Dam shoulder karst underground river is with horizontal pressure system and construction method

Abstract

The application relates to the technical field of water conservancy and hydropower engineering and discloses a dam shoulder karst underground river drainage and horizontal pressure relief system and a construction method, the dam shoulder karst underground river drainage and horizontal pressure relief system comprises an underground river pipeline blocking module used for filling the underground river pipeline and forming a water retaining structure; an underground river water drainage and removal module used for connecting the water bodies inside and outside the mountain and realizing flow transfer of the water bodies; a karst gas passage module used for connecting the gases inside and outside the mountain and realizing flow transfer of the gases; the underground river water drainage and removal module and the karst gas passage module form a gas passage and horizontal pressure relief structure, and the gas passage and horizontal pressure relief structure keeps the water balance between the inside and outside of the mountain based on the principle of a communicating vessel. The construction method is based on the dam shoulder karst underground river drainage and horizontal pressure relief system. Through cooperation of the three modules, multiple functions such as drainage, gas passage and horizontal pressure relief are realized, the gas passage and horizontal pressure relief structure based on the principle of a communicating vessel is formed, is used for drainage during the construction period and water and gas balance during the operation period, and is used for processing the dam shoulder karst underground river passage, so that the influence of karst water and gas on the dam is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of water conservancy and hydropower engineering construction design technology, specifically to a drainage and pressure system and construction method for karst underground rivers at the dam shoulder. Background Technology

[0002] Currently, when constructing dams in karst areas, it is common to encounter situations where the karst slopes are heavily developed, forming karst underground rivers. During the dam construction period, the long-term flow and seasonal inrush of these karst underground rivers can affect operations within the foundation pit, while also introducing safety and instability factors to the dam construction, necessitating drainage during the construction period. After the dam is completed, the karst underground rivers within the slopes primarily affect the integrity of the anti-seepage curtain, the durability of the dam foundation, and the stability of the mountains near the dam area. They also have a significant impact on the anti-sliding stability of the arch dam's abutments and the overall dam structure.

[0003] Therefore, targeted treatment plans should be formulated based on the location, development form and adverse effects of karst development. Underground river pipelines within the dam abutment area should be completely filled, and air venting and pressure equalization facilities should be installed for underground river pipelines upstream of the seepage prevention curtain line.

[0004] In existing technologies, when encountering karst underground rivers during dam construction, the common method is to excavate a construction tunnel along the direction of karst development from the river outlet inwards. During the dry season, the underground river tunnel is drained while concrete is being filled in. However, during the wet season, the increased drainage flow and rising water level in the underground river tunnel can easily cause the karst treatment construction to stall. While separate temporary drainage facilities such as drainage tunnels and pipes can be installed during construction, these are less economical. Utilizing temporary drainage facilities as a permanent, interconnected pressure-reducing structure would save on investment.

[0005] After the dam is built, the storage and release of water in the reservoir will cause gas explosion instability in karst caves, exacerbate the expansion and cracking of karst fissures and the development of karst, increase the possibility of local instability and collapse in karst caves, and induce earthquakes near the dam, thereby affecting the integrity of the curtain wall and the stability of the dam.

[0006] As shown above, the technical challenges that this invention needs to address are how to prevent the dam construction period from being disturbed by drainage during the high-water season and how to prevent the dam operation period from being affected by mountain explosions. Summary of the Invention

[0007] The technical problem to be solved by this invention is how to prevent the dam construction period from being disturbed by drainage during the high water period and how to prevent the dam operation period from being affected by gas explosions. The purpose is to provide a drainage pressure system and construction method for karst underground rivers on the dam shoulder to solve the above problems.

[0008] This invention is achieved through the following technical solution:

[0009] In a first aspect, the present invention provides a drainage and pressure system for karst underground rivers at the dam abutment, comprising:

[0010] Underground river pipeline sealing module, which is used to fill underground river pipelines and form a water-blocking structure;

[0011] The underground river drainage module is used to connect water bodies inside and outside the mountain and realize the flow and transfer of water.

