JP2021050505A - Tunnel support structure and tunnel support structure constructing method - Google Patents

Abstract

To efficiently construct a tunnel support structure.SOLUTION: A tunnel support structure 100 comprises a plurality of steel support portions 10 provided in an excavation pit 1 at predetermined intervals in the tunnel axial direction and extending in the tunnel circumferential direction, a concrete structure 21 provided between a plurality of steel support portions 10, and an easily compressive and deformable portion 22 which is provided adjacent to the concrete structure 21 in the circumferential direction of the tunnel and is easier to compress and deform in the circumferential direction of the tunnel as compared with the concrete structure 21. The easily compressive and deformable portion 22 has a plurality of precast blocks 23, and the plurality of precast blocks have different strength characteristics.SELECTED DRAWING: Figure 4

Description

The present invention relates to a tunnel support structure and a method for constructing a tunnel support structure.

When excavating a mountain tunnel by the NATM (New Austrian Tunneling Method) method or the like, the ground exposed by the tunnel excavation is supported by steel members and sprayed concrete to stabilize the tunnel. In high-covered tunnels and expansive grounds, large pressures may be applied from the grounds to the sprayed concrete.

Patent Document 1 discloses a support structure in which a compressionally deformable portion is provided adjacent to sprayed concrete. The easily compressively deformable portion is a hollow shell such as hollow glass fine particles or a concrete block containing 10% or more bubbles by volume. When a large pressure is applied from the ground to the support structure, the hollow shell or air bubbles in the easily compressive and deformable portion are crushed, and the easily compressive and deformable portion is deformed. After the hollow shell or air bubbles are crushed and the deformation of the easily compressive and deformable portion is converged, the easily compressive and deformable portion exhibits the required load bearing performance and supports the ground.

Japanese Unexamined Patent Publication No. 2018-1505048

In the support structure disclosed in Patent Document 1, in order to appropriately support the ground, it is preferable to adjust the strength characteristics of the easily compressively deformable portion according to the deformation characteristics of the ground. Since the strength characteristic of the easily compressively deformable portion in Patent Document 1 is mainly determined by the ratio of the hollow shell or the bubbles, it is necessary to determine the ratio of the hollow shell or the bubble according to the deformation characteristic of the ground.

However, it is difficult to grasp the deformation characteristics of the ground in advance, and it is usual to grasp it when excavating a tunnel. If the hollow shell or the ratio of air bubbles is determined after excavating the tunnel and grasping the deformation characteristics of the ground to manufacture the easily compressive deformation part, the support structure cannot be constructed efficiently.

An object of the present invention is to efficiently construct a tunnel support structure.

The tunnel support structure according to the present invention is provided in the excavation pit at a predetermined distance from each other in the tunnel axial direction, and is between a plurality of steel support portions extending in the tunnel circumferential direction and a plurality of steel support portions. It is provided with a concrete structure to be provided and a compression deformation easy portion which is provided adjacent to the concrete structure in the tunnel circumferential direction and is easy to compress and deform in the tunnel circumferential direction as compared with the concrete structure. The easy part has a plurality of precast blocks, and the plurality of precast blocks have different strength characteristics.

Further, the present invention is a method for constructing a tunnel support structure, wherein the tunnel support structure is provided in a drilling pit at predetermined intervals in the tunnel axial direction and extends in the tunnel circumferential direction. A concrete structure provided between a plurality of steel support portions, and a compression-deformable portion that is provided adjacent to the concrete structure in the tunnel circumferential direction and is easier to compress and deform than the concrete structure. The easily compressible and deformable part has a plurality of precast blocks having different strength characteristics, and the construction method is to leave the steel support part at a predetermined distance in the tunnel axial direction from the installed steel support part. A concrete structure is provided between the steel support part installation process to be installed and the steel support parts adjacent to each other in the tunnel axial direction, and a compression deformable part is provided adjacent to the concrete structure in the tunnel circumferential direction. It is equipped with a body / compression deformation easy part installation process.

According to the present invention, the tunnel support structure can be efficiently constructed.

It is sectional drawing of the tunnel support structure which concerns on embodiment of this invention, and shows the sectional view along line I-I of FIG. It is sectional drawing of the tunnel support structure which concerns on embodiment of this invention, (a) shows the cross section along the line IIA-IIA of FIG. Shown. It is a figure which shows the strength characteristic of the concrete support part shown in FIG. 1 and FIG. (A) is a schematic diagram of a precast block, and (b) and (c) are diagrams showing the strength characteristics of the precast block. It is sectional drawing of the tunnel support structure which concerns on the modification of embodiment in this invention.

Hereinafter, the tunnel support structure 100 and the method for constructing the tunnel support structure 100 according to the embodiment of the present invention will be described with reference to the drawings.

As shown in FIGS. 1 and 2, the tunnel support structure 100 is constructed in the excavation pit 1 formed by excavating the ground. The tunnel support structure 100 supports the inner wall surface of the excavation pit 1 and stabilizes the tunnel T.

