A refrigerable assembled support structure and construction method for a tunnel in high-content frozen soil

Abstract

The present invention relates to a refrigeratable assembled support structure and construction method for a high-content frozen soil tunnel. It solves the problems that the hydration heat of concrete in the existing support structure exacerbates the melting of frozen soil and the support is prone to intrusion, and improves the reliability and durability of the lining structure. The present invention is composed of capillary cooling pipes, corrugated steel plates, heat insulation layers, waterproof layers, secondary linings, and refrigerating machines. Capillary cooling pipes are installed on the side of the corrugated steel plate close to the frozen soil surrounding rock, and a heat insulation and thermal insulation layer is sprayed on the side close to the lining. The corrugated steel plates are connected by high-strength bolts. After the corrugated steel plates are installed, the refrigerating machine is started to refreeze the melted frozen soil, the waterproof layer is laid, and the secondary lining is poured; after the structure is excavated, the corrugated steel plate can form a load-bearing structure in time and will not generate heat. The melted frozen soil is refrozen by artificial refrigeration to improve the strength and stability of the frozen soil surrounding rock. The heat insulation layer is set to ensure the cooling effect and prevent the influence of the hydration heat of concrete on the frozen soil and prevent the frozen soil from melting again.

Description

Technical Field

[0001] The present invention relates to the field of tunnel engineering, and particularly to a refrigeratable assembled support structure for high ice-content frozen soil tunnels and a construction method therefor. Background Art

[0002] With the further improvement of the highway network and railway network, highways and railways have extended to extremely cold regions such as the Qinghai-Tibet Plateau and the Greater Hinggan Mountains in Northeast China, and it is necessary to cross permafrost strata.

[0003] Permafrost is a soil medium that is extremely sensitive to temperature. It is more difficult to build tunnels in permafrost, especially high ice-content frozen soil. During the construction of frozen soil tunnels, manual pneumatic pick excavation and mechanical excavation will disturb the original frozen soil, construction machinery and vehicles will dissipate heat, and concrete construction will generate hydration heat. These will cause the temperature in the tunnel to be positive, resulting in the melting of the surface layer of permafrost on the exposed excavation contour surface and gradually developing into a melting circle towards the deep. In high ice-content frozen soil, the melting will be faster, the depth will be deeper, and the harm will be greater, and even collapse may occur.

[0004] The existing support structures often use shotcrete support or cast-in-place concrete support structures. The concrete will release hydration heat, exacerbating the melting of frozen soil. Using shotcrete will make the working environment in the tunnel worse, and the support cycle operation time is long. The support structure is prone to deformation and intrusion, and the construction safety risk is high. Summary of the Invention

[0005] In order to solve the technical problems existing in the prior art, such as slow closing of the support into a ring during tunnel construction, release of hydration heat by concrete, large melting circle, easy intrusion of the support structure, and high construction safety risk, the present invention provides a refrigeratable assembled support structure for high ice-content frozen soil tunnels and a construction method therefor.

[0006] In order to solve the problems of the prior art, the technical solution adopted by the present invention is: a refrigeratable assembled support structure for high ice-content frozen soil tunnels, characterized in that: it includes precast corrugated steel plates assembled into a ring around the tunnel wall. Capillary cooling pipes are arranged in the grooves on the side of the precast corrugated steel plate close to the frozen soil, and a heat insulation layer is sprayed on the side close to the lining. A waterproof layer and a reinforced concrete secondary lining are sequentially arranged on the heat insulation layer. The support structure further includes temporary support channel steels arranged at the arch feet after the upper bench excavation is completed.

[0007] Furthermore, high-strength bolts are used to connect the adjacent precast corrugated steel plate rings and longitudinally. The capillary cooling pipes on the adjacent precast corrugated steel plates are connected through flexible connectors, and reserved connectors are also arranged on the capillary cooling pipes.

[0008] Furthermore, a cooling unit is connected to the cooling pipes.

[0009] Furthermore, the cooling unit consists of a refrigerating machine antifreeze solution pipe, an ammonia circulation system, an antifreeze solution circulation system, and a circulation pump. The refrigerating machine antifreeze solution pipe is connected to the reserved joint.

