A combined structure for reducing support pressure suitable for small-clearance tunnel in slate geology

Abstract

The utility model relates to tunnel construction technical field, concretely is a kind of support pressure combination structure for reducing suitable for slate geology small clear distance tunnel, including face, first hole, middle rock column, rear hole, further include recess, damping device, pair of pull anchor rod assembly;The pair of pull anchor rod assembly includes steel arch, a plurality of prestressed pair of pull anchor rod that transversely pass through middle rock column respectively fixed in the inner wall of first hole and rear hole, two steel plates respectively with steel arch, grouting steel flower pipe that is set to the prestressed pair of pull anchor rod outside, multiple grouting holes along grouting steel flower pipe axial helix line arrangement;The combination structure can absorb blasting vibration energy, reduce stress transmission, reduce the influence to middle rock column and first hole support;Through the component such as prestressed pair of pull anchor rod form three-dimensional restraint net, enhance middle rock column shear resistance;Dynamic secondary grouting can also be used to pre-buried grouting steel flower pipe, strengthen middle rock column rigidity, guarantee long-term reinforcement.

Description

Technical Field

[0001] This utility model relates to the field of tunnel construction technology, specifically a combined structure for reducing support pressure suitable for tunnels with small clearance in slate geology. Background Technology

[0002] As an important form of human development and utilization of underground space, tunnels are a key area of ​​tunnel and underground engineering. Drill-and-blast method, as a classic tunnel blasting construction technology, has always occupied a dominant position in my country's tunnel excavation market due to its significant advantages such as economic efficiency, strong practicality, simple operation, and flexible adaptability.

[0003] When constructing tunnels with small clearances in slate geology, the central rock column is prone to shear failure due to blasting vibration and bias pressure. Traditional single anchor-sprayed support structures are difficult to effectively control the deformation of the surrounding rock in slate strata, leading to excessive pressure on the support structure and even causing collapse accidents. At the same time, slate is highly sensitive to blasting vibration. The vibration energy generated by blasting during subsequent tunnel excavation can easily be transmitted to the support structure of the preceding tunnel through the central rock column, exacerbating the development of rock mass fissures and the instability of the support system. Existing grouting reinforcement and rigid support technologies have problems such as high cost and poor adaptability, making it difficult to meet the construction requirements of tunnels with small clearances in slate geology. Utility Model Content

[0004] The purpose of this utility model is to provide a combined structure for reducing support pressure in tunnels with small clearance in slate geology, in order to solve the problems of traditional anchor spraying support which makes it difficult to control the deformation of the surrounding rock and is prone to collapse, and the existing reinforcement and support technology which is costly, has poor adaptability and is difficult to meet construction requirements.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a combined structure for reducing support pressure in slate tunnels with small clearance, comprising a working face, a pilot tunnel, a central rock pillar, and a follow-up tunnel. The central rock pillar is located between the working face and the pilot tunnel, and the follow-up tunnel is located on the working face. It also includes a groove, a shock-absorbing device, and a tie rod assembly. The groove is located on the side of the working face near the central rock pillar and communicates with the sidewall of the central rock pillar. The shock-absorbing device is located on the sidewall of the central rock pillar and inside the groove. The tie rod... The components include steel arch frames fixed to the inner walls of the pilot tunnel and the follower tunnel respectively, multiple prestressed tie rods that transversely penetrate the central rock column, two steel plates respectively attached to the steel arch frames, grouting steel pipes sleeved on the outside of the prestressed tie rods, multiple grouting holes arranged in a spiral along the axial direction of the grouting steel pipes, and connectors respectively provided at both ends of the prestressed tie rods; an annular grouting space is formed between the prestressed tie rods and the grouting steel pipes; the two ends of the prestressed tie rods are connected to the corresponding steel arch frames through connectors.

[0006] Furthermore, the damping device includes a first connecting plate connected to the side wall of the central rock column, a second connecting plate arranged parallel to and spaced apart from the first connecting plate, a plurality of dampers evenly distributed between the first and second connecting plates, an epoxy resin anti-corrosion coating coated on the outside of the second connecting plate, and a rubber pad layer pasted on the outside of the epoxy resin anti-corrosion coating; the outer surface of the rubber pad layer is provided with an alternating textured structure.