[0012] Karst ventilation module, which is used to connect the gas inside and outside the mountain and realize the flow and transfer of gas;

[0013] Among them, the underground river drainage module and the karst ventilation module form a ventilation and pressure equalization structure, which maintains the water balance inside and outside the mountain based on the principle of communicating vessels.

[0014] In one possible design, the underground river pipeline sealing module includes an initial sealing section, a drainage and traffic tunnel, a treatment branch tunnel, and an underground river pipeline filling section;

[0015] The initial sealing section is located in the underground river pipeline. The initial sealing section contains an initial sealing body, which is used to separate the underground river pipeline into the initial sealing section and the original underground river cavity.

[0016] One end of the drainage tunnel connects to the initial sealing section, and the other end of the drainage tunnel extends outward. Correspondingly, the drainage tunnel connects with the original underground river cavity and forms a drainage tunnel.

[0017] One end of the treatment branch tunnel is connected to the drainage and traffic tunnel, and the other end of the treatment branch tunnel is connected to the underground river pipeline filling section, which is filled with concrete.

[0018] In one possible design, the initial sealing body is located upstream of the seepage barrier curtain line and is used to seal the connection between the initial sealing section and the drainage traffic tunnel, and the length of the initial sealing body is not less than the minimum sealing length calculated based on the maximum water-blocking height.

[0019] In one possible design, the underground river drainage module includes a drainage connecting pipe and an outer concrete layer;

[0020] The drainage connecting pipe is located in the drainage tunnel. One end of the drainage connecting pipe passes through the drainage traffic tunnel and the initial sealing body and then enters the original underground river cavity. The other end of the drainage connecting pipe extends outward along the drainage traffic tunnel and connects to the outside world.

[0021] An outer concrete layer is wrapped around the drainage connecting pipe.

[0022] In one possible design, the outer concrete layer is located in the drainage tunnel and connected to the sidewall of one side of the drainage tunnel, and correspondingly, the drainage connecting pipe passes through the outer concrete layer.

[0023] The diameter of the drainage connecting pipe shall not be less than the diameter corresponding to the minimum drainage flow rate during the construction period, and a water-blocking ring connected to the drainage connecting pipe shall be provided in the initial sealing body.

[0024] In one possible design, the karst ventilation module includes a ventilation tunnel and a ventilation hole; the ventilation tunnel is located above the drainage tunnel, with one end extending to the original underground river cavity and the other end connecting to the outside; the ventilation hole is located inside the mountain and has a protective pipe at the top, and the ventilation hole is used to connect the end of the ventilation tunnel and the original underground river cavity.

[0025] In one possible design, the bottom of the ventilation tunnel is higher than the highest water level outside, and the air intake end of the ventilation tunnel connecting to the outside is located on the mountain slope or is constructed as a grouting tunnel connecting to the top curtain.

[0026] In one possible design, multiple vents are provided, and a protective tube is placed at the top of the vent, with one end extending into the vent at a distance of not less than 30 cm above the bottom plate of the vent, in order to avoid water sealing.

[0027] In one possible design, the original underground river cavity, the drainage connecting pipe of the underground river drainage module, and the karst ventilation module including ventilation holes and ventilation openings form a ventilation and pressure equalization structure.

[0028] Secondly, the present invention provides a construction method for a drainage and pressure system for karst underground rivers at the dam abutment, comprising the following steps:

[0029] Construction was carried out in the upstream river channel above the upstream cofferdam, and a drainage and transportation tunnel was constructed into the mountain to connect with the underground river pipeline.

[0030] The original underground river cavity was drained until there was no water accumulation inside the cave; based on the condition that there was no water accumulation inside the cave, a treatment tunnel was constructed along the drainage and traffic tunnel until the treatment tunnel was connected to the underground river pipeline filling section.

[0031] The drainage tunnel and the treatment branch tunnel will serve as the traffic tunnels during the construction period;

[0032] After the construction of the adit is completed, a drainage connecting pipe is constructed along the side wall of the drainage and traffic tunnel;

[0033] After the drainage connecting pipe is constructed, the initial sealing body and outer concrete layer are constructed.