[0010] Furthermore, the temporary support channel steel includes a channel steel backing plate, a reinforcing rib plate, and a vertical steel plate; the channel steel backing plate is perpendicularly connected to the vertical steel plate, and the reinforcing rib plate is arranged at the joint of the channel steel backing plate and the vertical steel plate.

[0011] Furthermore, the capillary cooling tubes are arranged in a U shape on the side of the precast corrugated steel plate adjacent to the frozen soil.

[0012] Furthermore, each precast corrugated steel plate is arc-shaped and is treated by galvanizing.

[0013] A construction method for a refrigerated assembled support structure of a high-ice-content frozen soil tunnel, characterized in that the steps are as follows:

[0014] The tunnel is excavated by the bench method, and the temperature inside the tunnel is strictly controlled during the construction process. When the temperature inside the tunnel exceeds +10 °C, active cooling measures are implemented;

[0015] After the excavation of the upper bench is completed, level the springing and lay the temporary support channel steel. Use the modified excavator to lift the precast corrugated steel plate of the arch to the arch crown, insert the precast corrugated steel plate into the temporary support channel steel, and tighten the precast corrugated steel plate rings and longitudinally with high-strength bolts to form the arch support structure;

[0016] Connect the reserved joint of the capillary cooling tube of the arch to the joint of the refrigerating machine antifreeze solution pipe. The cooling unit uses ammonia as the refrigerant. Start the refrigerating machine, and the ammonia circulation system cools the antifreeze solution to -20 to -30 °C. Use the circulation pump to pump it into the capillary cooling tubes of the arch. After the low-temperature solution absorbs the heat outside the tubes, its temperature rises, and under the action of the circulation pump, it returns to the cooling unit to be cooled again, and circulates until the frozen soil in the arch thaws and refreezes;

[0017] Excavate the lower bench, remove the temporary support channel steel at the springing, install the precast corrugated steel plates of the side wall and the invert precast corrugated steel plate, tighten the bolts to form a precast corrugated steel plate ring-shaped support structure, connect the reserved cooling tube joints of the side wall and the invert to the joints of the refrigerating machine antifreeze solution pipe, and start the refrigerating machine to circulate until the surface frozen soil thaws and refreezes;

[0018] Close to the corrugated steel plate heat insulation layer, erect the annular support steel bars, hang the waterproof layer on the annular support steel bars, lay the waterproof layer, and pour the reinforced concrete secondary lining of the invert and the arch wall to form the lining structure of the high-ice-content frozen soil tunnel.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The prefabricated corrugated steel plates of the present invention are bent and formed in a factory, with capillary cooling pipes installed on the inner side and a heat insulation layer sprayed on the outer side. The corrugated plates are connected by high-strength bolts in the circumferential and longitudinal directions, having advantages such as high strength and easy quality control.

[0021] 2. During construction, the present invention can be quickly assembled with the assistance of an excavator and manual labor. The initial corrugated steel plate support does not generate hydration heat, avoiding the expansion of the melting circle, and the construction cycle speed is fast.

[0022] 3. The present invention uses preset capillary cooling pipes for cooling, enabling the frozen soil on the surface layer to refreeze, improving the self-bearing capacity of the frozen soil surrounding rock, and enhancing construction safety.

[0023] 4. The present invention is provided with a heat insulation layer to ensure the cooling effect, block the influence of the hydration heat of subsequent concrete construction on the frozen soil surrounding rock, and reduce the action of frost heaving force on the support.

[0024] 5. The refrigeration unit adopted by the present invention has high efficiency and fast cooling speed.