[0007] Furthermore, the prestressed tie rods are arranged in a matrix within the rock column, with a longitudinal spacing of 50cm and a circumferential spacing of 60cm.

[0008] Furthermore, the grouting steel pipe is made of seamless steel pipe, and the edges of the grouting holes are rounded; the grouting steel pipe is uniformly provided with multiple stiffening ribs along the axial direction; the spacing between adjacent stiffening ribs is ≤30cm.

[0009] Furthermore, the connecting component includes a grout-stopping ring that sleeves onto the prestressed tie rod and seals the end of the grouting steel pipe, an internally threaded connecting sleeve that is adapted to the external thread of the prestressed tie rod, and an internally threaded fastening sleeve for fastening the internally threaded connecting sleeve; one end of the internally threaded connecting sleeve abuts against the grout-stopping ring, and the other end is locked to the steel arch frame through the internally threaded fastening sleeve.

[0010] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0011] 1. By using the flexible buffering and damping energy dissipation mechanism of the shock absorption device, the vibration energy generated by the subsequent tunnel blasting is absorbed, reducing the transmission efficiency of blasting stress to the central rock pillar and the support structure of the initial tunnel, thereby reducing the impact of vibration on the stability of the central rock pillar and the load accumulation of the support structure of the initial tunnel.

[0012] 2. By using the lateral tensioning effect of prestressed tie rods penetrating the rock column, combined with the in-plane constraint of steel plates and steel arch frames, and the composite reinforcement layer formed by grouting steel pipes and rock mass, a three-dimensional constraint network is constructed to enhance the rock column's ability to resist shear deformation.

[0013] 3. Using pre-embedded grouting steel pipes, dynamic secondary grouting is carried out after excavation and blasting based on the actual development of the surrounding rock fissures. Through the filling and solidification of the rock fissures by the grout, the overall rigidity and deformation resistance of the central rock column are continuously strengthened, ensuring the long-term reinforcement effect of the support structure. Attached Figure Description

[0014] Figure 1 This is a cross-sectional schematic diagram of the pressure-reducing combined structure of the present invention, which is applicable to tunnels with small clearance in slate geology.

[0015] Figure 2 This is a cross-sectional schematic diagram of the pressure-reducing combined structure of the present invention, which is applicable to tunnels with small clearance in slate geology.

[0016] Figure 3 This is a cross-sectional schematic diagram of the shock absorption device of this utility model;

[0017] Figure 4 This is a schematic diagram of the structure of the grouting steel pipe and prestressed tie rod combination of this utility model;

[0018] Figure 5 This is a cross-sectional schematic diagram of the combination of grouting steel pipe and prestressed tie rod of this utility model;

[0019] Figure 6 This is a schematic diagram of the grouting steel perforated pipe of this utility model;

[0020] Figure 7 This is a cross-sectional schematic diagram of the grouting steel perforated pipe of this utility model;

[0021] Figure 8 This is a schematic diagram of the prestressed tie rod of this utility model;

[0022] Figure 9 This is a schematic diagram of the structure of the connector of this utility model;

[0023] Figure 10 This is a schematic diagram of the steel plate structure of this utility model.

[0024] In the diagram: 1. Working face; 2. Pre-tunnel; 3. Middle rock column; 4. Groove; 5. Vibration damping device; 6. Tie rod assembly; 7. First connecting plate; 8. Damper; 9. Second connecting plate; 10. Epoxy resin anti-corrosion coating; 11. Rubber pad; 12. Steel arch frame; 13. Steel plate; 14. Prestressed tie rod; 15. Grouting steel pipe; 16. Connector; 17. Stiffening rib; 18. Grouting hole; 19. Rear tunnel; 20. Grout stop ring; 21. Internal threaded connecting cylinder; 22. Internal threaded fastening cylinder. Detailed Implementation