[0034] A ventilation tunnel is constructed from the grouting hole on the bank slope or top curtain grouting hole to the top of the original underground river cavity;

[0035] After the ventilation tunnel is completed, a ventilation hole is constructed at the end of the tunnel to connect with the original underground river cavity, and a protective pipe is installed based on the ventilation hole;

[0036] The construction of the concrete filling body is completed by treating the adit.

[0037] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0038] Through the coordination and linkage of the three modules, multiple functions such as drainage, ventilation, and pressure equalization are achieved. By forming a ventilation and pressure equalization structure based on the principle of communicating vessels, it can be used for drainage during construction and for water and air balance during operation. This achieves the best treatment of the karst underground river channel on the dam shoulder and effectively solves the impact of karst water and air on the dam. Attached Figure Description

[0039] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0040] Figure 1 This is a schematic diagram of a drainage and pressure system for a karst underground river at the dam shoulder.

[0041] Figure 2 for Figure 1 Schematic diagram of the cross-sectional structure at section AA.

[0042] Figure 3 for Figure 1 Schematic diagram of the cross-sectional structure at section BB.

[0043] Figure 4 for Figure 1 A schematic diagram of the cross-sectional structure at section CC.

[0044] Figure 5 for Figure 1 Schematic diagram of the cross-sectional structure of section DD.

[0045] The attached diagram shows the markings and corresponding component names:

[0046] 1. Underground river pipeline sealing module; 2. Underground river drainage module; 3. Karst ventilation module; 4. Upstream river channel; 11. Initial sealing section; 12. Drainage and traffic tunnel; 13. Treatment branch tunnel; 14. Concrete filling body; 15. Initial sealing body; 21. Drainage connecting pipe; 22. Outer concrete layer; 23. Water-blocking ring; 31. Ventilation tunnel; 32. Ventilation hole; 33. Protective pipe. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0048] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known structures, circuits, materials, or methods have not been specifically described in order to avoid obscuring the invention.

[0049] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. Moreover, those skilled in the art will understand that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0050] In the description of this invention, the terms "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0051] Example:

[0052] like Figures 1-5 As shown, in a first aspect, the present invention provides a drainage and pressure system for karst underground rivers at the dam abutment, comprising:

[0053] Underground river pipeline sealing module 1, which is used to fill the underground river pipeline and form a water-blocking structure;

[0054] The underground river drainage module 2 is used to connect water bodies inside and outside the mountain and realize the flow and transfer of water.

[0055] Karst ventilation module 3 is used to connect the gas inside and outside the mountain and realize the flow and transfer of gas;

[0056] Among them, the underground river drainage module 2 and the karst ventilation module 3 form a ventilation and pressure equalization structure, which maintains the water balance inside and outside the mountain based on the principle of communicating vessels.

[0057] The karst underground river abutment is constructed on the slope of the dam using a drainage and pressure system, with the dam's completion marking the boundary. The construction period is defined as the dam's construction process, and the operational period is defined as the dam's completion and operation. The space within the mountain is referred to as the underground river conduit, through which underground river water or karst water flows.

[0058] The underground river pipeline sealing module 1 is used to fill the underground river pipeline, providing a water-retaining structure for drainage during construction, guiding the karst water in the mountain to the outside, eliminating unstable factors, and ensuring safety during construction. During operation, it is used to seal the seepage channels on the dam shoulder, preventing karst water from affecting the integrity of the anti-seepage curtain, the durability of the dam foundation, and the stability of the mountain near the dam area, which helps to ensure the anti-sliding stability of the arch dam shoulder arch seat and the dam as a whole.

[0059] The underground river drainage module 2 works in conjunction with the underground river pipeline sealing module 1 during the construction phase to complete drainage operations. During operation, it connects the inside and outside of the mountain, thus working in conjunction with the karst ventilation module 3 to balance the water levels inside and outside the mountain. Furthermore, the underground river drainage module 2 combines temporary facilities during construction with permanent connection structures, saving the investment required for constructing separate connection tunnels and improving the project's economic efficiency.

