JP7444763B2 - Tunnel lining structure and tunnel construction method - Google Patents

Description

The present invention relates to a tunnel lining structure and a tunnel construction method.

In the construction of mountain tunnels such as NATM, the ground surface exposed by excavation is closed off with a shoring system that combines shotcrete, steel shoring, rock bolts, etc., and then a predetermined thickness is installed on the inner side of the shoring. It is common to pour concrete lining. Lining concrete is constructed continuously along the length of the tunnel by repeating the work of assembling the slide center (formwork) inside the tunnel and pouring concrete between the slide center and the shoring. .
In the conventional tunnel construction method, it is necessary to repeatedly move, assemble, and dismantle a large-scale slide center, which takes time and effort. Furthermore, since all concrete of a predetermined thickness is poured on site, it takes time to pour and cure the concrete.
If a precast member is used as a waste formwork instead of a slide center, the movement and disassembly of the formwork (slide center) can be omitted, and workability can be improved. Furthermore, the construction period can be shortened by reducing the amount of cast-in-place concrete. Here, Patent Document 1 discloses a construction method in which a precast panel is installed along the inner surface of an existing lining of a tunnel, and a gap between the precast panel and the existing lining is filled with a filler material.
The filler material filling the back side of the precast panel rises from the legs of the precast panel and is closed at the top of the precast panel. Therefore, when the filler is injected into the precast panel, an excessive bending moment acts on the precast panel near the top due to the lateral pressure caused by the filler.

JP2003-227296A

An object of the present invention is to propose a tunnel lining structure and a tunnel construction method that can reduce the labor during construction by using precast members and alleviate the cross-sectional force generated in the precast members. .

The tunnel lining structure of the present invention for solving the above problem includes: an arch-shaped precast lining provided along the inner surface of the tunnel; and a filler filled between the precast lining and the inner surface of the tunnel. and a shape-retaining material that suppresses deformation of the precast lining due to pressure when injecting the filler . The shape-retaining material is a columnar member made of concrete interposed between the precast lining and the inner surface of the tunnel at the top end of the precast lining, or the inside thereof is filled with a fluid or a cement-based solidifying material. It is a bag made of plastic. Further, one end of the shape-retaining material is in contact with the inner surface of the steel shoring, and the other end of the shape-retaining material is in contact with the outer surface of the precast lining.
Further, the tunnel construction method of the present invention includes an excavation step of excavating the ground, a shoring step of closing the surface of the ground exposed by the excavation of the ground with a shoring, and an arch-shaped construction along the inner surface of the shoring. The method includes a lining member installation step for installing a precast lining, and a filling step for filling a gap between the precast lining and the ground surface with a filler material, and in the supporting step, steel shoring is erected. At the same time, shotcrete is sprayed, and in the lining member installation process, a shape-retaining material consisting of a columnar member made of concrete that suppresses deformation of the precast lining due to the pressure during injection of filler is attached to one end of the inner surface of the steel shoring. and the other end is placed in contact with the outer surface of the precast lining.
According to this tunnel lining structure and tunnel construction method, since a precast lining is used, the labor required for assembling, demolding, and moving the formwork is reduced compared to when using formwork such as a slide center. It is possible to reduce the amount of waste and improve workability. Further, by using a composite structure of a precast lining with a predetermined quality and a filler (for example, cast-in-place concrete), the lining can be made thinner. Furthermore, since the shape-retaining material is provided, even when lateral pressure from the filler is applied, upward displacement near the top of the precast lining is suppressed, and as a result, bending that occurs in the precast lining is suppressed. The moment can be alleviated.

Note that the precast lining is preferably formed by combining a plurality of precast panels. In tunnels where construction space is limited, using precast panels with an easy-to-handle shape and weight can improve the efficiency of precast lining installation.
Further, as the shape-retaining material, for example, a filler member interposed between the precast lining and the inner surface of the tunnel at the top end of the precast lining can be used. As such a filling member, a concrete spacer, a height-adjustable spacer, or a bag filled with a fluid or a cement-based solidifying material can be used.
Furthermore, from the viewpoint of ensuring more reliable filling properties, it is desirable to use high fluidity concrete as the filling material.

