A plugging and drainage device for karst depression bottom water falling hole

Abstract

The application discloses a kind of for karst depression bottom water cave plugging drainage device, including arc covering body, arc covering body includes planar bottom surface and smooth arc surface upper surface, the bottom surface of arc covering body covers the cave mouth of water cave, and the load-carrying capacity of smooth arc surface upper surface is enhanced arc covering body, transverse drain pipe, vertical drain pipe, upper drainage hole and lower drainage hole are arranged in the inside of arc covering body, meet the drainage demand when karst depression stores material residue, the plugging drainage device in the application also includes water-permeable water cave filling body, improve the foundation bearing capacity under the premise of solving site natural drainage and guarantee the stability of water cave, can meet the bearing capacity requirement and drainage requirement of larger construction material and abandoned slag storage site, the plugging drainage device in the application simple structure improves the safety and reliability of relevant construction site in karst low-lying area construction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water conservancy and hydropower, and in particular to a plugging and drainage device for a karst depression bottom falling water cave. BACKGROUND

[0002] At present, the construction of pumped storage power stations is vigorously promoted all over the country. In the southwest region of China, the mountainous terrain has large drop and rich water resources, which provides excellent conditions for the construction of pumped storage power stations. However, the karst falling water caves and other natural caves are widely developed in the southwest mountainous region, and the existence of these caves will seriously hinder the construction of projects and cause safety hazards. In the construction process of water conservancy and hydropower projects, low-lying or relatively flat terrain near the upper and lower reservoir sites is selected as much as possible to store construction fill or excavated waste during the construction process. However, sometimes the area suitable for building a large material slag yard will inevitably encounter complex geological conditions such as falling water caves. When these sites are selected as large material slag yards for storing construction materials or piling up construction waste, two basic problems are generally faced: one is how to plug the vertical cave to ensure the safety of the foundation bearing of the site; the other is how to solve the drainage problem of the site itself. Therefore, how to provide a simple and feasible, economically applicable karst depression bottom falling water cave plugging and drainage device and method is a problem that needs to be solved by relevant professionals. SUMMARY

[0003] In view of the defects in the prior art, the present application provides a plugging and drainage device for a karst depression bottom falling water cave to solve the safety hazards caused by falling water caves and other surface and underground caves and the drainage problem of the project site itself when building a material slag storage yard in a karst depression area with developed underground caves.

[0004] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a plugging and drainage device for a karst depression bottom falling water cave, comprising an arc-shaped cover body, the arc-shaped cover body comprises a bottom surface and an upper surface, the bottom surface is a plane, and the upper surface is a smooth arc surface, the upper surface is connected with the bottom surface, the arc-shaped cover body is arranged at the entrance of the falling water cave, the bottom surface of the arc-shaped cover body covers the entrance of the falling water cave, a horizontal drainage pipe is arranged inside the arc-shaped cover body, a vertical drainage pipe in communication with the horizontal drainage pipe is arranged inside the arc-shaped cover body, the vertical drainage pipe penetrates the bottom surface of the arc-shaped cover body, and the outlet of the vertical drainage pipe is arranged in the cave, a plurality of upper drainage holes are symmetrically arranged inside the arc-shaped cover body about the central axis of the arc-shaped cover body, the inlet of the upper drainage hole is arranged on the upper surface of the arc-shaped cover body, and the outlet of the upper drainage hole is arranged on the upper surface of the horizontal drainage pipe.

[0005] In an embodiment, a plurality of lower drainage holes are arranged between the lateral drainage pipe and the bottom surface, the inlet of the lower drainage hole is arranged on the lower surface of the lateral drainage pipe, the outlet of the lower drainage hole is arranged on the bottom surface of the arc-shaped cover, and the outlet of the lower drainage hole is located within the range of the hole opening of the sinkhole.