[0060] The karst ventilation module 3 is used to connect the gas inside and outside the mountain. During the construction period, when draining water, the karst ventilation module 3 is used to replenish the original underground river cavity with gas. During the operation period, it provides a ventilation and pressure equalization structure for the reservoir water and the karst water inside the mountain, and timely exhausts gas and equalizes pressure to avoid gas explosion instability in the karst caves inside the mountain, slow down the expansion of the solution fissures and the development of karst, and ensure the stability of the karst caves, the integrity of the curtain and the stability of the dam, making the operation of the dam safer.

[0061] Simultaneously, the karst ventilation module 3 and the underground river drainage module 2 work together to form a ventilation and pressure equalization structure. This structure utilizes the principle of communicating vessels to balance the water and air inside and outside the mountain. When a water level difference occurs between the reservoir water level and the karst water, the water flows from the higher water level to the lower water level until the inner and outer water levels are equal. Once the water levels are equal and the pressure difference is zero, the water no longer tends to flow, and the system reaches a state of static equilibrium. Thus, by equalizing the water levels inside and outside the mountain, the water levels inside the mountain and the reservoir water level change synchronously, maintaining internal and external water balance with relatively small water level fluctuations. This avoids hazards such as fissure splitting and karst cave collapse caused by long-term internal and external water level differences and rock seepage pressure.

[0062] Based on this, the drainage and pressure equalization system for the karst underground river at the dam shoulder achieves multiple functions such as drainage, ventilation, and pressure equalization through the cooperation and linkage of three modules. By forming a ventilation and pressure equalization structure based on the principle of communicating vessels, it can be used for drainage during construction and for water and air balance during operation, realizing the best treatment method for the karst underground river channel at the dam shoulder and effectively solving the impact of karst water and air on the dam.

[0063] In one possible implementation, the underground river pipeline sealing module 1 includes an initial sealing section 11, a drainage and traffic tunnel 12, a treatment branch tunnel 13, and an underground river pipeline filling section;

[0064] The initial sealing section 11 is located in the underground river pipeline. The initial sealing section 11 is equipped with an initial sealing body 15, which is used to separate the underground river pipeline into the initial sealing section 11 and the original underground river cavity.

[0065] One end of the drainage tunnel 12 is connected to the initial sealing section 11, and the other end of the drainage tunnel 12 extends outward. Correspondingly, the drainage tunnel 12 is connected to the original underground river cavity and forms a drainage tunnel.

[0066] One end of the treatment branch tunnel 13 is connected to the drainage traffic tunnel 12, and the other end of the treatment branch tunnel 13 is connected to the underground river pipeline filling section, which is equipped with a concrete filling body 14.

[0067] Based on the above design scheme, in the underground river pipeline, an appropriate location upstream of the seepage prevention curtain line is selected as the initial sealing section 11. By filling this part of the underground river pipeline, water is blocked during the construction period, providing a water-free environment for the construction of the underground river pipeline filling section, so that the construction inside the underground river pipeline is not disturbed by drainage. Correspondingly, the remaining part of the underground river pipeline is referred to as the original underground river cavity.

[0068] Preferably, such as Figure 1 As shown, the initial sealing section 11 is connected to the drainage and traffic tunnel 12. After the initial sealing body 15 fills the initial sealing section 11, during the construction period, the drainage and traffic tunnel 12 and the treatment branch tunnel 13 are used as traffic tunnels. After the construction is completed, the concrete filling body 14 is constructed using the treatment branch tunnel 13, and the concrete filling body 14 is connected to the initial sealing body 15 as a whole, with better integrity, thereby ensuring the sealing and seepage prevention performance of the curtain during the operation period, reducing the deformation of the dam shoulder and improving the stability and safety factor of the dam.

[0069] In one possible implementation, the initial sealing body 15 is located upstream of the seepage prevention curtain line and is used to seal the connection between the initial sealing section 11 and the drainage traffic tunnel 12, and the length of the initial sealing body 15 is not less than the minimum sealing length calculated based on the maximum water blocking height.

