JP7294965B2 - Joint structure between steel shoring and inverted concrete - Google Patents

Description

The present invention relates to the improvement of the joint structure between steel shoring and invert concrete when excavating a mountain tunnel. It relates to a possible connection structure.

Conventionally, in mountain tunnel construction represented by the NATM construction method, especially when the ground is soft rock, or even if it is medium-hard rock, cracks have developed, rock bolts and In addition to supporting with concrete, steel supports are erected along the wall along the tunnel circumferential direction at intervals in the longitudinal direction of the tunnel.

On the other hand, for the inverted concrete placed on the bottom slab side of the tunnel, the period when the mechanical effect expected of the inverted concrete is required and the degree of its effect vary depending on the ground conditions. Normally, inverting is not required to produce a mechanical effect at a particularly early stage, but in cases where tunnel deformation continues for a long period of time, or in expansive ground, large deformation occurs immediately after excavation. In such cases, or in cases where the ground becomes plastic and excessive soil pressure is generated, the rigidity of the tunnel should be improved by connecting the steel shoring and the inverted concrete at an early stage to close the cross section. , the deformation needs to converge early.

As shown in FIGS. 6 and 7, conventionally, as a connection structure between a steel shoring 50 and an inverted concrete 51, at both ends of the inverted concrete 51, the thickness of the concrete is increased on the back side to form a steel structure. A structure in which the base end of the shoring 50 is placed has been exclusively adopted. Further, in order to strengthen the closed structure in the circumferential direction, as shown in FIG.

Furthermore, in Patent Document 1 below, as shown in FIG. 9, a footing concrete 53 that looks like a foundation is constructed at the lower end of a steel shoring 50, and the steel shoring 50 is built on the upper surface of this footing concrete. is placed thereon, and both ends of the invar concrete 51 are connected to the footing concrete 53 .

JP 2018-138738 A

By the measures described above, the steel shoring 50 and the inverted concrete 51 can be closed early in the circumferential direction, and a predetermined effect can be expected for strengthening the entire shoring and preventing subsidence.

However, as shown in FIG. 6, the steel shoring 50 and the inverted concrete 51 are not connected in the normal direction and are bent, so the axial force applied to the steel shoring 50 is not smoothly transmitted. issue was still unresolved. Therefore, depending on the amount of deformation of the natural ground or the amount of extrusion, there is a risk that the inverted concrete at the lower end of the steel shoring 50 will break.

Therefore, the main object of the present invention is to improve the joint structure between the steel shoring and the invert concrete when excavating a mountain tunnel. In addition to strengthening the overall strength and preventing subsidence, the structure is designed to smoothly transmit the load (axial force) from the shoring to the inverted concrete, thereby preventing the collapse of the invert concrete at the lower end of the shoring. It is in.

In order to solve the above problem, the present invention according to claim 1 includes steel shorings arranged along the tunnel circumferential direction at intervals in the tunnel longitudinal direction during excavation of the tunnel, and on the bottom plate side of the tunnel. A joint structure for joining invert concrete to be placed,
A reinforcing connecting member is provided continuously downward from the lower end of the steel shoring, and the reinforcing connecting member includes a shoring extending member extended from the lower end of the steel shoring, and a shoring extending member extending from the lower end of the steel shoring. An invert connecting member integrally attached to the tunnel side surface of the member and in contact with or embedded in the back surface of the invert concrete, and a base plate provided at the lower end of the shoring extension member and the invert connecting member,
There is provided a joint structure between a steel shoring and an invert concrete, characterized in that an invert integration means embedded in the invert concrete is provided on the invert contact surface of the invert connecting member.

In the invention according to claim 1, the reinforcing connecting member is provided continuously downward from the lower end portion of the steel shoring. This reinforcing connection member is integrally attached to the shoring extending member extending from the lower end of the steel shoring and the surface of this shoring extending member on the tunnel side, and contacts or contacts the back surface of the inverted concrete. The structure includes an embedded invert connecting member, and a base plate provided at the lower end of the shoring extension member and the invert connecting member, and the invert integrally embedded in the invert concrete on the invert contact surface of the invert connecting member. There is a means for converting.

