Local water-rich anti-freezing drainage structure for tunnel surrounding rock in alpine region and construction method

Abstract

The invention relates to an alpine region tunnel surrounding rock local water-rich anti-freezing drainage structure and a construction method, and relates to the technical field of tunnel construction. Comprising a primary support, waterproof board geotechnical cloth and a tunnel lining. A groove is formed in the surrounding rock, the primary support is arranged on the groove, the waterproof board geotechnical cloth is arranged on the outer side of the primary support, the tunnel lining is arranged on the outer side of the waterproof board geotechnical cloth, and a water collecting groove is formed in the position, 50-80 cm away from a conservative freezing line, of the outer side of the surrounding rock. Transverse drainage pipes or blind ditches connected with a tunnel center drainage ditch pipe are excavated at the bottoms of the water collecting grooves. Under the low-temperature environment of the tunnel, underground water can enter the water collecting tank through the radial water collecting pipe and is smoothly discharged out of the tunnel through a transverse drainage pipe or a blind ditch connected to the bottom of the water collecting tank and a tunnel deep-buried center drainage ditch pipe.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel construction, and particularly to a local water-rich anti-freezing drainage structure and construction method for tunnel surrounding rock in alpine regions. Background Technique

[0002] There are varying degrees of frost damage in railway tunnels in high-altitude areas. Some frost damage is severe. After completion, there are generally seasonal water seepage and leakage in the tunnel, ice hanging and ice accumulation, and ice accumulation in the drainage ditch overflowing onto the road surface, affecting traffic. Correspondingly, many measures for treating diseases of water-seepage tunnels in alpine regions have also emerged. The currently commonly used measures for treating diseases are as follows:

[0003] Measures for treating diseases of water-seepage tunnels in alpine regions. The currently commonly used measures for treating diseases are as follows:

