Steel-UHPC shelter buffer layer for shed-tunnel structure in dangerous rockfall areas

Abstract

The present invention relates to a steel-UHPC square cabin buffer layer of a shed-tunnel structure in a dangerous rockfall area, wherein the buffer layer is covered above the shed-tunnel roof and is composed of a plurality of square cabins spliced ​​together, wherein the square cabin connecting rod is vertically inserted from top to bottom through the entire square cabin, and the bottom end is inserted into a reserved hole in the shed-tunnel roof for fixation. The present invention uses the high mechanical performance advantage of the UHPC thin plate to prevent the impact load breakdown and damage at the moment of contact between the falling rocks and the buffer layer; the square cabin constrains the deformation of the light polymer to prevent the polymer buffer material from splitting and damaging; the effective combination of the polymer in the cabin and the buffer spring prolongs the impact time to reduce the impact load; and the convenience of connecting the buffer layer with the shed-tunnel structure is improved by dividing the buffer layer into independent square cabin structures, thereby having strong buffering performance, light structural weight, easy construction and maintenance, a wide range of applications, and good economic benefits.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel engineering construction, and in particular to a steel-UHPC cabin buffer layer of a shed-tunnel structure in a dangerous rock and rockfall area. Background Art

[0002] Newly built railways in the dangerous mountainous areas of central and western China often cross V-shaped valleys with steep slopes and many dangerous rockfalls. According to the distribution pattern of rockfall movement, tunnel entrances are the places with the highest risk of rockfalls. Once they are hit by rockfalls, they will cause significant economic losses and even lead to catastrophic consequences.

[0003] The existing tunnel top buffer layer generally uses sand, and the weight of sand is generally 0.8 times the weight of concrete. When the sand buffer layer has good buffering performance, it is often thicker and heavier. The weight of sand often becomes the decisive factor in the design and control of the open hole structure, which has a great impact on the technical rationality and engineering economy. The existing bridge sheds mostly adopt the protection form of light steel frame plus grid net. This structure is not fully enclosed and cannot effectively intercept small falling rocks. When a fully enclosed shed is used, the weight of the shed and the buffer layer is applied to the bridge, making it impossible to reasonably design the bridge structure and even more impossible to achieve engineering economy. Although mature industrial products such as springs and damping bearings can be used to unload to achieve the goal of buffering and lightweighting, steel component products are prone to rust and failure during use. Their service life generally does not exceed 20 years, which does not match the 100-year life of the main structure of the project. They are usually only used in temporary rescue, temporary transition and other engineering practices. In addition, the cost of steel industrial products is often high, which is not conducive to the promotion of buffer materials.

[0004] The magnitude of the impact load that a structure bears depends on the weight of the falling rock, the speed of the falling rock when it hits the structure, and the duration of the impact. The mass of the falling rock and the impact speed are constants at the moment of impacting the structure, that is, the impulse when the falling rock hits the structure is a constant. According to the impulse theorem, when the structure bears the impact load for a long time, the impact load can be significantly reduced. Therefore, the key to reducing the impact load of falling rocks is to extend the duration of the load by laying a buffer layer.

[0005] In summary, the key technology for the effective protection of shed-tunnel structures against dangerous rockfall disasters lies in a reasonable buffer layer structure, and its design objectives should focus on buffer performance, structural weight, durability, and economy.

[0006] The bulk density of light polymer is about 0.01 times the weight of sand. When it is reasonably applied to the buffer layer of the shed-tunnel structure, due to its low tensile strength, it often directly penetrates or splits and is damaged at the moment of contact with the impact load. Falling rocks can still directly hit the main body of the shed-tunnel structure and cause damage. A new type of buffer layer developed using light polymer should have good buffering performance, light weight, low cost, easy construction and easy repair, which can significantly improve the technical advancement and economic rationality of shed-tunnel structure engineering in dangerous rock and rockfall areas. Summary of the invention

[0007] The purpose of the present invention is to provide a steel-UHPC cabin buffer layer for a shed-cave structure in a dangerous rockfall area, so as to reduce the deadweight of the structure and improve the protective performance of the structure.