According to the tunnel lining structure and tunnel construction method of the present invention, by using a precast member, it is possible to reduce the labor during construction and to alleviate the cross-sectional force generated in the precast member.

It is a cross-sectional view of the tunnel lining structure of the first embodiment. It is a longitudinal sectional view of the tunnel lining structure of the first embodiment. It is a flowchart of the tunnel construction method of a first embodiment. It is a perspective view showing an outline of a lining member installation process. It is a figure which shows the analysis result of a tunnel lining structure, Comprising: (a) is a displacement diagram of an Example, (b) is a displacement diagram of a comparative example. It is a figure which shows the analysis result of a tunnel lining structure, Comprising: (a) is a bending moment diagram of an Example, (b) is a bending moment diagram of a comparative example. It is a cross-sectional view of a tunnel lining structure of a second embodiment. It is a partially enlarged view showing a part of the tunnel lining structure of the second embodiment. (a) and (b) are cross-sectional views showing shape-retaining materials according to other embodiments.

In this embodiment, a case will be described in which the tunnel T is constructed using a mountain construction method such as NATM. In the mountain construction method, the work of excavating the ground G and advancing the face K of the tunnel T (the tip of the tunnel T), and the work of closing the ground G exposed by the excavation of the tunnel T with the support 2 are repeated. By doing so, a tunnel T of a predetermined length is formed. Furthermore, once the deformation of the surrounding ground of the tunnel T due to the excavation of the ground G has subsided, the tunnel lining structure 1 is constructed by forming the lining 3 inside the shoring 2 (on the inner side). . FIG. 1 shows a cross-sectional view of the tunnel lining structure 1 of this embodiment, and FIG. 2 shows a longitudinal cross-sectional view of the tunnel lining structure 1. As shown in FIG. 1, the tunnel lining structure 1 of this embodiment has an arched cross section and includes shoring 2 and a lining 3.
The shoring 2 is for quickly blocking the ground G exposed by the excavation of the tunnel T, and as shown in FIGS. 1 and 2, shotcrete 21 sprayed onto the ground G, It consists of steel supports 22 built at predetermined intervals in the axial direction of the tunnel, and rock bolts 23 driven into the ground G. The support structure of the support 2 shall be set according to the grade of the ground, and in the case of good ground G, the steel support 22 and the rock bolts 23 may be omitted. In addition, in the case of soft ground, auxiliary construction methods such as advance construction methods (for example, forepoling, pipe roofing, etc.) or ground improvement methods may be used instead of or in combination with rock bolts 23. There is also.

The lining 3 of this embodiment is formed along the inner surface of the shoring 2, and as shown in FIGS. material (backfilling material) 6.
The precast lining 4 has an arch shape and is provided with gaps along the inner surface of the shoring 2 (tunnel T).
The precast lining 4 is formed into an arch shape by combining a plurality of precast panels 41. The precast panel 41 is a panel (segment) made of reinforced concrete and has an arcuate cross-section depending on the cross-sectional shape of the tunnel. Joints are provided on the end faces of the precast panels 41, and the precast panels 41 are connected to each other by engaging the joints when the end faces of the precast panels 41 are butted together. In this embodiment, a wedge joint is employed as a joint of the precast panel 41 in the tunnel circumferential direction. In the precast lining 4, the joint portion of the precast panel 41 functions as a rotating spring, thereby alleviating the cross-sectional force. Further, in this embodiment, a pin insertion joint is employed as a joint of the precast panel 41 in the tunnel axis direction. The pin insertion joint is fitted by inserting a metal fitting protruding from the other precast panel 41 into a metal fitting embedded in one precast panel 41 .