[0070] Based on the above design scheme, during the construction phase, the initial sealing body 15 creates a water-free environment by blocking water flow. During the operation phase, the initial sealing body 15 blocks sudden water inflows to prevent structural damage. Furthermore, the initial sealing body 15 can be formed by water-filled glass, airbags, or curtain walls, offering a variety of options to adapt to different working environments.

[0071] Furthermore, regarding the length of the initial plugging body 15, those skilled in the art can select it as needed, while ensuring the plugging range, plugging stability, and plugging efficiency.

[0072] In one possible implementation, the underground river drainage module 2 includes a drainage connecting pipe 21 and an outer concrete layer 22;

[0073] The drainage connecting pipe 21 is located in the drainage tunnel. One end of the drainage connecting pipe 21 passes through the drainage traffic tunnel 12 and the initial sealing body 15 and then enters the original underground river cavity. The other end of the drainage connecting pipe 21 extends outward along the drainage traffic tunnel 12 and connects to the outside.

[0074] An outer concrete layer 22 covers the drainage connecting pipe 21.

[0075] Based on the above design scheme, during the construction phase, the drainage connecting pipe 21 is used for external drainage, such as introducing it into the upstream river channel 4, without interfering with the filling operation of the underground river pipeline sealing module 1 and the construction of the dam. During the operation phase, the drainage connecting pipe 21 is used to connect the inside and outside of the mountain to avoid excessive water level differences and increased seepage pressure in the mountain, which could cause the solution fissures to split. The outer concrete layer 22 is used to protect the drainage connecting pipe 21, enhance its structural strength, increase its compressive and impact resistance, and effectively improve the durability and service life of the drainage connecting pipe 21.

[0076] In one possible implementation, the outer concrete layer 22 is located in the drainage tunnel and connected to the sidewall of one side of the drainage tunnel, and correspondingly, the drainage connecting pipe 21 passes through the outer concrete layer 22.

[0077] Based on the above design scheme, the location of the drainage connecting pipe 21 helps to optimize space utilization, avoid the underground river drainage module 2 from occupying too much space, ensure traffic efficiency during construction, and improve construction convenience. In karst areas, the drainage connecting pipe 21, in conjunction with the grouting curtain, forms a blocking and drainage combination, which helps to improve drainage efficiency.

[0078] In one possible implementation, the diameter of the drainage connecting pipe 21 is not less than the diameter corresponding to the minimum drainage flow rate during the construction period, and the initial sealing body 15 is provided with a water-blocking ring 23 connected to the drainage connecting pipe 21.

[0079] Based on the above design, the diameter of the drainage connecting pipe 21 meets the drainage requirements and achieves flow velocity control to avoid impurity deposition inside the drainage connecting pipe 21, which helps reduce wear during use and extend its service life. The water-blocking ring 23 is used to prevent water seepage and avoid karst water from damaging the underground river drainage module 2.

[0080] In one possible implementation, the karst ventilation module 3 includes a ventilation tunnel 31 and a ventilation hole 32; the ventilation tunnel 31 is located above the drainage tunnel, one end of the ventilation tunnel 31 extends to the original underground river cavity, and the other end of the ventilation tunnel 31 connects to the outside; the ventilation hole 32 is located inside the mountain and is provided with a protective pipe 33 at the top of the hole, and the ventilation hole 32 is used to connect the end of the ventilation tunnel 31 and the original underground river cavity.

[0081] Based on the above design, the original underground river cavity is connected to the outside world through ventilation holes 32 and ventilation tunnels 31. During construction, gas flows sequentially through ventilation tunnels 31 and ventilation holes 32 and into the original underground river cavity, achieving gas replenishment and promoting drainage, thereby improving drainage efficiency. During operation, it works in conjunction with the underground river diversion and drainage module 2 to form a ventilation and pressure equalization structure, thereby utilizing the principle of communicating vessels to balance the water level inside and outside the mountain.

