JP2018040147A - Flexible member and tunnel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible member capable of ensuring the stability of the tunnel inner space, which is easily manufactured at a low cost, and a tunnel.SOLUTION: A flexible member 3 is interposed in an arcuate or ring shaped tunnel support so as to cross the tunnel support, includes: a body part 4 made of a hardening body of a cement material containing cement, a porous material and water; and a belt-like fiber sheet 5 which is spirally wrapped on the body part 4 in a direction crossing a tunnel circumferential direction.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a retractable member and a tunnel.

In mountain tunneling methods such as NATM, tunnel support such as shotcrete sprayed on the ground surface exposed by excavation, steel support constructed along the ground surface, and rock bolts placed in the ground Safety is secured by construction.
In a tunnel covered with a large earth cover, the amount of deformation of the ground around the tunnel increases, and a large stress may be generated on the tunnel support. The same applies to tunnels formed by excavating fault fracture zones and expansive grounds. In tunnels where large stresses are expected to act, the rigidity and strength of the tunnel support may be increased. Further, Patent Document 1 includes a retractable member made of a fiber-reinforced cement-based material containing steel fibers and hollow particles having a volume ratio of nearly 1.0% in a gap formed in a part of a tunnel support. And the stabilization method of the tunnel which absorbs the deformation | transformation of a natural ground with this retractable member is disclosed.

JP 2005-232958 A

Increasing the rigidity and strength of the tunnel support by improving the cross-sectional performance and increasing the rigidity of the steel support, increasing the shotcrete, and increasing the shot thickness will increase the material cost and labor of construction. The tunnel cross-sectional dimensions are also affected. In addition, the retractable member of Patent Document 1 is expensive in material and takes time and effort to manufacture because the steel fibers and the hollow particles are mixed in a special composition.
Therefore, an object of the present invention is to propose a retractable member and a tunnel that can be manufactured easily and inexpensively and that can secure the stability of the tunnel interior.

In order to solve the above-mentioned problem, the contractible member of the present invention has a body portion made of a cemented hardened body including a porous body, and two pressure surfaces facing each other, and the surface to be pressed of the body portion. The reinforcing body is characterized by being a sheet material spirally wound around the main body portion. In addition, it is desirable that the reinforcing body is spirally wound in a state where the edges of the sheet material are overlapped. The reinforcing body may have a multilayer structure by wrapping the sheet material in multiple layers.
The tunnel of the present invention is characterized by comprising an arch-shaped or ring-shaped tunnel support and the contractible member disposed so as to cross the tunnel support.

  In such a retractable member, toughness is ensured by suppressing brittle fracture by the reinforcing body and applying an appropriate restraining force to the main body. Therefore, when the retractable member is disposed so as to cross the tunnel support, it is possible to prevent the yield strength of the tunnel support structure from rapidly decreasing even when the main body portion is deformed. Moreover, since the reinforcing body is formed by winding a belt-like sheet material around the main body in a spiral shape, it is difficult to peel off from the main body. Therefore, even when the main body portion is deformed, the restraining effect of the main body portion can be maintained. Further, when the main body is axially compressed, the sheet material slides and overlaps in the axial direction (tunnel circumferential direction) of the main body, so that the restraining effect on the main body is improved. Further, by winding the band-shaped sheet material in multiple layers, it is possible to expect an improvement in restraining effect and an improvement in toughness.

Further, the retractable member is formed with a main body portion having a strength lower than that of the tunnel support by using a porous material. Generally, concrete has a positive correlation between strength and rigidity. If the strength of the main body is lower than the strength of the surrounding tunnel support, the rigidity of the main body is similarly smaller than the rigidity of the surrounding tunnel support. Therefore, even when deformation occurs in the natural ground, since the deformation concentrates on the retractable member, the tunnel support structure can be maintained.
Furthermore, the main body is composed of a mixture of cement-based solidified material and porous material, so it can be easily kneaded compared to concrete containing a large amount of steel fibers, reducing labor during production. Is possible.

  According to the retractable member and the tunnel of the present invention, it is possible to ensure the stability of the air in the tunnel easily and inexpensively in tunnel excavation under a natural ground condition where a large earth pressure acts in a large earth covered tunnel.

(A) is sectional drawing which shows the tunnel which concerns on this embodiment, (b) is a longitudinal section which shows the support structure of a tunnel. (A) is a perspective view which shows the installation condition of a retractable member, (b) is a perspective view which shows the installation condition of the retractable member which concerns on another form. It is a perspective view which shows a retractable member. It is a graph which shows the experimental result of the retractable member of this embodiment. It is a graph which shows the experimental result of the retractable member of another form.