[0004] 1. Leak plugging and repair method: In the water-rich section of the tunnel cave, in the seepage and leakage area, grouting and plugging of the lining seepage points are combined with circumferential grooving and half-pipe centralized drainage, and waterproof leak plugging agent is used for bridging treatment. Scheme evaluation: The scheme is feasible in the short term and achieves certain effects. Its disadvantages are: Under the action of freeze-thaw and frost heaving in alpine regions, the problem of seepage and leakage still cannot be solved. 2. Central deep buried drainage pipe method: The central drainage pipe of the tunnel is buried below the corresponding freezing depth, and the initial temperature of the groundwater is used to reach the freeze-thaw balance, and it is discharged outside the cave and discharged into the natural groove on the ground in the form of heat preservation of the water outlet, so as to achieve the purpose of anti-freezing. Scheme evaluation: The scheme is feasible and achieves certain effects. Its disadvantages are: During the construction of the tunnel: (1) When excavating the bottom of the tunnel, the excavation depth of the bottom of the deep buried drainage pipe trench is relatively large, and the disturbance area is relatively large, which is not conducive to construction safety. For existing traffic tunnels: a. It is necessary to terminate or affect the tunnel traffic; b. It destroys the stability of the closed loop, and the construction has an adverse impact on the stability of the inverted arch and the lining foundation and construction safety, especially in the soft rock section, which will inevitably threaten the stability of the entire lining. (2) If blasting is used for excavation, it will inevitably damage the surface appearance of the lining and the facilities in the cave, and have a certain impact on the project quality. Moreover, this scheme is in an ideal state, mainly considering the smoothness of the central drainage pipe. After the water in the longitudinal and circumferential drainage pipes behind the lining gradually freezes, the water around the lining cannot flow into the central drainage pipe. 3. Anti-freezing drainage ditch method: Thermal insulation layers are set on the top, bottom and side of the drainage ditch to ensure that the anti-freezing drainage ditch does not freeze. Scheme evaluation: The scheme is feasible for tunnels with a better environment and can achieve certain effects. Its disadvantages are: Due to the unique dark and humid environment in the tunnel and the drainage ditch, the thermal insulation material is feasible in the short term, but it is difficult to maintain good condition for a long time, resulting in the water around the lining not being drained out. 4. Heating drainage ditch method: The method of passing hot air or electric heating is used in the drainage ditch. Scheme evaluation: The scheme is feasible for tunnels with a better environment and can achieve certain effects. Its disadvantages are: The investment and later maintenance costs of the scheme using hot air or electric heating method are relatively high, and the equipment and electrical components are difficult to maintain good condition for a long time, resulting in the water around the lining not being drained out. 5. Surface treatment method: The method of changing the ditch and river on the tunnel surface, paving the bottom of the ditch or replacing the clay is used. Scheme evaluation: The scheme is feasible for tunnels with a better environment and can achieve certain effects. Its disadvantages are: It has little effect on tunnels with a large buried depth, and has no effect on the water coming from the longitudinal direction of the tunnel. 6. Shaft or well point dewatering method: In the water-rich section of the surrounding rock through which the tunnel passes, one or both sides of the tunnel body, shafts (supplemented by collecting pipes) or well points are excavated from the ground for dewatering. Two submersible sewage pumps (one in use and one in reserve) are installed at the bottom of the well, and heat preservation and heating facilities are installed on the pipeline. Scheme evaluation: The scheme is feasible for tunnels with better conditions and can achieve better effects. Its disadvantages are: It has little effect on tunnels with a large buried depth, the investment for tunnels with a large amount of water-rich sections in the tunnel is too large, the water pumps and pipelines are feasible in the short term, the later maintenance time is long and the cost is high, and it is difficult to maintain good operation for a long time. 7. Strengthening method inside the tunnel: After the lining of the water-rich section of the surrounding rock through which the tunnel passes, backfill grouting is carried out to fill the voids outside the lining and block the groundwater outside the grouting circle. Scheme evaluation: The scheme is feasible for tunnels with better conditions and can achieve better effects.Its disadvantages are as follows: It is very difficult to completely seal all the voids in the surrounding rock before the construction of the waterproof board, and it is impossible to achieve 100% sealing. When drilling in a traffic tunnel without passing through the waterproof board, the grouting can only fill the voids between the waterproof board and the lining. Drilling through the waterproof board will cause damage to the waterproof board. During the grouting process, it is easy to block the longitudinal and circumferential blind pipes of the drainage system, which is even more uneconomical. 8. Drainage tunnel method: It is to excavate drainage tunnels at a certain distance on both sides or below the tunnel, and divert water in parallel or through branch tunnels to introduce the groundwater in the water-rich area passed by the tunnel into the drainage tunnels and discharge it through the drainage tunnels. Scheme evaluation: The scheme is feasible and can achieve the effect. Its disadvantages are as follows: The short-tunnel scheme is still feasible, but for long tunnels with complex geological fracture zones and many water-rich sections. The number of drainage tunnels is large, and the terrain causes the drainage tunnels to be long. For the drainage tunnels parallel to the tunnel, the investment in the tunnel is huge and unacceptable.

[0005] For the measures to deal with the leakage diseases of tunnels commonly adopted at present, some treatments cannot completely eradicate the diseases, some require huge investments, some have long later maintenance times and high costs, some have little effect, and some work well in tunnels in warm regions. Although they seem feasible, they still cannot solve the leakage problem under the action of freeze-thaw and frost heaving environments in alpine regions. Thus, it can be seen that correctly understanding the causes and characteristics of tunnel leakage in alpine regions and solving the core causes are the keys to preventing and treating the leakage diseases of tunnels in alpine regions.

[0006] The existing tunnel structure designs for highways, railways, etc. can all meet the functions of structural stress and tunnel drainage in the environment of conventional regions. However, in alpine regions of plateaus or extremely cold regions at high latitudes, affected by the extremely cold weather, the environmental temperature inside the tunnel, especially at the portal section, drops. Under the condition of continuous extremely low temperature climate, the lining concrete freezes, and the freezing depth will penetrate through the tunnel lining concrete and reach the outer layer of the initial support concrete, and even have a certain depth of freezing effect on the external surrounding rock. The tunnel lining is generally C35 reinforced concrete with a thickness of 30 cm - 60 cm, and the external is the waterproof board geotextile and longitudinal and circumferential drainage pipes of the waterproof and drainage system. Under the condition of continuous extremely cold weather, the waterproof and drainage system between the tunnel lining and the initial support is also affected to varying degrees, reducing or even losing the efficacy of the waterproof and drainage system.