[0082] In one possible implementation, the bottom plate of the ventilation tunnel 31 is higher than the highest water level outside, and the air intake end of the ventilation tunnel 31 connecting to the outside is located on the slope of the mountain or constructed as a grouting tunnel connecting to the top layer of the mountain. Based on the above design scheme, the ventilation tunnel 31 is used to balance the air pressure inside and outside the mountain, ensure drainage efficiency, and help prevent cavitation and the resulting structural damage.

[0083] In one possible implementation, multiple vent holes 32 are provided, and a protective pipe 33 is located at the top of the vent holes, with one end extending into the vent 31 at a distance of at least 30 cm above the bottom plate of the vent 31. Based on the above design, multiple vent holes 32 are provided to increase the gas flow path and improve the gas replenishment efficiency. The protective pipe 33 is higher than the bottom plate of the vent 31 to ensure smooth gas flow and avoid water seal.

[0084] In one possible implementation, the original underground river cavity, the drainage connecting pipe 21 of the underground river drainage module 2, and the karst ventilation module 3, including ventilation holes 31 and ventilation holes 32, form a ventilation and pressure equalization structure.

[0085] Based on the above design scheme, the ventilation and pressure equalization structure utilizes the principle of communicating vessels to achieve water level balance inside and outside the mountain. That is, the ventilation tunnel 31 and ventilation hole 32 enable communication between the gas inside and outside the mountain, thereby ensuring that the gas pressure on the lava water and the water outside the mountain (such as the reservoir water of a dam) is consistent. At the same time, the drainage connecting pipe 21 connects the water bodies inside and outside the mountain. When the water level of one body fluctuates, the water flows, causing the water level of the other body to change synchronously until the water levels inside and outside are equal.

[0086] Secondly, the present invention provides a construction method for a drainage and pressure system for karst underground rivers at the dam abutment, comprising the following steps:

[0087] S10: Construction is carried out in the upstream river channel 4 above the upstream cofferdam, and a drainage and transportation tunnel 12 is constructed into the mountain to connect with the underground river pipeline.

[0088] S20: Drain the original underground river cavity until there is no water accumulation inside the cave; based on the condition that there is no water accumulation inside the cave, construct the treatment branch tunnel 13 along the drainage traffic tunnel 12 until the treatment branch tunnel 13 connects to the underground river pipeline filling section.

[0089] S30: Drainage tunnel 12 and treatment branch tunnel 13 are used as traffic tunnels during the construction period;

[0090] S40: After the construction of the auxiliary tunnel 13 is completed, a drainage connecting pipe 21 is constructed along the side wall of the drainage traffic tunnel 12;

[0091] S50: After the drainage connecting pipe 21 is constructed, the initial sealing body 15 and the outer concrete layer 22 are constructed.

[0092] S60: Construct a ventilation tunnel 31 from the bank slope or the top curtain grouting tunnel to the original underground river cavity;

[0093] S70: After the ventilation tunnel 31 is completed, a ventilation hole 32 connecting the original underground river cavity is constructed at the end of the tunnel, and a protective pipe 33 is installed based on the ventilation hole 32.

[0094] S80: Complete the construction of the concrete filling body 14 by treating the branch tunnel 13.

[0095] In S40, the drainage connecting pipe 21 enables the drainage and pressure-lowering system for the karst underground river at the dam shoulder to smoothly transition from the construction period to the operation period, thereby achieving pressure-lowering function during the operation period.

[0096] In S50, sealing is achieved through filling, transforming the drainage and pressure-regulating system of the karst underground river at the dam abutment from a "temporary structure" to a "permanent structure," changing the existing forced water flow interception and confrontational sealing to a dredging-style treatment. The initial sealing body 15 divides the underground river pipeline space, thereby creating conditions for filling the treatment branch tunnel 13. Correspondingly, the filling structure and the outer concrete layer 22 together serve as part of the subsequent "permanent structure," achieving the function of ventilation and pressure regulation.

