Construction method of high-ground-temperature tunnel supporting structure and supporting structure

Abstract

The invention belongs to the technical field of tunnel engineering, and discloses a construction method of a high-ground-temperature tunnel supporting structure, which comprises the following steps: leveling a tunnel after excavation, and spraying steel fiber reinforced concrete to form a primary support; laying a hose on the surface of the primary support, and installing a temperature sensor at a preset position; cooling water is introduced into the hose, the head end and the tail end are blocked, the pressure bearing capacity of the hose is improved, and the water pressure ranges from 0.2 Mpa to 0.5 Mpa; fixing a non-woven fabric and a high-temperature-resistant waterproof coiled material on the surfaces of the primary support and the hose to form a waterproof heat insulation layer; after the temperature is lower than the first preset temperature, secondary lining is poured, plugs at the head end and the tail end of the hose are opened after pouring is completed, and cooling water is continuously introduced for heat exchange; and after the temperature is lower than the second temperature, the cooling water is stopped being input into the hose, the cooling water in the hose is emptied, then the slurry is injected, and the supporting structure is formed after the slurry is solidified. The invention further provides the supporting structure obtained through the method. The method and the structure are particularly suitable for high-ground-temperature tunnels, the construction period can be shortened, and the stability is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel engineering lining structures, and particularly relates to a construction method and a support structure for a high geothermal tunnel support structure. Background Art

[0002] With the rapid development of transportation, a large number of high geothermal tunnels have emerged during the construction of railways, highways, water conservancy and hydropower projects. The high geothermal environment will not only deteriorate the material properties of the support structure but also generate temperature stress in the lining.

[0003] At present, some measures have been taken for tunnels passing through high geothermal strata, such as setting up heat insulation layers between the support structure and high-temperature rock masses, strengthening ventilation and heat dissipation in the tunnel, and cooling the support structure with water bodies. These measures can, to a certain extent, block heat sources and cool the tunnel. However, these measures still cannot solve the related problems in areas with relatively serious high-temperature water inrush. In actual engineering, many tunnels are long and have a large buried depth, and the effect of only relying on auxiliary cooling measures such as ventilation, ice cooling, and spray sprinkling cooling is not good. Furthermore, it is also necessary to solve the problem of high-temperature water inrush during tunnel construction. Summary of the Invention

[0004] In order to overcome the above-mentioned deficiencies and defects in the background art, the invention provides a construction method for a high geothermal tunnel support structure applicable to high geothermal tunnels and capable of reducing the construction period and improving stability, and a support structure obtained according to this method. To solve the above technical problems, the technical solution proposed by the invention is as follows: A construction method for a high geothermal tunnel support structure includes the following steps: After the tunnel is excavated, leveling treatment is carried out, and shotcrete with steel fibers is sprayed to form the primary support; A hose is laid on the surface of the primary support, and temperature sensors are installed at predetermined positions; Cooling water is introduced into the hose, and the head and tail ends are sealed to improve the pressure-bearing capacity of the hose, and the water pressure is 0.2 - 0.5 Mpa; Non-woven fabric and high-temperature resistant waterproof coiled material are fixed on the surface of the primary support and the hose to form a waterproof and heat insulation layer; After the temperature is lower than the first preset temperature, the secondary lining is poured. After the pouring is completed, the seals at the head and tail ends of the hose are opened, and cooling water is continuously introduced for heat exchange; After the temperature is lower than the second temperature, the input of cooling water into the hose is stopped, and the cooling water in the hose is drained, and then slurry is injected. After the slurry solidifies, a support structure is formed.

[0005] In an embodiment, it further includes spraying a rigid polyurethane heat insulation material on the surface of the primary support to form a heat insulation layer, and the density of the rigid polyurethane heat insulation material is 35 - 40 kg / m 3 .

[0006] In one embodiment, when laying the hose on the surface of the primary support, the hose is fixed to the surface of the primary support through a snap structure.

[0007] In one embodiment, detachable filters are installed at the head and tail ends of the hose to filter when cooling water is introduced, and the filters are removed after the cooling water is drained.

