JP2004156242A - Tunnel reinforcing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To construct a sufficiently load-resistant reinforcing layer without lessening the hollow section, namely by using only a thin thickness when an existing lining concrete of a tunnel deteriotates and cracks or the like generates. <P>SOLUTION: In the tunnel reinforcing construction method, when reinforcing a tunnel lining concrete, the surface of the lining concrete is covered with steel sheets or the surface of the lining concrete is internally wound with steel wires in mutual distances and a crack dispersion type fiber reinforced cement composite material is sprayed thereon. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a tunnel reinforcing method for performing strong reinforcement with a small thickness.
[0002]
[Prior art]
Conventionally, as a method of reinforcing the compressive force of a deformed tunnel, a reinforcing method for improving the stability of the ground, such as backfilling and rock bolts, and a covering method such as inwardly wrapped concrete or reinforced concrete, etc. Reinforcement methods for the purpose of improving the proof strength of concrete in itself are mainly employed.
[0003]
In the former case, the load on the lining concrete can be reduced, but no reinforcing effect can be expected on the deterioration of the lining concrete itself. Therefore, when the required performance of the lining concrete cannot be satisfied due to the deformation, it is effective to improve the proof strength of the lining concrete itself by the latter method, such as the inner winding concrete or the replacement concrete method.
[0004]
As shown in FIG. 1, when the inner wrapping concrete 2 is applied as a reinforcement when the existing primary lining concrete 1 is deteriorated and cracks are generated, the strength of the secondary lining is applied to the inner lining concrete 2. Since it is expected, it is necessary that the thickness of the inner wrapping concrete 2 be 300 mm or more, which is equivalent to the thickness of the primary lining concrete 1. For this reason, there may be a case where the inner cross section cannot be sufficiently secured. Since it is not possible to construct the inner concrete 2 beyond the architectural limit shown by the broken line in FIG. 1, the construction of the inner concrete is restricted if there is no room in the inner space section.
[0005]
According to the replacement method for removing the primary lining concrete, it is possible to secure the inner cross section, but it is necessary to prepare a great deal of labor and cost for removing the existing concrete. In addition, refillable concrete may not be able to achieve a sufficient reinforcing effect.
[0006]
In order to enhance the reinforcing effect, especially when a reinforcing effect against shearing or bending is also expected, an adhesive method using a sheet or steel sheet containing carbon fiber is applied, but in this case too much labor and labor are required. You have to be prepared for the cost.
[0007]
Patent Document 1 discloses a tunnel in which a shear bolt is driven into an old lining concrete with its head protruding in order to enhance the adhesion between the old lining concrete and the shotcrete, and then the shotcrete is constructed. It describes how to repair or reinforce the lining. Patent Literature 2 describes a crack-dispersed fiber-reinforced cement composite material, and Patent Literature 3 describes a mortar spray material containing PVA short fibers, which is a 28-year-old hardened material Shows a tensile strain of 1% or more in the tensile test.
[0008]
[Patent Document 1] Japanese Patent Publication No. 4-72038 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-7395 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-193653 [0009]
[Problems to be solved by the invention]
In order to provide sufficient reinforcement without increasing the thickness of the cast concrete, for example, a fiber reinforced spraying material as disclosed in Patent Document 2 is used to expect a high strength of the cast concrete itself. Although it is effective to increase the adhesive strength with the old lining concrete, the driving of the shear bolt as in Patent Document 1 may cause cracks in the old lining concrete, and the fiber reinforcement disclosed in Patent Document 3 Even if the material is wrapped inside, it is often difficult to expect the proof stress to withstand the compressive force of the deformed tunnel by itself.
[0010]
Accordingly, an object of the present invention is to provide a tunnel reinforcement method capable of stably exhibiting strength equivalent to that of the conventional cast-in-place concrete requiring a thickness of 300 mm or more, even in a state of a thickness of 100 mm or less, and in some cases even 70 mm or less. Is to make it happen.
[0011]
[Means for Solving the Problems]
According to the present invention, when reinforcing the tunnel lining concrete, the surface of the lining concrete is covered with a steel plate, and the surface of the steel plate is sprayed with a crack-dispersed fiber reinforced cement composite material. Provide a unique tunnel reinforcement method.
[0012]
Further, according to the present invention, when reinforcing the tunnel lining concrete, a steel strip is wound around the surface of the lining concrete at intervals, and a crack-dispersed fiber-reinforced cement composite material is formed thereon. A tunnel reinforcement method characterized by spraying is provided.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention combines the strength characteristics of steel with the specific strength characteristics of a fiber reinforced cement composite material of the crack dispersion type, so that even if the lining thickness is 100 mm or less, and even 70 mm or less, the conventional inner-rolled concrete 300 mm This ensures the same load-bearing capacity with respect to the compressive force as in the case, and thereby prevents the inner space section from decreasing as much as possible when reinforcing the tunnel.