[0006] In an embodiment, the distance between the pipe axis of the lateral drainage pipe and the bottom surface of the arc-shaped cover is 0.15-0.25 times the maximum distance between the upper surface of the arc-shaped cover and the bottom surface of the arc-shaped cover, the vertical drainage pipe is located on the central axis of the arc-shaped cover, and the lower drainage holes are symmetrically arranged about the central axis of the arc-shaped cover.

[0007] In an embodiment, the angle between the hole axis of the upper drainage hole and the horizontal ground surface is not less than 30°, and the angle between the hole axis of the lower drainage hole and the horizontal ground surface is 90°.

[0008] In an embodiment, a foundation backfill body is arranged above the arc-shaped cover, the foundation backfill body comprises a mesh layer, a mesh protection layer, a soil and stone protection layer, and a large stone layer, the mesh layer comprises a plurality of meshes laid on the upper surface of the arc-shaped cover, the mesh protection layer is laid on the mesh layer, the soil and stone protection layer is laid on the mesh protection layer, and the large stone layer is laid on the soil and stone protection layer.

[0009] In an embodiment, the height of the foundation backfill body is 1.5-3 times the maximum distance between the upper surface of the arc-shaped cover and the bottom surface of the arc-shaped cover.

[0010] In an embodiment, a drainage culvert is arranged on the side wall of the karst depression, a part of the drainage culvert is located within the foundation backfill body, and a part of the drainage culvert is located outside the foundation backfill body, the outlet of the drainage culvert is connected to the lateral drainage pipe.

[0011] In an embodiment, when the karst depression stores a material and slag body, the height of the inlet of the drainage culvert is 0.5-1 meters higher than the height of the upper surface of the material and slag body, the outlet of the drainage culvert is arranged in the lateral drainage pipe, the length of the drainage culvert entering the lateral drainage pipe is not less than 2 times the diameter of the drainage culvert, and the pipe connection part between the drainage culvert and the lateral drainage pipe adopts a sealed waterproof connection.

[0012] In an embodiment, a plurality of grouting anchor rods are arranged on the bottom surface of the arc-shaped cover, one end of the grouting anchor rod is inserted into the surrounding rock of the karst depression, and the other end of the grouting anchor rod is inserted into the arc-shaped cover.

[0013] In an embodiment, a sinkhole filling body is arranged inside the sinkhole, the sinkhole filling body fills up the sinkhole, the sinkhole filling body has water permeability, the sinkhole filling body comprises, in sequence from a lower port of the sinkhole to an upper port of the sinkhole, a riprap filling layer, a block stone filling layer, and a broken stone residue filling layer, and the outlet of the vertical drainage pipe is located in the riprap filling layer.

[0014] The advantageous effects of the plugging and drainage device for the sinkhole at the bottom of the karst depression in the present application are as follows:

[0015] The plugging and drainage device for the sinkhole at the bottom of the karst depression in the present application comprises an arc-shaped cover body, the arc-shaped cover body comprises a planar bottom surface and a smooth arc-shaped upper surface, the bottom surface of the arc-shaped cover body covers the hole of the sinkhole, the smooth arc-shaped upper surface enhances the bearing capacity of the arc-shaped cover body, a horizontal drainage pipe, a vertical drainage pipe, an upper drainage hole, and a lower drainage hole are arranged inside the arc-shaped cover body, the drainage requirements of the karst depression when storing residue are met, the plugging and drainage device in the present application further comprises a sinkhole filling body having water permeability, the sinkhole filling body fills up the sinkhole, the bearing capacity of the foundation is greatly improved and the stability of the sinkhole is ensured on the premise of solving the natural drainage of the site, the bearing capacity and drainage requirements of the large-scale construction material and residue storage site can be met. The plugging and drainage device in the present application has a simple structure, improves the safety reliability and green environmental protection of the construction of the relevant construction site in the karst low-lying area, expands the range of sites suitable for residue storage sites, solves the construction difficulties caused by the existence of sinkholes and other karst caves during the construction of the project, reduces the difficulty of engineering investment decision-making, and is beneficial to the shortening of the construction period. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0017] Figure 1 The structure of the plugging and drainage device for the sinkhole at the bottom of the karst depression in the embodiment of the present application is shown in the overall schematic view.

