Pile casing device for construction of pile foundation in karst cave area

Abstract

The present application belongs to the technical field of pile foundation construction, and particularly relates to a casing device for karst cave area pile foundation construction. The casing device comprises an inner casing and an outer detection device. The inner casing is in a straight cylindrical shape and is used for pouring a concrete pile foundation. The outer detection device comprises a variable-diameter outer protective frame and a karst cave space detector. The variable-diameter outer protective frame is arranged outside the inner casing, and the outer diameter of the variable-diameter outer protective frame can be adjusted to facilitate fixation in the karst cave area. The karst cave space detector is arranged on the variable-diameter outer protective frame and is used for detecting the spatial change of the karst cave. The karst cave space detector is arranged in the karst cave near the pile foundation through the variable-diameter outer protective frame. The spatial change of the karst cave is detected in real time through the karst cave space detector. If the karst cave develops too fast, grouting reinforcement can be adopted, that is, a grouting hole is drilled to the karst cave through the ground near the pile foundation and grouting reinforcement is performed. The method is a dynamic reinforcement measure for the pile foundation in the karst cave area, and the pile foundation construction cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of pile foundation construction technology, and specifically relates to a casing device for pile foundation construction in karst cave areas. Background Technology

[0002] With the development of infrastructure in my country, various geological conditions are encountered during bridge construction. When the surface geological structure of the selected pile foundation site consists of soil, rock, and gravel, while numerous karst caves and underground rivers are found underground, a double-layer casing structure is generally required. This involves using thick steel plates rolled into two casings of different diameters, with the outer casing having a much larger radius than the inner casing. During use, the outer casing is placed in the karst cave section of the pile hole, and concrete is poured between the two casings. This forms a solid concrete layer around the pile hole in the karst cave section, preventing the karst caves from affecting the pile foundation. While this double-layer casing construction method can achieve stable pile foundation construction in karst cave areas, the need to pour concrete between the two casings results in a long construction period. Furthermore, the outer casing, made of thick rolled steel plates, is not recycled after construction. Combined with the cost of the concrete between the two casings, the cost is high if traditional double-layer casings are used for all areas with numerous karst caves. Summary of the Invention

[0003] The purpose of this invention is to provide a casing device for pile foundation construction in karst cave areas, so as to at least solve the problem of high cost in the construction of double-layer casings.

[0004] To achieve the aforementioned objective, the present invention provides the following technical solution:

[0005] A casing device for pile foundation construction in karst cave areas includes an inner casing and an outer detection device. The inner casing is a straight cylinder used for pouring concrete pile foundations. The outer detection device includes a variable-diameter outer protective frame and a karst cave space detector. The variable-diameter outer protective frame is disposed outside the inner casing, and its outer diameter is adjustable to facilitate fixing in the karst cave area. The karst cave space detector is disposed on the variable-diameter outer protective frame and is used to detect changes in the karst cave space.

[0006] In the casing device for pile foundation construction in karst areas as described above, as a preferred embodiment, the variable diameter outer protective frame includes a sleeve and at least two variable diameter protectors. The at least two variable diameter protectors are arranged along the outer circumference of the sleeve. When the variable diameter protectors retract to near the outer wall of the sleeve, the outer diameter of the variable diameter outer protective frame is smaller than the inner diameter of the pile hole. When the variable diameter protectors extend away from the outer wall of the sleeve, the outer diameter of the variable diameter outer protective frame is larger than the inner diameter of the pile hole, thereby ensuring that the variable diameter outer protective frame is secured in the karst area.

[0007] In the casing device for pile foundation construction in karst areas as described above, as a preferred embodiment, the variable diameter protector includes a variable diameter elastic mechanism and an outer connecting plate. At least one end of the outer connecting plate is connected to the sleeve through the variable diameter elastic mechanism. When the variable diameter elastic mechanism is statically open, it supports the outer connecting plate away from the surface of the sleeve. When it is contracted by an external force, the variable diameter elastic mechanism contracts, pulling the outer connecting plate closer to the surface of the sleeve.

