 21 ... Mixer, 22 ... Receiving port, 23 ... Metering pump .

Claims (4)

  A mountain tunnel rear cavity filler characterized by containing water, hydraulic cement, and lightweight aggregate.   The mountain tunnel back cavity filler according to claim 1, further comprising a polycarboxylic acid-based water reducing agent.   The mountain tunnel back cavity filling material according to claim 1 or 2, wherein the lightweight aggregate is pearlite and / or foam beads. The mountain tunnel back surface cavity filling method which has the process of inject | pouring the mountain tunnel back surface cavity filler of any one of Claim 1 thru | or 3 in the back surface cavity of the tunnel formed in the mountain.

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