Reservoir head rock karst depression treatment method

Abstract

The application discloses a reservoir head karst depression treatment method, relates to the technical field of karst depression treatment, and solves the problem of properly disposing karst depression flood discharge and hole excavation residue disposal when a reservoir is built in a karst area. The reservoir head karst depression treatment method, wherein the karst depression is located on the upper part of a mountain body along the bank of the reservoir head, a water retaining dam is arranged at the reservoir head, and a seepage prevention curtain connected with the water retaining dam is arranged on the banks of the water retaining dam, comprises the following steps: a grouting hole is built from the two sides of the water retaining dam to the mountain body, and the seepage prevention curtain is formed by construction in the grouting hole; when the grouting hole is built, a communication hole is built on the side with the karst depression and is communicated between the karst depression and the grouting hole; the hole excavation residue of the grouting hole and the communication hole is filled in the karst depression to form permanent farmland; and the communication hole and the grouting hole are communicated to form a flood discharge hole connected from the karst depression to the reservoir area.

Description

Technical Field

[0001] This invention relates to the field of karst depression treatment technology, and in particular to a method for treating karst depressions at the head of a reservoir. Background Technology

[0002] Karst depressions in karst regions are high in elevation and have poor drainage capacity in the lower karst channels. When rainfall is heavy, these depressions are prone to flooding. Drainage tunnels are often installed in densely populated and farmland areas to solve the problem of flooding in karst depressions.

[0003] When constructing reservoirs in karst regions, it is necessary to install anti-seepage curtain grouting tunnels along the mountainsides on both sides of the dam at the reservoir head to construct the anti-seepage curtain and prevent reservoir water leakage. Dedicated disposal sites must be designated for excavated waste. The dumping of excavated waste not only occupies land and damages vegetation, but also serves as a source of debris flows, posing a potential environmental impact. If excavated waste is not properly disposed of, it will lead to various ecological and environmental problems and threaten sustainable development.

[0004] When a karst depression is near the head of a reservoir, in order to prevent the karst channels cut off by the seepage prevention curtain from being breached by floods from the karst depression, it is necessary to set up a flood discharge tunnel in the karst depression to drain the floodwaters away.

[0005] While this method of setting up drainage tunnels in karst depressions, grouting tunnels in reservoir head anti-seepage curtain construction, and waste disposal sites can meet the basic functional requirements, the project has high costs, poor economic benefits, and potential ecological and environmental problems.

[0006] To address this, a method for treating karst depressions at the reservoir head has been developed to effectively handle issues such as flood discharge from karst depressions and disposal of excavated waste during reservoir construction in karst regions. Summary of the Invention

[0007] The purpose of this invention is to propose a method for treating karst depressions at the head of a reservoir, which solves the problem of properly handling flood discharge and disposal of excavated waste from karst depressions when constructing reservoirs in karst areas.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for treating a karst depression at the head of a reservoir, wherein at least one side of the reservoir has the karst depression, the karst depression is located on the upper part of the mountain along the head of the reservoir, a dam is set at the head of the reservoir, and seepage prevention curtains are set on both sides of the dam to connect the dam. The method includes: constructing grouting tunnels from both sides of the dam toward the mountain, and constructing the seepage prevention curtains within the grouting tunnels; when constructing the grouting tunnels, constructing a connecting tunnel from the karst depression to the grouting tunnel on the side with the karst depression; filling the slag excavated from the grouting tunnel and the connecting tunnel into the karst depression to form permanent farmland; and connecting the connecting tunnel and the grouting tunnel to form a flood discharge tunnel.

[0010] Based on the above scheme and as a preferred option: to form the permanent arable land, the bottom of the karst depression is filled with the stone slag from the excavation of the cave to form a stone slag layer, the stone slag from the excavation of the cave and soil are mixed and filled on the stone slag layer to form a cushion layer, and soil is filled on the cushion layer to form a planting soil layer.

[0011] Based on the above scheme and as a preferred option, the location of the entrance to the connecting tunnel is at a height not lower than the location of the permanent cultivated land.

[0012] Based on the above scheme and as a preferred option: determine the preset value of the elevation of the permanent cultivated land according to the estimated amount of waste excavated from the tunnel and the calculated reservoir capacity of the karst depression; determine the design elevation of the entrance of the connecting tunnel according to the preset value of the elevation of the permanent cultivated land.

[0013] Based on the above scheme and as a preferred embodiment of the above scheme: by setting the bottom of the grouting hole to have an inclination towards the reservoir area and by setting the bottom of the connecting hole to have an inclination towards the grouting hole, the bottom of the flood discharge tunnel forms an inclination towards the reservoir area.

[0014] Based on the above scheme and as a preferred option: the flood discharge tunnel connects from the karst depression to the reservoir area.