In the following, the direction along the central axis of the tunnel T is referred to as "tunnel axis direction", the direction around the central axis of tunnel T is referred to as "tunnel circumferential direction", and the radial direction centered on the central axis of tunnel T is referred to as "tunnel axial direction". It is called "tunnel radial direction".

The tunnel support structure 100 includes a steel support portion 10 mainly formed of a steel material and a concrete support portion 20 mainly formed of a concrete material. A plurality of steel support portions 10 are provided in the excavation pit 1 at predetermined intervals in the tunnel axial direction. The concrete support portion 20 is provided between the steel support portions 10.

The steel support portion 10 includes a steel member 11 extending in the circumferential direction of the tunnel, and an easily compressive and deformable portion 12 adjacent to the steel member 11 in the circumferential direction of the tunnel. The steel member 11 is, for example, H-shaped steel. The compression deformation easy portion 12 is a precast block that is easy to compression deformation in the tunnel circumferential direction as compared with the steel member 11. A plurality of steel members 11 are provided at intervals in the tunnel circumferential direction, and a compression deformation easy portion 12 is provided between the steel members 11 adjacent to each other in the tunnel circumferential direction.

The concrete support portion 20 includes a concrete structure 21 provided between steel members 11 adjacent to each other in the tunnel axial direction, and a compression deformation easy portion 22 provided adjacent to the concrete structure 21 in the tunnel circumferential direction. ing.

The concrete structure 21 is a sprayed concrete formed by spraying a concrete material on the inner wall surface of the tunnel T, and a plurality of concrete structures 21 are provided at intervals in the circumferential direction of the tunnel. The concrete material is, for example, underwater non-separable concrete or high-fluidity concrete. Mortar may be used as a concrete material.

The easily compressively deformed portion 22 has a plurality of precast blocks 23 that are easily compressed and deformed in the circumferential direction of the tunnel as compared with the concrete structure 21. The compression deformation easy portion 22 is provided between the concrete structures 21 adjacent to each other in the circumferential direction of the tunnel.

In the examples shown in FIGS. 1 and 2, the steel member 11, the easily compressively deformable portion 12, the concrete structure 21 and the easily compressively deformable portion 22 are provided in the excavation pit 1 so as to be in contact with the inner wall surface of the excavation pit 1. However, it does not have to be in contact with the inner wall surface of the excavation pit 1. For example, a concrete material is sprayed on the entire inner wall surface of the excavation pit 1 to form a concrete layer, and a steel member 11, a compressively deformable portion 12, and a compressively deformable portion 22 are in contact with the inner peripheral surface of the concrete layer. The concrete structure 21 may be formed by spraying a concrete material on the inner peripheral surface of the concrete layer.

The easily compressive and deformable portions 12 and 22 are significantly compressively deformed as compared with the steel member 11 and the concrete structure 21 when subjected to a predetermined compressive stress, and exhibit a predetermined rigidity after the deformation converges. That is, the steel support portion 10 and the concrete support portion 20 are easily deformed until the compression deformations of the compression deformation easy portions 12 and 22 converge, but after the compression deformations of the compression deformation easy portions 12 and 22 have converged. It has strength characteristics that exhibit a predetermined rigidity.

The strength characteristics of the concrete support portion 20 will be described with reference to FIG. 3A. Since the strength characteristics of the steel support portion 10 are substantially the same as the strength characteristics of the concrete support portion 20, the details thereof will be omitted here.

FIG. 3A is a diagram showing an example of the strength characteristics of the concrete support portion 20. The horizontal axis represents the strain ε and the vertical axis represents the stress σ. That is, the strength characteristic shown in FIG. 3A is a stress-strain characteristic. In FIG. 3A, an example of stress-strain characteristics of the concrete structure 21 is also shown.

In FIG. 3 (a), ε1 is greater than 0 (zero), ε2 is greater than ε1, ε3 is greater than ε2, and ε4 is greater than ε3 (0 <ε1 <ε2 <ε3 <ε4). Further, σ1 is larger than 0 (zero), σ2 is larger than σ1, and σ3 is larger than σ2 (0 <σ1 <σ2 <σ3). σ3 corresponds to the yield strength of the concrete structure 21.

As shown in FIG. 3A, in the range of less than ε1, the stress σ in the concrete support portion 20 increases to σ1 as the strain ε increases. This is a state in which both the concrete structure 21 of the concrete support portion 20 and the compressively deformable portion 22 exhibit a predetermined rigidity.

In the range of ε1 or more and ε2 or less, the stress σ in the concrete support portion 20 is σ1 even if the strain ε increases. This is a state in which the concrete structure 21 exhibits a predetermined rigidity, but the easily compressive and deformable portion 22 exhibits almost no rigidity and is easily compressed and deformed in the circumferential direction of the tunnel. The state in which the concrete support portion 20 is distorted by ε2 corresponds to the state in which the compressive deformation of the compressive deformation easy portion 22 has converged.

