Splicing flexible pile casing structure for karst pile foundation and construction method

Abstract

The invention discloses a splicable flexible pile casing structure for a karst pile foundation and a construction method.The structure comprises a flexible cloth bag pile casing, a reinforcement cage, fixing devices and splicing devices, and the fixing devices fix the splicing devices to the two ends of the flexible cloth bag pile casing; the flexible cloth bag pile casing is lengthened through a splicing device fixed to the two ends and wraps the periphery of the reinforcement cage to form a closed space, the splicing device comprises a second splicing plate and a first splicing plate capable of being connected into the second splicing plate in a sleeved mode, and a protruding rotary buckle male buckle is arranged on the surface of one end of the first splicing plate in the circumferential direction. The plate wall of one end of the second splicing plate is provided with a female groove correspondingly connected with the rotary buckle male buckle in a clamped mode, the rotary buckle male buckle is embedded into the female groove and rotationally embedded into a circular groove in the end of the female groove to rapidly and firmly connect the first splicing plate and the second splicing plate, and therefore the flexible cloth bag pile casing is lengthened. And flexible adjustment of the pile length and efficient construction are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of pile foundation construction in karst areas, and more specifically, relates to a splicable flexible casing structure for karst pile foundations and a construction method. Background Art

[0002] Pile foundation construction in karst areas is a crucial step in infrastructure construction. Karst regions are widely distributed with carbonate rock formations, which, through long-term dissolution, have formed complex spatial forms such as caves, dissolution fissures, and soil caves. These complex geological conditions place extremely high demands on pile foundation construction. As the basic supporting structure of a building, the construction quality of pile foundations is directly related to the safety, economy, and construction efficiency of the infrastructure. In karst areas, pile foundation construction must not only cope with complex geological conditions but also ensure the safety and reliability of the construction process, while also controlling costs and improving construction efficiency. Therefore, the development of technologies suitable for pile foundation construction in karst areas is of extremely important practical significance. Among traditional construction methods, all-steel casing construction is costly and has limited technical adaptability. Concrete filling and backfilling with crushed stone are inefficient and have poor cave sealing effects.

[0003] At present, new technologies have been developed and applied in pile foundation construction in karst areas, such as the patent document number CN201810435982.5. The invention discloses a reinforced concrete bag pile structure and process for local filling of large karst formations, including a geotextile bag, a folding steel frame connected to the geotextile bag is provided in the geotextile bag, and the folding steel frame serves as an internal support. Concrete is poured into the geotextile bag; the filling boundary of the concrete is limited by the geotextile bag, and then the concrete is poured to achieve local filling of the cave. The present invention uses high-strength geotextile bags with isolation and drainage characteristics, and is easy to form piles. However, the bag piles of the invention are limited in length and cannot be adapted to long or ultra-long pile foundation construction. Summary of the Invention

[0004] In response to the above defects or improvement needs of the prior art, the present invention provides a splicable flexible casing structure and construction method for karst pile foundations, in which the splicing device is firmly fixed to the end of the flexible bag casing by a fixing device, and the flexible bag casing is quickly spliced ​​by the snap design of the splicing device to extend the pile length, thereby solving the pile foundation construction problems such as difficulty in filling karst caves and concrete leakage under complex geological conditions in karst areas, ensuring the quality of the pile foundation, and at the same time, enabling rapid splicing, thereby realizing flexible adjustment of the pile length and efficient construction.

[0005] To achieve the above-mentioned object, according to one aspect of the present invention, the present invention provides a splicable flexible casing structure for karst pile foundation, comprising a flexible cloth bag casing, a steel cage, a fixing device and a splicing device, wherein the flexible cloth bag casing is prefabricated in sections, the fixing device fixes the splicing device to both ends of the flexible cloth bag casing, the flexible cloth bag casing is extended by the splicing devices fixed at both ends and wrapped around the outer periphery of the steel cage to form a closed space, wherein,

[0006] The splicing device includes a second splicing plate and a first splicing plate that can be sleeved in the second splicing plate. A raised rotating snap male buckle is circumferentially provided on the surface of one end portion of the first splicing plate. A female groove corresponding to the rotating snap male buckle of the first splicing plate is provided on the plate wall of one end portion of the second splicing plate. The rotating snap male buckle is embedded in the female groove and rotated to firmly connect the first splicing plate and the second splicing plate, thereby realizing the extension of the flexible cloth bag casing.

