A semi-filled and unfilled karst cave isolation device and isolation method in karst areas

Abstract

The present invention discloses an isolation device for semi-filled and unfilled karst caves, which comprises a membrane bag and a grouting pipe. The interior of the membrane bag is divided into two chambers along the length direction. A vertically arranged channel with an open upper end is provided at the center of the membrane bag. Through holes communicating with the two chambers are respectively opened at the lower end of the channel. The diameter of the channel matches the diameter of the grouting pipe. The grouting pipe is inserted into the channel, and overflow holes corresponding to the through holes are opened at the lower end of the grouting pipe. The present invention can form a complete isolation wall in the karst cave, effectively improving the isolation efficiency of the karst cave and saving a large amount of materials.

Description

Technical Field

[0001] The present invention relates to the field of karst cave isolation devices. More specifically, the present invention relates to a karst area semi-filled and unfilled karst cave isolation device and an isolation method. Background Art

[0002] With the development of the national economy, the development of the above-ground space in cities is becoming increasingly saturated, and it is inevitable to develop towards the underground space. Karst regions are widely distributed in the southwest and south China regions. The unique hydrographic characteristics and geomorphic and geological characteristics in karst areas pose many difficulties to the construction of underground projects such as subways. Karst caves are one of the main geological disasters in karst areas. According to their filling conditions, they can be divided into unfilled karst caves, semi-filled karst caves, and fully filled karst caves. A large amount of karst water is stored in most unfilled karst caves. The fillers in semi-filled and fully filled karst caves are generally silt and loose fine sand, and the bearing capacity is very low. During the engineering construction process, if early warning cannot be given in time and effective measures cannot be taken, serious geological disasters such as water inrush, water and mud inrush, and karst collapse may be triggered, causing foundation sliding and surface subsidence on the ground surface, endangering the roadbed, road surface, and surface buildings, causing huge losses to the engineering construction, and even threatening the safe operation of the project after it is completed.

[0003] In order to ensure the safe implementation of engineering construction and later operation, it is necessary to treat karst caves within the scope threatening the engineering safety before engineering construction. Due to the irregular development of karst caves, some karst caves are partly within the scope threatening the engineering safety and partly outside the scope threatening the engineering safety. Considering the economy and efficiency of engineering construction, karst caves outside the scope threatening the engineering safety do not need to be treated, so it is necessary to isolate karst caves at the boundary of the scope threatening the engineering safety. For unfilled and semi-filled karst caves, the current commonly used isolation method is to pour low-strength plain concrete and cement-sodium silicate double-fluid slurry to form a wall. Since the space in unfilled karst caves is large and there is no lateral constraint, and most of the karst caves are filled with water, this method has large material consumption, low wall-forming quality, poor isolation effect, and the airtightness cannot be guaranteed. Summary of the Invention

[0004] An object of the present invention is to solve at least the above problems and provide at least the advantages described later.

[0005] To achieve these objects and other advantages according to the present invention, a karst area semi-filled and unfilled karst cave isolation device is provided, including a membrane bag and a grouting pipe. The interior of the membrane bag is divided into two chambers along the length direction. A channel with an open upper end is vertically arranged at the center of the membrane bag. Through holes communicating with the two chambers are respectively opened at the lower end of the channel. The diameter of the channel is matched with the diameter of the grouting pipe. The grouting pipe is inserted into the channel, and overflow holes corresponding to the through holes are opened at the lower end of the grouting pipe.

[0006] Preferably, a plurality of horizontal partitions are arranged at intervals in the vertical direction in any of the chambers, and the horizontal partitions are arranged in a staggered manner to divide the interior of the chamber into an S-shaped flow channel from bottom to top.

[0007] Preferably, a groove is opened downward at the center of the top surface of the membrane bag, the center of the groove coincides with the center of the channel, and its outer diameter is larger than the outer diameter of the channel.