[0008] In the casing device for pile foundation construction in karst areas as described above, as a preferred embodiment, the variable diameter elastic mechanism includes a sliding component and a connecting rod; the sliding component includes a guide rail, a slider, and an energy storage mechanism; the guide rail is disposed on the outside of the casing, and the direction of the guide rail is parallel to the central axis of the casing; the slider is configured to slide along the guide rail; one end of the energy storage mechanism is fixedly connected to the guide rail or the casing, and the other end of the energy storage mechanism is connected to the slider; as the slider moves on the guide rail, the energy storage mechanism stores energy, and when the slider is not subjected to external force, the energy storage mechanism moves the slider to a static position; both ends of the connecting rod are hinged to the slider and one end of the outer connecting plate, respectively; when the variable diameter elastic mechanism is statically open, the outer diameter of the variable diameter outer protective frame is larger than the inner diameter of the pile hole.

[0009] In the casing device for pile foundation construction in karst areas as described above, as a preferred embodiment, the connecting rod includes a telescopic sleeve and a telescopic spring located inside the telescopic sleeve. When the two ends of the connecting rod are subjected to force, the length of the connecting rod changes, and the telescopic spring deforms.

[0010] In the casing device for pile foundation construction in karst cave areas as described above, as a preferred embodiment, the length of the outer connecting plate is less than the height of the karst cave; the variable diameter protector includes at least two sliding components, which are respectively disposed at both ends of the sleeve, and the two ends of the outer connecting plate are respectively hinged to the corresponding sliders at both ends of the sleeve; when the variable diameter elastic mechanism is statically opened, the distance between the corresponding sliders at both ends of the variable diameter protector is greater than the height of the karst cave.

[0011] In the casing device for pile foundation construction in karst cave areas as described above, as a preferred embodiment, the karst cave space detector is a reflected wave radar, and a semiconductor resistance strain gauge is provided between the variable diameter outer protective frame and the inner casing to detect the displacement between the sleeve and the inner casing.

[0012] In the casing device for pile foundation construction in karst areas as described above, as a preferred embodiment, the casing includes two end casings and a connecting member in the middle, and the two end casings are fixedly connected by the connecting member.

[0013] In the casing device for pile foundation construction in karst areas as described above, as a preferred embodiment, the casing device further includes a flexible membrane, which is folded and wrapped around the outside of the variable diameter outer protective frame.

[0014] In the casing device for pile foundation construction in the karst cave area as described above, as a preferred embodiment, the flexible membrane, after being extended, forms an annular body with an outer diameter larger than the outer diameter of the variable diameter outer protective frame. When the variable diameter outer protective frame is installed inside the karst cave, a grouting pipe is provided inside the inner casing located in the karst cave section, leading from the ground to the space between the inner casing and the flexible membrane.

[0015] The protective casing device for pile foundation construction in karst areas provided by this invention uses a variable-diameter outer protective frame to place a karst space detector inside a karst cave near the pile foundation. The detector monitors the spatial changes of the karst cave in real time. If the karst cave is found to be developing too rapidly, reinforcement can be carried out by grouting. This involves drilling grouting holes in the ground near the pile foundation into the karst cave and injecting grout for reinforcement. This method provides dynamic reinforcement for pile foundations in karst areas, reducing construction costs. By using a telescopic connecting rod and sliding components, the variable-diameter outer protective frame can be installed without an additional power source. The overall structure is simple, with low strength requirements, thus significantly reducing construction costs. Furthermore, because this device eliminates the need for concrete construction in the karst cave area surrounding the pile foundation hole, it greatly improves construction efficiency. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein:

[0017] Figure 1 This is a schematic diagram of the casing device for pile foundation construction in karst cave areas according to an embodiment of the present invention;

[0018] Figure 2 This is a cross-sectional view of the casing device for pile foundation construction in karst cave areas under contraction state according to an embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of the installation of the casing device for pile foundation construction in a karst cave area according to an embodiment of the present invention at the karst cave of the pile foundation hole.

[0020] The following are the labeling elements in the diagram: 1. Inner protective sleeve; 2. Variable diameter outer protective frame; 3. Sleeve; 301. End sleeve; 302. Connector; 4. Variable diameter protector; 5. Variable diameter elastic mechanism; 6. Outer connecting plate; 7. Sliding assembly; 8. Connecting rod; 9. Guide rail; 10. Slider; 11. Energy storage mechanism; 12. Reflected wave radar; 13. Semiconductor resistive strain gauge. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0022] According to embodiments of the present invention, such as Figures 1 to 3 As shown, where Figure 1 This is a schematic diagram of the casing device for pile foundation construction in karst cave areas according to an embodiment of the present invention; Figure 2 This is a cross-sectional view of the casing device for pile foundation construction in karst cave areas under contraction state according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the installation of the casing device for pile foundation construction in a karst cave area according to an embodiment of the present invention at the karst cave of the pile foundation hole.