[0007] The formation process of the frozen drainage system behind the tunnel lining: In the early stage, as the low temperature inside the tunnel gradually forms a freeze-thaw circle, first the lining is frozen, gradually penetrating the initial support layer, and further expanding outward into the surrounding rock. When a certain balance is reached with the ground temperature in the surrounding rock, the freeze-thaw circle ends. When the freeze-thaw circle passes through the drainage system behind the lining, the circumferential perforated blind pipes and longitudinal drainage pipes, the water in the pipes gradually freezes and reduces the water passing area. The groundwater drainage outside the lining is unfavorable, resulting in congestion. The groundwater level rises, and the water pressure gradually increases. It finds the weak points of the lining and enters the tunnel, causing leakage. Further low temperature causes the drainage pipes to freeze and block, and the groundwater outside the lining freezes to form an impermeable layer, and the leakage of the lining decreases or stops.

[0008] Therefore, how to provide a local water-rich anti-freezing drainage structure and construction method for tunnel surrounding rock in alpine regions has become a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0009] To achieve the above object, the present invention provides a local water-rich anti-freezing drainage structure and construction method for tunnel surrounding rock in alpine regions, ensuring that under the low-temperature environment of the tunnel, groundwater can enter the water collection tank through the radial water collection pipes, and is smoothly discharged from the tunnel through the transverse drainage pipes or blind ditches connected to the bottom of the water collection tank and the deep-buried central drainage pipe of the tunnel.

[0010] To achieve the above object, the present invention provides a local water-rich anti-freezing drainage structure for tunnel surrounding rock in alpine regions, including: primary support, waterproof board geotextile and tunnel lining; a groove is provided on the surrounding rock, the primary support is arranged on the groove, the waterproof board geotextile is arranged outside the primary support, the tunnel lining is arranged outside the waterproof board geotextile, a water collection tank is arranged at a position 50-80 cm outside the conservative freezing line on the outside of the surrounding rock, and a transverse drainage pipe or blind ditch connecting the tunnel central drainage pipe is excavated at the bottom of the water collection tank.

[0011] Further, transverse thermal insulation board fixing steel bars are arranged at intervals of 50 cm in the circumferential direction of the water collection tank, and thermal insulation boards with a height of 50 cm and a width of 50-100 cm are inserted and fixed one by one in the circumferential direction. Thermal insulation cotton is stuffed between the thermal insulation boards and between the thermal insulation boards and the surrounding rock to thermally insulate and seal the water collection tank.

[0012] Further, a plurality of water collection holes are provided on the water collection tank, and perforated water collection diversion pipes are inserted through the water collection holes.

[0013] Further, an inspection and maintenance working passage is reserved in the surrounding rock, the passage is 150 cm high and 80 cm wide, and double-layer thermal insulation doors are installed inside and at the entrance of the tunnel.

[0014] Further, an electric heating device and a temperature controller are arranged in the inspection and maintenance working passage, and the temperature controller is electrically connected to the electric heating device.

[0015] A construction method for a local water-rich anti-freezing drainage structure of tunnel surrounding rock in alpine regions includes the following steps:

[0016] Step S1, structural design: determining the grooving depth, thermal insulation board thickness and the number of structural units in the section of a single local water-rich anti-freezing drainage structure of tunnel surrounding rock;

[0017] Step S2, location selection: During the tunnel excavation and support construction process, immediately select and judge the location of the local water-rich anti-freezing drainage structure of the tunnel surrounding rock;

[0018] Step S3, surrounding rock grooving: When there is a steel arch section, observe and analyze to determine the water-rich concentrated water outlet position. First, construct the support for the steel arches on both sides and the shotcrete. Leave a 100-cm-wide position temporarily unsupported. According to the estimated conservative freezing depth, excavate the surrounding rock outward to a distance of 50 - 80 cm outside the conservative freezing line to set up a water collection trough. Excavate the bottom of the water collection trough to set up a horizontal drainage pipe or culvert connecting to the tunnel center drainage ditch pipe.

[0019] Step S4, grooving support: Refer to the designed surrounding rock support parameters according to the surrounding rock category. Set up a steel arch at the bottom corner of the water collection trough. Install a steel mesh, mortar bolts, and connecting steel bars in the U-shaped groove at the bottom of the water collection trough, and connect them to the primary support. Spray shotcrete to seal the U-shaped groove to form the grooving support.