[0097] In S60 and S70, the ventilation tunnel 31 and ventilation hole 32 work together to connect the inside and outside, ensuring the dynamic stability of the pressure inside the closed cavity of the underground river. This is the core measure to achieve the dynamic balance between the karst water in the mountain near the dam area and the reservoir water.

[0098] In S80, the cavity of the underground river pipeline is filled to ensure the integrity of the seepage prevention curtain. After this step, the pipeline's sealing body and filling body serve as a permanent water-retaining and pressure-bearing structure.

[0099] In sections S10-S40, the structures constructed are generally used as temporary structures, but combined with subsequent construction, a preliminary "permanent-temporary combination" is achieved. Compared to the sealing schemes used in existing technologies, which neglect the drainage needs of the mountain during the high-water season, leading to work stoppages, the proposed construction method establishes an independent and reliable drainage and traffic system during the construction period through drainage and traffic tunnel 12 and drainage connecting pipe 21. This ensures that subsequent operations can be carried out under water-free conditions, fundamentally solving the problem of construction stagnation during the high-water season. The drainage pipes at this stage are temporary facilities, but their design axis, elevation, and cross-section have been reserved for future conversion into permanent structures.

[0100] In sections S50-S80, the characteristics of the karst underground river were fully utilized. Initial sealing bodies 15 and drainage connecting pipes 21 were used to divert the underground river water into the upstream river channel 4, avoiding interference from drainage with karst construction. By using the construction drainage connecting pipe 21 as a connection channel between the karst water within the mountain and the reservoir water, not only were drainage and ventilation pressure-regulating structures integrated into a system, saving costs and construction time, but it also has multiple functions during the construction and operation phases. Furthermore, it solves the problems of gas explosion instability in karst caves caused by reservoir storage and release, avoiding karst collapse and local instability within karst caves that could induce near-dam earthquakes. It has excellent practicality and application prospects, providing a good reference for similar projects.

[0101] In summary, the construction method described above embodies a systematic approach of "combining permanent and temporary functions and transforming functions," transforming the traditional approach of forcibly cutting off water flow and resistive blocking into a dredging and management approach. The design of the temporary structure incorporates the genes of permanent functions from the very beginning, organically linking the construction period with the operation period, and forming a reliable multi-functional system.

[0102] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A drainage and pressure system for karst underground rivers at the dam abutment, characterized in that, include: An underground river pipeline sealing module (1) is used to fill the underground river pipeline and form a water-blocking structure; The underground river drainage module (2) is used to connect the water bodies inside and outside the mountain and realize the flow and transfer of water bodies. Karst ventilation module (3), which is used to connect the gas inside and outside the mountain and realize the flow and transfer of gas and water; Among them, the underground river drainage module (2) and the karst ventilation module (3) form a ventilation and pressure equalization structure. The ventilation and pressure equalization structure maintains the water balance inside and outside the mountain based on the principle of communicating vessels. The underground river pipeline sealing module (1) includes an initial sealing section (11), a drainage and traffic tunnel (12), a treatment branch tunnel (13), and an underground river pipeline filling section; The initial sealing section (11) is located in the underground river pipeline. The initial sealing section (11) is equipped with an initial sealing body (15). The initial sealing body (15) is used to separate the underground river pipeline into the initial sealing section (11) and the original underground river cavity. One end of the drainage tunnel (12) is connected to the initial sealing section (11), and the other end of the drainage tunnel (12) extends outward. Correspondingly, the drainage tunnel (12) is connected to the original underground river cavity and forms a drainage tunnel. One end of the treatment branch tunnel (13) is connected to the drainage traffic tunnel (12), and the other end of the treatment branch tunnel (13) is connected to the underground river pipeline filling section. The underground river pipeline filling section is equipped with a concrete filling body (14). The underground river drainage module (2) includes a drainage connecting pipe (21) and an outer concrete layer (22). The drainage connecting pipe (21) is located in the drainage tunnel. One end of the drainage connecting pipe (21) passes through the drainage traffic tunnel (12) and the initial sealing body (15) and then enters the original underground river cavity. The other end of the drainage connecting pipe (21) extends outward along the drainage traffic tunnel (12) and connects to the outside world. An outer concrete layer (22) covers the drainage connecting pipe (21).