[0018] Figure 2 The connection of the drainage culvert and the arc-shaped cover body and the partial section enlargement schematic view of the foundation backfill body in the embodiment of the present application are shown.

[0019] Figure 3 The partial section enlargement schematic view of the sinkhole filling body and the arc-shaped cover body in the embodiment of the present application is shown.

[0020] Figure 4 is a top view of the arc-shaped cover body in the embodiment of the present application.

[0021] Fig. 1 is an arc-shaped cover body, Fig. 2 is an upper drainage hole, Fig. 3 is a vertical drainage pipe, Fig. 4 is a horizontal drainage pipe, Fig. 5 is a foundation backfill body, Fig. 6 is a sinkhole filling body, Fig. 7 is a drainage culvert, Fig. 8 is a foundation clearing line, Fig. 9 is a drainage culvert inlet, Fig. 10 is a drainage culvert outlet, Fig. 11 is an original terrain line, Fig. 12 is a soil backfill layer, Fig. 13 is a grouting anchor rod, Fig. 14 is a material residue body, Fig. 15 is a sinkhole, Fig. 16 is an underground tunnel system, Fig. 17 is rainwater, Fig. 18 is a mesh, Fig. 19 is a mesh protection layer, Fig. 20 is a soil and stone residue protection layer, Fig. 21 is a large stone layer, Fig. 22 is a lower drainage hole, Fig. 23 is a crushed stone residue filling layer, Fig. 24 is a block stone filling layer, Fig. 25 is a riprap filling layer, and Fig. 26 is a pipe connection position. DETAILED DESCRIPTION

[0022] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0024] As shown in Figures 1-4 the embodiment of the present application provides a plugging and drainage device for a sinkhole bottom sinkhole, which comprises an arc-shaped cover body 1. The arc-shaped cover body 1 comprises a bottom surface and an upper surface. The bottom surface of the arc-shaped cover body 1 is a plane. The upper surface of the arc-shaped cover body 1 is a smooth arc surface. The upper surface of the arc-shaped cover body 1 is connected with the bottom surface of the arc-shaped cover body 1. The arc-shaped cover body 1 is arranged on the hole of the sinkhole 15. The bottom surface of the arc-shaped cover body 1 covers the hole of the sinkhole 15. A horizontal drainage pipe 4 is arranged inside the arc-shaped cover body 1. The horizontal drainage pipe 4 horizontally penetrates the arc-shaped cover body 1. A vertical drainage pipe 3 in communication with the horizontal drainage pipe 4 is arranged inside the arc-shaped cover body 1. The vertical drainage pipe 3 penetrates the bottom surface of the arc-shaped cover body 1. The outlet of the vertical drainage pipe 3 is arranged in the hole of the sinkhole 15. A plurality of upper drainage holes 2 are symmetrically arranged inside the arc-shaped cover body 1 about the central axis of the arc-shaped cover body 1. The inlet of the upper drainage hole 2 is arranged on the upper surface of the arc-shaped cover body 1. The outlet of the upper drainage hole 2 is arranged on the upper surface of the horizontal drainage pipe 4.

[0025] AsFigures 2-4 As shown in the drawings, in order to better discharge the rainwater in the lateral drainage pipe 4, a plurality of lower drainage holes 22 are arranged between the lateral drainage pipe 4 and the bottom surface of the arc-shaped cover body 1, the inlet of the lower drainage hole 22 is arranged on the lower surface of the lateral drainage pipe 4, the outlet of the lower drainage hole 22 is arranged on the bottom surface of the arc-shaped cover body 1, and the outlet of the lower drainage hole 22 is located within the range of the hole opening of the downspout 15.