[0025] 6. The modular structure of the present invention can implement active refrigeration to make the melted frozen soil refreeze, which is beneficial to restoring the strength of the frozen soil, can timely form a bearing support structure, the initial support does not generate hydration heat, setting the heat insulation layer can ensure the cooling effect, also reduce the influence of the hydration heat of subsequent concrete construction on the frozen soil, eliminate the melting circle, and improve construction safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of the refrigeration and assembled lining structure applicable to high-ice-content frozen soil of the present invention;

[0027] Figure 2 is a schematic diagram of the splicing of the prefabricated corrugated steel plate and capillary cooling pipe of the present invention;

[0028] Figure 3 is a schematic diagram of the installation of the prefabricated corrugated steel plate after the construction of the upper bench of the present invention;

[0029] Figure 4 is a schematic diagram of the connection between the corrugated steel plate and the temporary channel steel joint at the bench of the present invention;

[0030] Figure 5 is a schematic diagram of the installation of the prefabricated corrugated steel plate after the construction of the lower bench of the present invention;

[0031] Figure 6 is a schematic diagram of the construction of the waterproof layer and lining structure of the present invention;

[0032] Figure 7 is a schematic diagram of the working principle of the external cooling unit of the present invention;

[0033] The marks in the figure are:

[0034] 1 - Prefabricated corrugated steel plate, 2 - Capillary cooling pipe, 3 - Cooling unit, 4 - Thermal insulation layer, 5 - Waterproof layer, 6 - Reinforced concrete secondary lining, 7 - Temporary support channel steel, 8 - Ring support steel bars.

[0035] 1-1 - High-strength bolt;

[0036] 2-1 - Flexible connector, 2-2 - Reserved joint of capillary cooling pipe;

[0037] 3-1 - Refrigerant antifreeze solution pipe, 3-2 - Ammonia circulation system, 3-3 - Antifreeze solution circulation system;

[0038] 7-1 - Channel steel backing plate, 7-2 - Reinforcing rib plate, 7-3 - Vertical steel plate; Specific implementation mode

[0039] The specific implementation mode of the present invention will be further described below in conjunction with the accompanying drawings:

[0040] The present invention provides a refrigeration and assembled support structure for high-ice-content frozen soil tunnels, as Figure 1 shown, including a prefabricated corrugated steel plate 1, a capillary cooling pipe 2, an external cooling unit 3, a thermal insulation layer 4, a waterproof layer 5, and a reinforced concrete secondary lining 6;

[0041] A capillary cooling pipe 2 is arranged in the groove on the frozen soil side of the prefabricated corrugated steel plate 1, and a thermal insulation layer 4 is sprayed on the lining side. The capillary cooling pipe 2 is placed in a U shape on the outer (facing the frozen soil) side of the prefabricated corrugated steel plate 1, and a thermal insulation layer 4 is sprayed on the inner (facing the lining) side of the prefabricated corrugated steel plate 1; The prefabricated corrugated steel plates 1 are connected by high-strength bolts 1-1 in the circumferential and longitudinal directions. The capillary cooling pipes 2 on different prefabricated corrugated steel plates 1 are connected by flexible connectors 2-1, as Figure 2 shown, and a waterproof layer 5 and a reinforced concrete secondary lining 6 are sequentially arranged on the thermal insulation layer 4.

[0042] After the upper bench excavation is completed, the arch prefabricated corrugated steel plates 1 are assembled into shape by high-strength bolts 1-1, and the lower ends of the lowest corrugated steel plates on both sides of the upper bench are supported on the temporary support channel steel 7 at the bench, completing the assembly of the arch corrugated steel plates in the upper bench. The reserved joint 2-2 on the capillary cooling pipe 2 is connected to the refrigerant antifreeze solution pipe 3-1 of the refrigerator, and the cooling unit 3 is started to freeze and thaw the frozen soil surrounding rock, as Figure 3 shown.

[0043] The temporary support channel steel 7 includes a channel steel backing plate 7-1, a reinforcing rib plate 7-2, and a vertical steel plate 7-3. The channel steel backing plate 7-1 is vertically connected to the vertical steel plate 7-3, and the reinforcing rib plate 7-2 is arranged at the connection of the channel steel backing plate 7-1 and the vertical steel plate 7-3; The prefabricated corrugated steel plate 1 is placed between the vertical steel plate 7-3 and the side wall of the tunnel hole wall, as Figure 4 shown.

[0044] Excavate the lower bench, remove the temporary support channel steel 7, install the side wall and prefabricated corrugated steel plate 1, connect the reserved joints 2-2 of the capillary cooling pipes for the side wall and invert with the antifreeze solution pipe 3-1 of the refrigerating machine, start the cooling unit 3, and thaw and refreeze the frozen soil surrounding rock. As Figure 5 shown.