2. The drainage and pressure system for karst underground rivers at the dam abutment according to claim 1, characterized in that, The initial sealing body (15) is located upstream of the seepage prevention curtain line and is used to seal the connection between the initial sealing section (11) and the drainage traffic tunnel (12), and the length of the initial sealing body (15) is not less than the minimum sealing length calculated based on the maximum water blocking height.

3. The drainage and pressure system for karst underground rivers at the dam abutment according to claim 1, characterized in that, The outer concrete layer (22) is located in the drainage tunnel and is connected to the side wall of the drainage tunnel. Correspondingly, the drainage connecting pipe (21) is installed in the outer concrete layer (22). The diameter of the drainage connecting pipe (21) is not less than the pipe diameter corresponding to the minimum drainage flow rate during the construction period, and the initial sealing body (15) is provided with a water-blocking ring (23) connected to the drainage connecting pipe (21).

4. The drainage and pressure system for karst underground rivers at the dam abutment according to claim 3, characterized in that, The karst ventilation module (3) includes a ventilation tunnel (31) and a ventilation hole (32); the ventilation tunnel (31) is located above the drainage tunnel, one end of the ventilation tunnel (31) extends to the top of the original underground river cavity, and the other end of the ventilation tunnel (31) is connected to the outside; the ventilation hole (32) is located inside the mountain and is equipped with a protective pipe (33) at the top of the hole, and the ventilation hole (32) is used to connect the end of the ventilation tunnel (31) and the original underground river cavity.

5. The drainage and pressure system for karst underground rivers at the dam abutment according to claim 4, characterized in that, The bottom plate of the ventilation tunnel (31) is higher than the highest water level outside, and the air intake end of the ventilation tunnel (31) connecting to the outside is set on the mountain slope or is constructed as a grouting tunnel connecting the top curtain.

6. The drainage and pressure system for karst underground rivers at the dam abutment according to claim 5, characterized in that, Multiple ventilation holes (32) are provided. The protective tube (33) is set at the top of the ventilation hole and the end of the tube extending into the ventilation hole (31) is at least 30 cm above the bottom plate of the ventilation hole (31) to avoid water seal.

7. The drainage and pressure system for karst underground rivers at the dam abutment according to any one of claims 1-6, characterized in that, The original underground river cavity, the drainage connecting pipe (21) of the underground river drainage module (2), and the karst ventilation module (3) including ventilation hole (31) and ventilation hole (32) form a ventilation and pressure-relieving structure.

8. A construction method for a drainage and pressure system for karst underground rivers at the dam abutment based on any one of claims 1-7, characterized in that, Includes the following steps: Construction was carried out in the upstream river channel (4) above the upstream cofferdam, and a drainage and transportation tunnel (12) connecting the underground river pipeline was constructed into the mountain. The original underground river cavity was drained until there was no water accumulation inside the cave; based on the condition that there was no water accumulation inside the cave, the treatment branch tunnel (13) was constructed along the drainage traffic tunnel (12) until the treatment branch tunnel (13) was connected to the underground river pipeline filling section; The drainage tunnel (12) and the treatment branch tunnel (13) are used as the traffic tunnels during the construction period; After the construction of the treatment tunnel (13) is completed, a drainage connecting pipe (21) is constructed along the side wall of the drainage traffic tunnel (12). After the drainage connecting pipe (21) is constructed, the initial sealing body (15) and the outer concrete layer (22) are constructed. A ventilation tunnel is constructed from the slope or the top curtain grouting tunnel to the original underground river cavity above the ventilated cavity (31). After the ventilation tunnel (31) is completed, a ventilation hole (32) connecting the original underground river cavity is constructed at the end of the tunnel, and a protective pipe (33) is installed based on the ventilation hole (32). The construction of the concrete filling body (14) is completed by treating the adit (13).

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