[0026] The distance between the pipe axis of the lateral drainage pipe 4 and the bottom surface of the arc-shaped cover body 1 is 0.15-0.25 times the maximum distance between the upper surface of the arc-shaped cover body 1 and the bottom surface of the arc-shaped cover body 1, the vertical drainage pipe 3 is located on the central axis of the arc-shaped cover body 1, and the lower drainage hole 22 is symmetrically arranged about the central axis of the arc-shaped cover body 1.

[0027] The arc-shaped cover body 1 can improve the bearing capacity of the cover body 1, in order to strengthen the bearing capacity of the arc-shaped cover body 1, the arc-shaped cover body 1 in the embodiment is a semicircular spherical body, the upper drainage hole 2 is arranged at an equal angle about the center of the semicircular spherical body, and the arc-shaped cover body 1 is a reinforced concrete cover body, wherein the concrete grade, steel bar type and other device layout are calculated by the bending resistance, shear resistance and bearing capacity of the slag body. In the embodiment, the diameters of the upper drainage hole 2 and the lower drainage hole 22 are the same, and are less than or equal to 1 / 10 of the diameter of the lateral drainage pipe 4. In order to make the water flow through the lateral drainage pipe 4 and flow into the downspout 15 along the drainage hole more quickly, the angle between the hole axis of the upper drainage hole 2 and the horizontal ground surface is not less than 30°, and the angle between the hole axis of the lower drainage hole 22 and the horizontal ground surface is 90°. In other embodiments, the arc-shaped cover body 1 can be a 1 / 4 spherical body, or an arc-shaped cover body 1 with a parabolic upper surface.

[0028] In order to make the stress of the arc-shaped cover body 1 more uniform and stable, as shown in Figure 1 , 2 , a foundation backfill body 5 is arranged above the arc-shaped cover body 1, the foundation backfill body 5 has water permeability, and water can pass through the foundation backfill body 5 to the upper drainage hole 2. The foundation backfill body 5 includes a mesh layer 18, a mesh protection layer 19, a soil and stone slag protection layer 20 and a large stone layer 21. The mesh layer 18 includes a plurality of meshes laid on the upper surface of the arc-shaped cover body 1, the thickness of the mesh layer 18 is not less than 20 cm, the mesh is composed of steel bars, the diameter of the steel bars is not greater than 20 mm, and the mesh layer 18 can prevent debris from blocking the drainage hole. The mesh protection layer 19 is laid on the mesh layer 18 to protect the mesh 18, and the mesh protection layer 19 is geotextile or asphalt oil felt. The soil and stone slag protection layer 20 is laid on the mesh protection layer 19 to protect the mesh protection layer 19, and the large stone layer 21 is laid on the soil and stone slag protection layer 20, so that the foundation backfill body 5 has water permeability.

[0029] When the karst depression stores the material slag body 14, in order to avoid the material slag in the material slag body 14 falling into the large stone layer 21, the earth and stone slag protection layer 20 is laid on the upper surface of the large stone layer 21. Wherein, the earth and stone slag protection layer 20 and the large stone layer 21 in the foundation backfill body 5 are compacted, the thickness ratio is determined according to the actual engineering condition, in principle, the foundation bearing capacity of the foundation backfill body 5 is satisfied, and the drainage requirements of the upper drainage hole 2 and the lower drainage hole 22 in the arc-shaped covering body 1 are ensured. The height of the foundation backfill body 5 is 1.5-3 times of the maximum distance between the upper surface of the arc-shaped covering body 1 and the bottom surface of the arc-shaped covering body 1.