The filling member 5 is a shape-retaining material for suppressing the deformation of the precast lining 4 due to the pressure when injecting the filler, and is a material that maintains the shape of the precast lining 4 and the shoring 2 ( (inner surface of the tunnel). As shown in FIG. 2, a plurality of filler members 5 are provided at predetermined intervals in the tunnel axis direction. The filling member 5 of this embodiment is a spacer made of concrete. The filler member 5 has a height equivalent to the gap between the precast lining 4 and the shoring 2 at the top end of the precast lining 4. The shape of the filler member 5 is not limited, and may be, for example, a square prism or a cylinder.

The filler 6 is a solidifying material (high fluidity concrete in this embodiment) filled in the gap between the precast lining 4 and the inner surface of the shoring 2 (tunnel T). After forming the precast lining 4, the filler 6 is pumped into the gap between the precast lining 4 and the shoring 2, and is cured for a predetermined period of time to develop the strength required for the concrete lining. Note that reinforcing bars may be arranged in the gap between the precast lining 4 and the shoring 2 as necessary.

The tunnel construction method will be explained below. FIG. 3 shows a flowchart of the tunnel construction method of this embodiment. The tunnel construction method of this embodiment includes an excavation step S1, a shoring step S2, a lining member installation step S3, and a filling step S4.
In the excavation process S1, the ground G is excavated and the face K is advanced. The method of excavating the ground G is not limited, and may be mechanical excavation or blast excavation.

In the shoring step S2, the surface of the ground exposed by excavating the ground G is closed with the shoring 2. In the shoring process S2, steel shoring 22 is erected along the ground G exposed by the excavation, and shotcrete 21 is sprayed. After spraying the shotcrete 21, rock bolts 23 are placed. Note that the shotcrete 21 may be sprayed in two parts: primary spraying and secondary spraying, before and after the steel shoring 22 is erected. The spraying thickness of the shotcrete 21, the composition of the shotcrete 21, etc. can be changed as appropriate depending on the ground conditions. Similarly, the specifications of the steel shoring 22 and the rock bolts 23 are determined depending on the ground condition (ground grade).

In the lining member installation step S3, an arch-shaped precast lining 4 is installed along the inner surface of the shoring 2. Precast lining 4 is formed by combining a plurality of precast panels 41. FIG. 4 is a diagram showing how the precast lining 4 is installed. When assembling the precast lining 4, the precast panel 41 is supported by the support machine M from the hollow side of the tunnel, as shown in FIG. In this embodiment, a so-called forklift truck having an arm that can move up and down is used as the support machine M. The support machine M holds a support frame M1 for supporting the precast panel 41, and arranges the precast panel 41 (precast lining 4) supported by the support frame M1 at a predetermined position.
In the lining member installation step S3, a filler member 5 is interposed between the precast lining 4 and the shoring 2 at the top end of the precast lining 4. The filler member 5 may be installed at a predetermined position by attaching it to the precast panel 41 constituting the top end of the precast lining 4 in advance, or it may be installed in the precast lining while assembling the precast lining 4. 4 and the shoring 2 may be interposed.

In the filling step S4, the gap between the precast lining 4 and the shoring 2 is filled with the filler 6. The filler 6 is injected into the gap between the precast lining 4 and the shoring 2 by pumping high fluidity concrete. In addition, when injecting the filler 6, the end face of the gap between the precast lining 4 and the shoring 2 (the tip side of the precast lining 4) is filled with the end plate. At this time, the precast lining 4 assembled in an arch shape is self-supporting.