In the present embodiment, as shown in FIG. 1A, a support structure in which a retractable member 3 is interposed in a part of a tunnel support 2 in a tunnel 1 constructed by NATM will be described.
The tunnel support 2 of the present embodiment includes a shotcrete 21, a steel support 22, and a lock bolt 23 as shown in FIG. The shotcrete 21 and the steel support 22 are formed in an arch shape (horseshoe shape). Note that the shapes of the shotcrete 21 and the steel support 22 are not limited, and may be ring-shaped.

  Tunnel support 2 performs primary spraying 21a (part of sprayed concrete 21) on ground G exposed by excavation of natural ground G (around tunnel 3), and then builds steel support 22 In addition, the secondary spraying 21b (the remaining portion of the shotcrete 21) and the lock bolt 23 are driven. The steel support 22 is built at a predetermined interval from the steel support 22 built in the previous construction cycle. The placement of the lock bolt 23 is performed by drilling a lock bolt hole in a natural ground around the tunnel 1 and inserting the lock bolt 23 into the lock bolt hole.

  In addition, the structure of the tunnel support work 2 can be suitably changed according to the natural ground situation. For example, you may change suitably the spraying thickness of the shotcrete 21, the arrangement | positioning pitch, steel material dimension, etc. of steel supporters. Further, instead of the lock bolt 23, a fore poling method, an AGF method or the like may be employed. Furthermore, you may combine an auxiliary construction method as needed. Moreover, the shotcrete 21 does not necessarily need to be divided into a plurality of layers (primary spraying 21a and secondary spraying 21b). Moreover, you may drive the lock bolt 23 with construction of the steel supporter 22 after construction of the primary spraying 21a.

  The contractible member 3 is disposed so as to cross the shotcrete 21 formed in an arch shape as shown in FIG. In this embodiment, the retractable member 3 is disposed by spraying the spray concrete 21 against the ground G in a state where the retractable member 3 is disposed in advance at a predetermined position. In addition, the installation method to the shotcrete 21 of the retractable member 3 is not limited, For example, you may form the recessed part for installing a retractable member after construction of the shotcrete 21. FIG. Alternatively, at the time of constructing the shotcrete 21, a gap along the tunnel axis direction may be formed in the shotcrete 21 in advance by boxing or the like, and the retractable member 3 may be disposed in this gap. Moreover, after construction of the primary spray 21a, the retractable member 3 may be arranged so as to cross the secondary spray 21b, and the secondary spray 21b may be constructed.

In the present embodiment, the retractable members 3 are disposed at four locations with respect to one transverse section of the tunnel 1. The number and arrangement of the retractable members 3 are not limited. In the present embodiment, as shown in FIG. 2A, a plurality of retractable members 3 are continuously disposed in the axial direction of the tunnel 1. It is desirable that gaps are formed between the adjacent retractable members 3 and between the back surfaces of the retractable members 3 (the surface of the natural ground G). Further, the retractable member 3 may be disposed intermittently. Moreover, as shown in FIG.2 (b), the contractible member 3 may be interposed between the steel materials 22a which comprise the steel support work 22. As shown in FIG.
As shown in FIG. 3, the contractible member 3 is a belt-shaped body body 4 that is formed in a columnar shape and is circumferentially provided (covered) on a surface other than two opposing surfaces (surfaces to be pressed) of the body portion 4. And a reinforcing body made of a fiber sheet (sheet material) 5. In addition, the shape of the retractable member 3 is not limited, For example, square shape may be sufficient.

  The main body 4 is formed of a mortar cured body. The mortar contains cement, a porous material, and water. In this embodiment, pearlite is used as the porous material. Here, “pearlite” in the present specification is a porous lightweight aggregate formed by rapidly heating and foaming a rock material (for example, volcanic rock such as obsidian) at a high temperature. The porous material is not limited to pearlite as long as it is a granular material containing many voids. For example, so-called artificial lightweight aggregate, foamed brick, glass foam, or polystyrene foam may be used. As the porous material, a commercially available material may be used, or a material manufactured for the retractable member 3 may be used. Moreover, the main-body part 4 is not limited to mortar, For example, concrete may be sufficient. The blending of the main body 4 is not limited, but the blending is such that the compressive strength of the main body 4 is lower than the compressive strength of the shotcrete 21. In addition, since it is anticipated that the compressive strength of the main-body part 4 will depend on the intensity | strength of a porous material, it is desirable to select or manufacture the porous material which can ensure desired compressive strength.