[0025] Please see Figure 1-10A pressure-reducing composite structure suitable for tunnels with small clearance in slate geology includes a tunnel face 1, a pilot tunnel 2, a central rock pillar 3, and a rear tunnel 19. The central rock pillar 3 is located between the tunnel face 1 and the pilot tunnel 2, and the rear tunnel 19 is located on the tunnel face 1. The structure also includes a groove 4, a shock-absorbing device 5, and a tie rod assembly 6. The groove 4 is located on the side of the tunnel face 1 near the central rock pillar 3 and communicates with the side wall of the central rock pillar 3. The shock-absorbing device 5 is located on the side wall of the central rock pillar 3 and inside the groove 4. The tie rod assembly 6 includes steel arch frames 12 fixed to the inner walls of the pilot tunnel 2 and the rear tunnel 19, respectively, and multiple transversely penetrating the central rock pillar 19. The prestressed tie rod 14 of column 3, two steel plates 13 respectively attached to the steel arch frame 12, a grouting steel pipe 15 sleeved on the outside of the prestressed tie rod 14, multiple grouting holes 18 arranged spirally along the axial direction of the grouting steel pipe 15, and connectors 16 respectively located at both ends of the prestressed tie rod 14; an annular grouting space is formed between the prestressed tie rod 14 and the grouting steel pipe 15, the length of which is dynamically adjusted according to the tunnel clearance; both ends of the prestressed tie rod 14 are connected to the corresponding side of the steel arch frame 12 through the connectors 16; the total thickness of the vibration damping device 5 is 10~20cm. The grouting pressure threshold of the secondary grouting module is set to 0.5MPa~1.0MPa, and the grout is a cement-water glass two-liquid grout with a water-cement ratio of 0.8:1~1:1.

[0026] The combination of groove 4 and vibration damping device 5 can absorb the vibration energy of subsequent tunnel blasting, reducing the impact of vibration on the support structure of the central rock column 3 and the pilot tunnel 2; the tie rod assembly 6, through the combined effect of prestressed tie rod 14 and grouting steel pipe 15, forms a three-dimensional constraint network in the central rock column 3, enhancing the shear resistance of the rock mass; the steel plate 13 and steel arch frame 12 work together with the prestressed tie rod 14 to transfer loads, improving the overall stiffness of the support structure; the annular grouting space combined with the secondary grouting module can dynamically fill grout according to the rock mass fissures, strengthening the integrity of the central rock column 3; this combined structure solves the problems of easy shear failure of the central rock column 3 and excessive support pressure in slate strata, and achieves the effects of blasting vibration dissipation, surrounding rock pressure dispersion and improved stability of the central rock column 3.

[0027] The vibration damping device 5 includes a first connecting plate 7 connected to the side wall of the central rock column 3, a second connecting plate 9 arranged parallel to and spaced apart from the first connecting plate 7, multiple dampers 8 evenly distributed between the first connecting plate 7 and the second connecting plate 9, an epoxy resin anti-corrosion coating 10 coated on the outside of the second connecting plate 9, and a rubber pad 11 adhered to the outside of the epoxy resin anti-corrosion coating 10. The outer surface of the rubber pad 11 is provided with an alternating textured structure to enhance frictional resistance. The composite structure of the epoxy resin anti-corrosion coating 10 and the rubber pad 11 further absorbs residual vibration through flexible deformation, while the textured structure on the outer surface of the rubber pad 11 enhances frictional resistance with the surrounding rock, preventing the vibration damping device 5 from slipping during vibration and ensuring its continuous and stable operation. Through its rigid-flexible structure, the vibration damping device 5 can block the transmission of blasting vibration from the subsequent tunnel 19 to the central rock column 3 and the support structure of the preceding tunnel 2, reducing the impact of vibration on the stability of the central rock column 3 and improving the overall safety during the construction of tunnels with small clearances.

[0028] The prestressed tie rods 14 are arranged in a matrix within the central rock column 3, with a longitudinal spacing of 50 cm and a circumferential spacing of 60 cm. Through the longitudinal and circumferential spacing, multiple prestressed tie rods 14 form a uniformly distributed lateral constraint system. This arrangement allows the prestressed load to be evenly distributed to all parts of the central rock column 3, avoiding local stress concentration and improving the overall shear strength of the central rock column 3. The matrix-style prestressed tie rods 14 work synergistically with the grouting steel pipes 15 to form a three-dimensional reinforcement network within the central rock column 3, enhancing the constraint effect on the slate strata bedding planes and inhibiting rock mass sliding along the bedding planes. The uniformly distributed spacing of the prestressed tie rods 14 can exert a group anchoring effect, enabling the central rock column 3 to remain stable under dynamic loads such as blasting vibration, reducing the surrounding rock pressure on the support structure.