[0045] Erect the circular support steel bars 8, hang the waterproof layer 5 on the circular support steel bars 8 to complete the laying of the waterproof layer, pour the reinforced concrete secondary lining invert, construct the invert backfill concrete, pour the reinforced concrete arch wall secondary lining, and complete the construction of the reinforced concrete secondary lining 6. As Figure 6 shown.

[0046] The cooling unit 3 consists of an antifreeze solution pipe 3-1 of the refrigerating machine, an ammonia circulation system 3-2, and an antifreeze solution circulation system 3-3. The ammonia circulation system 3-1 cools the antifreeze solution to a predetermined temperature and then pumps it to the capillary cooling pipe 2 to freeze the melted surrounding rock. As Figure 7 shown.

[0047] The present invention also provides a construction method for a refrigerable assembled support structure for a tunnel in highly frozen soil, as follows:

[0048] The tunnel is excavated by the bench method. During the construction process, the temperature inside the tunnel is strictly controlled. When the temperature inside the tunnel exceeds +10°C, active cooling measures are implemented;

[0049] Bend the prefabricated corrugated steel plate 1 into shape at the outside processing factory, install the capillary cooling pipe 2 on the outer (adjacent to the frozen soil) side, and spray the heat insulation layer 4 on the inner (adjacent to the lining) side.

[0050] Excavate the upper bench, level the arch feet and install the temporary support channel steel 7. At the working face, use a modified excavator to lift the bracket to push the prefabricated corrugated steel plate 1 to be closely attached to the surrounding rock surface. Tighten the prefabricated corrugated steel plate 1 in the circumferential and longitudinal directions with high-strength bolts 1-1 to form an arch support structure. Insert the lower end of the lowermost prefabricated corrugated steel plate 1 on both sides of the upper bench into the reserved gap between the temporary support channel steel 7 at the bench and the tunnel wall.

[0051] Connect the reserved joints 2-2 of the capillary cooling pipes 2 in the arch part with the joints of the antifreeze solution pipe 3-1 of the refrigerating machine. The cooling unit 3 uses ammonia as the refrigerant. Start the refrigerating machine. The ammonia circulation system 3-2 cools the antifreeze solution to -20 to -30°C, and uses a circulation pump to pump the antifreeze solution into the capillary cooling pipe 2. The negative-temperature antifreeze solution absorbs the heat outside the pipe to refreeze the melted frozen soil. After the antifreeze solution absorbs heat, its temperature rises, and under the action of the circulation pump, it returns to the cooling unit 3 to be cooled again, and circulates until the melted frozen soil in the arch part is refrozen.

[0052] Excavate the lower bench, remove the temporary support channel steel 7, install the side wall precast corrugated steel plate 1 and the invert precast corrugated steel plate 1 until they are closed into a ring, tighten the bolts to form a precast corrugated steel plate 1 ring-shaped support structure. Connect the reserved cooling pipe joint 2-2 of the corrugated steel plate at the side wall foot to the antifreeze solution pipe 3-1 of the cooling unit, turn on the refrigeration, cool the frozen soil surrounding rock, and freeze the surface thawed surrounding rock.

[0053] Close to the corrugated steel plate heat insulation layer 4, erect the ring-shaped support steel bars 8, hang the waterproof layer 5 on the ring-shaped support steel bars 8, pour the invert of the reinforced concrete secondary lining 6, construct the invert backfill, pour the arch wall of the reinforced concrete secondary lining, and complete the construction of the high-reinforcement concrete secondary lining 6 structure.