According to the tunnel lining structure 1 and tunnel construction method of this embodiment, since the precast lining 4 is used, the assembly, demolding, and movement of the formwork are easier than when using formwork such as a slide center. It is possible to reduce the labor required for etc. and improve workability.
The composite structure of the precast lining 4 and the filler 6 can ensure structural performance equivalent to or better than existing linings.
Furthermore, if it is a precast product, high-strength concrete that is not suitable for cast-in-place can be used, and furthermore, it can be cured in water or in steam, so it is easy to improve the quality of the precast lining 4. By forming a composite structure of such high-quality precast lining 4 and filler 6 (for example, cast-in-place concrete), the lining can be made thinner.
Furthermore, since the filler member 5 is provided at the top end of the precast lining 4, even when lateral pressure from the filler 6 is applied, upward displacement near the top end of the precast lining 4 is suppressed. As a result, the bending moment generated in the precast lining 4 can be alleviated.
Further, by forming the precast lining 4 by combining a plurality of precast panels 41, it is possible to improve the efficiency of installing the precast lining 4 in a tunnel where construction space is limited.
Furthermore, since high fluidity concrete is used for the filler 6, it has excellent filling properties.

Below, the results of an analysis performed on the tunnel lining structure 1 of this embodiment will be shown. In this analysis, the cross-sectional force ( displacement and bending moment) were calculated. Furthermore, as a comparative example, the cross-sectional force of the precast lining 4 that would occur when the filler member 5 was not installed was also calculated. FIG. 5(a) shows the displacement amount of the example calculated by analysis, and FIG. 5(b) shows the displacement amount of the comparative example. Further, FIG. 6(a) shows a bending moment diagram of the example, and FIG. 6(b) shows a bending moment diagram of a comparative example.

As shown in FIG. 5(b), in the comparative example, the lateral pressure during concrete pouring resulted in large displacements of 15.0 mm at the legs and 11.6 mm at the top of the precast lining 4. On the other hand, in the example, as shown in Fig. 5(a), the amount of displacement can be significantly reduced to 3.7 mm at the legs, 2.8 mm at the shoulders, and 0 mm at the top of the precast lining 4. was completed.
In addition, as shown in FIG. 6(b), in the comparative example, a bending moment of 63.9 kNm was generated at the leg portion and -33.2 kNm at the top portion, whereas in the example, as shown in FIG. As shown in Figure 2, it was 39.8 kNm at the legs and -20.0 kNm at the shoulders. In this way, the bending moment can also be significantly reduced in the legs and the upper half of the tunnel.

<Second embodiment>
In the second embodiment, similarly to the first embodiment, when constructing the tunnel T by forming the lining 3 inside the shoring 2 (inner space side) and constructing the tunnel lining structure 1. I will explain about it. FIG. 7 shows a tunnel lining structure 1 of the second embodiment. As shown in FIG. 7, the tunnel lining structure 1 of the second embodiment uses a spacer 51 attached to a precast panel 41 as a shape-retaining material, and the filling member 5 is used as a precast lining 4 and a shoring 2. This is different from the tunnel lining structure 1 of Cited Document 1, which is interposed between the two. The details of the shoring 2 are the same as the shoring 2 of the first embodiment, so a detailed explanation will be omitted.

The lining 3 of this embodiment of the second embodiment is formed along the inner surface of the shoring 2, and includes a precast lining 4, a spacer 51 (shape retaining material), and a filler (backfilling material) 6. It is equipped with Note that the details of the filler 6 are the same as the filler 6 of the first embodiment, so a detailed explanation will be omitted.
The precast lining 4 has an arch shape and is provided with gaps along the inner surface of the shoring 2 (tunnel T).
The precast lining 4 is formed into an arch shape by combining a plurality of precast panels 41. As shown in FIG. 8(a), the precast panel 41 has bolt holes 42 threaded (female threads) formed on the inner surface. Bolt holes 42 pass through precast panel 41. A recess 43 having an inner diameter larger than the inner diameter of the bolt hole 42 is formed at the inner end of the bolt hole 42 . As shown in FIG. 8(b), a lid member 44 can be attached to the recess 43 from the inner cavity side of the precast lining 4. In this embodiment, one bolt hole 42 is formed in each precast panel 41, but the number and arrangement of bolt holes formed in the precast panel 41 are not limited. The other details of the precast panel 41 (precast lining 4) are the same as those shown in the first embodiment, so a detailed explanation will be omitted.

