Tunnel circumferential blind pipe protection structure for weak surrounding rock stratum

Abstract

The utility model discloses a tunnel annular blind pipe protection structure for a weak surrounding rock stratum, which is arranged between a primary support concrete layer and a lining layer and comprises a blind pipe groove carved on the surface of the primary support concrete layer, the shape of the interior of the blind pipe groove is similar to that of an annular blind pipe to be installed, the inner diameter of the blind pipe groove is 1-2cm larger than the outer diameter of the annular blind pipe, and the inner diameter of the blind pipe groove is 1-2cm larger than the outer diameter of the annular blind pipe. Gaps among the blind pipes, the grooves and the linings are filled with non-fine concrete; a waterproof plate is laid on the opening side of the blind pipe groove, the tail end of the annular blind pipe penetrates through the waterproof plate to enter the lining layer, and a saddle-shaped rubber gasket is glued to the penetrating-connecting position of the waterproof plate and tightly connected to the periphery of the annular blind pipe in a clamped mode. The annular blind pipe protection structure can effectively avoid the problem of unsmooth drainage caused by extrusion deformation of the blind pipe due to pouring vibration of lining concrete; and meanwhile, the blind pipe is arranged in the groove and does not invade into the lining structure any more, the groove can restrain dislocation of the blind pipe, the defects that the lining is thinned and cut, is not thick enough, is disengaged and the like can be overcome, and the bearing performance of the lining can be improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of tunnels and underground engineering, and relates to a tunnel annular blind pipe protection structure used in soft surrounding rock formations. Background Art

[0002] In tunnel construction, the initial support shotcrete is usually sprayed to the designed thickness to level the surface, and then an annular blind pipe is laid close to the surface. The end of the annular blind pipe directly penetrates the waterproof board and enters the inner trench of the tunnel. However, practice has shown that this approach can cause local damage to the blind pipe, local voids and insufficient thickness of the lining, and poor tunnel drainage. This is especially true in soft strata such as loess, mudstone, and other geologically complex formations. Once voids, insufficient thickness, and water leakage occur in the lining, the tunnel's bearing capacity will continue to deteriorate.

[0003] The shortcomings of conventional practices are as follows:

[0004] 1) After the annular blind pipe is laid on a flat primary support surface, direct pouring and vibration of the lining concrete will cause a large impact and extrusion on the blind pipe, causing deformation of the blind pipe and resulting in poor drainage in the local area of ​​the blind pipe;

[0005] 2) The lining design thickness and limits are fixed, and concrete is poured directly against the primary support surface. This will inevitably cause blind pipes to intrude into the lining structure, thinning the lining and cutting the lining into multiple segments. If the blind pipes shift during lining pouring and vibration, this will cause voids and looseness behind the lining, which will weaken the lining's bearing capacity to a certain extent and affect tunnel operation safety.

[0006] 3) The end of the blind pipe directly penetrates the waterproof board and enters the inner trench of the tunnel. The water in the external bedrock fissures will penetrate into the tunnel along the puncture surface, destroying the overall waterproof performance of the waterproof board.

[0007] In summary, whether annular blind pipes can be effectively installed in loess, mudstone and other soft strata with complex geological conditions has become an important factor affecting the safety of tunnel operations in the later stages, and this issue needs to be urgently addressed. Utility Model Content

[0008] The purpose of the utility model is to provide a tunnel annular blind pipe protection structure for soft surrounding rock formations, so as to overcome the shortcomings of the annular blind pipe being squeezed and deformed, the lining being hollow and not thick enough in conventional practices, and to improve the tunnel waterproofing and drainage effects.

[0009] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0010] A tunnel annular blind pipe protection structure for soft surrounding rock formations is arranged between the primary support concrete layer and the lining layer, including a blind pipe groove engraved on the surface of the primary support concrete layer. The interior of the blind pipe groove is similar in shape to the annular blind pipe to be installed, and the inner diameter of the blind pipe groove is 1 to 2 cm larger than the outer diameter of the annular blind pipe; a waterproof board is laid on the open side of the blind pipe groove, and the end of the annular blind pipe passes through the waterproof board and enters the lining layer. A saddle-shaped rubber gasket is glued to the joint on the waterproof board, and the saddle-shaped rubber gasket is tightly clamped to the outer circumference of the annular blind pipe.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] 1) Placing the annular blind pipe in the blind pipe groove can effectively prevent the blind pipe from being squeezed and deformed during the pouring and vibration of the lining concrete, which can lead to poor drainage.

[0013] 2) The annular blind pipe is placed in the blind pipe groove, and the pores are filled with sandless concrete to prevent the blind pipe from intruding into the lining structure. The blind pipe groove can restrain the blind pipe from moving, preventing defects such as thinning, cutting, insufficient thickness, and voids in the lining. This will help improve the bearing capacity of the lining, especially in weak surrounding rock formations.

[0014] 3) Saddle-shaped rubber gaskets are used at the ends of the annular blind pipes to enhance waterproofing, which can solve the leakage problem caused by the blind pipes piercing the waterproofing board. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall structure of the utility model.

[0016] Figure 2 for Figure 1 Diagram of the steps for constructing the center blind pipe groove.

[0017] Figure 3 for Figure 1 Waterproof structure diagram of the middle ring blind pipe end.