[0008] Another object of the present invention is to provide a method for isolating semi-filled and unfilled karst caves in karst areas, including the following steps:

[0009] Step 1: Drill grouting holes at corresponding positions above the karst cave and stop drilling when reaching below the top of the karst cave;

[0010] Step 2: Lower the karst cave isolation device along the grouting hole to the designated position;

[0011] Step 3: Connect a pressure gauge, a grout stop valve and a grouting pipeline to the top of the grouting pipe, and grout into the membrane bag; the grout fills the membrane bag, and the membrane bag expands to form an isolation wall in the karst cave;

[0012] Step 4: Stop grouting when the grouting pressure reaches the design pressure, and close the grout stop valve.

[0013] Preferably, before drilling the grouting hole in Step 1, first determine the spatial position of the karst cave to be isolated, and then determine the karst cave isolation dividing line; drill the grouting hole at the middle position of the karst cave isolation dividing line.

[0014] Preferably, the karst cave isolation dividing line is the boundary line of the range threatening the safety of underground projects.

[0015] Preferably, drill exhaust holes in the area between the grouting hole and the side of the karst cave and stop drilling when reaching below the top of the karst cave; plug the exhaust holes after stopping grouting in Step 4.

[0016] Preferably, in Step 2, during the lowering process of the karst cave isolation device, keep the longitudinal axis of the membrane bag coincident with the karst cave isolation dividing line.

[0017] Preferably, grout into the membrane bag in a low-pressure and slow-injection manner in Step 3, and the grouting pressure is calculated according to the following formula:

[0018]

[0019] In the formula, P is the design pressure; α is the safety factor; P0 is the maximum design pressure for karst cave filling; γ is the specific gravity of the karst cave filling grout; H is the height of the karst cave; μ is the friction coefficient of the karst cave wall.

[0020] The present invention has at least the following beneficial effects:

[0021] The karst area semi-filled and unfilled cave isolation device provided by the present invention utilizes the good airtightness of the membrane bag to form a complete isolation wall in the cave, effectively improving the isolation efficiency and quality of the cave; and by restricting the migration direction of the slurry with the membrane bag, it is only necessary to fill the membrane bag with the slurry, which can save a large amount of materials.

[0022] The karst area semi-filled and unfilled cave isolation method provided by the present invention uses the boundary line of the threat to engineering safety given during the underground engineering design as the cave isolation dividing line. For the cave located on the cave isolation dividing line, a cave isolation device is used to set up an isolation wall in the cave, separating the area that needs to be treated and the area that does not need to be treated from the cave, improving the cave treatment efficiency.

[0023] Other advantages, objectives and features of the present invention will be partially reflected by the following description, and partially will also be understood by those skilled in the art through the research and practice of the present invention. Brief Description of the Drawings

[0024] Figure 1 It is a schematic vertical cross-sectional structure diagram of the membrane bag described in the present invention;

[0025] Figure 2 is Figure 1 Schematic A-A cross-sectional structure diagram of

[0026] Figure 3 It is a schematic side structure diagram of the grouting pipe described in the present invention;

[0027] Figure 4 It is a schematic structure diagram of the cave isolation device described in the present invention in the cave; Detailed Description of the Invention

[0028] The following further describes the present invention in detail with reference to the drawings, so that those skilled in the art can implement it according to the description in the specification.

[0029] It should be noted that the experimental methods described in the following implementation plans are all conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified; in the description of the present invention, the orientation or positional relationship indicated by the terms "horizontal", "vertical", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0030] Such as Figures 1 to 4As shown in the figure, the present invention provides a separation device for semi-filled and unfilled karst caves, including a membrane bag 1 and a grouting pipe 6. The interior of the membrane bag 1 is divided into two chambers 3 along the length direction. A vertically arranged channel 2 with an open upper end is provided at the center of the membrane bag 1. Through holes 21 communicating with the two chambers 3 are respectively opened at the lower end of the channel 2. The diameter of the channel 2 is matched with the diameter of the grouting pipe 6. The grouting pipe 6 is inserted into the channel 2, and slurry overflow holes 7 are provided at the lower end of the grouting pipe 6 corresponding to the through holes 21.