In the range of more than ε2 and less than ε4, the stress σ in the concrete support portion 20 increases from σ1 to σ3 as the strain ε increases. This is a state in which the compressive deformation of the easily compressive and deformable portion 22 has converged, and both the concrete structure 21 and the easily compressive and deformable portion 22 exhibit a predetermined rigidity.

The rigidity in the range of more than ε2 and ε4 or less does not have to match the rigidity in the range of less than ε1, and may be higher than the rigidity in the range of ε1 or more and ε2 or less. The rigidity corresponds to the slope in the stress-strain characteristic diagram.

In the range exceeding ε4, the stress σ in the concrete support portion 20 exceeds σ3. In this case, since the stress σ equal to or greater than the proof stress acts on the concrete structure 21, the concrete structure 21 cannot exert the supporting function. That is, the concrete support portion 20 is designed so that the strain ε does not exceed ε4.

As described above, the strength characteristics of the concrete support portion 20 include a first rigidity region R1 that exhibits a predetermined rigidity in a range of less than ε1, a deformable region D that hardly exhibits rigidity and is easily deformable, and ε2. It has a second rigidity region R2 that exhibits a predetermined rigidity in a range exceeding the range. Therefore, the concrete support portion 20 exhibits a predetermined rigidity after allowing some deformation of the ground (displacement of the inner wall surface of the excavation pit 1).

The advantage that the concrete support portion 20 exhibits a predetermined rigidity after allowing the deformation of the ground to some extent will be described with reference to FIG. 3 (a). FIG. 3A shows an example of the earth pressure characteristics of the ground. The earth pressure characteristics shown in FIG. 3 (a) are confirmed in the ground where the high earth cover tunnel is constructed and the expansive ground. As shown in FIG. 3A, the earth pressure of the ground tends to be increased (decreased) with the deformation (strain) of the ground.

In the range of less than ε3, the earth pressure in the earth pressure characteristic of the ground is larger than the stress σ in the strength characteristic of the concrete support portion 20. Therefore, the concrete support portion 20 is distorted so as to be compressed and deformed in the circumferential direction of the tunnel under the earth pressure of the ground. With the strain of the concrete support portion 20, the ground is deformed and the earth pressure is lowered.

When the strain ε of the concrete support portion 20 reaches ε3, the ground pressure of the ground and the stress σ of the concrete support portion 20 are balanced (the ground pressure characteristic curve of the ground and the strength characteristic curve of the concrete support portion 20 intersect. ). Therefore, the deformation of the ground and the concrete support portion 20 converges, and the tunnel T becomes stable.

If the concrete support portion is formed only of the concrete structure 21, that is, if the concrete support portion does not have the easily compressively deformable portion 22, the strength characteristic of the concrete support portion is the strength of the concrete structure 21. Consistent with the characteristics. When the earth has the earth pressure characteristics shown in FIG. 3A, the earth pressure of the earth and the stress σ of the concrete structure 21 are not balanced in the range of σ3 or less. Therefore, the deformation of the ground cannot be converged, and the tunnel T cannot be stabilized. In order to converge the deformation of the ground and stabilize the tunnel T, it is necessary to stack the concrete structures 21 in double or triple or more in the tunnel radial direction to disperse the earth pressure of the ground. As a result, the number of times the concrete structure 21 is constructed increases, it takes time to construct the tunnel support structure, and the construction cost of the tunnel support structure increases.

When the inner wall surface of the excavation pit 1 is supported by using the concrete support portion 20 provided with the easily compressively deformable portion 22 as in the present embodiment, the deformation of the ground is allowed to some extent. Since the pressure of the ground decreases with the deformation of the ground, the earth pressure of the ground and the stress σ of the concrete structure 21 are balanced in the range of σ3 or less. Therefore, the deformation of the ground can be converged and the tunnel T can be stabilized without overlapping the concrete structures 21. As a result, the number of times the concrete structure 21 is constructed can be reduced, and the labor required for constructing the tunnel support structure 100 and the construction cost of the tunnel support structure 100 can be reduced.

As described above, in the tunnel support structure 100, the concrete support portion 20 exerts a predetermined rigidity after allowing the deformation of the ground to some extent, so that the labor required for the construction of the tunnel support structure 100 and the construction cost of the tunnel support structure 100 are exhibited. Can be reduced.

The strength characteristics of the concrete support portion 20 are preferably set by adjusting the strength characteristics of the compressively deformable portion 22 according to the earth pressure characteristics of the ground.

For example, when the ground has the ground pressure characteristics shown in FIG. 3 (b) and the concrete support portion 20 has the strength characteristics shown by the solid line, the ground pressure and the concrete structure 21 of the ground are in the range of σ3 or less. The stress σ of is not balanced. Therefore, the deformation of the ground cannot be converged, and the stability of the tunnel T may decrease. In order to stabilize the tunnel T, the easily deformable part is compressed so that the concrete support part 20 has the strength characteristic (strength characteristic indicated by the alternate long and short dash line) having the easily deformable area D2 wider than the easily deformable area D1 of the strength characteristic shown by the solid line. It is preferable to adjust the strength characteristics of 22.