[0007] Furthermore, the female groove is an L-shaped groove and a circular groove is provided at the end thereof, and the rotating buckle male buckle is rotated until it is embedded in the circular groove at the end of the female groove.

[0008] Furthermore, the flexible bag casing sleeved on the outer periphery of the steel cage is tied with hoops at intervals that can freely stretch as the flexible bag casing expands.

[0009] Furthermore, the first splicing plate and the second splicing plate walls are both provided with second circular holes spaced evenly along the circumferential direction.

[0010] Furthermore, a first circular hole having the same diameter and a corresponding spacing as the second circular holes of the first splicing plate and the second splicing plate is opened at the end of the flexible bag casing along the circumferential direction of the wall surface for connecting the splicing device.

[0011] Furthermore, the fixing device includes a clamping gasket and a fixing bolt, and the first circular hole of the flexible cloth bag casing is aligned with the second circular hole of the first splicing plate or the second splicing plate and clamped between the two clamping gaskets. The flexible cloth bag casing and the first splicing plate or the second splicing plate are fixed by the fixing bolt passing through the clamping gasket circular hole, the first circular hole and the second circular hole.

[0012] Furthermore, each of the flexible bag casing and the first splicing plate or the second splicing plate is circumferentially provided with at least six groups of the fixing devices, and each pair of the splicing devices is provided with at least six groups of the rotating buckle male buckles and the female grooves.

[0013] Furthermore, the flexible bag casing is prefabricated in sections from high-strength geotextile.

[0014] Furthermore, the splicing device is made of an aluminum alloy annular plate.

[0015] According to another aspect of the present invention, a construction method of a splicable flexible casing structure for a karst pile foundation is provided, which is implemented using the above-mentioned splicable flexible casing structure for a karst pile foundation, and comprises the following steps:

[0016] S100: Pile foundation layout and positioning, drilling and cleaning holes according to the designed pile foundation dimensions, and detecting and locating the location and size of karst caves;

[0017] S200: Producing the steel cage and the flexible bag casing in sections on site, producing a splicing device according to the size of the steel cage, and fixing the first splicing plate and the second splicing plate of the splicing device to the end of the flexible bag casing using a fixing device;

[0018] S300: Put the flexible bag casing on the outer periphery of the first section steel cage and tie it with retractable hoops at intervals, and turn the bottom of the first section flexible casing inward and fix it to the bottom of the first section steel cage;

[0019] S400: Gradually lower the first section casing to the hole position and temporarily fix it, hoist the second section casing, weld the steel cage, and then make the rotating buckle male buckle of the first splicing plate at the bottom of the second section flexible bag casing fit into the female groove of the second splicing plate at the top of the first section flexible bag casing, and rotate until the rotating buckle male buckle fits into the circular groove at the end of the female groove, completing the connection between the first and second sections of the flexible bag casing;

[0020] S500: Repeat steps S300 to S400 to lower other steel cage segments with flexible bag casings, weld the steel cages and connect them through a splicing device to extend the flexible casing piles;

[0021] S600: pouring concrete from bottom to top, and adjusting the grouting pressure and flow rate in real time according to the location and size of the cave located in step S100. During the process, the concrete liquid level is constantly monitored. When the concrete liquid level reaches the elevation, pouring is stopped to form a closed pile body;

[0022] S700: After the pile foundation is maintained and tested to meet the requirements, the superstructure construction is carried out.