[0020] Step S5, driving perforated water collection and diversion pipes: In the 180-degree range of the water collection trough outside the freezing line, arrange perforated water collection and diversion pipes according to the water volume and the size of the surrounding rock. Drill radially and insert 3 - 5-meter perforated water collection and diversion pipes. The groundwater in the surrounding rock enters the water collection trough.

[0021] Step S6, thermal insulation and sealing: After the construction of the grooving support and the perforated water collection and diversion pipes is completed, at the position of the conservative freezing line of the water collection trough, set up horizontal thermal insulation board fixing steel bars at intervals of 50 cm circumferentially. Insert and fix thermal insulation boards with a height of 50 cm and a width of 50 - 100 cm one by one circumferentially. Fill thermal insulation cotton between the thermal insulation boards and between the thermal insulation boards and the surrounding rock to thermally insulate and seal the water collection trough.

[0022] Step S7, primary support sealing: After the thermal insulation and sealing are completed, weld and install a steel mesh and arch connection steel bars between the primary support steel arches at the left and right of the water collection trough opening, and spray shotcrete to fill the gap in the primary support.

[0023] Step S8, waterway connection: The lower part of the water collection trough is connected through a horizontal drainage pipe or culvert to drain the groundwater into the tunnel center drainage ditch pipe and discharge it out of the tunnel through the tunnel center drainage ditch pipe.

[0024] Furthermore, it also includes the following steps:

[0025] Step S9, sealing the inspection and maintenance passage: When the local or sectional groundwater volume in the tunnel surrounding rock is large and continuous, in order to facilitate the inspection and maintenance of the water collection trough in the future, reserve an inspection and maintenance working passage during the construction of the tunnel lining and the anti-freezing drainage structure. The passage is 150 cm high and 80 cm wide, and double-layer thermal insulation doors are installed inside and at the entrance of the tunnel.

[0026] The beneficial effects of the present invention are as follows:

[0027] When the present invention is applied to the water-rich section of the surrounding rock during tunnel construction, an anti-freezing drainage structure is set at a selected position. After the initial support, a water collection trough is excavated in the surrounding rock. A perforated water collection and diversion pipe is drilled in the water collection trough to collect the groundwater in the surrounding rock around it. The surrounding rock in the water collection trough is supported, the notch is thermally insulated and sealed, and the external support is sealed and filled. The bottom of the water collection trough is connected to the central drainage ditch of the tunnel through a horizontal drainage pipe or a blind ditch, and the groundwater in the water-rich surrounding rock section is drained out of the tunnel, thus solving the problems that the longitudinal drainage pipes in the circumferential direction after lining are frozen, blocked and invalid in a low-temperature environment, and in the water-rich section where the surrounding rock of the tunnel is broken, the groundwater level in the circumferential lining rises, resulting in the occurrence of lining leakage. Brief Description of the Drawings

[0028] Figure 1 is a three-dimensional structural schematic diagram of the present invention;

[0029] Figure 2 is a construction flow chart of the water collection trough of the present invention.

[0030] In the figure: 1 - initial support; 2 - waterproof board geotextile; 3 - tunnel lining; 4 - surrounding rock; 5 - water collection trough; 6 - horizontal drainage pipe; 7 - thermal insulation board; 8 - perforated water collection and diversion pipe. Detailed Embodiments

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so as to describe the embodiments of the present invention here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0033] In the present invention, the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit that the indicated devices, elements or components must have a specific orientation or be constructed and operated in a specific orientation.

[0034] Moreover, in addition to being used to represent the orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0035] In addition, the terms "installed", "set", "provided with", "connected", "linked", "socketed" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral structure; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, or there may be internal communication between two devices, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] To achieve the above object, as Figure 1-2 shown, the present invention provides a local water-rich anti-freezing drainage structure for tunnel surrounding rock in alpine regions, including: primary support 1, waterproof board geotextile 2 and tunnel lining 3; a groove is provided on the surrounding rock 4, the primary support 1 is arranged on the groove, the waterproof board geotextile 2 is arranged outside the primary support 1, the tunnel lining 3 is arranged outside the waterproof board geotextile 2, a water collecting tank 5 is arranged at a position 50 - 80 cm outside the outer side of the surrounding rock 4 and excavated to a position beyond the conservative freezing line, and a transverse drain pipe 6 or a blind ditch connecting to the central drainage ditch pipe of the tunnel is excavated at the bottom of the water collecting tank 5.