Further, when the ground has the ground pressure characteristics shown in FIG. 3C and the concrete support portion 20 has the strength characteristics shown by the solid line, the ground pressure of the ground and the stress σ in the concrete support portion 20 are , Balanced in the easily deformable area D. In this case, the inner wall surface of the excavation pit 1 is displaced more than necessary, and it is necessary to increase the extra digging of the excavation pit 1. As a result, the construction cost of the tunnel T increases. In order to reduce the construction cost of the tunnel T, the concrete support portion 20 is compressed so as to have the strength characteristic (strength characteristic indicated by the alternate long and short dash line) having the easily deformable region D3 narrower than the easily deformable region D1 of the strength characteristic shown by the solid line. It is preferable to adjust the strength characteristics of the easily deformable portion 22.

However, it is difficult to grasp the earth pressure characteristics of the ground in advance, and it is usual to grasp the earth pressure characteristics of the ground while excavating the ground. In addition, the earth pressure characteristics of the ground also differ depending on the position in the tunnel axial direction. If the precast block 23 was manufactured by digging the ground and grasping the ground pressure characteristics of the ground and then determining the strength characteristics of the easily compressive and deformable portion 22, it is possible to efficiently construct the tunnel support structure 100. Can not.

In the present embodiment, the plurality of precast blocks 23 have different strength characteristics. Therefore, the strength characteristics of the easily compressive and deformable portion 22 change according to the combination of the precast blocks 23. Therefore, the precast block 23 is manufactured in advance before grasping the earth pressure characteristics of the ground, and the precast block 23 can be easily compressed and deformed according to the earth pressure characteristics of the ground grasped at the time of constructing the tunnel support structure 100. The strength characteristics of the portion 22 can be adjusted. As a result, the tunnel support structure 100 can be efficiently constructed.

The structure and strength characteristics of the precast block 23 will be described with reference to FIG. FIG. 4A is a schematic view of the precast block 23 in which the compression strength in a predetermined direction (vertical direction of the paper surface) is higher than that of other directions (horizontal direction of the paper surface and the front-back direction of the paper surface).

As shown in FIG. 4, the precast block 23 is a substantially cubic member having improved strength by blending fibers 23b with resin 23a. The resin 23a is, for example, a hard urethane resin, and the fiber 23b is, for example, a glass fiber.

The fibers 23b are blended in the resin 23a so that the orientation is biased in the vertical direction of the paper surface, and the compression strength of the precast block 23 in the vertical direction of the paper surface is higher than that in the horizontal direction of the paper surface and the front-rear direction of the paper surface by the fibers 23b. .. In FIG. 4A, for convenience of explanation, the fibers 23b are drawn parallel to the paper surface in the vertical direction, but more than half of the fibers 23b are drawn within 45 degrees with respect to the paper surface vertical direction. It only has to be tilted. In other words, a part of the fiber 23b may be blended with the resin 23a so as to be along the left-right or front-back direction of the paper surface.

In the following, the direction in which the directions of the fibers 23b are biased (the vertical direction of the paper surface in the example shown in FIG. 4A) is referred to as the “high strength direction”, and the direction orthogonal to the high strength direction (shown in FIG. 4A). In the example, the left-right and up-down directions of the paper surface) are referred to as "low-strength directions".

FIG. 4B is a diagram showing an example of the strength characteristics of the precast block 23. The horizontal axis represents the strain ε and the vertical axis represents the stress σ. That is, the strength characteristic shown in FIG. 4B is a stress-strain characteristic. In FIG. 4B, the solid line is the strength characteristic when the precast block 23 is compressed in the high strength direction, and the broken line is the strength characteristic when the precast block 23 is compressed in the low strength direction.

In FIG. 4 (b), ε5 is greater than 0 (zero), ε6 is greater than ε5, ε7 is greater than ε6, and ε8 is greater than ε7 (0 <ε5 <ε6 <ε7 <ε8).

As shown by the solid line in FIG. 4B, when the precast block 23 is compressed in the high intensity direction, the stress σ in the precast block 23 increases as the strain ε increases in the range of less than ε5. That is, the precast block 23 exhibits a predetermined rigidity. In the range of ε5 or more and less than ε6, the stress σ in the precast block 23 is substantially constant or slightly decreases even if the strain ε increases. In the range of ε6 or more and less than ε8, the stress σ in the precast block 23 decreases as the strain ε increases. In the range of ε8 or more, the stress σ in the precast block 23 is substantially constant even if the strain ε increases, and is smaller than the stress σ in the range of ε5 or more and less than ε6.

Further, as shown by a broken line in FIG. 4 (b), when the precast block 23 is compressed in the low intensity direction, the stress σ in the precast block 23 increases as the strain ε increases, but in the range of less than ε7. The stress σ in the precast block 23 is lower than the stress σ when the precast block 23 is compressed in the high strength direction. That is, the precast block 23 is deformed more easily when compressed in the low-strength direction than when compressed in the high-strength direction.

