T-shaped damping inverted arch structure for tunnel

Abstract

The application discloses a T-shaped damping inverted arch structure for a tunnel, which comprises a concrete partition wall, a drainage pipeline, a grid, a gravel layer, a concrete base and a spring damping device. According to the equal stress axis ratio theory, the excavation depth of the inverted arch structure is determined, the stability of the tunnel is ensured, the excavation positions are few, and the excavation disturbance area of the tunnel is reduced. The rubber concrete partition wall has a certain horizontal expansion and contraction, plays a damping role, and reduces the extrusion of the horizontal ground stress on the tunnel bottom, thereby reducing the tunnel bottom heave. The gravel layer arranged at the tunnel bottom uniformly disperses the force from the vehicle on the concrete base to the tunnel bottom, and is also beneficial to the drainage in the tunnel. The inverted arch structure adopts the rigid-flexible combination mode, provides a certain deformation space for the surrounding rock of the tunnel bottom, improves the stability of the tunnel bottom, and effectively controls the tunnel bottom heave.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel construction, in particular to a T-shaped damping inverted arch structure for a tunnel. BACKGROUND

[0002] With the rapid development of China's economy, the role of transportation is becoming increasingly critical, and the requirements for roads are also increasing. Many highway tunnels are multi-lane large-span tunnels. Large-span tunnels have high requirements for construction and tunnel structure stability. In order to reduce the damage caused by tunnel floor heave, inverted arches are often used to set the tunnel floor. Due to the large span of the tunnel, the curvature of the inverted arch is required to be large, which means that the tunnel excavation workload is increased.

[0003] At present, the prevention and treatment of tunnel floor heave disease mostly adopts the method of anchoring. Invention patent CN111502706A discloses a tunnel inverted arch structure and method suitable for floor heave deformation control. A plurality of energy-absorbing anchor rods are arranged at the tunnel bottom to improve the ability of the tunnel bottom to resist deformation. However, for complex stratified rock mass, the surrounding rock structure is diverse, the soft interlayer and stratification are very developed, and the stability is very poor, which cannot guarantee the supporting effect of the anchor rod. Moreover, the anchor rods of the tunnel inverted arch structure are arranged perpendicular to the inverted arch surface, which cannot constrain the tangential deformation of the tunnel bottom. Invention patent CN107630706A discloses a tunnel bottom structure and construction method for eliminating tunnel inverted arch uplift in high ground pressure areas. A plurality of pressure relief holes are arranged at the tunnel bottom for excavation and backfilling with gravel to release ground stress. Although this method has a simple structure, arranging pressure relief holes in a large area at the tunnel bottom not only increases the construction workload, but also causes stress redistribution, which increases the damage and disturbance area of the surrounding rock mass and reduces the integrity of the surrounding rock mass. SUMMARY

[0004] To solve the problem of structural damage caused by large floor heave amplitude of large-span tunnel inverted arches, the present application provides a T-shaped damping inverted arch structure for a tunnel. The inverted arch structure adopts a rigid-flexible combination mode, giving the tunnel surrounding rock a certain deformation space to release the strain energy generated by high ground stress. When the concrete retaining wall deforms to the limit, it takes on the role of resisting deformation, making the tunnel bottom segmented in the horizontal direction and improving the stability of the tunnel bottom, effectively controlling the tunnel floor heave.

[0005] In order to achieve the above object, the present application is realized by the technical scheme as follows: a T-shaped damping inverted arch structure for a tunnel is designed, characterized in that the inverted arch structure comprises a concrete partition wall, a drainage pipeline, a grid, a gravel layer, a concrete base and a spring damping device, wherein the concrete base, the gravel layer, the grid, the drainage pipeline and the concrete partition wall are sequentially arranged from top to bottom, the width of the concrete base is smaller than that of the gravel layer, and the concrete base is arranged in the middle of the top surface of the gravel layer; the grid is laid in the middle of the bottom surface of the gravel layer, the top end of the drainage pipeline is connected with the middle of the bottom surface of the grid, and the bottom of the drainage pipeline is connected with the top surface of the concrete partition wall; the width of the grid is not less than that of the drainage pipeline, and the width of the drainage pipeline is equal to that of the concrete partition wall;

[0006] The spring damping device is arranged between the two sides of the concrete base and the side walls of the tunnel, and the base and the movable end of the spring damping device are in contact with one side of the concrete base and the side wall of the tunnel on the same side, respectively.