[0023] An embodiment of the present invention provides a casing device for pile foundation construction in a karst cave area, comprising an inner casing 1 and an outer detection device; the inner casing 1 is a straight cylinder for pouring concrete pile foundation; the outer detection device includes a variable diameter outer protective frame 2 and a karst cave space detector; the variable diameter outer protective frame 2 is disposed outside the inner casing 1, and the outer diameter of the variable diameter outer protective frame 2 can be adjusted to facilitate fixing in the karst cave area; the karst cave space detector is disposed on the variable diameter outer protective frame 2 for detecting changes in the karst cave space.

[0024] In use, the karst cave space detector is set in the karst cave near the pile foundation through the variable diameter outer protective frame 2. The karst cave space detector can detect the spatial changes of the karst cave in real time. If the karst cave is found to be developing too fast, grouting reinforcement can be carried out to strengthen it. That is, grouting holes are drilled in the ground near the pile foundation to the karst cave and grouting is performed to reinforce it. This method is a dynamic reinforcement measure for the pile foundation in the karst cave area, which reduces the construction cost of the pile foundation.

[0025] Furthermore, the variable-diameter outer protective frame 2 includes a sleeve 3 and three variable-diameter protectors 4. The three variable-diameter protectors 4 are evenly distributed along the outer circumference of the sleeve 3. When the variable-diameter protectors 4 retract to near the outer wall of the sleeve 3, the outer diameter of the variable-diameter outer protective frame 2 is smaller than the inner diameter of the pile hole; when the variable-diameter protectors 4 extend away from the outer wall of the sleeve 3, the outer diameter of the variable-diameter outer protective frame 2 is larger than the inner diameter of the pile hole, thereby ensuring that the variable-diameter outer protective frame 2 is secured in the karst cave area. In this invention, because the sleeve 3 does not need to provide significant support and does not need to bear concrete, its strength requirements are greatly reduced. It can be made of plastic or thin steel rolled up, and its cost is significantly lower than that of the outer sleeve 3 in the prior art.

[0026] Furthermore, the variable diameter protector 4 includes a variable diameter elastic mechanism 5 and an outer connecting plate 6. At least one end of the outer connecting plate 6 is connected to the sleeve 3 through the variable diameter elastic mechanism 5. When the variable diameter elastic mechanism 5 is statically open, it supports the outer connecting plate 6 away from the surface of the sleeve 3. When it is contracted by an external force, the variable diameter elastic mechanism 5 contracts, pulling the outer connecting plate 6 closer to the surface of the sleeve 3.

[0027] Specifically, the variable diameter elastic mechanism 5 includes a sliding component 7 and a connecting rod 8; the sliding component 7 includes a guide rail 9, a slider 10, and an energy storage mechanism 11. The guide rail 9 is located on the outside of the sleeve 3, and the direction of the guide rail 9 is parallel to the central axis of the sleeve 3; the slider 10 is configured to slide along the guide rail 9; one end of the energy storage mechanism 11 is fixedly connected to the guide rail 9 or the sleeve 3, and the other end of the energy storage mechanism 11 is connected to the slider 10; as the slider 10 moves on the guide rail 9, the energy storage mechanism 11 stores energy, and when the slider 10 is not subjected to external force, the energy storage mechanism 11 moves the slider 10 to a static position; both ends of the connecting rod 8 are hinged to the slider 10 and one end of the outer connecting plate 6, respectively; when the variable diameter elastic mechanism 5 is statically opened, the outer diameter of the variable diameter outer protective frame 2 is larger than the inner diameter of the pile hole. In this embodiment, the energy storage mechanism 11 is a spring, and the guide rail 9 is specifically a through guide groove opened in the side wall of the sleeve 3 along the length direction of the sleeve 3. The slider 10 is configured to slide along the guide groove. The use of the guide groove method results in a simple structure and low cost.

[0028] Furthermore, the connecting rod 8 includes a telescopic sleeve and a telescopic spring (not shown) located inside the telescopic sleeve. When the two ends of the connecting rod 8 are subjected to force, the length of the connecting rod 8 changes, and the telescopic spring deforms.