As described above, the precast block 23 has anisotropy in which the strength differs depending on the compression direction.

FIG. 4B shows the strength characteristics when a plurality of precast blocks 23 are connected by a alternate long and short dash line. Here, the plurality of precast blocks 23 have the same number of precast blocks 23 directed so that the high strength directions coincide with each other with respect to the compression direction and the precast blocks 23 directed so as to coincide with the low strength directions. It is assumed that it is connected to.

As shown by the alternate long and short dash line in FIG. 4B, the strength characteristics when a plurality of precast blocks 23 are combined are the strength characteristics when the precast blocks 23 are compressed in the high strength direction and the strength characteristics when the precast blocks 23 are compressed in the low strength direction. The characteristics are intermediate with the strength characteristics. Although not shown, when the number of precast blocks 23 directed so that the high-strength direction coincides with the compression direction is increased and the number of precast blocks 23 directed so as to coincide with the low-strength direction decreases, The strength characteristics approach the strength characteristics when the precast block 23 is compressed in the high strength direction. That is, the strength characteristics when a plurality of precast blocks 23 are combined are such that the precast block 23 directed so that the high strength direction coincides with the compression direction and the precast block 23 directed so that the low strength direction coincides with each other. Determined by the ratio with.

As shown in FIG. 1, the compressively deformable portion 22 has a plurality of precast blocks 23 having anisotropy. Therefore, the strength characteristic of the easily compressive and deformable portion 22 is the ratio of the precast block 23 directed so that the high strength direction coincides with the compression direction and the precast block 23 directed so that the low strength direction coincides. It changes accordingly.

The strength characteristic of the concrete support portion 20 changes due to the change in the strength characteristic of the easily compressively deformable portion 22. For example, when the number of precast blocks 23 oriented so that the high-strength direction coincides with the compression direction is reduced and the number of precast blocks 23 oriented so that the low-strength direction coincides with each other is increased, the concrete support portion 20 The easily deformable region D in the strength characteristics of is expanded (see FIG. 3 (b)). Further, when the number of precast blocks 23 directed so that the high strength direction coincides with the compression direction is increased and the number of precast blocks 23 directed so as to coincide with the low strength direction is reduced, the concrete support portion 20 The easily deformable region D in the strength characteristics of is narrowed (see FIG. 3C).

As described above, the strength characteristics of the concrete support portion 20 change depending on the combination of the orientations of the precast blocks 23. Therefore, the strength characteristics of the easily compressively deformable portion 22 can be adjusted at the time of construction of the tunnel support structure 100 by using the precast block 23 manufactured in advance before grasping the earth pressure characteristics of the ground, and the tunnel support structure 100 can be adjusted. It can be built efficiently.

The strength characteristics of the precast block 23 are also changed by changing the ratio of the fibers 23b to the resin 23a. FIG. 4C is a diagram showing the strength characteristics of the precast block 23 when the ratio of the fibers 23b is changed.

In FIG. 4 (c), the solid line V1 and the broken line H1 are the strength characteristics shown by the solid line and the broken line in FIG. 4 (b). The solid line V2 and the broken line H2 are the strength characteristics of the precast block 23 in which the ratio of the fibers 23b is higher than that of the precast block 23 having the strength characteristics shown by the solid line V1 and the broken line H1. The solid lines V1 and V2 are the strength characteristics when the precast block 23 is compressed in the high strength direction, and the broken lines H1 and H2 are the strength characteristics when the precast block 23 is compressed in the low strength direction.

As shown in FIG. 4C, the strength characteristics of the precast block 23 also differ depending on the ratio of the fibers 23b. Therefore, the strength characteristics of the easily compressive and deformable portion 22 can be finely adjusted by making the ratio of the fibers 23b in one precast block 23 of the easily compressive and deformable portion 22 different from the ratio of the fibers 23b in the other precast block 23. it can. Therefore, the strength characteristics of the concrete support portion 20 can be set more appropriately according to the earth pressure characteristics of the ground.

As shown in FIGS. 1 and 2 (b), a plurality of compressively deformable portions 22 are provided with the concrete structure 21 sandwiched between them in the circumferential direction of the tunnel. A plurality of compression-deformable portions 22 in one of the plurality of compression-deformability-easy portions 22 and another compression-deformation-easy portion 22 located at intervals in the tunnel circumferential direction from the one compression-deformation-easy portion 22. It is possible to make different combinations of orientations of the precast blocks 23. Therefore, the strength characteristic of the easily compressive and deformable portion 22 can be set according to the position in the tunnel circumferential direction. For example, the easily deformable region D of the strength characteristics of the easily compressively deformable portion 22 near the bottom surface of the tunnel T can be made wider than the easily deformable portion 22 near the top surface of the tunnel T. Therefore, the stability of the tunnel T can be improved.