Therefore, since the reinforcing connecting member firmly supports the load of the shoring during invert excavation, it is possible to prevent the shoring from sinking, so that the tunnel structure is stabilized until the invert concrete is placed, ensuring safety during construction. can be ensured. In addition, since the steel shoring and the inverted concrete form a closed cross-section through the reinforcing connection member, the stability of the tunnel structure against deformation during construction is improved. Once in service, a ring structure consisting of shoring, lining and inverted concrete will be formed, improving the long-term stability of the tunnel.

In the present invention, an invert connecting member, which contacts or is embedded in the back surface of the inverted concrete, is provided integrally with the tunnel-side surface of the shoring extension member. An invert integration means embedded in the invert concrete is provided on the invert contact surface of the invert connecting member. Therefore, it is possible to strengthen the entire shoring structure and prevent subsidence, and at the same time, the structure is such that the load (axial force) from the shoring structure can be transmitted to the invert, and the destruction of the invert at the lower end of the shoring structure can be prevented. Become.

As the present invention according to claim 2, the extending member for the shoring is a member having the same cross-sectional shape as the steel shoring, and extends from the lower end of the steel shoring toward the inside of the tunnel with a bending angle. There is provided a joint structure of steel shoring and inverted concrete according to claim 1.

The invention according to claim 2 is a preferred embodiment of the stretching member for shoring. Specifically, the extension member for the shoring is a member having the same cross-sectional shape as the steel shoring in order to smoothly transmit the axial force from the steel shoring. In addition, in order to make the invert contact surface of the invert connecting member easy to follow the back surface of the invert concrete, the steel support is extended from the lower end portion toward the inside of the tunnel with a bending angle. there is

As the present invention according to claim 3, there is provided a connection structure between a steel shoring and inverted concrete according to any one of claims 1 and 2, wherein the invert integration means is an L-shaped steel and/or a dowel. be.

In the third aspect of the invention, the invert integration means is specifically exemplified. Specifically, for example, an L-shaped steel and/or a dowel can be suitably used as the invert integration means.

As the present invention according to claim 4, the orientation angle of the invert contact surface of the invert connection member is approximated to the orientation angle of the back surface of the invert concrete, and at least the design invert thickness is within the arrangement range of the invert connection member. There is provided a joint structure between a steel shoring and inverted concrete according to any one of claims 1 to 3, wherein is ensured.

In the invention according to claim 4, a preferred arrangement mode of the invert connecting member is defined. Specifically, the orientation angle of the invert contact surface of the invert connecting member is made to approximate the orientation angle of the back surface of the invert concrete, and the design invert thickness is ensured at least within the arrangement range of the invert connecting member. It is desirable to

As the present invention according to claim 5, the joint portion between the steel shoring and the reinforcing connecting member includes a base plate provided at the lower end of the steel shoring and a joint plate provided at the top of the reinforcing connecting member. are superimposed and both are fastened with bolts and nuts.

The invention according to claim 5 defines an example of the joint structure between the steel shoring and the reinforcing connection member. Specifically, it is desirable to have a structure in which a base plate provided at the lower end of the steel shoring and a joint plate provided at the top of the reinforcing connection member are overlapped and fastened with bolts and nuts.

As described in detail above, according to the present invention, the joint structure between the steel shoring and the invert concrete is improved when excavating a mountain tunnel. Strengthening of the entire shoring and prevention of subsidence, while also having a structure that can smoothly transmit the load (axial force) from the shoring to the inverted concrete, prevent the destruction of the inverted concrete at the lower end of the shoring. become able to.

1 is a cross-sectional view of a tunnel showing a structure of a connecting portion between a steel shoring 2 and an inverted concrete 3 according to the present invention; FIG. FIG. 2 is an enlarged view of part A in FIG. 1; 1(A) is a front view, (B) is a side view, and (C) is a sectional view taken along line C-C of (B), showing a reinforcing connecting member 4 according to the present invention. 1(A) is a cross-sectional view, and (B) is a front view showing the procedure for constructing a reinforcing connecting member 4 according to the present invention. FIG. (A) is a front view and (B) is a side view showing a modification of the reinforcing connecting member 4. FIG. FIG. 3 is a cross-sectional view of a tunnel showing a joint structure between a conventional steel shoring 50 and inverted concrete 51; 7 is an enlarged view of part A in FIG. 6. FIG. It is an example (part 1) of reinforcement of a connecting portion between a steel shoring 50 and an inverted concrete 51. FIG. It is an example (part 2) of reinforcement of the connecting portion between the steel shoring 50 and the inverted concrete 51 .