[0031] In this technical solution, for the karst caves located at the boundary of the range threatening the project safety, isolation is required. The karst cave isolation device is placed into the karst cave to be isolated, and slurry is injected into the membrane bag 1 through the grouting pipe 6 to form an isolation wall in the karst cave after the membrane bag 1 expands. Then, the part of the karst cave within the boundary of the range threatening the project safety is processed. During use, the membrane bag 1 can adopt high-strength and wear-resistant geotextile bags, and the horizontal partition layer 4 can be selected as geotextile. The interior of the membrane bag 1 can be divided into two chambers 3 by geotextile, and the channel 2 is formed in the middle for the grouting pipe 6 to be inserted. The shape of the membrane bag 1 can be selected as rectangular or trapezoidal according to actual needs, which is not limited herein.

[0032] Further, a plurality of horizontal partition layers 4 are arranged at intervals along the vertical direction in any of the chambers 3, and the horizontal partition layers 4 are arranged in a staggered manner to divide the interior of the chamber 3 into an S-shaped flow channel from bottom to top. The S-shaped flow channel restricts the migration direction of the slurry inside the membrane bag 1, enabling the slurry to fill the membrane bag 1 orderly and completely from bottom to top and from the center to both sides. The flow direction of the slurry in the membrane bag 1 refers to Figure 1 the arrow direction in the figure.

[0033] In another embodiment, a groove 5 is opened downward at the center of the top surface of the membrane bag 1. The center of the groove 5 coincides with the center of the channel 2, and its outer diameter is larger than the outer diameter of the channel 2. The top of the membrane bag 1 is separated from the grouting pipe 6 through the groove 5. When the slurry fills to the top of the membrane bag 1, the top of the membrane bag 1 can be lifted, and thus the filling height of the membrane bag 1 can be flexibly selected according to the height of the karst cave, enabling the part of the membrane bag 1 in contact with the top of the karst cave to be better sealed.

[0034] The present invention also provides a method for isolating semi-filled and unfilled karst caves in karst areas, including the following steps:

[0035] Step 1: Drill a grouting hole at the corresponding position above the karst cave and stop drilling when reaching below the top of the karst cave;

[0036] Step 2: Lower the karst cave isolation device along the grouting hole to the designated position;

[0037] Step 3: Connect a grout stop valve 9, a pressure gauge 10, a grouting pipeline 11, and a grouting pump 12 to the top of the grouting pipe 6, and grout into the membrane bag 1; the grout fills the membrane bag 1, and after the membrane bag 1 expands, a partition wall is formed in the karst cave.

[0038] Step 4: Stop grouting when the grouting pressure reaches the design pressure, and close the grout stop valve 9.

[0039] Prepare the karst cave isolation device in advance, insert the grouting pipe 6 into the channel 2, and align the slurry overflow holes 7 at the lower end of the grouting pipe 6 with the through holes at the lower end of the channel 2 one by one. Then fold both sides of the membrane bag 1 along the longitudinal axis at a certain distance on both sides of the grouting pipe 6, and use rubber bands for simple fixation to facilitate later placement. If the required length of the grouting pipe is relatively large, a sleeve connection is used between two sections of the grouting pipe. In Step 3, open the grout stop valve 9, and grout into the grouting pipe 6 and the membrane bag 1 through the grouting pump 12 and the grouting pipeline 11, and monitor the grouting pressure through the pressure gauge 10.

[0040] Further, before drilling the grouting hole in Step 1, first determine the spatial position of the karst cave to be isolated, and then determine the karst cave isolation dividing line; drill the grouting hole at the middle position of the karst cave isolation dividing line. Before drilling, a method combining drilling and geophysical prospecting is used to accurately determine the spatial position of the karst cave to be isolated, and the karst cave isolation dividing line is delimited according to the project requirements; specifically, the karst cave isolation dividing line is the boundary line of the range threatening the safety of the underground project. The boundary line of the range threatening the safety of the underground project is given during the design of the underground project. Drill an exhaust hole 8 in the area between the grouting hole and the side of the karst cave, and stop drilling when reaching below the top of the karst cave; after stopping grouting in Step 4, block the exhaust hole 8.