[0008] In one embodiment, the cooling water at the water inlet end of the hose comes from the high-temperature water inrush area of the tunnel, and the high-temperature water inrush area is heat-exchanged through an absorption refrigeration system to obtain cooling water.

[0009] In one embodiment, the slurry components are 50% - 55% ordinary Portland cement, 15 - 20% sulfoaluminate cement, 5 - 8% expansion agent, 15 - 20% fly ash, 5 - 10% silica fume, and lithium carbonate is added externally.

[0010] In one embodiment, the first preset temperature is 55°C, and the second temperature is 45°C. After the temperature sensor monitors that the temperature inside the support structure is lower than 55°C, the secondary lining pouring work is started. After the temperature sensor monitors that the temperature inside the support structure is lower than 45°C, the cooling water in the hose is drained, and slurry is injected.

[0011] The hose is a PVC hose with a diameter of 2 - 3 cm.

[0012] Based on the same inventive concept, there is also provided a support structure obtained by the construction method of the high geothermal tunnel support structure as described above, including: a primary support structure; A hose provided on the surface of the primary support, and a support structure is arranged inside the hose; A waterproof and heat-insulating layer, including a non-woven fabric and a high-temperature resistant waterproof coil provided on the non-woven fabric; A secondary lining structure covering the waterproof and heat-insulating layer.

[0013] In one embodiment, a heat-insulating layer formed of rigid polyurethane heat-insulating material is provided on the surface of the primary support.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: For high geothermal tunnels with high-temperature gushing water, by using the support method of the present application and laying flexible hoses, it can better fit the surface of the surrounding rock. Compared with laying steel pipes and then treating the water flow, the cost of laying steel pipes is much higher than that of flexible hoses, and steel pipes cannot fit the surface of the surrounding rock well. Further, first, cooling water is introduced. Firstly, the high-temperature gushing water in the tunnel itself can be utilized. Secondly, the temperature during the support construction process can be reduced, preventing the surface of the secondary lining support construction from cracking due to excessive temperature, greatly reducing the stability of the lining structure, facilitating the stable formation of the support structure, and enabling the support structure to solidify faster, shortening the construction period and simplifying the maintenance procedure. Finally, after the temperature reduction treatment is achieved, after the secondary lining support is stable, slurry is injected into the flexible hose, and the slurry finally solidifies to form a strengthening structure, realizing the strengthening support effect on the overall support structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0016] Figure 1 It is a schematic flow chart of the construction method of the high geothermal tunnel support structure in an embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] For the convenience of understanding the present invention, the following will describe the present invention more comprehensively and meticulously in combination with the specification drawings and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0018] Unless otherwise defined, all the technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0019] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through the market or prepared by existing methods.

[0020] Please refer to Figure 1 , a construction method of a high geothermal tunnel support structure, comprising the following steps: S10. After the tunnel is excavated, leveling treatment is carried out, and steel fiber concrete is sprayed to form the primary support.

[0021] Specifically, in one embodiment, it further includes spraying rigid polyurethane heat-insulating material on the surface of the primary support to form a heat-insulating layer, and the density of the rigid polyurethane heat-insulating material is 35-40 kg / m 3 . The thermal conductivity of this material is only 0.018-0.024 W / (m·k), which is the lowest among all thermal insulation materials. The heat-insulating layer formed by using rigid polyurethane material has moisture-proof and waterproof properties. This heat-insulating layer can not only prevent the high temperature of the surrounding rock from further transferring out, but also has the functions of waterproof and moisture-proof, which is beneficial to the overall stability of the support structure.

[0022] In one embodiment, when laying the hose on the surface of the primary support, the hose is fixed on the surface of the primary support through a buckle structure. Since some parts of the surface of the surrounding rock are uneven, the hose can be better fixed through the buckle structure.

[0023] Preferably, the hose is a PVC hose with a diameter of 2-3 cm. The PVC hose has the advantages of chemical stability, high corrosion resistance, not easy to burn, not easy to deform, long service life, and convenient installation.

[0024] S20: Lay the hose on the surface of the primary support and install temperature sensors at predetermined positions.