The spacer 51 is a shape-retaining material for suppressing the deformation of the precast lining 4 due to the pressure when injecting the filler, and as shown in FIG. The proximal end is screwed on. A plate member 52 having a larger cross section than the spacer 51 is fixed to the tip of the spacer 51 . Further, an engagement hole 53 having a polygonal cross section for engaging a tightening jig is opened in the base end surface of the spacer 51. The spacer 51 is inserted into the engagement hole 53 with the tightening jig 54 inserted, and by rotating the tightening jig, the protrusion length from the precast panel 41 is changed, and the plate material 52 is attached to the shoring 2. Let them come into contact with you.
In this embodiment, a plurality of spacers 51 are provided in the circumferential direction of the tunnel, but the number and arrangement of spacers 51 are not limited. may be set. Moreover, the spacer 51 does not necessarily need to be brought into contact with the shoring 2. Further, the plate material 52 may be omitted.

The tunnel construction method of the second embodiment will be described below. Similar to the first embodiment, the tunnel construction method of this embodiment includes an excavation step S1, a shoring step S2, a lining member installation step S3, and a filling step S4. The details of the excavation process S1, the shoring process S2, and the filling process S4 are the same as those in the first embodiment, so detailed explanations will be omitted.
In the lining member installation step S3, an arch-shaped precast lining 4 is installed along the inner surface of the shoring 2. Precast lining 4 is formed by combining a plurality of precast panels 41. In the lining member installation step S3, the spacers 51 are adjusted as the precast lining 4 is formed. A spacer 51 is attached to the bolt hole 42 of the precast panel 41 in advance. After the precast panel 41 is placed in a predetermined position, the protruding length of the spacer 51 is adjusted from the inner space via the tightening jig 54 to bring the plate material 52 into contact with the shoring 2. The precast lining 4 has a plurality of spacers 51 arranged in the circumferential direction brought into contact with the shoring 2, thereby ensuring a reaction force from the shoring 2 that can resist the pressure at the time of filling material injection. Can be assembled. When the adjustment of the spacer 51 is completed, the tightening jig 54 is removed and the cover member 44 is attached to the recess 43. The lid member 44 has a threaded portion 45 that can be screwed into the bolt hole 42 and a lid portion 46 that has the same shape as the recess 43. By screwing the threaded portion 45 into the bolt hole 42, the lid can be closed. The bolt hole 42 (recess 43) is covered by the portion 46. At this time, a water stop material is interposed between the lid member 44 and the recess 43 if necessary.
The other details of the lining member installation step S3 are the same as those shown in the first embodiment, so detailed explanation will be omitted.

According to the tunnel lining structure 1 and tunnel construction method of the second embodiment, since the spacer 51 is provided protruding from the precast panel 41, the displacement of the precast lining 4 is prevented even when lateral pressure from the filler 6 is applied. As a result, the bending moment generated in the precast lining 4 can be alleviated.
Since the bolt holes 42 are covered by the cover material 44, penetration of underground water is suppressed.
The effects of the other tunnel lining structure 1 of the second embodiment are similar to those of the tunnel lining structure 1 of the first embodiment, so detailed explanations will be omitted.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and each of the above-mentioned components can be modified as appropriate without departing from the spirit of the present invention.
In the first embodiment, a case where a concrete member is used as the filler member 5 has been described, but the members constituting the filler member 5 are not limited, and for example, a height-adjustable spacer may be used. good. If the height of the filler member 5 is adjustable, it can follow changes in the size of the gap between the precast lining 4 and the shoring 2 due to construction errors or the like. Further, the filler member 5 may be a bag body filled with the filler material 6 inside. According to the filler member 5, it is possible to follow changes in the size of the gap between the precast lining 4 and the shoring 2, and the filler member 5 can be easily installed. That is, after inserting an injection tube with a bag at its tip into the gap and setting the bag at a predetermined position, the bag is filled with a cement-based solidifying material (the same material as the filler 6 may be used). Thus, the filling member 5 can be formed. If the bag body is filled with a fluid such as water, the fluid can be discharged from the bag body and the bag body can be removed when the filler 6 has been injected to a predetermined height on the back side of the precast lining 4. You can also do it.