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows steel shorings 2 placed along the tunnel circumferential direction at intervals in the longitudinal direction of the tunnel behind the lower half face during excavation work of a mountain tunnel 1, and placed on the bottom plate of the tunnel. By closing the invert concrete 3 at an early stage, a ring-shaped structure is constructed, and the load-bearing capacity against earth pressure, water pressure, etc. expected in the long term is added to improve structural stability. be.

In joining the steel shoring 2 and the invert concrete 2, as shown in detail in FIG. A reinforcing connecting member 4 is provided at the rear end position, and the steel shoring 2 and the inverted concrete 3 are joined by the reinforcing connecting member 4 . According to the reinforcing connecting member 4, the strength of the entire shoring can be strengthened and subsidence can be prevented. It can be prevented before it happens. In addition, on the inner hollow side of the tunnel of the steel shoring 2, the lining concrete 5 is poured after the excavation, so that a continuous concrete structure is constructed by the lining concrete 5 and the inverted concrete. will be

As shown in detail in FIG. 3, the reinforcing connecting member 4 is a member having substantially the same cross-sectional shape as the steel shoring 2 and bent from the lower end of the steel shoring 2 toward the inside of the tunnel. an invert connecting member 7 that is integrally attached to the surface of the shoring extension member 6 on the tunnel side and is in contact with or embedded in the back surface of the invert concrete 3; An invert integrating means 8 including these shoring extending members 6 and a base plate 9 provided at the lower end of the invert connecting member 7 and embedded in the invert concrete 3 is provided on the invert contact surface of the invert connecting member 7. There is.

The reinforcing connecting member 4 will be described in more detail below.

As shown in FIG. 3, the extension member 6 of the shoring is a member having substantially the same cross-sectional shape as the steel shoring 2, and is bent from the lower end of the steel shoring 2 toward the inside of the tunnel. It is a member extended with a corner. H-section steel is generally used as the steel support 2 . Therefore, H-shaped steel having the same cross section is suitably used as the shoring extension member 6 . Since the shoring extension member 6 is a member that transmits the axial force acting on the steel shoring 2, it is possible to efficiently transmit the axial force by forming the same cross-sectional shape.

The steel shoring 2 and the inverted concrete 3 are not connected in the normal direction, and have a shape that is greatly bent by interposing an arc-shaped wire with a small radius of curvature at the junction. Therefore, in order for the extension member 6 of the shoring to follow the inverted concrete 3 while smoothly transmitting the axial force, a bending angle α is formed from the lower end of the steel shoring 2 toward the inside of the tunnel. I'm holding it and stretching it. The bending angle α toward the inside of the tunnel with respect to the extending direction of the steel support 2 is preferably about 10 to 25°, preferably about 15 to 20°.

The invert connecting member 7 is integrally attached to the surface of the shoring extending member 6 on the tunnel side. Specifically, as shown in FIG. 3, a member having a substantially T-shaped cross section is used, and the length of the web (T-shaped longitudinal member) is gradually increased from the top to the bottom to create a side shape. It is designed to form a substantially triangular shape. As a result, the surface on the side of the invert concrete 2 (invert contact surface 7A) can be shaped to follow the back surface of the invert concrete 3, and can be in contact with or embedded in the back surface of the invert concrete 3.

An invert integration means 8 embedded in the invert concrete 3 is provided on the invert contact surface 7A of the invert connecting member 7 . As the invert integration means 8, L-shaped steel (equal or unequal sides) is used in this embodiment, and one side is fixed to the invert contact surface 7A by welding or the like. As shown in the figure, it is desirable that a plurality of the invert integrating means 8 be arranged in multiple stages in the vertical direction. In the illustrated example, they are arranged in four stages in the vertical direction.

A horizontally oriented joint plate 10 is provided at the top of the shoring extension member 6 and the invert connecting member 7, and a horizontally oriented base plate 9 is provided at the lower end.