  As shown in FIG. 3, the fiber sheet 5 is wound around the main body 4 in a spiral shape with the edges thereof overlapped. In this embodiment, a woven fabric formed by weaving polypropylene fibers vertically and horizontally is used as the fiber sheet 5. This woven fabric is generally used as a so-called civil engineering sheet. The fiber sheet 5 is formed by cutting the woven fabric into a strip having a width of 5 cm. In this embodiment, the overlap margin at the time of winding the fiber sheet 5 is 1 cm. In addition, the width | variety and overlap margin of the fiber sheet 5 are not limited, What is necessary is just to determine suitably.

The fiber sheet 5 is wound around the main body 4 in a direction intersecting the tunnel circumferential direction. That is, the end surface (surface to be pressed) of the main body 4 in the tunnel circumferential direction is exposed without being covered with the fiber sheet 5. Note that the fiber sheet 5 may be wound around the main body portion 4 in multiple layers. Moreover, the fiber which comprises the fiber sheet 5 is not limited to a polypropylene, For example, an aramid fiber, a polyethylene fiber, etc. may be sufficient.
In the present embodiment, a primer is applied to the main body 4 to smooth the unevenness on the side surface of the main body 4, and then an appropriate amount of epoxy resin is applied. Then, after winding the fiber sheet 5, an epoxy resin is apply | coated to the outer periphery of the shrinkable member 3 (fiber sheet 5), and it is made to immerse in the fiber sheet 5. FIG. In addition, what is necessary is just to apply | coat a primer as needed. The adhesive is not limited to epoxy resin. Further, the application range does not necessarily have to be applied to the entire side surface of the main body 4.

  According to the retractable member 3 of the present embodiment, toughness is ensured by suppressing brittle fracture by the fiber sheet 5 and applying an appropriate restraining force to the main body portion 4. Therefore, even when the main body portion 4 is deformed, the proof stress as the tunnel support structure is prevented from rapidly decreasing. Moreover, since the strip-shaped fiber sheet 5 is wound around the main body 4 in a spiral shape, the fiber sheet 5 slides even when the main body 4 is compressed (axially compressed) in the tunnel circumferential direction. The restraining effect of the main body can be maintained without bending. Moreover, since the fiber sheet 5 slides when the main body part 4 is axially compressed, the fiber sheet 5 is in a stacked state, so that the lateral restraining effect is improved.

  In addition, since the retractable member 3 includes the main body 4 having a strength lower than that of the shotcrete 21, the deformation of the tunnel support structure due to external force can be concentrated on the retractable member 3. Therefore, deformation of the tunnel support 2 does not occur, and the safety as the lining (support structure) of the tunnel 1 can be maintained. Since the outer periphery of the main body 4 other than the surface to be pressed is constrained by the fiber sheet 5, lateral deformation that occurs when the main body 4 is compressed is suppressed. Therefore, the main-body part 4 will be in a triaxial compression state, and stress will not fall rapidly as the whole retractable member 3 after yielding. Moreover, since the porous material (pearlite) is used as an aggregate, the main-body part 4 lower in strength than the shotcrete 21 can be easily formed. Moreover, since the main-body part 4 is comprised with the mixture of a cement-type solidification material and a porous material, it can be knead | mixed easily compared with the concrete containing a large amount of steel fibers, and hassles at the time of manufacture Reduction is possible. Since the main body 4 and the fiber sheet 5 constituting the retractable member 3 are made of a material that is relatively easily available, they are inexpensive.

Next, the result of performing a uniaxial compression test on the retractable member 3 of the present embodiment will be described.
In this experiment, the contractible member 3 in which a polypropylene fiber sheet 5 is spirally wound around a side surface (a surface other than a surface to be pressed) of a cylindrical main body 4 made of mortar using pearlite as an aggregate is uniaxial. A compression test was performed. The retractable member 3 was obtained by winding a fiber sheet 5 having a width of 5 cm around a main body 4 having a diameter of 100 mm and a height of H 200 mm with an overlap of 1 cm.
In this experiment, a uniaxial compression test was performed on the fiber sheet 5 wound in a single layer (Example 1) and the one wound twice (Example 2). In addition, as Comparative Example 1, a uniaxial compression test was also performed on a specimen in which a fiber sheet having the same width as the height of the main body portion 4 (H200 mm) was made to make one turn on the outer surface of the main body portion 4. Further, as Comparative Example 2, a uniaxial compression test was performed on a contractible member in which only the epoxy resin was applied to the main body portion 4.
The test results are shown in FIG.