As shown in FIG. 1, a plurality of compression deformation easy portions 22 are provided with a steel support portion 10 sandwiched between them in the tunnel axial direction. A plurality of compression-deformable portions 22 of one of the plurality of compression-deformability-easy portions 22 and another compression-deformation-easy portion 22 located at intervals in the tunnel axial direction from the one compression-deformation-easy portion 22. It is possible to make different combinations of precast blocks 23. Therefore, the strength characteristics of the concrete support portion 20 can be set according to the earth pressure characteristics that differ depending on the position in the tunnel axial direction. Therefore, the stability of the tunnel T can be improved.

Similar to the concrete support portion 20, the steel support portion 10 includes a compression deformation easy portion 12. Therefore, the steel support portion 10 exhibits a predetermined rigidity after allowing some deformation of the ground, like the concrete support portion 20. Therefore, the deformation of the ground can be converged and the tunnel T can be stabilized without overlapping the steel members 11 in the tunnel radial direction. As a result, the number of times the steel member 11 is constructed can be reduced, and the labor required for constructing the tunnel support structure 100 and the construction cost of the tunnel support structure 100 can be reduced.

The easily compressive and deformable portion 12 of the steel support portion 10 may be the same precast block as the precast block 23 used for the easily compressive and deformable portion 22, or the precast block 23 may be a different precast block. Further, the compression deformation easy portion 12 may be formed of one precast block or may be formed of a plurality of precast blocks.

Next, a method of constructing the tunnel support structure 100 will be described. Here, it is assumed that a plurality of precast blocks 23 are manufactured in advance for each type having a different ratio of fibers 23b.

The method of constructing the tunnel support structure 100 includes a steel support section installation step in which the steel support section 10 is installed at a predetermined interval in the tunnel axial direction from the installed steel support section 10 and adjacent to the tunnel axial direction. It is provided with a concrete structure / easy compression deformation part installation step in which a concrete structure 21 is provided between the matching steel support portions 10 and a compression deformation easy part 22 is provided adjacent to the concrete structure 21 in the tunnel circumferential direction. ing.

The steel support section installation step is performed after excavating the ground and extending the excavation pit 1 by a predetermined length (for example, 1 to 3 m). In the steel support section installation process, the steel member 11 and the easily compressive deformable section 12 are installed along the inner wall surface of the drilling pit 1 in the vicinity of the face (not shown) of the drilling pit 1. At this time, the newly installed steel member 11 and the easily compressively deformable portion 12 are separated from the already installed steel member 11 and the easily compressively deformable portion 12 for a predetermined time in the tunnel axial direction. In addition, the strength characteristics of the easily compressive and deformable portion 12 are adjusted according to the earth pressure characteristics grasped by excavation of the ground.

The step of installing the concrete structure / easily deformable part is performed after the step of installing the steel member.

In the step of installing the concrete structure / easily compressive and deformable portion, first, the easily compressive and deformable portion 22 is installed between the easily compressive and deformable portions 12 adjacent to each other in the tunnel axial direction. Specifically, the precast block 23 used for the easily compressive and deformable portion 22 is selected from a plurality of precast blocks 23 manufactured in advance, and is installed between the easily deformable compressive and deformable portions 12 adjacent to each other in the tunnel axial direction. At this time, the orientation of each of the precast blocks 23 is adjusted to adjust the strength characteristics of the easily compressive and deformable portion 22. The precast blocks 23 selected may have the same or different proportions of fibers 23b.

Next, the concrete material is sprayed between the steel members 11 adjacent to each other in the tunnel axial direction, and the concrete structure 21 is installed. As a result, the easily compressive and deformable portion 22 is adjacent to the concrete structure 21 in the circumferential direction of the tunnel. In the concrete structure installation process, before spraying the concrete material, it is preferable to cure the precast block 23 with a sheet or the like so that the concrete material is not sprayed.

Every time the excavation pit 1 is extended by a predetermined length (for example, 1 to 3 m), a steel member installation process and a concrete structure / compression deformation easy part installation process are performed to support the tunnel over the entire length of the tunnel T. The structure 100 is constructed. Although not shown, lining concrete may be formed inside the steel support portion 10 and the concrete support portion 20.

In the step of installing the concrete structure / easily compressive and deformable part, after spraying the concrete material between the steel members 11 adjacent to each other in the tunnel axial direction, the space between the easily compressive and deformable parts 12 adjacent to each other in the tunnel axial direction is sprayed. The compression deformation easy portion 22 may be installed in the. In this case, the concrete material may be sprayed with a space for installing the easily compressive and deformable portion 22, or a part of the concrete material is cut out after the concrete material is sprayed and the easily compressive and deformable portion 22 is installed. Space may be formed.

According to the above embodiment, the following effects are exhibited.

In the tunnel support structure 100, the easily compressive and deformable portion 22 has a plurality of precast blocks 23, and the plurality of precast blocks 23 have different strength characteristics. Therefore, the strength characteristics of the easily compressive and deformable portion 22 change according to the combination of the precast blocks 23. Therefore, the strength characteristics of the easily compressively deformable portion 22 can be adjusted at the time of construction of the tunnel support structure 100 by using the precast block 23 manufactured in advance before grasping the earth pressure characteristics of the ground, and the tunnel support structure 100 can be adjusted. It can be built efficiently.

