JPS63184699A - Method of cut-off reinforcing construction of tunnel concrete - 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 (Technical Field) The present invention relates to a method for reinforcing water-stopping of tunnel concrete. More specifically, the invention provides
This invention relates to an improved tunnel construction method that can effectively repair crack damage, deterioration, etc. on the concrete surface and stop water in the M construction method.

(Background technology) The NA'rM tunnel construction method uses shotcrete concrete and rock bolts as supporting materials, utilizes the single load supporting capacity of other mountains, and pours secondary lining concrete on top of the supporting materials. It is known that it is a tunnel construction method that is based on rationality and safety.

However, A, which is an excellent tunnel construction method,
Even with the TM construction method, there were problems such as cracks occurring on the concrete surface of the secondary lining or deterioration at the joints of the supporting materials, which remained an issue that needed to be rectified as soon as possible. .

The causes of this crack damage and deterioration are thought to be drying shrinkage, stress changes in the ground, increased loads due to spring water, and deterioration of concrete properties. Of these, particular emphasis is placed on the increased load caused by spring water and the deterioration of the 21 concrete surface.

Conventionally, in order to deal with this problem, and in particular the prevention of spring water, which is considered to be the cause of the problem, the following methods were used: Met. The waterproof sheet used in this case is made of synthetic rubber, synthetic resin, rubber asphalt, or the like.

However, it seems to be relatively stable and effective when looking only immediately after the construction of the secondary lining, but waterproof sheets 1~
It is a so-called vinyl sheet, and as it is forced to constantly come into contact with cement and seepage water with a pH of about 12, chemical deterioration of this vinyl sheet over time is unavoidable. Damage such as breakage and compression of the tarpaulin sheet due to changes in excavated pressure stress is unavoidable, and for this reason, long-term waterproofing cannot be expected depending on the tarpaulin sheet.

What's even more problematic is that it is completely impossible to repair or renew the tarpaulin.

As alternatives to such waterproof sheets, methods such as alfalt waterproofing, mortar waterproofing, and permeable coating waterproofing, which are commonly used as water-stopping methods, are being considered, but none of these methods are suitable for large-scale tunnels. Currently, it cannot be used in construction methods.

Therefore, it is desired to develop a new construction method that takes advantage of the excellent features of the NATM construction method, effectively stops water, suppresses damage and deterioration of concrete 1/surface, and facilitates its repair. was.

(Purpose of the invention) This invention was made in view of the above circumstances, and it suppresses damage and deterioration without the drawbacks of conventional construction methods, and also facilitates repair, effectively providing +L The purpose of this invention is to provide an improved NA'I''M construction method capable of carrying out water treatment.

(Disclosure of the Invention) In order to achieve the above-mentioned purpose, the improved tunnel concrete waterproof strengthening method of the present invention is achieved by supporting with shotcrete and rock bolts, and then pouring secondary lining concrete 1. In the tunnel NATM construction method, Voltland cement composition is applied to the shotcrete surface.
It is characterized by applying a crystal growth agent containing fine silica and a water-soluble fluoride of silica containing hydrolase and magnesia.

Explaining the crystal growth agent used in the construction method of the present invention, this crystal growth agent has a crystal formation action that completely densifies the structure of concrete to the depths. Indispensable for this crystal formation effect is water-soluble fluoride of silica containing water glass and magnesia.

The concrete cast on the tunnel wall in the N A 1M construction method is composed of cement hardening paste and aggregate. It consists essentially of calcium, trisulfate, and monosulfate.

When viewed as a concrete structure, it has a microstructure of crystalline cement gel (approximately 50%), Ca(OH)2 (approximately 25%), and voids/pores (approximately 25%), of which Ca ( OH) 2 is precipitated in capillary-like voids and pores. These capillary tubes, as well as fine racks due to increased internal stress and load, and voids and pores created by air bubbles and bleeding water channels, allow spring water, air, carbon dioxide gas, etc. to enter, causing concrete damage and damage. Causes reactions that cause deterioration.

When there is spring water, the water that enters into the voids and pores not only begins to leak through these voids and pores, but also dissolves Ca(OH)2 precipitated in the voids and pores, producing deterioration reaction products. I will change it to For example, the production of calcium carbonate through reaction with carbon dioxide gas, the neutralization of concrete, and the alkali
Acceleration of aggregate reaction, salt damage, and frost damage may occur. Reinforcing bars rust and corrode due to carbonation or salt damage.

The crystal growth agent of the present invention suppresses the elution of Ca (OH) 2 and its transformation into a deterioration reactant. Basically, concrete deterioration is suppressed through the following reactions.