[0007] The drainage pipeline is a space with the same width as the concrete partition wall, which is surrounded by the bottom surface of the grid, the top surface of the concrete partition wall and the rock mass above the two sides of the top of the concrete partition wall.

[0008] The lengths of the concrete partition wall, the drainage pipeline, the grid, the gravel layer and the concrete base are equal to the length of the tunnel.

[0009] Compared with the prior art, the present application has the following beneficial effects: the T-shaped damping inverted arch structure for a tunnel designed in the present application first determines the excavation depth according to the equal stress axis ratio theory, ensures the stability of the tunnel, and has fewer excavation positions, avoids excessive disturbance to the surrounding rock, reduces the excavation disturbance area of the tunnel and maintains the integrity of the surrounding rock; secondly, the rubber concrete partition wall has a certain horizontal direction elasticity and plays a damping role, reducing the extrusion of the horizontal ground stress on the tunnel bottom and causing the tunnel bottom to swell; finally, the gravel layer arranged at the tunnel bottom can uniformly disperse the force from the vehicle on the concrete base to the tunnel bottom, which is also conducive to the drainage in the tunnel. The inverted arch structure adopts a rigid-flexible combination mode, gives the surrounding rock of the tunnel bottom a certain deformation space, releases the strain energy generated by high ground stress, and when the concrete retaining wall deforms to the limit, plays a role in resisting deformation, divides the tunnel bottom in the horizontal direction, improves the stability of the tunnel bottom and effectively controls the tunnel bottom swelling. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 The figure is a cross-sectional structure diagram of an embodiment of the T-shaped damping inverted arch structure for a tunnel (i.e. a structure diagram on the tunnel excavation section, a vertical cross-sectional view in the tunnel width direction).

[0011] Figure 2Fig. 1 is a schematic diagram of tunnel excavation section size of an embodiment of the T-shaped damping inverted arch structure for tunnel of the present application.

[0012] Figure 3 Fig. 2 is a tunnel bottom plate vertical displacement curve diagram of Model 2 in Embodiment 1 of the T-shaped damping inverted arch structure for tunnel of the present application and other two models (Model 1, Model 3) obtained by numerical simulation.

[0013] Figure 4 Fig. 3 is a displacement cloud diagram of tunnel bottom plate of different tunnel models obtained by numerical simulation, wherein, Figure 4 (1) in Fig. 3 is a displacement cloud diagram of tunnel bottom plate of Model 1, Figure 4 (2) in Fig. 3 is a displacement cloud diagram of tunnel bottom plate of Model 2, Figure 4 (3) in Fig. 3 is a displacement cloud diagram of tunnel bottom plate of Model 3 (a gray scale diagram of a color diagram, in the actual result diagram, the upper half of the middle part of the diagram is a blue gradient result, corresponding to the lower part of the left color scale; the lower half of the middle part of the diagram is a red gradient result, corresponding to the upper part of the left color scale).

[0014] In the drawings: 1 - concrete partition wall, 2 - drainage pipeline, 3 - grid, 4 - gravel layer, 5 - concrete base, 6 - spring damping device. DETAILED DESCRIPTION

[0015] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0016] The present application provides a T-shaped damping inverted arch structure (referred to as inverted arch structure, see Figure 1 ) for tunnel, which comprises a concrete partition wall 1, a drainage pipeline 2, a grid 3, a gravel layer 4, a concrete base 5 and a spring damping device 6, wherein the concrete base 5, the gravel layer 4, the grid 3, the drainage pipeline 2 and the concrete partition wall 1 are sequentially arranged from top to bottom, the width of the concrete base 5 is smaller than the width of the gravel layer 4, and the concrete base 5 is arranged at the center of the top surface of the gravel layer 4; the grid 3 is laid on the center of the bottom surface of the gravel layer 4, the top end of the drainage pipeline 2 is connected with the middle part of the bottom surface of the grid 3, and the bottom of the drainage pipeline 2 is connected with the top surface of the concrete partition wall 1. The width of the grid 3 is not less than the width of the drainage pipeline 2, and the width of the drainage pipeline 2 is equal to the width of the concrete partition wall 1. The grid 3 prevents the gravel layer 4 from blocking the drainage pipeline 2.