[0025] The real-time temperature inside the support structure can be detected through the temperature sensors. During the construction process, detecting the support temperature can determine the time to introduce cooling water and the time to input slurry.

[0026] S30: Introduce cooling water into the hose and seal the head and tail ends to improve the pressure-bearing capacity of the hose, and the water pressure is 0.2-0.5 Mpa.

[0027] Since the hose has a certain flexibility, if the secondary lining is directly made on its surface, it may cause the water pipe to be flattened or even damaged. Therefore, before the secondary lining construction, cooling water is introduced and sealed, which can not only reduce the temperature of the support structure, but also prevent the water pipe from being flattened or damaged.

[0028] Preferably, in one embodiment, detachable filters are installed at the head and tail ends of the hose to filter when cooling water is introduced, and the filters are removed after the cooling water is drained. And the cooling water at the water inlet end of the hose comes from the high-temperature water inrush area of the tunnel, and the cooling water is obtained by heat exchange of the high-temperature water inrush area through an absorption refrigeration system. This construction method is particularly suitable for the situation where there is high-temperature water inrush in the tunnel itself. Since a large amount of high-temperature water inrush needs to be treated, after filtering the high-temperature water inrush through the filter, and then cooling the high-temperature water inrush through the refrigeration device and reusing it through the hose. There is no need to introduce water sources from the outside, and the water source of the high-temperature water inrush can be utilized, and at the same time, the generated heat can be applied to other equipment to achieve the reuse of resources.

[0029] S40. Fix the non-woven fabric and high temperature resistant waterproof membrane on the surface of the initial support and the hose to form a waterproof and heat insulating layer.

[0030] On the basis of the heat insulation layer formed by the rigid polyurethane heat insulation material, the second layer of waterproof heat insulation layer with both waterproof and heat insulation capacity is formed by non-woven fabric and high temperature resistant waterproof roll material. The waterproof heat insulation layer has high heat resistance and aging resistance, and forms a double waterproof and double-layer heat insulation safety barrier with the heat insulation layer formed by the rigid polyurethane heat insulation material.

[0031] S50, after the temperature is lower than the first preset temperature, pour the secondary lining, after pouring is completed, open the plugging at the first and tail ends of the hose, and continue to pass cooling water for heat exchange.

[0032] S60, when the temperature is lower than the second temperature, stop inputting cooling water into the hose and drain the cooling water in the hose, then inject slurry, and the slurry solidifies to form a support structure.

[0033] In one embodiment, the first preset temperature is 55°C, the second temperature is 45°C, and when the temperature sensor detects that the internal temperature of the support structure is lower than 55°C, the secondary lining pouring work is started. When the temperature sensor detects that the internal temperature of the support structure is lower than 45°C, the cooling water in the hose is drained and the slurry is injected. In one embodiment, the slurry components are 50% to 55% of ordinary silica cement, 15 to 20% of sulphoaluminate cement, 5 to 8% of expansion agent, 15 to 20% of fly ash, 5 to 10% of silica ash, and lithium carbonate is added. The slurry adopts the above components, and through the combination of sulphoaluminate cement and ordinary silica cement, the slurry can solidify and harden quickly and have high early strength. Doping with lithium carbonate can further shorten the setting time and improve the flexural strength. Through the action of fly ash and silica ash, the hydration products can be further reacted to accelerate the formation of calcium sulfonate. It will reduce the cost and shorten the setting time of the slurry, and the strength is higher.

[0034] The present invention also provides a support structure obtained according to the construction method of the above-mentioned high geothermal tunnel support structure, including: an initial support structure; a hose arranged on the surface of the initial support, wherein a support structure is arranged inside the hose; a waterproof and heat-insulating layer, including a non-woven fabric and a high-temperature resistant waterproof coiled material arranged on the non-woven fabric; and a secondary lining structure, covering the waterproof and heat-insulating layer.