[0008] The technical solution adopted by the present invention is:

[0009] The steel-UHPC shelter buffer layer of the shed-tunnel structure in dangerous rockfall areas is characterized by:

[0010] The buffer layer covers the top of the shed hole and is composed of multiple square cabins. The square cabin connecting rod is vertically inserted from top to bottom to penetrate the whole square cabin, and the bottom end is inserted into the reserved hole of the shed hole top plate to be fixed.

[0011] The shelter comprises a shelter bottom plate, shelter side plates and a shelter top plate. Both the shelter bottom plate and the shelter top plate are arc panels adapted to the curved surface of the shelter top plate.

[0012] The cabin connecting rod is vertically inserted from the cabin top plate to the cabin bottom plate and penetrates the entire cabin;

[0013] The top end of the cabin connecting rod is exposed and provided with an external thread, which is fixed by a closed nut; the bottom end of the cabin connecting rod extends out and is inserted into the reserved hole of the roof plate of the shed hole.

[0014] The roof of the shelter is a prefabricated panel made of UHPC material.

[0015] The bottom plate and side plates of the shelter are both steel plates, and the side plates of the shelter are welded to the bottom plate of the shelter to form an open-type shelter.

[0016] A connecting rod through hole is provided on the bottom plate of the square cabin, and a connecting rod mounting hole is provided on the top plate of the square cabin. The connecting rod through hole and the connecting rod mounting hole correspond to each other up and down. The upper part of the square cabin connecting rod is inserted into the connecting rod mounting hole, and the lower part is inserted into the connecting rod through hole and then inserted into the reserved hole correspondingly provided on the top plate of the shed.

[0017] A buffer spring perpendicular to the bottom plate of the shelter is arranged on the surface of the shelter. The bottom end of the buffer spring is welded and fixed to the bottom plate of the shelter, and the top end is in contact with the bottom surface of the top plate of the shelter.

[0018] The cabin is filled with high molecular polymer as a cushioning material.

[0019] The top plate of the square cabin is provided with a square cabin buffer material injection port and a square cabin buffer material discharge port. The buffer material is injected into the square cabin from the square cabin buffer material injection port and overflows through the square cabin buffer material discharge port.

[0020] The filling port of the shelter buffer material and the discharge port of the shelter buffer material are closed by a closing nut and a closing washer.

[0021] The present invention has the following advantages:

[0022] (1) Strong buffering performance

[0023] The present invention mainly realizes the buffering function through the buffer springs and light high molecular polymers in the cabin. The buffer springs can be arranged freely in the plane. For example, when the impact energy is large, multiple groups of buffer springs can be arranged in the cabin, and the material properties of the buffer springs can be freely adjusted. High-performance springs can be customized using high-strength steel. The buffering performance of the light high molecular polymer increases with the increase of its thickness, and its weight increases slowly with the increase of thickness, which has little impact on the shed cave structure.

[0024] (2) Light structure

[0025] The main components of the present invention are steel boxes, UHPC cabin roofs, springs and light polymers. The steel box is mainly used for forming and displacement constraint, and is generally not thick; the UHPC cabin roof is an ultra-high performance concrete thin plate, and the thickness and weight can be greatly reduced; the springs are distributed to meet the temporary support of the cabin roof, and are only used as an auxiliary for the polymer in the buffering work, and the volume and weight are small; the light polymer is the decisive factor in the buffering effect, and the volume accounts for more than 90% of the entire buffer layer structure, but its own weight is only 1% of ordinary sand, and its own weight can be ignored. In summary, the steel-UHPC cabin buffer layer structure is light in weight.

[0026] (3) Easy construction and maintenance

[0027] The cabin steel box, connectors, buffer springs and UHPC cabin roof in the structure of the present invention can all be customized and processed in the factory. The main construction processes of the cabin steel box are cutting, hole drilling, welding and other mature processes. The UHPC cabin roof is a general casting construction of ultra-high performance concrete thin plates. The light polymer is formed by adding a foaming agent to the resin material and heating and softening it to generate gas, and the process is simple and mature.