In the second embodiment, the protrusion length of the spacer 51 is adjusted by engaging the tightening jig 54 with the engagement hole 53 having a polygonal cross section formed in the base end surface of the spacer 51. The hole 53 may be a female screw threaded on the inner surface. In this case, a male bolt having a head is screwed into the engagement hole 53 from the inner space side of the precast panel 41, and the protruding length of the spacer 51 is adjusted by rotating the male bolt. After the filler 6 hardens, the male bolt is pulled out from the engagement hole 53, thereby eliminating the protruding portion on the tunnel inner space side. By doing so, the spacer 51 can be installed using a highly versatile male bolt without requiring a dedicated tightening jig.

The shape-retaining material is not limited to those shown in the above embodiments (the filling member 5 and the spacer 51), and for example, as shown in FIG. 9(a), the shape-retaining material is It may also be a suspended weight 55. Moreover, the weight 55 may be a weight 55 provided so as to apply a downward force to the top of the breakcast lining 4 via a wire 56 or the like, as shown in FIG. 9(b). In this way, by installing the weight 55 at the top of the precast lining 4, it is possible to suppress the vertical displacement that occurs at the top of the precast lining 4 due to the lateral pressure when the filler is injected.

In the embodiment described above, the precast panels 41 are assembled inside the tunnel to form the precast lining 4, but the precast lining 4 assembled outside the tunnel may be carried into the tunnel.
The method of supporting the precast lining 4 in the lining member installation step S3 is not limited to using a forklift; for example, other supporting machines M may be used, or a frame or the like may be installed. .
The filler 6 may be injected through an injection hole formed in the precast lining 4, or may be injected through an injection hole formed in an end plate provided on the end surface of the precast lining 4.
The joint structure between precast panels 41 is not limited.

1 Tunnel lining structure 2 Shoring 3 Lining 4 Precast lining 41 Precast panel 5 Filling member 6 Filling material G Earth T Tunnel

Claims (4)

An arch-shaped precast lining installed along the inner surface of the tunnel,
a filler filled between the precast lining and the tunnel inner surface;
A tunnel lining structure comprising: a shape retaining material that suppresses deformation of the precast lining due to pressure during injection of filler,
The shape retaining material is a concrete columnar member interposed between the precast lining and the inner surface of the tunnel at the top end of the precast lining, or the inside thereof is filled with a fluid or a cement solidification material. It is a bag body that has been
A tunnel lining structure, wherein one end of the shape-retaining material is in contact with an inner surface of a steel shoring, and the other end of the shape-retaining material is in contact with an outer surface of the precast lining. The tunnel lining structure according to claim 1, wherein the precast lining is formed by combining a plurality of precast panels. The tunnel lining structure according to claim 1 or 2 , wherein the filler is high fluidity concrete. An excavation process to excavate the ground;
A shoring process in which the ground surface exposed by excavation of the ground is closed with shoring;
a lining member installation step of installing an arch-shaped precast lining along the inner surface of the shoring;
A tunnel construction method comprising a filling step of filling a gap between the precast lining and the ground surface with a filler,
In the shoring process, steel shoring is erected and shotcrete is sprayed,
In the lining member installation step, one end of a shape-retaining material made of a concrete columnar member that suppresses deformation of the precast lining due to pressure during injection of filler material is brought into contact with the inner surface of the steel shoring. A tunnel construction method, characterized in that the other end of the precast lining is placed in contact with the outer surface of the precast lining.

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