[0030] In order to better drain the rainwater of the karst depression, the drainage culvert 7 is arranged on the side wall of the karst depression, part of the drainage culvert 7 is located in the foundation backfill body 5, and part of the drainage culvert 7 is located outside the foundation backfill body 5, the drainage culvert outlet 10 is connected with the transverse drainage pipe 4, as shown in Figure 1 When the karst depression stores the material slag body 14, the height of the drainage culvert inlet 9 should be higher than the height of the upper surface of the material slag body 14. In the embodiment, the height of the drainage culvert inlet 9 is 0.5-1 meters higher than the height of the upper surface of the material slag body 14, the drainage culvert outlet 10 is arranged in the transverse drainage pipe 4, and the length of the drainage culvert 7 entering the transverse drainage pipe 4 is not less than 2 times of the diameter of the drainage culvert 7, the pipe connection part 26 between the drainage culvert 7 and the transverse drainage pipe 4 adopts a sealed waterproof connection. The vertical drainage pipe 3 and the transverse drainage pipe 4 both adopt cast iron pipes to increase the service life of the drainage pipe.

[0031] The original terrain line 11 of the karst depression is not flat, in order to enhance the stability of the arc-shaped covering body 1 and the drainage culvert 7, the clean base line 8 is arranged on the inner wall of the karst depression, the clean base line 8 is a certain distance away from the original terrain line 11, and the arc-shaped covering body 1 and the drainage culvert 7 are arranged on the clean base line 8. In order to place the arc-shaped covering body 1 and lay the drainage culvert 7 at the entrance of the sinkhole 15, the original terrain line 11 needs to be expanded and excavated to the clean base line 8. The earthwork backfill layer 12 is arranged on the upper surface of the drainage culvert 7 outside the foundation backfill body 5, and the earth and stone slag protection layer 20 is arranged on the upper surface of the drainage culvert 7 inside the foundation backfill body 5, the thickness of the earthwork backfill layer 12 and the thickness of the earth and stone slag protection layer 20 are both 1-2 times of the diameter of the drainage culvert 7.

[0032] In order to enhance the stability of the sealing drainage device, the included angle between the clean base line 8 near the side surface of the foundation backfill body 5 and the horizontal ground surface line is in the range of 30°-50°, a plurality of grouting anchor rods 13 are arranged on the bottom surface of the arc-shaped covering body 1 in contact with the clean base line 8, one end of the grouting anchor rod 13 is inserted into the surrounding rock of the karst depression, and the other end of the grouting anchor rod 13 is inserted into the arc-shaped covering body 1, so as to enhance the stability strength of the surrounding rock near the sinkhole 15 and enhance the connection between the arc-shaped covering body 1 and the surrounding rock.

[0033] In this embodiment, the maximum distance between the upper surface of the arc-shaped cover 1 and the bottom surface of the arc-shaped cover 1 is not less than 2 times the maximum of the hole diameter of the sinkhole 15 and the diameter of the drainage culvert 7, and the diameter of the bottom surface of the arc-shaped cover 1 is also not less than 2 times the maximum of the hole diameter of the sinkhole 15 and the diameter of the drainage culvert 7. The central axis of the arc-shaped cover 1 coincides with the axis of the sinkhole 15, the diameter of the horizontal drainage pipe 4 is slightly larger than the diameter of the drainage culvert 7, and the diameter of the vertical drainage pipe 3 is approximately equal to the diameter of the horizontal drainage pipe 4.

[0034] Without substantially damaging the karst landform, in order to further ensure the bearing capacity requirement of the site foundation and meet the water discharge and safety stability, economic and applicable requirements after the actual engineering hydrology calculation. Figure 1 、 3 As shown in the drawings, the sinkhole filling body 6 is arranged in the sinkhole 15, the sinkhole filling body 6 fills the sinkhole 15, and the sinkhole filling body 6 has water permeability. The person skilled in the art knows that the lower end of the sinkhole 15 is connected with the underground tunnel system 16, and the sinkhole filling body 6 includes, in sequence from the lower end of the sinkhole 15 to the upper end of the sinkhole 15, a riprap filling layer 25, a block stone filling layer 24 and a gravel slag filling layer 23. The outlet of the vertical drainage pipe 3 is located in the riprap filling layer 25, and the outlet of the vertical drainage pipe 3 penetrates into the riprap filling layer 25 by 0.5-1.5 meters.