[0018] In the figure, 1. lining layer, 2. primary support concrete layer, 3. steel arch frame, 4. annular blind pipe, 5. blind pipe groove, 6. waterproof board, 7. saddle-shaped rubber gasket, 8. groove mold, 9. sandless concrete layer. DETAILED DESCRIPTION

[0019] The present invention will be further explained below with reference to the accompanying drawings.

[0020] like Figure 1-3As shown, a tunnel annular blind pipe protection structure for soft surrounding rock formations is arranged between the primary support concrete layer 2 and the lining layer 1, and is characterized by: including a blind pipe groove 5 engraved on the surface of the primary support concrete layer 2, the interior of the blind pipe groove 5 is similar in shape to the annular blind pipe 4 to be installed, and the inner diameter of the blind pipe groove 5 is 1-2 cm larger than the outer diameter of the annular blind pipe 4, and the gaps between the blind pipe, the groove and the waterproof board are filled with sandless concrete to form a sandless concrete layer 9; a waterproof board 6 is laid on the open side of the blind pipe groove 5, and the end of the annular blind pipe 4 passes through the waterproof board 6 and enters the lining layer 1, and a saddle-shaped rubber gasket 7 is glued to the joint on the waterproof board 6, and the saddle-shaped rubber gasket 7 is tightly clamped to the outer periphery of the annular blind pipe 4.

[0021] The specific construction methods are as follows:

[0022] A. To prevent the annular blind pipe 4 from being squeezed, deformed, or displaced during the pouring of the lining layer 1, which may result in lining voids or insufficient thickness around the blind pipe, a blind pipe groove 5 should be prefabricated in the primary concrete layer 2 according to the size of the blind pipe. The blind pipe groove 5 is made of a groove mold 8 with a similar shape and size. The material of the groove mold 8 is not limited, and it should be hard, smooth, and non-deformed. Figure 2 As shown, in order to avoid the primary concrete layer 2 behind the grooved mold 8 from becoming loose or hollow due to the placement of the grooved mold 8, the primary concrete layer 2 should be applied in two times. The first time, the thickness is sprayed to the outer edge of the grooved mold 8. After spraying it flat, the grooved mold 8 is fixed and installed. The second time, it is sprayed to the designed thickness.

[0023] B. At the same time, when setting the blind pipe groove 5, care should be taken to avoid the steel arch frame 3 to prevent the steel arch frame 3 from being damaged. After the initial support concrete layer 2 is completed, the groove mold 8 is removed to form the blind pipe groove 5.

[0024] C. To prevent the clogging of the annular blind pipe 4 by particles entrained in the bedrock fissure water from eroding the surrounding rock, the annular blind pipe 4 is wrapped with geotextile and then placed in the blind pipe groove 5. To further enhance the filtration of water seepage from the surrounding rock and ensure the smoothness of the primary support surface, the gaps between the annular blind pipe, the blind pipe groove and the waterproof board are filled with sandless concrete.

[0025] D. In order to overcome the disadvantage that the end of the annular blind pipe 4 directly penetrates the waterproof board 6 and causes water leakage on the puncture surface, structural adhesive is applied to the contact surface between the annular blind pipe 4 and the waterproof board 6 and a saddle-shaped rubber gasket 7 is installed to make the annular blind pipe 4 and the waterproof board 6 fit tightly to prevent leakage, and then the lining layer 1 is poured.

[0026] The arrangement and connection methods of the remaining longitudinal blind pipes and drainage ditches are the same as those in the prior art and will not be described in detail here.

[0027] In summary, the annular blind pipe protection structure of the utility model can effectively avoid the blind pipe from being squeezed and deformed due to the pouring and vibration of the lining concrete, resulting in the problem of poor drainage. At the same time, the blind pipe is placed in the groove and no longer invades the lining structure. The groove can restrain the movement of the blind pipe, which can avoid defects such as thinning, cutting, insufficient thickness, and hollowing of the lining. This will be beneficial to improving the bearing performance of the lining. In addition, the saddle rubber gasket is used at the end of the blind pipe to enhance waterproofing, which can solve the problem of leakage caused by the blind pipe piercing the waterproof board. In short, the construction process of the protection structure is simple, easy to implement, overcomes the problems existing in the existing technology, and is highly practical.

Claims

1. A tunnel annular blind pipe protection structure for soft surrounding rock formations, arranged between a primary support concrete layer (2) and a lining layer (1), characterized in that: The invention comprises a blind pipe groove (5) engraved on the surface of the primary support concrete layer (2), wherein the interior of the blind pipe groove (5) is similar in shape to the annular blind pipe (4) to be installed, and the inner diameter of the blind pipe groove (5) is 1 to 2 cm larger than the outer diameter of the annular blind pipe (4); a waterproof board (6) is laid on the opening side of the blind pipe groove (5), and the end of the annular blind pipe (4) penetrates the waterproof board (6) and enters the lining layer (1), and a saddle-shaped rubber gasket (7) is glued to the penetration point on the waterproof board (6), and the saddle-shaped rubber gasket (7) is tightly clamped on the outer periphery of the annular blind pipe (4).

2. A tunnel annular blind pipe protection structure for use in soft surrounding rock formations according to claim 1, characterized in that: The outer periphery of the annular blind pipe (4) is also wrapped with geotextile.

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