[0028] Since the main components of the buffer layer are prefabricated in the factory, when replacing, the components of the same size can be manufactured in the factory and then disassembled and assembled on site. The main construction processes during replacement are only steel plate welding, UHPC plate buckling, and on-site foaming of light polymers. The above are all mature processes and are simple and easy to operate.

[0029] (4) Wide range of applications

[0030] In the design of protection against falling rocks, the bridge scaffolding structure mostly adopts a grid mesh laid on a light steel frame. The main reason for not adopting a fully enclosed shed tunnel is the lack of a light and high-energy buffer layer. The present invention can completely meet the requirements of lightness and high efficiency, solve the key technical problems for the integrated design of bridge shed tunnels, and can be widely promoted on bridge scaffolding. Compared with the sand buffer layer used in conventional tunnel open holes, the present invention greatly reduces the deadweight of the buffer layer. Through the setting of the invention, the thickness of the open hole top plate and the steel content of the top plate can be reduced under the premise of ensuring the safety of the same impact load. The technology is advanced and has a promotion prospect in tunnel open hole structures.

[0031] (5) Good economic benefits

[0032] The materials in the structure of the present invention are mainly: steel plates, connectors, springs, UHPC prefabricated plates, and light polymers. Among them, steel and UHPC account for about 10% of the volume of the buffer layer, which is a common material in engineering structures. It is easy to obtain and process, and has general economic indicators. The volume proportion of light polymers is as high as 90%, and the foaming material is cheap and the production process is simple. Therefore, the economic benefit advantage of the present invention is obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a comparison of the general plan for protection against dangerous rock falls in tunnel open holes and bridge scaffoldings.

[0034] Figure 2 This is a picture of the bottom plate of the shelter.

[0035] Figure 3 This is a picture of an open shelter and an uninstalled shelter roof.

[0036] Figure 4 This is the structural diagram of the cabin before injection.

[0037] Figure 5 This is the general diagram of the steel-UHPC shelter buffer layer.

[0038] The symbols in the figure are:

[0039] 1- Roof plate of shed;

[0040] 2- Shelter bottom plate;

[0041] 3- Shelter side panels;

[0042] 4- Cabin roof;

[0043] 5- Cabin connecting rod;

[0044] 6-Connecting rod through hole;

[0045] 7- buffer spring;

[0046] 8-Open type shelter;

[0047] 9-Connecting rod mounting hole;

[0048] 10- Inlet for the buffer material of the shelter;

[0049] 11-Discharge port of shelter buffer material;

[0050] 12-closed nut;

[0051] 13-Close the gasket. DETAILED DESCRIPTION

[0052] The present invention is described in detail below in conjunction with specific implementation modes.

[0053] There are two main types of tunnels with dangerous rockfall disaster risks in dangerous mountainous areas. One is that when the roadbed section is connected to the tunnel, the tunnel exit is protected by a tunnel open hole structure, and the other is that when the bridge section is connected to the tunnel, the top surface of the bridge is protected by a bridge scaffolding structure. The tunnel roof 1 is a weak area for rockfall impact damage. The present invention relates to a steel-UHPC cabin buffer layer of a tunnel structure in a dangerous rockfall area, which covers the top of the tunnel roof 1 to buffer the rockfall speed and reduce the impact load.

[0054] The present invention is composed of multiple square cabins, and the number and arrangement of the square cabin buffer layers are determined according to the protection range. The square cabin connecting rod 5 is vertically inserted from top to bottom to penetrate the entire square cabin, and the bottom end is inserted into the reserved hole of the roof plate 1 of the shed to achieve fixation.

[0055] The shelter comprises a shelter bottom plate 2, a shelter side plate 3 and a shelter top plate 4. The shelter bottom plate 2 and the shelter top plate 4 are both curved panels, adapted to the curved surface of the shelter top plate 1. A shelter connecting rod 5 is vertically inserted from the shelter top plate 4 to the shelter bottom plate 2 and penetrates the entire shelter; the top end of the shelter connecting rod 5 is exposed and provided with an external thread, which is fixed by a closed nut 12; the bottom end of the shelter connecting rod 5 extends out and is inserted into the reserved hole of the shelter top plate 4.