[0035] The riprap filling layer 25 should be filled from the bottom of the underground tunnel system 16, and a certain space should be reserved when approaching the outlet end elevation position of the vertical drainage pipe 3 so that the outlet end of the vertical drainage pipe 3 can smoothly penetrate into the riprap filling layer 25. The upper surface of the gravel slag filling layer 23 is flush with the bottom surface of the arc-shaped cover 1, and the gravel slag filling layer 23 and the block stone filling layer 24 should both leave appropriate space for the insertion of the vertical drainage pipe 3 when filled. The filling proportions of the riprap filling layer 25, the block stone filling layer 24 and the gravel slag filling layer 23 are determined according to the actual engineering drainage needs, but in principle, the basic ratio of the riprap filling layer 25 being the thickest, the block stone filling layer 24 being the second, and the gravel slag filling layer 23 being the thinnest should be maintained.

[0036] The specific sizes of the vertical drainage pipe 3, the horizontal drainage pipe 4, the drainage culvert 7, the upper drainage hole 2 and the lower drainage hole 22, and the specific proportional thicknesses between different backfill layers in the foundation backfill body 5 and the specific proportional thicknesses between different filling layers of the sinkhole filling body 6 should all be determined through actual hydrology calculation to meet the water discharge requirements of different actual projects.

[0037] As shown in the drawings, Figure 1As shown, rainwater 17 passes through drainage culvert inlet 9, drainage culvert inlet 10, horizontal drainage pipe 4, vertical drainage pipe 3, lower drainage hole 22 in sequence, and finally is filtered and discharged to underground tunnel system 16 through the filtering of falling water hole filler 6 inside falling water hole 15. Water or gas inside slag body 14 seeps from foundation backfill 5 into upper drainage hole 2, is discharged to horizontal drainage pipe 4, and finally flows into falling water hole 15 through vertical drainage pipe 3, and is discharged after being filtered and discharged to underground tunnel system 16 through falling water hole filler 6.

[0038] The embodiment of the present application also provides a plugging and drainage method for a falling water hole at the bottom of a karst depression, which adopts the plugging and drainage device and comprises the following steps.

[0039] S1, surveying and investigating falling water hole 15, counting the hole opening plane size and depth of falling water hole 15, performing relevant hydrology calculation to determine the size of drainage culvert 7 and designing arc-shaped covering body 1;

[0040] S2, expanding and excavating the area near the hole opening of falling water hole 15 to clear foundation bottom line 8;

[0041] S3, filling the inside of falling water hole 15 from bottom to top with riprap filling layer 25, block stone filling layer 24 and slag filling layer 23 in sequence;

[0042] S4, pouring arc-shaped covering body 1;

[0043] S5, clearing the irregular original terrain line 11 of the karst depression to flat clear foundation bottom line 8 and laying drainage culvert 7 thereon;

[0044] S6, laying foundation backfill 5 on the surface of arc-shaped covering body 1, and simultaneously setting soil and rock backfill layer 12 for drainage culvert 7.

[0045] In step S2, after the expansion and excavation of the clear foundation, grouting anchor 13 is arranged on the clear foundation surface near the hole opening of falling water hole 15.

[0046] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A plugging and draining device for a sinkhole bottom sink, characterized in that, The arc-shaped cover includes a bottom surface and an upper surface, the bottom surface is a plane, and the upper surface is a smooth arc surface, the upper surface is connected with the bottom surface, the arc-shaped cover is arranged on a hole of a sinkhole, the bottom surface of the arc-shaped cover covers the hole of the sinkhole, a horizontal drainage pipe is arranged in the arc-shaped cover, the horizontal drainage pipe horizontally penetrates the arc-shaped cover, a vertical drainage pipe in communication with the horizontal drainage pipe is arranged in the arc-shaped cover, the vertical drainage pipe penetrates the bottom surface of the arc-shaped cover, and an outlet of the vertical drainage pipe is arranged in a hole of the sinkhole, a plurality of upper drainage holes are symmetrically arranged in the arc-shaped cover with respect to a central axis of the arc-shaped cover, an inlet of the upper drainage hole is arranged on the upper surface of the arc-shaped cover, and an outlet of the upper drainage hole is arranged on an upper surface of the horizontal drainage pipe, a plurality of lower drainage holes are arranged between the horizontal drainage pipe and the bottom surface, an inlet of the lower drainage hole is arranged on a lower surface of the horizontal drainage pipe, and an outlet of the lower drainage hole is arranged on the bottom surface of the arc-shaped cover and located in a range of the hole of the sinkhole.