Claims

1. Construction method of refrigerable assembled support structure for high-content frozen soil tunnel, Characterized in that: The steps are as follows: The tunnel is excavated by the bench method. During the construction process, the temperature inside the tunnel is strictly controlled. When the temperature inside the tunnel exceeds +10 °C, active cooling measures are implemented; After the upper bench excavation is completed, level the arch feet and lay the temporary support channel steel (7). Use the modified excavator to lift the precast corrugated steel plate (1) of the arch to the arch top, insert the precast corrugated steel plate (1) into the temporary support channel steel, and tighten the precast corrugated steel plate (1) circumferentially and longitudinally with high-strength bolts (1-1) to form the arch support structure; Connect the reserved joint (2-2) of the capillary cooling pipe (2) of the arch with the joint of the antifreeze solution pipe (3-1) of the refrigerating machine. The cooling unit (3) uses ammonia as the refrigerant. Start the refrigerating machine, and the ammonia circulation system (3-2) cools the antifreeze solution to -20 to -30 °C. Use the circulation pump to pump it into the capillary cooling pipe (2) of the arch. After the low-temperature solution absorbs the heat outside the pipe, its temperature rises, and under the action of the circulation pump, it returns to the cooling unit (3) to be cooled again, and circulates until the frozen soil in the arch thaws and refreezes; Excavate the lower bench, remove the temporary support channel steel (7) of the arch feet, install the precast corrugated steel plate (1) of the side wall and the precast corrugated steel plate (1) of the inverted arch, tighten the bolts to form the ring-shaped support structure of the precast corrugated steel plate (1), connect the reserved cooling pipe joints of the side wall and the inverted arch with the joint of the antifreeze solution pipe (3-1) of the refrigerating machine, and start the refrigerating machine to circulate until the surface frozen soil thaws and refreezes; Closely attach to the corrugated steel plate heat insulation layer (4), erect the ring-shaped support steel bars (8), hang the waterproof layer (5) on the ring-shaped support steel bars (8), lay the waterproof layer (5), and pour the reinforced concrete secondary lining (6) of the inverted arch and the arch wall to form the lining structure of the high-content frozen soil tunnel; The refrigerable assembled support structure for the high-content frozen soil tunnel includes the precast corrugated steel plate (1) assembled into a ring around the tunnel wall. The capillary cooling pipe (2) is arranged in the groove on the side close to the frozen soil of the precast corrugated steel plate (1), and the heat insulation layer (4) is sprayed on the side close to the lining. The waterproof layer (5) and the reinforced concrete secondary lining (6) are sequentially arranged on the heat insulation layer (4). The support structure also includes the temporary support channel steel (7) arranged at the arch feet after the upper bench excavation is completed.

2. The construction method of the refrigerable assembled support structure for the high-content frozen soil tunnel according to claim 1, Characterized in that: The adjacent precast corrugated steel plates (1) are connected circumferentially and longitudinally by high-strength bolts (1-1). The capillary cooling pipes (2) on the adjacent precast corrugated steel plates (1) are connected by flexible connectors (2-1), and the capillary cooling pipes (2) are also provided with reserved joints (2-2).

3. The construction method of the refrigerable assembled support structure for the high-content frozen soil tunnel according to claim 1 or 2, Characterized in that: The cooling pipe (2) is connected with a cooling unit (3).

4. The construction method of the refrigerable assembled support structure for the high-content frozen soil tunnel according to claim 3, Characterized in that: The described cooling unit (3) consists of a refrigerating machine antifreeze solution pipe (3-1), an ammonia circulation system (3-2), an antifreeze solution circulation system (3-3) and a circulation pump. The refrigerating machine antifreeze solution pipe (3-1) is connected to the reserved joint (2-2).

5. The construction method of a refrigerable assembled support structure for a high-content frozen soil tunnel according to claim 4, characterized in that: The described temporary support channel steel (7) includes a channel steel backing plate (7-1), a reinforcing rib plate (7-2), and a vertical steel plate (7-3); the channel steel backing plate (7-1) is perpendicularly connected to the vertical steel plate (7-3), and the reinforcing rib plate (7-2) is arranged at the junction of the channel steel backing plate (7-1) and the vertical steel plate (7-3).

6. The construction method of a refrigerable assembled support structure for a high-content frozen soil tunnel according to claim 5, characterized in that: The described capillary cooling pipe (2) is arranged in a U shape on the side of the precast corrugated steel plate (1) adjacent to the frozen soil.

7. The construction method of a refrigerable assembled support structure for a high-content frozen soil tunnel according to claim 6, characterized in that: Each precast corrugated steel plate (1) is arc-shaped and is treated by galvanizing.

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