Further, the plurality of precast blocks 23 have anisotropy in which the strength differs depending on the compression direction. Therefore, the strength characteristics of the easily compressive and deformable portion 22 can be finely adjusted according to the combination of the orientations of the precast blocks 23. Therefore, the strength characteristics of the concrete support portion 20 can be set more appropriately according to the earth pressure characteristics of the ground.

Further, the plurality of precast blocks 23 include a resin 23a and a fiber 23b that is blended with the resin 23a so that the orientation is biased in a predetermined direction to increase the compressive strength in the predetermined direction more than the compressive strength in the other direction. Therefore, the strength characteristics of the easily compressively deformable portion 22 are the precast block 23 in which the direction in which the direction of the fiber 23b is biased coincides with the compression direction, and the direction in which the direction of the fiber 23b is biased. It varies according to the ratio of the precast block 23, which is oriented so that another direction coincides with the compression direction. Therefore, the strength characteristics of the easily compressive and deformable portion 22 can be adjusted at the time of constructing the tunnel support structure 100, and the tunnel support structure 100 can be efficiently constructed.

Further, one precast block 23 in the easily compressive and deformable portion 22 has a different ratio of fibers 23b to resin 23a from the other precast blocks 23. Therefore, the strength characteristics of the easily compressive and deformable portion 22 can be adjusted more finely. Therefore, the strength characteristics of the concrete support portion 20 can be set more appropriately according to the earth pressure characteristics of the ground.

Further, a plurality of compressively deformable portions 22 are provided with the concrete structure 21 sandwiched between them in the circumferential direction of the tunnel, and one of the plurality of easily compressively deformable portions 22 is provided with a plurality of precast easily deformable portions 22. The combination of the orientations of the blocks 23 is different from the other easily compressive and deformable portions 22 located at intervals in the circumferential direction of the tunnel from the one easily compressive and deformable portion 22. Therefore, the concrete support portion 20 is provided with a plurality of compressively deformable portions 22 having different strength characteristics at intervals in the circumferential direction of the tunnel. The stability of the tunnel T can be improved by setting the strength characteristics of the easily compressive and deformable portion 22 according to the position in the tunnel circumferential direction.

Further, a plurality of easily compressive and deformable portions 22 are provided with a steel support portion 10 sandwiched between them in the tunnel axial direction, and one of the plurality of easily compressive and deformable portions 22 is a plurality of easily compressive and deformable portions 22. The combination of orientations of the precast block 23 is different from the other easily compressive and deformable portions 22 located at intervals in the tunnel axial direction from the one easily compressive and deformable portion 22. Therefore, in the tunnel support structure 100, a plurality of compressively deformable parts 12 having different strength characteristics are provided side by side in the tunnel axial direction with the steel support parts 10 sandwiched between them. The stability of the tunnel T can be improved by setting the strength characteristics of the easily compressive and deformable portion 22 according to the position in the tunnel axial direction.

Further, the tunnel support structure 100 is further provided with a compression deformation easy portion 12 which is provided adjacent to the steel member 11 in the tunnel circumferential direction and is easier to compress and deform in the tunnel circumferential direction as compared with the steel member 11. ing. Therefore, the steel support portion 10 exhibits a predetermined rigidity after allowing some deformation of the ground, like the concrete support portion 20. Therefore, the deformation of the ground can be converged and the tunnel T can be stabilized without overlapping the steel members 11 in the tunnel radial direction. As a result, the number of times the steel member 11 is constructed can be reduced, and the labor required for constructing the tunnel support structure 100 and the construction cost of the tunnel support structure 100 can be reduced.

In the method of constructing the tunnel support structure 100, a concrete structure / compression deformation is formed by providing a plurality of precast blocks 23 having different strength characteristics between steel support portions 10 adjacent to each other in the tunnel axial direction to form a compression deformation easy portion 22. Equipped with an easy part installation process. Therefore, the strength characteristics of the easily compressive and deformable portion 22 change according to the combination of the precast blocks 23. Therefore, the strength characteristics of the easily compressively deformable portion 22 can be adjusted at the time of construction of the tunnel support structure 100 by using the precast block 23 manufactured in advance before grasping the earth pressure characteristics of the ground, and the tunnel support structure 100 can be adjusted. It can be built efficiently.

Further, in the step of installing the concrete structure / easy compression / deformation part, the orientations of the plurality of precast blocks 23 are adjusted to adjust the strength characteristics of the easy compression / deformation part 22. Therefore, the strength characteristics of the easily compressive and deformable portion 22 are determined when the easily compressive and deformable portion 22 is installed. Therefore, the strength characteristic of the concrete support portion 20 can be set according to the earth pressure characteristic grasped by the excavation of the ground, and the stability of the tunnel T can be further improved.

Although the embodiments of the present invention have been described above, the above embodiments are only a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configurations of the above embodiments. Absent.