[0041] In another embodiment, in Step 2, during the lowering process of the karst cave isolation device, keep the longitudinal axis of the membrane bag coincident with the karst cave isolation dividing line. Align the grouting pipe 6 and the membrane bags on both sides with the karst cave isolation dividing line, and lower them into the karst cave along the grouting hole at the middle position of the karst cave isolation dividing line. When lowering, pay attention not to rotate the grouting pipe 6 to prevent the direction from deflecting and affecting the grouting effect.

[0042] In another embodiment, in Step 3, grout into the membrane bag 1 in a low-pressure and slow-injection manner, and the grouting pressure is calculated according to the following formula:

[0043]

[0044] In the formula, P is the design pressure (kPa); α is the safety factor; P0 is the maximum design pressure for karst cave filling (kPa); γ is the unit weight of the karst cave filling slurry (kg / m3); H is the height of the karst cave (m); μ is the karst cave wall friction coefficient.

[0045] By adopting the method of low-pressure slow injection, the slurry slowly fills the membrane bag 1, and after the membrane bag 1 expands, a partition wall embedded inside the karst cave is formed.

[0046] Although the embodiments of the present invention have been disclosed above, it is not limited to the applications listed in the specification and the embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the illustrated examples described herein.

Claims

1. An isolation device for semi-filled and unfilled karst caves in karst areas, characterized in that, It includes a membrane bag and a grouting pipe. The interior of the membrane bag is divided into two chambers along the length direction. A channel with an open upper end is vertically arranged at the center of the membrane bag. Through holes communicating with the two chambers are respectively opened at the lower end of the channel. The diameter of the channel matches the diameter of the grouting pipe. The grouting pipe is inserted into the channel, and overflow holes are opened at the lower end of the grouting pipe corresponding to each through hole. A plurality of horizontal partitions are arranged at intervals in the vertical direction in any of the chambers, and the horizontal partitions are arranged in a staggered manner to divide the interior of the chamber into an S-shaped flow channel from bottom to top.

2. The karst area semi-filled and unfilled cave isolation device according to claim 1, characterized in that, A groove is opened downward at the center of the top surface of the membrane bag. The center of the groove coincides with the center of the channel, and its outer diameter is larger than the outer diameter of the channel.

3. An isolation method using the karst area semi-filled and unfilled cave isolation device according to any one of claims 1 to 2, characterized in that, It includes the following steps: Step 1: Drill a grouting hole at a corresponding position above the karst cave and stop drilling when reaching below the top of the karst cave. Step 2: Lower the karst cave isolation device along the grouting hole to the designated position. Step 3: Connect a pressure gauge, a grout stop valve, and a grouting pipeline to the top of the grouting pipe and grout into the membrane bag. The slurry fills the membrane bag, and after the membrane bag expands, an isolation wall is formed in the karst cave. Step 4: Stop grouting when the grouting pressure reaches the design pressure and close the grout stop valve.

4. The karst area semi-filled and unfilled cave isolation method according to claim 3, characterized in that, Before drilling the grouting hole in Step 1, first determine the spatial position of the karst cave to be isolated, and then determine the karst cave isolation dividing line. Drill the grouting hole at the middle position of the karst cave isolation dividing line.

5. The karst area semi-filled and unfilled cave isolation method according to claim 4, characterized in that, The karst cave isolation dividing line is the boundary line threatening the safety range of the underground project.

6. The karst area semi-filled and unfilled cave isolation method according to claim 4, characterized in that, Drill an exhaust hole in the area between the grouting hole and the side of the karst cave and stop drilling when reaching below the top of the karst cave. After stopping grouting in Step 4, block the exhaust hole.

7. The karst area semi-filled and unfilled cave isolation method according to claim 4, characterized in that, In Step 2, during the process of lowering the karst cave isolation device, keep the longitudinal axis of the membrane bag coinciding with the karst cave isolation dividing line.

8. The karst area semi-filled and unfilled cave isolation method according to claim 3, characterized in that, In Step 3, grout into the membrane bag in a low-pressure and slow-injection manner, and the grouting pressure is calculated according to the following formula: In the formula, P is the design pressure; α is the safety factor; P0 is the maximum design pressure for filling the karst cave; γ is the specific gravity of the karst cave filling slurry; H is the height of the karst cave; μ is the friction coefficient of the karst cave wall.

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