[0056] The shelter roof 4 is a prefabricated panel made of UHPC (ultra-high performance concrete). The shelter bottom plate 2 and the shelter side plate 3 are both steel plates, and the shelter side plate 3 is welded to the shelter bottom plate 2 to form an open shelter 8.

[0057] A connecting rod through hole 6 is provided on the bottom plate 2 of the square cabin, and a connecting rod mounting hole 9 is provided on the top plate 4 of the square cabin. The connecting rod through hole 6 and the connecting rod mounting hole 9 correspond to each other up and down. The upper part of the square cabin connecting rod 5 is inserted into the connecting rod mounting hole 9, and the lower part is inserted into the connecting rod through hole 6 and then inserted into the reserved hole correspondingly provided on the top plate 1 of the shed.

[0058] A buffer spring 7 perpendicular to the bottom plate 2 of the shelter is provided on the surface for temporary support. The bottom end of the buffer spring 7 is welded and fixed to the bottom plate 2 of the shelter, and the top is in contact with the bottom surface of the top plate 4 of the shelter.

[0059] The shelter is filled with high molecular polymer as a cushioning material. Common high molecular polymers are chemical on-site foaming materials such as polystyrene foam (EPS, commonly known as foam board) or polyethylene foam (EPE). The shelter top plate 4 is provided with a shelter cushioning material injection port 10 and a shelter cushioning material discharge port 11. The cushioning material is injected into the shelter from the shelter cushioning material injection port 10 and overflows through the shelter cushioning material discharge port 11. After injection molding, the shelter cushioning material injection port 10 and the shelter cushioning material discharge port 11 are closed by a closing nut 12 and a closing washer 13.

[0060] The present invention uses the advantages of the high mechanical properties of UHPC thin plates to prevent the impact load breakdown and damage when falling rocks contact the buffer layer; uses the square cabin to constrain the deformation of light polymers to prevent the polymer buffer material from splitting and damaging; effectively combines the polymers and buffer springs in the cabin to extend the impact time to reduce the impact load; and improves the convenience of connecting the buffer layer and the shed structure by dividing the buffer layer into independent square cabin structures. The square cabin roof, square cabin coaming, square cabin filler, etc. in the present invention are all replaceable parts, which can be restored through maintenance once major damage occurs. The steel-UHPC square cabin buffer layer gives full play to the engineering characteristics of various materials through structural design, and ultimately achieves strong buffering performance, light structural weight, easy construction and maintenance, wide range of applications, and good economic benefits.

[0061] The construction steps of the present invention include:

[0062] Step 1: Survey and special investigation of the morphology of the mountain slope with dangerous rocks and rockfall, identify and evaluate the risk of rockfall, implement the engineering design of active and passive protection of the mountain slope, and determine the maximum impact energy that the buffer layer of the cabin of the present invention needs to withstand on the upper part of the roof of the shed through simulation analysis.

[0063] Step 2: According to the maximum impact energy in step 1, calculate the minimum thickness of the UHPC roof of the shelter under the breakdown load, calculate the minimum thickness of the polymer filling, calculate the minimum number of spring arrangements, and check the side panels and connectors of the shelter. According to the calculation results, the structure and details of the shelter are designed and the design drawings are completed.

[0064] Step 3: Carry out the processing and manufacturing of the steel-UHPC shelter buffer layer according to the design drawings of step 2. The steel component factory processes the shelter bottom plate 2 and the shelter side plate 3 through cutting and hole making processes; the buffer spring 7 is completed by processes such as material selection, rolling, and stress relief annealing, and the finished product can generally be purchased directly; the shelter connecting rod 5 and the closed nut 12 are completed by processes such as cold drawing, annealing, cold forging, and heat treatment, and the finished product can generally be purchased directly. The concrete component factory processes the shelter top plate 4 according to the design drawings of step 2. The shelter top plate is made of UHPC (ultra-high performance concrete) material. The processing of the shelter top plate should accurately position and reserve the shelter connecting rod 5, the shelter buffer material injection port 10, and the shelter buffer material discharge port 11.