The orientation angle θ (angle θ from the horizontal line) of the invert contact surface 7A of the invert connecting member 7 is preferably close to the orientation angle of the back surface of the invert concrete 3, and the invert connecting member shown in FIG. In the arrangement range S of 7, it is desirable that the thickness T of the inverted concrete 3 is at least the design inverted thickness.

The joining portion between the reinforcing connecting member 4 and the steel shoring 2 is formed by overlapping a base plate 2A provided at the lower end of the steel shoring 2 and a joint plate 10 provided at the top of the reinforcing connecting member 4. , are fastened together with bolts and nuts 11 .

By the way, when installing the reinforcing connecting member 4, as shown in FIG. It is desirable to install In practice, ground excavation (H) is performed so that the reinforcing connecting member 4 can be installed from the lower half of the wall, and the reinforcing connecting member 4 is installed at the same time as the steel shoring 2 is installed. This makes it possible to prevent the entire steel shoring 2 from sinking during invert excavation.

[Other form examples]
(1) In the above embodiment, the extending member 6 of the shoring is a member having the same cross-sectional shape as the steel shoring 2 and is bent from the lower end of the steel shoring 2 toward the inside of the tunnel. Although the members are elongated, members with different cross sections may be used as long as the axial force from the steel shoring 2 can be smoothly transmitted. It is also possible to arrange the steel shoring 2 at a straight linear position without a bent angle.

(2) In the above embodiment, L-shaped steel is used as the invert integrating means 8, but as shown in FIG. 5, a dowel 12 may be used together with or instead of this.

(3) In the above embodiment, the horizontally oriented joint plate 10 is provided above the shoring extending member 6 and the invert connecting member 7, but this is omitted and the steel shoring 2 is extended as it is. Alternatively, the extending member 6 for the shoring can be joined directly to the lower end of the steel shoring 2 by welding or the like. Also, as shown in FIG. 1, the upper half steel shoring 2A and the lower half steel shoring 2B are usually joined together by the spring line SL in many cases. It is also possible to have a structure integrated with the lower half steel shoring 2B.

DESCRIPTION OF SYMBOLS 1... Mountain tunnel, 2... Steel shoring, 3... Invert concrete, 4... Reinforcement connection member, 5... Lining concrete, 6... Extension member of shoring, 7... Invert connection member, 7A... Invert contact surface, 8 ... Invert integration means, 9 ... base plate, 10 ... joint plate, 11 ... bolt and nut, 12 ... dowel

Claims (5)

This joint structure is used to join the steel shoring, which is placed along the circumference of the tunnel at intervals in the longitudinal direction of the tunnel, and the invert concrete that is placed on the bottom slab side of the tunnel when the tunnel is excavated. There is
A reinforcing connecting member is provided continuously downward from the lower end of the steel shoring, and the reinforcing connecting member includes a shoring extending member extended from the lower end of the steel shoring, and a shoring extending member extending from the lower end of the steel shoring. An invert connecting member integrally attached to the tunnel side surface of the member and in contact with or embedded in the back surface of the invert concrete, and a base plate provided at the lower end of the shoring extension member and the invert connecting member,
A connection structure between a steel shoring and an invert concrete, wherein an invert integration means embedded in the invert concrete is provided on the invert contact surface of the invert connecting member. 2. The steel according to claim 1, wherein said extending member for shoring has the same cross-sectional shape as said steel shoring, and extends from the lower end of said steel shoring toward the inside of the tunnel with a bending angle. Joint structure between shoring and inverted concrete. 3. The joint structure of steel shoring and invert concrete according to claim 1, wherein said invert integration means is an L-shaped steel and/or a dowel. The orientation angle of the invert contact surface of the invert connecting member is approximated to the orientation angle of the back surface of the invert concrete, and at least the design invert thickness is ensured within the arrangement range of the invert connecting member. 3. The joint structure between steel shoring and inverted concrete according to any one of 3. The joint portion between the steel shoring and the reinforcing connecting member is formed by superimposing a base plate provided at the lower end of the steel shoring and a joint plate provided at the top of the reinforcing connecting member, and joining them together with bolts and nuts. 5. The joint structure between the steel shoring and the invert concrete according to any one of claims 1 to 4, wherein the structure is fastened by .

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