[0029] Furthermore, the length of the outer connecting plate 6 is less than the height of the cave; the variable diameter protector 4 includes at least two sliding components 7, which are respectively disposed at both ends of the sleeve 3, and the two ends of the outer connecting plate 6 are respectively hinged to the corresponding sliders 10 at both ends of the sleeve 3; when the variable diameter elastic mechanism 5 is statically opened, the distance between the corresponding sliders 10 at both ends of the variable diameter protector 4 is greater than the height of the cave.

[0030] In this embodiment, the karst cave space detector is a reflected wave radar 12. A semiconductor resistance strain gauge 13 is installed between the variable diameter outer protective frame 2 (specifically the sleeve 3) and the inner protective casing 1 to detect the displacement between the sleeve 3 and the inner protective casing 1. After the pile foundation is poured, the displacement change between the sleeve 3 and the inner protective casing 1 is detected in real time by the semiconductor resistance strain gauge 13. Since the inner protective casing 1 is relatively stationary with respect to the concrete pile and the sleeve 3 is relatively stationary with respect to the karst cave, the displacement detected by the semiconductor resistance strain gauge 13 is the settlement of the karst cave relative to the concrete pile. By detecting the settlement and the development and changes of the karst cave, the stability of the pile foundation can be accurately predicted. When it is predicted that the stability of the pile foundation may be affected, grouting reinforcement can be carried out.

[0031] To further reduce costs, such as Figure 2 As shown, the sleeve 3 includes two end sleeves 301 and a connecting member 302 in the middle. The two end sleeves 301 are fixedly connected by the connecting member 302. The connecting member 302 can be made of steel plate or steel bar and can be directly welded to the two end sleeves 301.

[0032] Furthermore, the protective casing also includes a flexible membrane (not shown in the figure), which is folded and wrapped around the outside of the variable diameter outer protective frame 2 to protect the reflective wave radar 12 and prevent environmental changes inside the cave from damaging or affecting the normal operation of the reflective wave radar 12.

[0033] Furthermore, after the flexible membrane is stretched out, it forms an annular body with an outer diameter larger than the outer diameter of the variable diameter outer protective frame 2. When the variable diameter outer protective frame 2 is installed in the karst cave, a grouting pipe is installed in the inner protective casing 1 located in the karst cave section, which leads from the ground to the inner protective casing 1 and the flexible membrane. When it is detected that the changes in the karst cave may affect the pile foundation, grout can be injected into the flexible membrane through the grouting pipe for reinforcement. Due to the wrapping of the flexible membrane, the grouting liquid can be prevented from spreading excessively along the karst cave and wasting grouting material.

[0034] The specific usage method of the casing device for pile foundation construction in the karst cave area in this example is as follows:

[0035] like Figure 2 and Figure 3 As shown, when the variable diameter outer protective frame 2 is in a contracted state, the connecting rod 8 is compressed and shortened, and the energy storage mechanism 11 is stretched and slides to the bottom along the guide groove. At this time, the outside of the variable diameter outer protective frame 2 is tied with a rope to prevent it from opening. The outer detection device in the contracted state is lowered into the karst cave area of ​​the pile foundation hole along with the inner protective sleeve 1. The tying rope is pulled down, and the variable diameter outer protective frame 2 gradually opens under the restoring force of the connecting rod 8 and the energy storage mechanism 11, so that the outer connecting plate 6 and the connecting rod 8 form a relatively stable trapezoidal shape. The connecting rod 8 is stuck in the upper and lower walls of the karst cave, thereby realizing the stable installation of the variable diameter outer protective frame 2.