[0065] Step 4: Transport the various components of the shelter buffer layer manufactured in step 3 to the construction site of the shed tunnel where they need to be installed. The open tunnel structure or bridge scaffolding structure for protection against dangerous rock falls is cast in the formwork. When tying the steel bars on the shed tunnel roof 1, attention should be paid to the setting out, positioning and pre-embedding of the shelter connecting rods. The cast shed tunnel is maintained until it reaches the designed strength.

[0066] Arrangement 5: The shelter bottom plate 6 is sequentially buckled on the shed cave top plate 1 cast in step 4, and the shelter side plate 3 and the buffer spring 8 are welded on the shelter bottom plate. The initial position of the buffer spring after bearing the deadweight load of the shelter top plate 4 should be accurately positioned. The shelter is closed at the top of the connecting rod installation hole by the closing nut 12, and only the shelter buffer material injection port 10 and the shelter buffer material discharge port 11 are retained.

[0067] Step 6: Inject high molecular polymer into the formed shelter buffer layer in step 5, and judge whether the shelter is full by whether high molecular polymer overflows from the shelter buffer material outlet 11. After filling, the buffer material injection port 10 and the shelter buffer material outlet 11 are closed with a closed nut 12 and a closed gasket 13.

[0068] Step 7: Repeat steps 5 to 6 until all the steel-UHPC cabin buffer layers on the top of the shed are completed. After passing the acceptance, the present invention and the shed structure can be delivered for operation.

[0069] Step 8: The UHPC board of the shelter roof can effectively resist the impact of falling rocks with small impact energy. When falling rocks with large impact energy hit the shelter cave under extreme natural conditions, the side panels, buffer springs, and high molecular polymers of the shelter buffer layer will undergo large plastic deformation. The parts with large deformation should be disassembled and steps 5 to 7 should be repeated.

[0070] The content of the present invention is not limited to the embodiments listed, and any equivalent changes made to the technical solution of the present invention by ordinary technicians in this field after reading the description of the present invention are covered by the claims of the present invention.

Claims

1. The construction method of the steel-UHPC shelter buffer layer of the shed-tunnel structure in the dangerous rock and rockfall area is characterized by: The buffer layer covers the top of the shed cave roof (1) and is composed of a plurality of square cabins spliced ​​together. The square cabin connecting rod (5) is vertically inserted from top to bottom to penetrate the entire square cabin, and the bottom end is inserted into a reserved hole in the shed cave roof (1) to achieve fixation; The construction method of the buffer layer is as follows: Step 1: Survey and special survey of the slope morphology of dangerous rocks and rockfalls, identify and evaluate the risk of rockfalls, implement the active and passive protection design of the slope, and determine the maximum impact energy that the shelter buffer layer on the top of the shed roof needs to withstand through simulation analysis; Step 2: According to the maximum impact energy in step 1, calculate the minimum thickness of the UHPC roof of the shelter under the breakdown load, calculate the minimum thickness of the polymer filling, calculate the minimum number of spring arrangements, and check the side panels and connectors of the shelter; perform structural and detailed design of the shelter according to the calculation results and complete the design drawings; Step 3: Carry out the processing and manufacturing of the steel-UHPC shelter buffer layer according to the design drawings of step 2; Step 4: transport the various components of the shelter buffer layer manufactured in step 3 to the construction site of the shed tunnel where they need to be installed; erect a formwork to cast the tunnel open hole structure or bridge scaffold structure for protection against dangerous rockfalls; when tying the steel bars of the shed tunnel top plate (1), attention should be paid to setting out, positioning and pre-embedding the shelter connecting rods; and the cast shed tunnel should be maintained until it reaches the designed strength; Step 5: The shelter bottom plate (2) is sequentially fastened on the shed cave top plate (1) cast in step 4, and the shelter side plate (3) and the buffer spring (7) are welded on the shelter bottom plate. The initial position of the buffer spring after bearing the deadweight load of the shelter top plate (4) should be accurately positioned; the shelter is closed at the top of the connecting rod mounting hole by a sealing nut (12), and only the shelter buffer material injection port (10) and the shelter buffer material discharge port (11) are retained; Step 6: injecting high molecular polymer into the shelter buffer layer formed in step 5, and judging whether the shelter is full by whether high molecular polymer overflows from the shelter buffer material outlet (11); after the shelter is full, the buffer material injection port (10) and the shelter buffer material outlet (11) are sealed with a sealing nut (12) and a sealing washer (13); Step 7: Repeat steps 5 to 6 until all the steel-UHPC shelter buffer layers on the top of the shed are completed and can be delivered for operation together with the shed structure after passing the acceptance. Step 8: The UHPC board on the top plate of the shelter can effectively resist the impact of falling rocks with small impact energy. When falling rocks with large impact energy hit the shelter cave under extreme natural conditions, the side panels, buffer springs, and high molecular polymers of the shelter buffer layer will undergo plastic deformation. The deformed parts are disassembled and steps 5 to 7 are repeated.