[0037] Further optimizing the technical solution, transverse insulation board fixing steel bars are arranged at intervals of 50 cm in the circumferential direction inside the water collecting tank 5, and insulation boards 7 with a height of 50 cm and a width of 50 - 100 cm are inserted and fixed circumferentially one by one, and heat preservation cotton is filled between the insulation boards and between the insulation boards and the surrounding rock to thermally insulate and enclose the water collecting tank.

[0038] Further optimizing the technical solution, a plurality of water collecting holes are provided on the water collecting tank, and a perforated water collecting diversion pipe 8 is inserted through the water collecting holes.

[0039] Further optimizing the technical solution, an inspection and maintenance working passage is reserved in the surrounding rock, the passage is 150 cm high and 80 cm wide, and double-layer thermal insulation doors are installed inside and at the entrance of the tunnel.

[0040] Further optimize the technical solution. An electric heating device and a temperature controller are arranged in the inspection and maintenance working passage, and the temperature controller is electrically connected to the electric heating device.

[0041] After the construction of the anti-freezing drainage structure for local water-rich surrounding rock of the tunnel is completed, the water collection tank with a small amount of water and its supporting facilities are relatively small and are enclosed behind the initial support of the lining. The water collection tank with a large amount of water and its supporting facilities are relatively large, and there is an anti-freezing drainage structure with an inspection and maintenance working passage. In an extremely cold environment, an electric heating device can be additionally installed inside the passage between the inner and outer double-layer heat-insulating doors, and the control temperature inside the passage is set to automatically increase the temperature, and the appropriate temperature inside the passage is balanced and controlled to ensure that under the low-temperature environment of the tunnel, groundwater can enter the water collection tank through the radial water collecting pipes, and is smoothly discharged from the tunnel through the drain ditch connected to the bottom of the water collection tank and the central drainage pipe of the tunnel design buried depth.

[0042] The present invention also provides a construction method for an anti-freezing drainage structure for local water-rich surrounding rock of a tunnel in alpine regions, including the following steps:

[0043] Step S1, structural design: During the construction of the tunnel under construction, by comparing the geological design such as the fault interlayer of the surrounding rock, observing the water outflow of the surrounding rock during on-site construction, infrared water exploration, and judging the groundwater conditions in the water-rich section, seepage water section, and even the section with gushing water of the surrounding rock, according to the length and water output of the water-rich section or the water leakage section, and the expected conservative freezing depth under the low-temperature environment at this position, determine the grooving depth, thickness of the thermal insulation board, and the number of structural settings in the section of the anti-freezing drainage structure for local water-rich surrounding rock of a single tunnel.

[0044] Step S2, location selection: During the tunnel excavation and support construction process, immediately select and judge the location of the anti-freezing drainage structure for local water-rich surrounding rock; it is divided into two types of surrounding rock sections with and without steel arch frames. For the section without steel arch frames, refer to the design of grooving, support, heat insulation, and sealing for the section with steel arch frames.

[0045] Step S3, surrounding rock grooving: When there is a steel arch frame section, observe and analyze to determine the location of concentrated water outflow in the water-rich area. First, construct the support of the steel arch frames on both sides and the shotcrete, leaving a 100-centimeter-wide position temporarily unsupported. According to the expected conservative freezing depth, excavate the surrounding rock outward to 50 - 80 centimeters outside the conservative freezing line to set the water collection tank, and excavate the bottom of the water collection tank to set a transverse drainage pipe or hidden ditch connecting to the tunnel central drainage pipe.

[0046] Step S4, grooving support: According to the surrounding rock category, refer to the designed surrounding rock support parameters, set steel arch frames at the bottom corners of the water collection tank, set a steel bar mesh, mortar bolts, and connecting steel bars in the U-shaped groove at the bottom of the water collection tank, and connect them to the initial support, and spray shotcrete to seal the U-shaped groove to form the grooving support.

[0047] Step S5, Install perforated water-collecting and diversion pipes: In the 180-degree range of the water-collecting tank outside the freezing line, arrange perforated water-collecting and diversion pipes according to the amount of water and the size of the surrounding rock. Drill radially and insert perforated water-collecting and diversion pipes with a length of 3 - 5 meters. The groundwater in the surrounding rock enters the water-collecting tank. The key is to arrange and insert perforated water-collecting and diversion pipes at the positions of the main water outlets.