As shown in FIG. 4, the epoxy resin alone (Comparative Example 2) had almost no restraining effect, and the stress immediately decreased after the yielding of the main body. On the other hand, Example 1 resulted in the stress continuing to 30% strain after the yielding of the main body 4. Therefore, it has been confirmed that the constraining effect can be obtained even after the yielding of the main body 4 by the retractable member 3 of this embodiment.
Further, when comparing Comparative Example 1 and Example 1, in Comparative Example 1, the stress starts to decrease after the strain exceeds 15%, whereas in Example 1, the stress decreases until the strain reaches about 30%. Did not occur. This is because the fiber sheet 5 is wound in a spiral shape, and even if axial compression (compression in the tunnel circumferential direction) occurs in the main body 4, the fiber sheet 5 does not peel off, and the fiber sheet 5 is broken to the breaking strength. This is because the sheet 5 suppresses lateral deformation of the main body 4. Therefore, it was proved that the restraining effect of the main body 4 is improved by winding the fiber sheet 5 in a spiral shape.

Moreover, the tendency of the inclination (gradient) of the stress-strain relationship in the hardening process after yielding of the main body 4 was almost the same between Comparative Example 1 and Example 1. Therefore, by winding the fiber sheet 5 in a spiral shape, the restraining effect of the main body 4 (the effect of suppressing lateral deformation) is the same as when the fiber sheet is normally wound (Comparative Example 1), but larger. It can be seen that even axial strain can be followed.
Here, the “curing process” is in the range of the axial strain after the yielding of the main body 4, and the lateral deformation of the main body 4 caused by the axial compression deformation eliminates loosening and loosening when winding the fiber sheet. And the fiber sheet 5 means the range of the axial strain to which axial stress increases with the increase in axial strain when the side deformation | transformation of the main-body part 4 begins to be restrained effectively.

  Further, in Example 2 in which the fiber sheet 5 is wound twice, the gradient of the curing process is larger than in Example 1 in which the fiber sheet 5 is wound in a single layer. Moreover, while Example 1 maintained the stress up to 30% strain, Example 2 achieved that the stress was maintained up to 35% strain. Therefore, it turns out that the toughness of the retractable member 3 improves more by winding the fiber sheet 5 twice. Further, when the fiber sheet 5 is wound in a plurality of layers (multiple times), the type of the fiber sheet is changed for each layer (for example, the first is 2700 N / 5 cm width, the second is 1000 N / 5 cm width) It is considered possible to adjust the gradient of the curing process.

Next, the results of a uniaxial compression test performed on the compressible member 3 in which a fiber sheet 5 having a width of 5 cm is wound around a 20 cm square cubic body portion 4 made of mortar using pearlite as an aggregate at an overlap of 1 cm are described. In this experiment, it performed about what wound the fiber sheet 5 single (Example 3) and what wound twice (Example 4). The test results are shown in FIG.
As shown in FIG. 5, in Example 3, it was possible to achieve a sustained stress up to 40% strain, and in Example 4, it was possible to achieve a sustained stress up to 50% strain. As a result, even when the main body portion 4 is a prismatic shape, Example 4 in which the fiber sheet 5 is wound in a double manner has a larger gradient in the curing process than Example 3 in which the fiber sheet 5 is wound in a single layer. .

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the above-described constituent elements can be appropriately changed without departing from the spirit of the present invention.
For example, the retractable member 3 can change the rigidity and strength of the main body portion 4 and the fiber sheet 5 (reinforcing body) in strength required in design.
As long as the fiber sheet 5 can restrain the side surface of the main body 4, it is not always necessary to wind the fiber sheet 5 in a state where the edges overlap each other.
If the material which comprises a reinforcement body is a strip | belt-shaped sheet material, it does not necessarily need to be a fiber sheet.

DESCRIPTION OF SYMBOLS 1 Tunnel 2 Tunnel support 21 Shotcrete 22 Steel support 3 Retractable member 4 Body part 5 Fiber sheet (reinforcement body)

Claims (4)

A retractable member having two opposite surfaces as a surface to be pressed,
A main body portion composed of a cement-based cured body including a porous body;
A reinforcing body coated on a surface other than the pressed surface of the main body, and
The said reinforcing body is a sheet | seat material spirally wound around the said main-body part, The shrinkable member characterized by the above-mentioned.   The contractible member according to claim 1, wherein the sheet material is spirally wound in a state where edges thereof are overlapped with each other.   The retractable member according to claim 1, wherein the sheet material is wound around the main body in a multiple manner. Arched or ring-shaped tunnel support works,
A retractable member according to any one of claims 1 to 3, which is disposed so as to cross the tunnel support work.

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