[0029] The grouting steel pipe 15 is made of seamless steel pipe. Non-shrink cement grout is injected into the grouting steel pipe 15. The edges of the grouting holes 18 are rounded to avoid obstruction of grout flow, ensure smooth grouting process, and improve the uniformity of grouting reinforcement of the central rock column 3. The grouting steel pipe 15 is uniformly provided with multiple stiffening ribs 17 along the axial direction. The spacing between adjacent stiffening ribs 17 is ≤30cm, which can increase the contact area between the grouting steel pipe 15 and the rock mass, enhance the bonding strength between the two, and make the grouting steel pipe 15 and the rock mass form a tighter whole, thereby improving the shear resistance and stability of the central rock column 3. The injection of non-shrink cement grout can fill the rock mass fissures, further enhance the grouting reinforcement effect, reduce rock mass deformation, and ensure tunnel construction safety.

[0030] The connector 16 includes a grout-stopping ring 20 that sleeves onto the prestressed tie rod 14 and seals the end of the grouting steel pipe 15; an internally threaded connecting sleeve 21 that is adapted to the external thread of the prestressed tie rod 14; and an internally threaded fastening sleeve 22 for fastening the internally threaded connecting sleeve 21. One end of the internally threaded connecting sleeve 21 abuts against the grout-stopping ring 20, and the other end is locked to the steel arch frame 12 through the internally threaded fastening sleeve 22. The sealing fit between the grout-stopping ring 20 and the grouting steel pipe 15 prevents grout leakage and ensures the grouting reinforcement effect. The threaded connection between the internally threaded connecting sleeve 21 and the prestressed tie rod 14 enables reliable force transmission between the steel arch frame 12 and the prestressed tie rod 14, enhancing the lateral constraint on the central rock column 3. The locking mechanism of the internally threaded fastening sleeve 22 can resist dynamic loads such as blasting vibration and prevent loosening of the connection.

[0031] A construction method for a pressure-reducing composite structure suitable for tunnels with small clearance in slate geology, the method comprising the following steps:

[0032] Step 1: Excavate the pilot tunnel 2, and drill holes on the side of the central rock column 3 at intervals of 50cm longitudinally and 60cm circumferentially, with the hole depth penetrating the central rock column 3 to 20cm from the design outline of the subsequent tunnel 19; insert prestressed tie rods 14 with pre-reserved external threads at the ends, so that they pass through the central rock column 3 and through the pre-reserved holes in the steel plate 13, and are temporarily fixed to the steel arch frame 12 of the pilot tunnel 2 through the connector 16;

[0033] Step 2: Nest a grouting steel pipe 15 outside the prestressed tie rod 14, install a grout stop ring 20 at the tail, and inject non-shrink concrete through a grouting pump to fill the annular space between the prestressed tie rod 14 and the grouting steel pipe 15.

[0034] Step 3: When excavating the rear tunnel 19, a groove 4 is excavated on the side of the face 1 near the central rock pillar 3. After installing the shock absorption device 5, blasting excavation is carried out. Initial support is carried out in a timely manner after the excavation is completed.

[0035] Step 4: After the steel plate 13 of the rear tunnel 19 and the steel arch frame 12 are in place, apply prestress to the prestressed tie rod 14 by hydraulic jack, tighten the internal thread connecting cylinder 21 and lock the internal thread fastening cylinder 22 to form a lateral constraint on the central rock column 3.

[0036] Step 5: Grouting reinforcement of the central rock column 3 is carried out using the pre-embedded grouting steel pipe 15. The fractured rock mass is replenished and reinforced in real time through the dynamic grouting module. The grouting pressure is controlled at 0.5MPa~1.0MPa, and the grout is a cement-water glass double liquid grout with a water-cement ratio of 0.8:1~1:1.