[0014]
That is, as shown in FIG. 2, when the existing primary lining concrete 1 is deteriorated and cracks or the like occur, its surface is covered with a steel plate 3 and then a layer of a crack-dispersed fiber-reinforced cement composite material (hereinafter referred to as a layer). , A high toughness FRC material layer) 4. The total thickness of the steel sheet 3 and the high-toughness FRC material layer 4 is 100 mm or less, and in some cases, 70 mm or less. With this thickness, the load carrying capacity equal to or more than that of the inner-wound concrete 2 in FIG. 1 is secured. Thereby, even if it exceeds the building limit indicated by the broken line in FIG. 1, this can be avoided in FIG.
[0015]
FIG. 3 is an enlarged view of a portion A in FIG. As shown in the figure, the steel plate 3 is interposed between the primary lining concrete 1 and the high toughness FRC material layer 4, but the steel plate 3 may be penetrated to the primary lining concrete 1 or the rock 5 as necessary. Using an anchor (not shown). When a gap that cannot be ignored is generated on the back surface of the steel plate 3, the gap is filled with an adhesive. If there is a lot of water leakage, a waterproof sheet will be installed on the back.
[0016]
FIG. 4 is an enlarged cross-sectional view taken along line XX of FIG. 2, and shows a state in which a rib 6 is provided on the inner surface of the steel plate 3 along the tunnel cross section. The ribs 6 are preferably attached to the steel plate 3 so as to be continuous along the cross section of the tunnel from the lower end of one side wall to the lower end of the other side wall. By arranging the ribs 6 at predetermined intervals in the tunnel direction, The load carrying capacity of the steel plate 3 can be further enhanced. The high-toughness FRC material layer 4 is laid so as not to generate a gap between the rib 6 and the steel plate 3 and to cover the rib 3, so that it is sufficient for the compressive force of the tunnel in which the deformation has occurred. To endure.
[0017]
FIG. 5 shows the same reinforcing method of the present invention as that of FIG. 4 except that a steel bar 3 is used instead of the steel plate 3. In the example of FIG. 5, an I-type steel is used as the bar steel 7, and this is internally wound along the tunnel section from the lower end of one side wall to the lower end of the other side wall with respect to the surface of the lining concrete 1. Are continuously arranged at predetermined intervals in the tunnel direction. Then, the high toughness FRC material layer 4 is formed by spraying so as to surround the laid I-type steel. In place of the I-beam, an L-beam or another deformed steel may be used. In any case, the inner winding of the steel bar 7 and the high-toughness FRC material layer 4 can sufficiently withstand the compressive force of the deformed tunnel.
[0018]
In any of the embodiments, as the high toughness FRC material used in the present invention, for example, a high toughness FRC material described in JP-A-2000-7395, which is improved for spraying, is used. That is, in the present invention, 1 vol. Of PVA (Poly Vinyl Alcohol) short fiber satisfying the following condition [F1] is added to a cement mixture matrix satisfying the following condition [M1]. % Or more and 3 vol. % Of a crack-dispersed fiber-reinforced cement composite material compounded in an amount of not more than 0.1%.
[M1]
Weight percentage of water binder (W / C): 25% or more Weight ratio of fine aggregate and binder (S / C): 1.5 or less Unit water amount: 250 to 450 kg / m ³
Air volume immediately after kneading: 3.5 to 20%
High-performance AE water reducing agent: 30Kg / ^m less than ³ [F1]
Fiber diameter: 0.05mm or less Fiber length: 5-20mm
Fiber tensile strength: 1500-2400MPa
[0019]
The vinylon staple fiber satisfying the condition [F1] is preferably a staple fiber having an elastic coefficient equal to or higher than that of concrete manufactured from a polyvinyl alcohol resin, and typically has a tensile strength of 90 kgf. / Cm ² class, a modulus of elasticity (Young's modulus) of 2900 kgf / mm ² class, a specific gravity of about 1.3 and a shape of 0.66 mmφ × 30 mm (Kuraray Co., Ltd.) can be used. When the blending amount of vinylon short fiber is 1 vol. %, The yield strength after cracking is not sufficient, and the purpose of preventing spalling cannot be sufficiently achieved. On the other hand, when the blending amount of vinylon short fiber is 3.0 vol. %, It becomes difficult to satisfy the fluidity required for construction.
[0020]
As the high-performance AE water reducing agent used in the high toughness FRC material, a polycarboxylic acid type, a polyether type, a naphthalene type, a melamine type, an aminosulfonic acid type or the like can be used. Among them, polycarboxylic acid type or polyether type is preferable.