[0015] To address the issues of properly handling flood discharge from karst depressions and disposing of excavated waste during reservoir construction in karst regions, this invention offers the following advantages:

[0016] The present invention provides a method for treating karst depressions at the head of a reservoir. By connecting a grouting tunnel with a connecting tunnel, a flood discharge tunnel is formed to divert floodwater from the karst depression near the head of the reservoir into the reservoir area, thus solving the flood discharge problem of the karst depression. Furthermore, by filling the karst depression with excavated waste from the tunneling process, permanent arable land is created, thus solving the problem of proper disposal of excavated waste. This not only avoids various ecological and environmental problems that may result from improper disposal of excavated waste, but also improves land utilization, increases available arable land, and increases the inflow of water into the reservoir.

[0017] Furthermore, it reduces the cost of constructing drainage channels separately for karst depressions. In addition, the connecting tunnels also serve as construction adits, and the excavated waste is dumped nearby, saving the long-distance transportation costs of excavated waste and greatly reducing the cost budget for reservoir construction.

[0018] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0019] Figure 1 This is a schematic plan view of the karst depression treatment structure at the head of the reservoir according to the present invention;

[0020] Figure 2 This is a schematic cross-sectional view of the karst depression treatment structure at the head of the reservoir according to the present invention.

[0021] Figure 3 This is an enlarged view of part A of the present invention.

[0022] Explanation of reference numerals in the attached figures:

[0023] 100 - Reservoir; 200 - Dam; 300 - Anti-seepage curtain; 301 - Grouting tunnel; 302

[0024] - Connecting tunnel; 400- Drainage tunnel; 500- Karst depression; 600- Permanent farmland; 601- Stone slag layer, 602- Subbase layer, 603- Planting soil layer; 700- Mountain body, 701- Interception ditch, 702- Karst passage; 800- Village. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0026] See Figure 1-3 This invention discloses a method for treating a karst depression 500 at the head of a reservoir 100. This method solves the problem of properly handling flood discharge and disposal of excavated waste from the karst depression 500 when constructing a reservoir 100 in a karst region.

[0027] like Figure 1 and Figure 2 As shown, in the treatment method of the karst depression 500 at the head of reservoir 100, at least one side of the reservoir 100 has a karst depression 500, which is located on the upper part of the mountain 700 along the head of reservoir 100. A water-retaining dam 200 is set at the head of reservoir 100, and seepage prevention curtains 300 are set on both sides of the water-retaining dam 200, which include: constructing grouting tunnels 301 from both sides of the water-retaining dam 200 towards the mountain. 1. An anti-seepage curtain 300 is formed during construction. When constructing the grouting tunnel 301, a connecting tunnel 302 is constructed on one side of the karst depression 500, connecting the karst depression 500 to the grouting tunnel 301. The excavated waste from the anti-seepage curtain 300, the grouting tunnel 301, and the connecting tunnel 302 is piled up in the karst depression 500 to form permanent arable land 600. The connecting tunnel 302 and the grouting tunnel 301 are connected to form a flood discharge tunnel 400 connecting the karst depression 500 to the reservoir area 100.

[0028] The present invention provides a method for treating the karst depression 500 at the head of reservoir 100. By connecting the grouting tunnel 301 to the connecting tunnel 302, floodwater from the karst depression 500 near the head of reservoir 100 is diverted into the flood discharge tunnel 400 of reservoir 100, thus solving the flood discharge problem of the karst depression 500. Furthermore, by filling the excavated waste from the tunneling process into the karst depression 500 to form permanent arable land 600 for use by nearby villages 800, the proper disposal of excavated waste from the tunneling process is solved. This method not only avoids various ecological and environmental problems that may result from improper disposal of excavated waste from the tunneling process, but also improves land utilization, increases available arable land, and increases the water inflow into reservoir 100.

[0029] Since the karst depression 500 is adjacent to the head of the reservoir 100, the floodwater in the karst depression 500 should be drained in time to prevent the karst channel 702 cut off on the anti-seepage curtain 300 from being breached by the floodwater in the karst depression 500, which could lead to uncontrollable leakage of the reservoir 100.

[0030] Furthermore, it reduced the cost of constructing drainage channels separately for the karst depression 500, and by using the connecting tunnel as a construction adit, the excavated waste could be dumped nearby, saving the long-distance transportation costs of excavated waste and greatly reducing the cost budget for the construction of the reservoir 100.

[0031] To prevent floodwaters from entering the permanent farmland 600 filled into the karst depression 500 during the rainy season, a drainage ditch 701 is constructed within the karst depression 500 to divert floodwaters into a drainage tunnel 400. The drainage ditch 701 continuously encircles the inner perimeter of the karst depression 500, ensuring its location is no lower than the elevation of the permanent farmland 600. This effectively intercepts flash floods within the karst depression 500, preventing floodwaters from entering the permanent farmland 600.