[0017] The spring damping device 6 is arranged between the concrete base 5 and the tunnel side wall on both sides, and the base and the movable end of the spring damping device 6 are in contact with one side of the concrete base 5 and the tunnel side wall on the same side, respectively. The spring damping device 6 is uniformly arranged along the length direction of the tunnel.

[0018] The maximum compression amount of the spring damping device 6 is less than the safety allowable deformation amount of the tunnel.

[0019] The drainage pipeline is a space with the same width as the concrete partition wall 1, which is surrounded by the bottom surface of the grid 3, the top surface of the concrete partition wall 1, and the rock mass above the two sides of the top of the concrete partition wall 1.

[0020] The lengths of the concrete partition wall 1, the drainage pipeline 2, the grid 3, the gravel layer 4, and the concrete base 5 are equal to the length of the tunnel.

[0021] The bottom surface of the gravel layer 4 is a curved surface, and the cross section of the bottom surface in the vertical direction (i.e., the tunnel excavation section, as shown in FIG. 1) is a circular arc that is convex downward. Figure 1

[0022] The concrete partition wall 1 is rubber concrete and has a certain horizontal extension, which plays a damping role. The width of the concrete partition wall 1 is determined according to the safety allowable deformation amount of the tunnel and the deformation rate of the rubber concrete. The deformation amount of the concrete partition wall 1 is the product of the width and the deformation rate, and the value should be less than the safety allowable deformation amount of the tunnel.

[0023] The height of the concrete partition wall 1 is determined by the width and height of the tunnel excavation section, and the ratio of the horizontal load to the vertical load of the tunnel. According to the equal stress axis ratio theory, for an elliptical tunnel, the stability of the tunnel engineering is the strongest when the ratio of the vertical axis to the horizontal axis of the tunnel is equal to the ratio of the vertical load to the horizontal load. The specific determination steps are as follows: ① Obtain the ratio λ of the horizontal load to the vertical load of the tunnel excavation position in advance; ② Determine the maximum width a and height h of the tunnel excavation section according to actual needs; ③ According to the equal stress axis ratio theory, Determine the tunnel bottom excavation depth x, which is the sum of the height of the concrete partition wall 1 and the height of the drainage pipeline 2.

[0024] The gravel particle size used in the gravel layer 4 should be 3 cm to 7 cm, the density ≥1.6 g / cm 3 , the thickness of the gravel layer 4 ≥15 cm, and the support stiffness ≥70 kN / mm, so as to ensure the support and shock absorption effects of the gravel layer 4. The thickness of the gravel layer 4 refers to the distance from the lowest point of the bottom surface to the highest point of the top surface.

[0025] The concrete base 5 uses cast-in-place reinforced concrete, and the thickness is ≥50 cm and greater than 0.1a (a is the maximum width of the tunnel excavation section).

[0026] Example 1

[0027] This embodiment provides a T-shaped damping inverted arch structure for a tunnel. The inverted arch structure is as described above, and the elastic modulus of the concrete partition wall is 0.2 times that of the surrounding rock (i.e., the rock mass below the gravel layer 4). The tunnel provided with the inverted arch structure is model 2.​

[0028] The setting model 1 is a horseshoe-shaped tunnel with the upper arch being semicircular, and the setting model 3 is a circular tunnel.