[0037] Working process and principle: After the excavation of the pilot tunnel 2, holes are drilled on the side of the central rock column 3 at intervals of 50cm longitudinally and 60cm circumferentially. Prestressed tie rods 6 with external threads at the ends are inserted and temporarily fixed to the steel arch frame 12 of the pilot tunnel 2 through the reserved holes of the steel plate 13 after passing through the central rock column 3. The outer side is nested with grouting steel pipe 15 and injected with non-shrink concrete to form a composite reinforcement system of "anchor rod-steel pipe". The grout is filled with grout in the annular grouting space to enhance the integrity of the central rock column 3. When the subsequent tunnel 19 is excavated, a groove 4 is excavated on the side of the working face 1 near the central rock column 3 and a shock-absorbing device 5 with a total thickness of 10~20cm is installed. The convex and concave structure of the rubber pad layer 11 and multiple dampers 8 work together to reduce the vibration. The blasting vibration energy is used to reduce the impact of vibration on the support of the central rock column 3 and the pilot tunnel 2. After the steel plate 13 and steel arch frame 12 of the subsequent tunnel 19 are in place, prestress is applied to the prestressed tie rod 6 by hydraulic jacks. The tie rod assembly 6 forms a lateral constraint on the central rock column 3 by locking it through the grout stop ring 20, the internal threaded connecting cylinder 21 and the fastening cylinder 22. Finally, cement-water glass double liquid grout is injected at a pressure of 0.5MPa~1.0MPa using the pre-embedded steel pipe 15. According to the dynamic reinforcement of rock mass fissures, the energy dissipation of the vibration damping device 5, the prestress constraint of the prestressed tie rod 6 and the secondary grouting reinforcement are combined to reduce the pressure on the support structure and improve the stability of the central rock column 3.

[0038] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A combined structure for reducing support pressure, which is suitable for slate geological small-clearance tunnels, comprising a working face (1), a pilot hole (2), a middle rock pillar (3), and a subsequent hole (19), wherein the middle rock pillar (3) is located between the working face (1) and the pilot hole (2), and the subsequent hole (19) is arranged on the working face (1), characterized in that, It also includes a groove (4), a shock-absorbing device (5), and a tie rod assembly (6); the groove (4) is opened on the side of the working face (1) near the central rock column (3) and communicates with the side wall of the central rock column (3); the shock-absorbing device (5) is located on the side wall of the central rock column (3) and inside the groove (4); the tie rod assembly (6) includes a steel arch frame (12) fixed to the inner wall of the pilot tunnel (2) and the rear tunnel (19) respectively, multiple prestressed tie rods (14) that transversely penetrate the central rock column (3), and two pieces respectively connected to the steel arch. The prestressed tie rod (14) is fitted with a steel plate (13), a grouting steel pipe (15) is sleeved on the outside of the prestressed tie rod (14), a plurality of grouting holes (18) are arranged in a spiral line along the axial direction of the grouting steel pipe (15), and connectors (16) are respectively provided at both ends of the prestressed tie rod (14); an annular grouting space is formed between the prestressed tie rod (14) and the grouting steel pipe (15); the two ends of the prestressed tie rod (14) are connected to the corresponding steel arch frame (12) through connectors (16).

2. The combined structure of the pressure-reducing support according to claim 1, characterized by, The shock absorption device (5) includes a first connecting plate (7) connected to the side wall of the central rock column (3), a second connecting plate (9) arranged parallel to and spaced apart from the first connecting plate (7), a plurality of dampers (8) evenly distributed between the first connecting plate (7) and the second connecting plate (9), an epoxy resin anti-corrosion coating (10) coated on the outside of the second connecting plate (9), and a rubber pad (11) pasted on the outside of the epoxy resin anti-corrosion coating (10); the outer surface of the rubber pad (11) is provided with an interlaced textured structure.

3. The combined structure of the pressure-reducing support according to claim 1, characterized by, The prestressed tie rods (14) are arranged in a matrix within the rock column (3), with a longitudinal spacing of 50cm and a circumferential spacing of 60cm.

4. The combined structure of the pressure-reducing support according to claim 1, characterized by The grouting steel pipe (15) is made of seamless steel pipe, and the edges of the grouting hole (18) are rounded. The grouting steel pipe (15) is uniformly provided with multiple stiffening ribs (17) along the axial direction. The spacing between adjacent stiffening ribs (17) is ≤30cm.

5. The reduced support pressure combination structure according to claim 1, characterized by The connector (16) includes a grout stop ring (20) that fits into the prestressed tie rod (14) and seals the end of the grouting steel pipe (15), an internal thread connecting sleeve (21) that is adapted to the external thread of the prestressed tie rod (14), and an internal thread fastening sleeve (22) for fastening the internal thread connecting sleeve (21); one end of the internal thread connecting sleeve (21) abuts against the grout stop ring (20), and the other end is locked to the steel arch frame (12) through the internal thread fastening sleeve (22).

Images