[0035] In one embodiment, a heat insulating layer formed of a hard polyurethane heat insulating material is provided on the surface of the initial support.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows: For high geothermal tunnels with high-temperature gushing water, by adopting the support method of the present application and laying flexible hoses, it can better fit the surface of the surrounding rock. Compared with the treatment of passing water after laying steel pipes, the cost of laying steel pipes is much higher than that of flexible hoses, and the steel pipes cannot fit the surface of the surrounding rock well. Further, first, cooling water is introduced. Firstly, the high-temperature gushing water in the tunnel itself can be utilized. Secondly, the temperature during the support construction process can be reduced, preventing the surface of the secondary lining support from cracking due to excessive temperature during construction, greatly reducing the stability of the lining structure, facilitating the stable formation of the support structure, enabling the support structure to solidify faster, shortening the construction period, and simplifying the maintenance procedure. Finally, after the temperature reduction treatment is achieved and the secondary lining support is stable, grout is injected into the flexible hose, and the grout finally solidifies to form a strengthening structure, realizing the strengthening support effect on the overall support structure.

Claims

1. A construction method for a high ground temperature tunnel support structure, characterized in that: The following steps are involved: After tunnel excavation, the tunnel is leveled and sprayed with steel fiber concrete to form the initial support; Lay hoses on the initial support surface and install temperature sensors at predetermined locations; Inject cooling water into the hose and seal the ends to increase the hose's pressure-bearing capacity. The water pressure is 0.2-0.5Mpa. Fix the non-woven fabric and high temperature resistant waterproof membrane on the surface of the initial support and hose to form a waterproof and heat insulating layer; After the temperature is lower than the first preset temperature, the secondary lining is poured. After the pouring is completed, the plugging at the head and tail ends of the hose is opened, and cooling water is continuously introduced for heat exchange; When the temperature is lower than the second temperature, the cooling water is stopped from being input into the hose and the cooling water in the hose is drained, and then the slurry is injected, and the slurry is solidified to form a support structure.

2. The construction method of the high ground temperature tunnel support structure according to claim 1 is characterized in that: It also includes spraying hard polyurethane insulation material on the initial support surface to form an insulation layer. The density of the hard polyurethane insulation material is 35-40kg / m 3 .

3. The construction method of the high ground temperature tunnel support structure according to claim 1, characterized in that: When the hose is laid on the initial support surface, the hose is fixed to the initial support surface by a buckle structure.

4. The construction method of the high ground temperature tunnel support structure according to claim 1 is characterized in that: The first and second ends of the hose are provided with detachable filter elements, which are used to filter cooling water when it is introduced and are removed after the cooling water is drained.

5. The construction method of the high ground temperature tunnel support structure according to claim 1, characterized in that: The cooling water at the water inlet end of the hose comes from the high-temperature water gushing area of ​​the tunnel, and the high-temperature water gushing area is heat-exchanged by the absorption refrigeration system to obtain the cooling water.

6. The construction method of the high ground temperature tunnel support structure according to claim 1, characterized in that: The slurry components include 50%-55% of ordinary silica cement, 15%-20% of sulphoaluminate cement, 5%-8% of expansion agent, 15%-20% of fly ash, 5%-10% of silica fume, and lithium carbonate is added.

7. The construction method of the high ground temperature tunnel support structure according to claim 6 is characterized in that: The first preset temperature is 55°C, and the second temperature is 45°C. When the temperature sensor detects that the internal temperature of the support structure is lower than 55°C, the secondary lining pouring work is started. When the temperature sensor detects that the internal temperature of the support structure is lower than 45°C, the cooling water in the hose is drained and the slurry is injected.

8. The construction method of the high ground temperature tunnel support structure according to claim 1, characterized in that: The hose is a PVC hose with a diameter of 2-3 cm.

9. The support structure obtained by the construction method of the high ground temperature tunnel support structure according to claims 1-8 is characterized in that: include: Initial support structure; A hose disposed on the initial support surface, wherein the hose has a support structure therein; A waterproof and heat-insulating layer, comprising a non-woven fabric and a high-temperature-resistant waterproof roll material arranged on the non-woven fabric; Secondary lining structure, covered with waterproof and thermal insulation layer.

10. The supporting structure according to claim 9, characterized in that: A heat insulation layer formed by hard polyurethane heat insulation material is provided on the initial support surface.

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