In the tunnel support structure 100, the plurality of precast blocks 23 in the easily compressive and deformable portion 22 are arranged in the tunnel axial direction, but the present invention is not limited to this form. FIG. 5A is a cross-sectional view showing a tunnel support structure 101 according to a modified example of the embodiment of the present invention. As shown in FIG. 5A, the easily compressively deformable portion 22 of the concrete support portion 20 may be formed by arranging precast blocks 23 having different strength characteristics depending on the compression direction in the tunnel circumferential direction. Similarly, the easily compressively deformable portion 12 of the steel support portion 10 may be formed by arranging precast blocks 23 having different strength characteristics depending on the compression direction in the tunnel circumferential direction.

In the tunnel support structure 100, a plurality of concrete structures 21 are provided at intervals in the tunnel circumferential direction, and compression deformation easy portions 22 are provided between the concrete structures 21 adjacent to each other in the tunnel circumferential direction. , The present invention is not limited to this form. FIG. 5B is a cross-sectional view showing a tunnel support structure 102 according to another modification of the embodiment of the present invention. As shown in FIG. 5B, the concrete support portion 20 includes one concrete structure 21, and the compressively deformable portion 22 is provided between the concrete structure 21 and the bottom surface 1a of the excavation pit 1. You may be. Although not shown, the steel support portion 10 includes one steel member 11, and the easily compressive deformation portion 12 may be provided between the steel member 11 and the bottom surface 1a of the excavation pit 1. Good.

In the tunnel support structure 100, the steel support portion 10 includes the steel member 11 and the easily compressively deformable portion 12, but the steel support portion 10 does not have to include the easily compressively deformable portion 12. That is, the steel support portion 10 may be formed only of the steel member 11.

The plurality of precast blocks 23 have anisotropy in which the strength differs depending on the compression direction, but the precast blocks 23 may not have anisotropy and only have different strength characteristics. That is, precast blocks 23 having different strengths are manufactured in advance, and in the concrete structure / compression deformation easy section installation step, the precast block 23 to be used for the compression deformation easy section 22 is selected, and the strength characteristics of the compression deformation easy section 22 are determined. You may adjust.

100, 101, 102 ... Tunnel support structure 1 ... Excavation pit 10 ... Steel support part 11 ... Steel member 12 ... Compressive deformation easy part (Steel support compression deformation easy part)
21 ... Concrete structure 22 ... Compressive deformation easy part 23 ... Precast block 23a ... Resin 23b ... Fiber T ... Tunnel

Claims (6)

It is a tunnel support structure
A plurality of steel support parts provided in the excavation pit at predetermined intervals in the tunnel axial direction and extending in the tunnel circumferential direction, and
A concrete structure provided between the plurality of steel supports and
The concrete structure is provided adjacent to the tunnel circumferential direction, and is provided with an easily compressive and deformable portion that is easily compressively deformed in the tunnel circumferential direction as compared with the concrete structure.
The easily compressive and deformable portion has a plurality of precast blocks, and has a plurality of precast blocks.
The plurality of precast blocks have different strength characteristics.
Tunnel support structure. The plurality of precast blocks have anisotropy in which the strength differs depending on the compression direction.
The tunnel support structure according to claim 1. The plurality of precast blocks include a resin and fibers blended in the resin so that the orientation is biased in a predetermined direction.
The tunnel support structure according to claim 1. The steel support section
The steel member extending in the circumferential direction of the tunnel and
Claim 1 is provided with a steel support compressive deformation easy portion which is provided adjacent to the steel member in the tunnel circumferential direction and is easier to compress and deform in the tunnel circumferential direction as compared with the steel member. The tunnel support structure according to any one of 3 to 3. It is a method of constructing a tunnel support structure.
The tunnel support structure is provided between a plurality of steel support portions provided in the excavation pit at predetermined intervals in the tunnel axial direction and extending in the tunnel circumferential direction, and concrete provided between the plurality of steel support portions. The structure is provided adjacent to the concrete structure in the circumferential direction of the tunnel and is easily compressively deformed as compared with the concrete structure. The easily compressively deformed portion has strength. It has multiple precast blocks with different characteristics and has multiple precast blocks.
The construction method is
A steel support section installation process in which the steel support section is installed at a predetermined interval in the tunnel axial direction from the already installed steel support section.
The concrete structure is provided between the steel support portions adjacent to each other in the tunnel axial direction, and the plurality of precast blocks are provided between the steel support portions adjacent to each other in the tunnel axial direction to compress and deform the concrete structure. It is equipped with a concrete structure that forms an easy part and an installation process of an easy part that is easily compressed and deformed.
How to build a tunnel support structure. The plurality of precast blocks have anisotropy in which the strength differs depending on the compression direction.
In the step of installing the concrete structure / easily compressive and deformable portion, the orientation of the plurality of precast blocks is adjusted to adjust the strength characteristics of the easily compressive and deformable portion in the circumferential direction of the tunnel.
The method for constructing a tunnel support structure according to claim 5.

Images