[0048] Step S6, Thermal insulation and sealing: After the construction of the inner support in the grooved area and the perforated water-collecting and diversion pipes is completed, at the position of the conservative freezing line of the water-collecting tank, set transverse thermal insulation board fixing steel bars at intervals of 50 cm circumferentially, and insert and fix thermal insulation boards with a height of 50 cm * a width of 50 - 100 cm piece by piece circumferentially. Fill thermal insulation cotton between the thermal insulation boards and between the thermal insulation boards and the surrounding rock to thermally insulate and seal the water-collecting tank.

[0049] Step S7, Initial support sealing: After the thermal insulation and sealing are completed, between the initial support steel arch frames on the left and right of the water-collecting tank opening, weld and install wire mesh and arch frame connecting steel bars, and spray concrete to fill and level the gap of the initial support. For those with a deeper surrounding rock grooving, formwork can be hung on the surface of the initial support to pour and fill concrete to level it.

[0050] Step S8, Waterway connection: The lower part of the water-collecting tank is connected through a transverse drain pipe or a blind ditch to discharge the groundwater into the tunnel central drainage pipe and then drain it out of the tunnel through the tunnel central drainage pipe.

[0051] Step S9, Seal the inspection and maintenance passage: When the local or sectional groundwater volume in the tunnel surrounding rock is large and continuous, in order to facilitate the inspection and maintenance of the water-collecting tank in the future, reserve an inspection and maintenance working passage during the construction of the tunnel lining and the anti-freezing drainage structure. The passage is 150 cm high and 80 cm wide, and double-layer thermal insulation doors are installed inside and at the entrance of the tunnel.

[0052] After the construction of the local water-rich anti-freezing drainage structure for the tunnel surrounding rock of the present invention, even in tunnels in high-altitude and cold regions or high-latitude and extremely cold regions, in the face of a long-term extremely low-temperature environment where the tunnel lining and the insulation layer are frozen and the longitudinal and circumferential blind pipes of the post-lining drainage system are frozen, the groundwater can still enter the thermal insulation and drainage passage of the water-collecting tank outside the freezing line through the radially perforated water-collecting and diversion pipes driven into the surrounding rock, and then enter the tunnel central drainage pipe through the transverse drain pipe or blind ditch connected to the bottom of the water-collecting tank and be drained out of the tunnel. It will not cause the pipes to freeze, the groundwater cannot be drained, the water volume accumulates and the water level rises, and water intrusion into the tunnel forms lining leakage.

[0053] The construction method of the local water-rich anti-freezing drainage structure for the tunnel surrounding rock of the present invention, compared with other commonly adopted measures, has a high construction safety factor, less construction manpower and material resources input, small engineering quantity, low engineering cost input, and low later maintenance input cost. The treatment effect of tunnel lining leakage is prominent. Such as in high-altitude and cold regions or high-latitude and extremely cold regions, existing open tunnels and under-construction tunnels, and even water-rich tunnels in ordinary normal-temperature regions, it has been widely promoted and used, and its economic benefits will also be huge.

[0054] As described above, it is only the preferred embodiment of the present invention, and does not impose any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A local water-rich anti-freezing drainage structure for tunnel surrounding rock in alpine regions, characterized in that, Including: Initial support, waterproof board geotextile, and tunnel lining; there are grooves provided on the surrounding rock, the initial support is arranged on the grooves, the waterproof board geotextile is arranged outside the initial support, the tunnel lining is arranged outside the waterproof board geotextile, a water collecting tank is arranged at a position 50 - 80 cm outside the outer side of the surrounding rock excavated to beyond the conservative freezing line, and a horizontal drain pipe or a blind ditch connecting the tunnel central drainage ditch pipe is excavated at the bottom of the water collecting tank.

2. The local water-rich anti-freezing drainage structure for tunnel surrounding rock in alpine regions according to claim 1, characterized in that, Horizontal thermal insulation board fixing steel bars are arranged circumferentially every 50 cm inside the water collecting tank, and thermal insulation boards with a height of 50 cm * a width of 50 - 100 cm are inserted and fixed circumferentially one by one. Thermal insulation cotton is filled between the thermal insulation boards and between the thermal insulation boards and the surrounding rock to thermally insulate and seal the water collecting tank.