[0036] In summary, the casing device for pile foundation construction in karst areas provided by this invention, by setting up a variable-diameter outer protective frame and placing a karst space detector inside the karst cave near the pile foundation, allows for real-time monitoring of spatial changes within the karst cave. If the karst cave is found to be developing too rapidly, reinforcement can be achieved through grouting. This involves drilling grouting holes in the ground near the pile foundation into the karst cave and injecting grout for reinforcement. This method provides dynamic reinforcement for pile foundations in karst areas, reducing construction costs. By using a telescopic connecting rod and sliding components, the variable-diameter outer protective frame can be installed without an additional power source. The overall structure is simple, with low strength requirements, significantly reducing construction costs. Furthermore, because this device eliminates the need for concrete construction in the karst cave area surrounding the pile foundation hole, it greatly improves construction efficiency.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. 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 casing device for pile foundation construction in karst cave areas, characterized in that: Includes an inner protective casing and an outer detection device; The inner casing is cylindrical and used for pouring concrete pile foundations; The outer detection device includes a variable-diameter outer protective frame and a cave space detector; The variable-diameter outer protective frame is installed outside the inner protective cylinder, and the outer diameter of the variable-diameter outer protective frame can be adjusted to facilitate fixing in the karst cave area; The cave space detector is mounted on the variable-diameter outer protective frame and is used to detect changes in the cave space. The protective sleeve device also includes a flexible membrane, which is folded and wrapped around the outside of the variable diameter outer protective frame; After the flexible membrane is extended, it forms an annular body with an outer diameter larger than the outer diameter of the variable diameter outer protective frame. When the variable diameter outer protective frame is installed in the karst cave, a grouting pipe is installed in the inner protective casing located in the karst cave section, which leads from the ground to the space between the inner protective casing and the flexible membrane. If the cave is found to be developing too rapidly, it should be reinforced by grouting.

2. The casing device for pile foundation construction in karst cave areas according to claim 1, characterized in that: The variable diameter outer protective frame includes a sleeve and at least two variable diameter protectors. The at least two variable diameter protectors are arranged along the outer circumference of the sleeve. When the variable diameter protectors retract to near the outer wall of the sleeve, the outer diameter of the variable diameter outer protective frame is smaller than the inner diameter of the pile hole. When the variable diameter protectors extend to away from the outer wall of the sleeve, the outer diameter of the variable diameter outer protective frame is larger than the inner diameter of the pile hole, thereby ensuring that the variable diameter outer protective frame is secured in the karst cave area.

3. The casing device for pile foundation construction in karst cave areas according to claim 2, characterized in that: The variable diameter protector includes a variable diameter elastic mechanism and an outer connecting plate, and at least one end of the outer connecting plate is connected to the sleeve through the variable diameter elastic mechanism; When the variable diameter elastic mechanism is statically open, it supports the outer connecting plate away from the sleeve surface; When subjected to external force, the variable diameter elastic mechanism contracts, pulling the outer connecting plate closer to the sleeve surface.

4. The casing device for pile foundation construction in karst cave areas according to claim 3, characterized in that: The variable diameter elastic mechanism includes a sliding component and a connecting rod; The sliding assembly includes a guide rail, a slider, and an energy storage mechanism. The guide rail is disposed on the outside of the sleeve, and the direction of the guide rail is parallel to the central axis of the sleeve. The slider is configured to slide along the guide rail. One end of the energy storage mechanism is fixedly connected to the guide rail or the sleeve, and the other end of the energy storage mechanism is connected to the slider. As the slider moves on the guide rail, the energy storage mechanism stores energy. When the slider is not subjected to external force, the energy storage mechanism moves the slider to a static position. The two ends of the connecting rod are respectively hinged to the slider and one end of the outer connecting plate; When the variable diameter elastic mechanism is statically open, the outer diameter of the variable diameter outer protective frame is larger than the inner diameter of the pile foundation hole.

5. The casing device for pile foundation construction in karst cave areas according to claim 4, characterized in that: The connecting rod includes a telescopic sleeve and a telescopic spring located inside the telescopic sleeve. When the two ends of the connecting rod are subjected to force, the length of the connecting rod changes and the telescopic spring deforms.

6. The casing device for pile foundation construction in karst cave areas according to claim 4 or 5, characterized in that: The length of the outer connecting plate is less than the height of the cave. The variable diameter protector includes at least two sliding components, which are respectively disposed at both ends of the sleeve, and the two ends of the outer connecting plate are respectively hinged to the corresponding sliders at both ends of the sleeve. When the variable diameter elastic mechanism is statically open, the distance between the corresponding sliders at both ends of the variable diameter protector is greater than the height of the karst cave.

7. The casing device for pile foundation construction in karst cave areas according to claim 1, characterized in that: The cave space detector is a reflected wave radar, and a semiconductor resistive strain gauge is provided between the variable diameter outer protective frame and the inner protective sleeve to detect the displacement between the sleeve and the inner protective sleeve.

8. The casing device for pile foundation construction in karst cave areas according to claim 2, characterized in that: The sleeve includes two end sleeves and a connecting member in the middle, and the two end sleeves are fixedly connected by the connecting member.

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