2. The construction method of the steel-UHPC shelter buffer layer of the shed-tunnel structure in the dangerous rock and rockfall area according to claim 1 is characterized by: The shelter comprises a shelter bottom plate (2), shelter side plates (3) and a shelter top plate (4); the shelter bottom plate (2) and the shelter top plate (4) are both curved panels adapted to the curved surface of the shelter top plate (1).

3. The construction method of the steel-UHPC shelter buffer layer of the shed-tunnel structure in the dangerous rock and rockfall area according to claim 2 is characterized by: The cabin connecting rod (5) is vertically inserted from the cabin top plate (4) to the cabin bottom plate (2) and penetrates the entire cabin; The top end of the cabin connecting rod (5) is exposed and provided with an external thread, and is fixed by a closed nut (12); the bottom end of the cabin connecting rod (5) extends out and is inserted into a reserved hole of the shed cave top plate (1).

4. The construction method of the steel-UHPC shelter buffer layer of the shed-tunnel structure in the dangerous rock and rockfall area according to claim 3 is characterized by: The shelter roof (4) is a prefabricated plate made of UHPC material.

5. The construction method of the steel-UHPC shelter buffer layer of the shed-tunnel structure in the dangerous rock and rockfall area according to claim 4 is characterized by: The cabin bottom plate (2) and the cabin side plates (3) are both steel plates, and the cabin side plates (3) are welded to the cabin bottom plate (2) to form an open-type cabin (8).

6. The construction method of the steel-UHPC shelter buffer layer of the shed-tunnel structure in the dangerous rock and rockfall area according to claim 5 is characterized by: A connecting rod through hole (6) is provided on the bottom plate (2) of the shelter, and a connecting rod mounting hole (9) is provided on the top plate (4) of the shelter. The connecting rod through hole (6) and the connecting rod mounting hole (9) correspond to each other from top to bottom. The upper part of the shelter connecting rod (5) is inserted into the connecting rod mounting hole (9), and the lower part is inserted into the connecting rod through hole (6) and then inserted into the corresponding reserved hole provided on the top plate (1) of the shed.

7. The construction method of the steel-UHPC shelter buffer layer of the shed-tunnel structure in the dangerous rock and rockfall area according to claim 6 is characterized by: A buffer spring (7) is arranged on the surface of the cabin bottom plate (2) and is perpendicular thereto. The bottom end of the buffer spring (7) is welded and fixed to the cabin bottom plate (2), and the top end is in contact with the bottom surface of the cabin top plate (4).

8. The construction method of the steel-UHPC shelter buffer layer of the shed-tunnel structure in the dangerous rock and rockfall area according to claim 7 is characterized by: The cabin is filled with high molecular polymer as a cushioning material.

9. The construction method of the steel-UHPC shelter buffer layer of the shed-tunnel structure in the dangerous rock and rockfall area according to claim 8 is characterized by: A cabin buffer material injection port (10) and a cabin buffer material discharge port (11) are provided on the cabin top plate (4); the buffer material is injected into the cabin from the cabin buffer material injection port (10) and overflows from the cabin buffer material discharge port (11).

10. The construction method of the steel-UHPC shelter buffer layer of the shed-tunnel structure in the dangerous rock and rockfall area according to claim 9 is characterized by: The cabin buffer material injection port (10) and the cabin buffer material discharge port (11) are sealed by means of a sealing nut (12) and a sealing washer (13).

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