[0021]
In order to spray the high toughness FRC material, the mortar flow value immediately after mixing is 165 mm or more, preferably 170 to 180 mm. If it is less than 165 mm, the material may not be properly dispersed at the spray gun tip and may not be uniformly attached to the spray surface. However, if the flow value is too high, material separation occurs at the time of pumping, and fibers may aggregate to produce fiber balls. Therefore, the flow rate is preferably 180 mm or less. In order to stably secure such a mortar flow value, a high-performance AE water reducing agent of less than 30 kg / m ³ is blended, and the air amount immediately after kneading is 3.5 to 20%, preferably 10 to 20%. Good to do. Further, it is preferable to add a thickener in order to increase the material separation resistance while maintaining such fluidity. In particular, use of a biopolymer for microbial fermentation such as welan gum (about 0.01 to 0.2% based on unit water amount) is useful.
[0022]
In addition, in order to secure an appropriate amount of powder with a proper particle size, part of the cement is replaced with admixtures such as fly ash and blast furnace slag, and the maximum particle size of the aggregate is 0.8 mm or less. It is preferable to use fine aggregate having a diameter of 0.4 mm or less. Therefore, it is preferable to further add, as the condition [M1], a requirement that the fine aggregate has a maximum particle diameter of 0.8 mm or less and an average particle diameter of 0.4 mm or less. The fine aggregate and the binder are preferably blended so that the weight ratio (S / C) is 1.5 or less. The water binder ratio (W / C) needs to be 25% or more to improve the spraying workability.
[0023]
The high-toughness FRC material layer 4 sprayed in this manner exhibits a tensile strain of 1% or more in a tensile test of a 28-day-old hardened body as long as the conditions of [F1] and [M1] are satisfied. It becomes a crack-dispersed high toughness FRC material layer. For this reason, as described above, the mechanism of crack generation when applied to tunnel lining is that countless minute cracks are generated, and a large width crack is not reached.
[0024]
After the steel plate 3 or the bar steel 7 is applied to the primary lining concrete 2 and then reinforced with the high toughness FRC material layer 4, in addition to the excellent load-bearing capacity of the steel plate 3 or the bar steel 7, 10 times or more load-bearing capacity), high toughness FRC material 4 has high bending strength (usually about 10 MPa), so that tensile stress can be tolerated in the cross section, resulting in equivalent cross-sectional thickness compared to normal lining concrete In addition to being able to demonstrate the same lining performance even when thin, it can absorb the deformation even if the rock is deformed.
[0025]
【The invention's effect】
As described above, according to the present invention, when the existing lining concrete layer is deteriorated and cracks or the like occur, the thickness is reduced even to 1/3 or less of the inner wrapping concrete. Since the above load capacity can be ensured, construction can be performed even when there is no room in the inner space section. Further, the reinforcing method of the present invention is excellent in the effect of reinforcing against shearing and bending due to the strength characteristics of the steel material and the strength characteristics peculiar to the high toughness FRC material.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view illustrating a conventional tunnel reinforcing method using inner winding concrete.
FIG. 2 is a schematic sectional view illustrating a tunnel reinforcing method according to the present invention.
FIG. 3 is an enlarged view of a portion B in FIG. 2;
FIG. 4 is a sectional view taken along line XX of FIG. 2;
FIG. 5 is a sectional view similar to FIG. 4, showing another example of the tunnel reinforcing method according to the present invention.
[Explanation of symbols]
1 Existing primary lining concrete 2 Inner winding concrete 3 Steel plate 4 High toughness FRC material layer 5 Rock 6 Rib 7 I-type steel

Claims (4)

A method for reinforcing a tunnel lining concrete, wherein the surface of the lining concrete is covered with a steel plate, and the steel plate surface is sprayed with a crack-dispersed fiber reinforced cement composite material. . When reinforcing tunnel lining concrete, a steel bar is wound around the surface of the lining concrete at intervals and sprayed with crack-dispersed fiber-reinforced cement composite material. Tunnel reinforcement method. The tunnel reinforcing method according to claim 1 or 2, wherein the crack-dispersed fiber-reinforced cement composite material exhibits a tensile strain of 1% or more in a tensile test of a hardened body of 28 days of age. The crack-dispersed fiber-reinforced cement composite material is prepared by mixing 1 vol. Of PVA (Poly Vinyl Alcohol) short fiber satisfying the following condition [F1] in a cement mixture matrix satisfying the following condition [M1]. % Or more and 3 vol. The tunnel lining structure according to claim 1, wherein the tunnel lining structure is blended in a blending amount of not more than%.
[M1]
Weight percentage of water binder (W / C): 25% or more Weight ratio of fine aggregate and binder (S / C): 1.5 or less Unit water amount: 250 to 450 kg / m ³
Air volume immediately after kneading: 3.5 to 20%
High-performance AE water reducing agent: 30Kg / ^m less than ³ [F1]
Fiber diameter: 0.05mm or less Fiber length: 5-20mm
Fiber tensile strength: 1500-2400MPa

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