3. The local water-rich anti-freezing drainage structure for tunnel surrounding rock in alpine regions according to claim 2, characterized in that, A plurality of water collecting holes are provided on the water collecting tank, and perforated water collecting diversion pipes are inserted through the water collecting holes.

4. The local water-rich anti-freezing drainage structure for tunnel surrounding rock in alpine regions according to claim 1, characterized in that, A inspection and maintenance working channel is reserved in the surrounding rock, the channel is 150 cm high and 80 cm wide, and double-layer thermal insulation doors are installed inside and at the entrance of the tunnel.

5. The local water-rich anti-freezing drainage structure for tunnel surrounding rock in alpine regions according to claim 4, characterized in that, An electric heating device and a temperature controller are arranged in the inspection and maintenance working channel, and the temperature controller is electrically connected to the electric heating device.

6. Construction method of local water-rich anti-freezing drainage structure for tunnel surrounding rock in alpine regions, characterized in that, Including the following steps: Step S1, structural design: Determine the grooving depth, the thickness of the thermal insulation board, and the number of structural units arranged in the section of the local water-rich and freeze-proof drainage structure of a single tunnel surrounding rock. Step S2, location selection: During the tunnel excavation and support construction process, immediately select and judge the location of the local water-rich and freeze-proof drainage structure of the surrounding rock. Step S3, surrounding rock grooving: When there is a steel arch frame section, observe and analyze to determine the location of concentrated water outflow in the water-rich area. The steel arch frames on both sides and the shotcrete are first supported, leaving a 100-cm-wide position temporarily unsupported. According to the expected conservative freezing depth, excavate to 50 - 80 cm outside the conservative freezing line on the outer side of the surrounding rock to set up a water collecting tank, and a horizontal drain pipe or a blind ditch connecting the tunnel central drainage ditch pipe is excavated at the bottom of the water collecting tank. Step S4, grooving support: Refer to the designed surrounding rock support parameters according to the surrounding rock category, set up a steel arch frame at the bottom corner of the water collecting tank, install a steel bar mesh, mortar bolts, and connecting steel bars in the U-shaped groove at the bottom of the water collecting tank, and connect them to the initial support. The U-shaped groove is sealed with shotcrete to form the grooving support. Step S5, driving the perforated water collecting diversion pipe: In the 180-degree range of the water collecting tank outside the freezing line, arrange the perforated water collecting diversion pipes according to the amount of water in the surrounding rock. Radially drill holes and insert the 3 - 5-meter-long perforated water collecting diversion pipes, and the groundwater in the surrounding rock enters the water collecting tank. Step S6, thermal insulation and sealing: After the construction of the inner support of the groove and the perforated water collecting diversion pipe is completed, at the position of the conservative freezing line of the water collecting tank, arrange horizontal thermal insulation board fixing steel bars at intervals of 50 cm circumferentially, insert and fix the thermal insulation boards with a height of 50 cm * a width of 50 - 100 cm circumferentially one by one. Thermal insulation cotton is filled between the thermal insulation boards and between the thermal insulation boards and the surrounding rock to thermally insulate and seal the water collecting tank. Step S7, initial support sealing: After the thermal insulation and sealing are completed, weld and install a steel bar mesh and arch frame connecting steel bars between the initial support steel arch frames on the left and right of the water collecting tank opening, and use shotcrete to fill and level the gap of the initial support. Step S8, waterway connection: The lower part of the water collecting tank is connected through a horizontal drain pipe or a blind ditch, and the groundwater is discharged into the tunnel central drainage ditch pipe and discharged out of the tunnel through the tunnel central drainage ditch pipe.

7. The local water-rich anti-freezing drainage structure for tunnel surrounding rock in alpine regions according to claim 6, characterized in that, It also includes the following steps: Step S9, seal and thermally insulate the inspection and maintenance passage: When there is a large and continuous local or sectional groundwater volume in the tunnel surrounding rock, in order to facilitate future inspection and maintenance of the catchment tank, a passage for inspection and maintenance work is reserved during the construction of the tunnel lining and the anti-freezing drainage structure. The passage is 150 cm high and 80 cm wide, and double-layer thermal insulation doors are installed inside and at the entrance of the tunnel.

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