[0032] Based on the location of the karst depression 500, the location of the water-retaining dam 200, and the location of the karst channel 702 exposed in the riverbed, the anti-seepage curtain 300 and the grouting tunnel 301 are arranged on the bank slope section to cut off the karst depression 500 and the main karst channel downstream of the anti-seepage curtain 300 on the bank slope section.

[0033] Among them, the intercepting ditch 701 has an overall slope that is inclined towards the inlet of the connecting tunnel 302. By constructing the overall slope of the intercepting ditch 701, the intercepted water flow is effectively introduced into the flood discharge tunnel 400.

[0034] The location of the entrance to the connecting tunnel 302 must be at a height no lower than that of the permanent cultivated land 600. If it is lower, the soil in the permanent cultivated land 600 is easily washed into the flood discharge tunnel 400 by rainwater during the rainy season, causing river pollution.

[0035] To determine the inlet location of connecting tunnel 302 before construction, since the excavated soil required for the permanent cultivated land 600 backfill is supplied from excavations during the construction of grouting tunnel 301 and connecting tunnel 302, a preset height for the permanent cultivated land 600 was determined based on the estimated amount of excavated waste and the calculated reservoir capacity of karst depression 500. The design height of the connecting tunnel 302 inlet was then determined based on this preset height. In practice, situations arose where the excavated waste backfill height was slightly higher or lower than the connecting tunnel 302 inlet. These adjustments could be made appropriately based on site conditions after the completion of the anti-seepage curtain 300 and before the construction of intercepting ditch 701.

[0036] like Figure 3 To create fertile and drought-resistant permanent farmland 600, the bottom layer of the karst depression 500 is filled with excavated rock debris to form a rock debris layer 601. Above this layer 601, a mixture of excavated rock debris and soil forms a cushion layer 602. Finally, soil is filled onto the cushion layer 602 to form a planting soil layer 603. The bottom rock debris layer 601 stabilizes the foundation of the fill, while the cushion layer 602 reduces rainwater infiltration, mitigates soil drought, and prevents land subsidence and the formation of silt pits. The planting soil layer 603 has a thickness of not less than 0.6 meters and not more than 1.2 meters.

[0037] To ensure the flood discharge capacity of the flood discharge tunnel 400, the bottom of the grouting tunnel 301 is inclined towards the reservoir area of ​​reservoir 100, and the bottom of the connecting tunnel 302 is also inclined towards the grouting tunnel 301. This ensures that the bottom of the flood discharge tunnel 400 is inclined towards the reservoir area of ​​reservoir 100, thereby effectively ensuring that floodwater from the direction of the karst depression 500 is introduced into the reservoir area of ​​reservoir 100, and that the water flow does not accumulate in the flood discharge tunnel 400.

[0038] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for treating a karst depression at the head of a reservoir, wherein at least one side of the reservoir (100) has the karst depression (500), the karst depression (500) is located on the upper part of the mountain (700) along the head of the reservoir (100), a water-retaining dam (200) is provided at the head of the reservoir (100), and seepage-proof curtains (300) connecting the water-retaining dam (200) are respectively provided on both sides of the water-retaining dam (200), characterized in that, include: Grouting tunnels (301) are constructed from both sides of the water-retaining dam (200) towards the mountain, and the seepage prevention curtain (300) is formed inside the grouting tunnels (301). When constructing the grouting tunnel (301), a connecting tunnel (302) is constructed on one side of the karst depression (500) that connects the karst depression (500) to the grouting tunnel (301). The excavated waste from the grouting tunnel (301) and the connecting tunnel (302) is piled up in the karst depression (500) to form permanent farmland (600). The connecting tunnel (302) and the grouting tunnel (301) are connected to form a flood discharge tunnel (400). To form the permanent farmland (600), the bottom of the karst depression (500) is filled with the stone debris from the excavation of the tunnel to form a stone debris layer (601). The stone debris layer (601) is filled with a mixture of stone debris from the excavation of the tunnel and soil to form a cushion layer (602). The cushion layer (602) is filled with soil to form a planting soil layer (603). The height of the entrance to the connecting tunnel (302) is not lower than the height of the permanent cultivated land (600); The preset value of the height of the permanent cultivated land (600) is determined based on the estimated amount of waste excavated from the tunnel and the calculated reservoir capacity of the karst depression (500); the design height of the inlet of the connecting tunnel (302) is determined based on the preset value of the height of the permanent cultivated land (600). By setting the bottom of the grouting hole (301) to have an inclination towards the reservoir (100) area and by setting the bottom of the connecting hole (302) to have an inclination towards the grouting hole (301), the bottom of the flood discharge hole (400) is made to have an inclination towards the reservoir (100) area. The drainage tunnel (400) connects from the karst depression (500) to the reservoir (100) area.

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