[0029] The deformation of surrounding rock of different models is studied by numerical simulation, in the performance research test, the influence of the upper concrete base and the gravel layer is ignored, only the vertical displacement of the bottom plate of different excavation structures under the same geological condition is calculated. Assuming that the ratio of horizontal stress to vertical stress at the tunnel excavation position is λ=1, the width of the three tunnel models is 15m, the vertical displacement curve and the vertical displacement nephogram of the tunnel bottom plate under the action of ground stress are shown in Figure 3 and Figure 4 It can be seen that the arching displacement of the tunnel bottom plate of model 1 is the largest, and the maximum vertical displacement points of model 2 and model 3 are not at the same position, but the displacement is basically the same, according to the equal stress axis ratio theory, model 3 is the most stable excavation method, but for large-span tunnels, the excavation amount of model 3 is too large, and model 2 can achieve the same effect as model 3 under the condition of little excavation amount, which reduces the construction amount and achieves the ideal effect.

[0030] The unmentioned part of the present application is applicable to the prior art.

Claims

1. A T-shaped damping invert arch structure for tunnels, characterized in that, The inverted arch structure includes a concrete partition wall, drainage pipes, a grid mesh, a crushed stone layer, a concrete base, and a spring damping device. The concrete base, crushed stone layer, grid mesh, drainage pipes, and concrete partition wall are arranged sequentially from top to bottom. The width of the concrete base is smaller than the width of the crushed stone layer, and the concrete base is centrally located at the top center of the crushed stone layer. The grid mesh is laid at the bottom center of the crushed stone layer. The top of the drainage pipe connects to the middle of the bottom surface of the grid mesh, and the bottom of the drainage pipe connects to the top surface of the concrete partition wall. The width of the grid mesh is not less than the width of the drainage pipe, and the width of the drainage pipe is equal to the width of the concrete partition wall. Spring damping devices are installed between the concrete base and the tunnel sidewall on both sides. The base and movable end of the spring damping device contact one side of the concrete base and the tunnel sidewall on the same side, respectively. The drainage pipe is a space of the same width as the concrete partition wall, enclosed by the bottom surface of the grid mesh, the top surface of the concrete partition wall, and the rock mass above the top two sides of the concrete partition wall. The lengths of the concrete partition walls, drainage pipes, grid mesh, crushed stone layer, and concrete base are all equal to the length of the tunnel. The maximum compression of the spring damping device is less than the allowable deformation for tunnel safety.

2. The T-shaped damping invert arch structure for tunnels according to claim 1, characterized in that, The bottom surface of the crushed stone layer is curved, and the bottom surface is a downward-convex arc in its vertical cross-section.

3. A T-shaped damping invert arch structure for tunnels according to claim 1, characterized in that, The spring damping devices are evenly arranged along the length of the tunnel.

4. A T-shaped damping invert arch structure for tunnels according to claim 1, characterized in that, The concrete partition wall is made of rubber concrete, which has a certain degree of horizontal expansion and contraction, thus playing a damping role.

5. A T-shaped damping invert arch structure for tunnels according to claim 4, characterized in that, The width of the concrete partition wall is determined based on the allowable deformation of the tunnel and the deformation rate of the rubber concrete. The deformation of the concrete partition wall is the width multiplied by the deformation rate, and its value is less than the allowable deformation of the tunnel.

6. A T-shaped damping invert arch structure for tunnels according to claim 1, characterized in that, The height of the concrete partition wall is determined by the width and height of the tunnel excavation section and the ratio of the horizontal load to the vertical load of the tunnel. The specific determination steps are as follows: ① Obtain the ratio of the horizontal load to the vertical load at the tunnel excavation location through advance survey. ; ② Determine the maximum width of the tunnel excavation section according to actual needs. a and height h ③ According to the theory of equal stress axis ratio, Determine the depth of tunnel bottom excavation x Tunnel bottom excavation depth x It is the sum of the height of the concrete partition wall and the height of the drainage pipe.

7. A T-shaped damping invert arch structure for tunnels according to claim 1, characterized in that, The crushed stone layer uses crushed stone with a particle size of 3cm to 7cm and a density of ≥1.6g / cm³. 3 .

8. A T-shaped damping invert arch structure for tunnels according to claim 1, characterized in that, The thickness of the crushed stone layer is ≥15cm, and the supporting stiffness is ≥70kN / mm.

9. A T-shaped damping invert arch structure for tunnels according to claim 1, characterized in that, The concrete base is made of cast-in-place reinforced concrete with a thickness of ≥50cm and greater than 0.1 times the maximum width of the tunnel excavation section.

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