(1) Water glass Na O-2SiO, +3Ca (Kano>2 +11
201-e3CaO・2Si02-31120+2Na
OIl (2) Magnesia-containing silica water-soluble fluoride HoS
iF6+3Ca(0 old 2 1→3Cat2+Hg5iO3-311,,0 reaction(1
), extremely highly water-soluble water glass is transported through capillary channels by osmotic pressure and capillary action, and is reacted with Ca(Oll)2 precipitated in voids and pores to form insoluble Ca-
A 51-H2O crystal structure is generated. 3Ca0・
This crystal of 2S 102 .3H20 becomes an insoluble fibrous aphyllite crystal. Similarly, the reaction (
In 2), Cal is an insoluble equiaxed crystal. Then, insoluble orthorhombic enstatite is formed.

The important thing in this reaction (1>(2) is the reaction (]) (2
) requires water, and reaction (2) produces water. The two reactions continue to cause crystal growth in a chain reaction, and the crystals generated by the re-reaction coagulate in an intertwined manner, filling the pores and voids of the concrete. . These proliferating crystals have the same structure as the hardened cement structure.
・3 It is an inorganic crystal mainly composed of H20, and it exists permanently as long as the concrete frame exists, and shows the effect of preventing deterioration, repairing, and city water.Furthermore, after construction, cracks may occur due to some reason. Even in the gaps between the rock bolts used in the NATM construction method and the concrete, the crystallization reaction immediately resumes and the cracks are automatically filled with crystals.
I end up getting a minute hit.

In the construction method of the present invention, the physical strength of the concrete structure is also increased due to the formation and densification of crystals.

In the crystal growth agent of this invention, Ia #(II) In reaction (1) in which the presence of silica is also important, N;, t
An alkali of OH is generated, but this N a OH has a large specific surface area, is formed into a tR structure, and has a high reaction activity.
1 fine silica, 2S iO+2Na011←Na2O−2SiO2÷I
f20 water glass component is produced, which again reacts with Ca(OH)2 to form 3CaO-2Si0
・Produces 3H20 crystals.

The particle size of the fine silica can be about 30 to 500 μm.

The crystal growth agent as described above used in the method of this invention is:
Its standard composition is Si 0215-25%, C
a025-35%, MgO10-20%, Na 20
2 to 8%, and the other components have almost the same composition as Boltland cement. Fluoride is S
It may be in any form of I Fe or M g Si F 6.

Of course, Bortland cement, water glass, etc. are known to contain other components of the @star, and the actual reaction is 'FLm. Reactions (1) and (2) are only shown as basic ones.Actual composition adjustment of the crystallizing agent is N A
It may be selected as appropriate depending on the composition conditions of the concrete to be cast using the i'M construction method.

In addition, other ingredients contained include AJ 203
, P20s, etc., but these also act as hardening agents, adsorbing and fixing alkali to form a dense tissue.

There are no particular limitations on the method of applying this crystal growth agent; various modes for application may be selected. For example, after the primary lining is done by spraying concrete, a slightly thicker layer is sprayed. −
Depending on the condition of the next lining wall, a drilling method may be added,
Furthermore, a water conveyance method may be used.

Next, as an example, the crystal growth agent of the present invention and its effects will be explained below. This example makes clear the excellent water-stopping effect of the NATM tunnel construction method and the effect of improving the reinforcement of concrete.

Of course, the invention is not limited to the following examples.

Example (1) Ordinary concrete ditch 1 cock wall (thickness 20al
I) Boltland cement (35%) on one side, Na
20, other Na compounds (7%), MgO-310S
A mixture of crystal growth agent consisting of I Fe and other minerals (58%) and water was applied and left for 6 days. It was confirmed that needle-shaped crystals clustered and grew outward from the pores on the opposite untreated surface.

The formation of these insoluble crystals provided a complete water-stopping effect.

(2) I'1vQ4. :φ10QIIX 10tyn
f)=1 nk! J-Toni A water permeability test was then conducted. In addition, a compressive strength test was conducted by applying a crystal growth agent to the front surface of φ10 (!1×20) concrete.

In the water permeability test, when the water permeability pressure is 5 m/cJ, the pressure is 1
The water permeation amount after 20 hours was 0. On the other hand, the amount of water permeation when not coated was 15.9a+1.

In addition, the compressive strength is 297 kof /aj (N/mm2
) was there. If not applied, 285 kff/
=i (N/cm2).

It can be seen that this invention produces extremely excellent effects.

Claims (1)

[Claims] In the tunnel NATM construction method, in which the tunnel is supported by shotcrete and rock bolts, and then a secondary lining concrete is cast, a boltland cement composition, fine silica, and an aqueous solution of silica containing water glass and magnesia are applied to the shotcrete surface. A method for strengthening water-stopping of tunnel concrete, which is characterized by applying a crystal growth agent containing a fluoride.