2. The plugging and draining device for the bottom water-falling cave of karst depression according to claim 1, characterized in that, A distance between a pipe axis of the horizontal drainage pipe and the bottom surface of the arc-shaped cover is 0.15-0.25 times a maximum distance between the upper surface of the arc-shaped cover and the bottom surface of the arc-shaped cover, the vertical drainage pipe is located on the central axis of the arc-shaped cover, and the lower drainage holes are symmetrically arranged with respect to the central axis of the arc-shaped cover.

3. The plugging and draining device for the bottom water-falling cave of karst depression according to claim 1, characterized in that, An angle between a hole axis of the upper drainage hole and a horizontal ground surface is not less than 30 degrees, and an angle between a hole axis of the lower drainage hole and the horizontal ground surface is 90 degrees.

4. The plugging and draining device for the bottom water-falling cave of karst depression according to claim 1, characterized in that, A foundation backfill body is arranged above the arc-shaped cover, the foundation backfill body includes a mesh layer, a mesh protection layer, a soil and stone protection layer and a large stone layer, the mesh layer includes a plurality of meshes arranged on the upper surface of the arc-shaped cover, the mesh protection layer is arranged on the mesh layer, the soil and stone protection layer is arranged on the mesh protection layer, and the large stone layer is arranged on the soil and stone protection layer.

5. The plugging and draining device for the bottom water-falling cave of karst depression according to claim 4, characterized in that, A height of the foundation backfill body is 1.5-3 times a maximum distance between the upper surface of the arc-shaped cover and the bottom surface of the arc-shaped cover.

6. The plugging and draining device for the bottom water-falling cave of karst depression according to claim 4, characterized in that, A drainage culvert is arranged on a side wall of the karst depression, a part of the drainage culvert is located in the foundation backfill body, and another part of the drainage culvert is located outside the foundation backfill body, an outlet of the drainage culvert is connected with the horizontal drainage pipe.

7. The plugging and draining device for the bottom water-falling cave of karst depression according to claim 6, characterized in that, When the karst depression stores a material and slag body, a height of an inlet of the drainage culvert is 0.5-1 meters higher than a height of an upper surface of the material and slag body, the outlet of the drainage culvert is arranged in the horizontal drainage pipe, a length of the drainage culvert entering the horizontal drainage pipe is not less than 2 times a diameter of the drainage culvert, and a pipe connection part between the drainage culvert and the horizontal drainage pipe is sealed and waterproof.

8. The plugging and draining device for the bottom water-falling cave of karst depression according to claim 1, characterized in that, A plurality of grouting anchor rods are arranged on the bottom surface of the arc-shaped cover, one end of the grouting anchor rod is inserted into surrounding rock of the karst depression, and the other end of the grouting anchor rod is inserted into the arc-shaped cover.

9. The plugging and draining device for the bottom water-falling cave of karst depression according to claim 1, characterized in that, A sink hole filler is arranged inside the sink hole, the sink hole filler fills up the sink hole, the sink hole filler has water permeability, the sink hole filler comprises, in sequence from a lower port of the sink hole to an upper port of the sink hole, a riprap filling layer, a block stone filling layer and a gravel slag filling layer, and the outlet of the vertical drain pipe is located in the riprap filling layer.

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