[0023] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0024] 1. The splicable flexible casing structure for karst pile foundations of the present invention adopts a flexible cloth bag casing sleeved on the outside of the steel mesh. The cloth bag can not only restrict the flow of aggregate but also expand radially under pressure during concrete pouring. The end of the flexible cloth bag casing is fixed with a splicing device through a fixing device. The upper and lower plates of the splicing device can be quickly connected by rotating and nesting through a buckle to achieve precise sealing of karst caves of any length, solve the problem of irregular leakage of slurry on the hole wall, and improve the success rate of concrete pouring and the quality of the pile body. The process is simple and efficient, shortening the cycle and reducing costs. The equipment format is unified and easy to industrialize and has wide applicability, providing a safe and economical pile construction solution for karst area infrastructure.

[0025] 2. The spliced ​​flexible casing structure for karst pile foundation of the present invention adopts an aluminum alloy annular splicing device, which is divided into a first splicing plate and a second splicing plate. The first splicing plate can be inserted into the second splicing plate, and the first splicing plate is provided with a rotating snap buckle male buckle, a second splicing plate matching female groove and a circular groove. It can be quickly connected by inserting and rotating. The splicing device is reinforced on the flexible bag casing with the aid of six sets of clamping gaskets and fixing bolts to ensure the strength and sealing of the splicing. It breaks through the length limit of traditional bag piles and can splice and extend the pile length according to the depth of the cave, realizing flexible adjustment of the pile length, and improving construction efficiency through rapid extension by snap buckles.

[0026] 3. The present invention's splicable flexible casing structure for karst pile foundations is compatible with traditional cast-in-place pile processes. After drilling, the splicing device is fabricated and fixed to the flexible bag casing. This device is then placed over the reinforcement cage and lowered in stages for splicing. No additional equipment is required, requiring only bolt fastening and snap-fit ​​connections. This reduces construction difficulty and equipment dependency, improves efficiency, and reduces labor and material investment.

[0027] 4. The splicable flexible casing structure for karst pile foundations of the present invention adopts a flexible cloth bag casing that is sleeved on the outside of the steel mesh and fixed by a retractable hoop. On the one hand, it prevents the flexible cloth bag casing from sliding relative to the steel cage when lowered; on the other hand, it can freely stretch as the flexible cloth bag casing expands to adapt to the expansion deformation of the cloth bag, thereby improving the structural stability and applicability.

[0028] 5. The flexible bag casing of the splicable flexible casing structure for karst pile foundations of the present invention is made of high-strength geotextile, which is flexible and fits the irregular hole wall, has good pressure bearing capacity, and is light and easy to operate; the splicing device is made of aluminum alloy, which is light and strong; the end of the flexible bag casing is precisely positioned and connected to the splicing device through small holes, which improves the stability of the overall structure and is superior to traditional isolation materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a structural schematic diagram of a splicable flexible casing structure for karst pile foundations according to an embodiment of the present invention;

[0030] Figure 2This is a schematic cross-sectional view of a splicable flexible casing structure for a karst pile foundation according to an embodiment of the present invention;

[0031] Figure 3 The figure is a schematic diagram of the splicing form of a splicable flexible casing structure for karst pile foundation according to an embodiment of the present invention.

[0032] Figure 4 This is a schematic diagram of the splicing form of a splicable flexible casing structure for karst pile foundations and a flow chart of the construction method according to an embodiment of the present invention.

[0033] In all the drawings, the same reference numerals represent the same technical features, specifically: 1-flexible cloth bag casing, 2-rebar cage, 3-fixing device, 31-clamping gasket, 32-fixing bolt, 4-splicing device, 41-first splicing plate, 411-rotating snap male buckle, 42-second splicing plate, 412-female groove. DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0035] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, inside, outside, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0036] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0037] In the present invention, the terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0038] Example 1

[0039] like Figure 1-2 As shown, an embodiment of the present invention provides a splicable flexible casing structure for karst pile foundations, comprising a flexible cloth bag casing 1, a steel cage 2, a fixing device 3, and a splicing device 4. The flexible cloth bag casing 1 is wrapped around the outer periphery of the steel cage 2 to form a closed space, which serves to isolate the karst geological environment and prevent concrete leakage. At the same time, its flexible characteristics can adapt to complex in-hole terrain. The fixing device 3 firmly fixes the splicing device 4 to the end of the flexible cloth bag casing 1, forming a stable structure and ensuring the strength and sealing of the splicing. The splicing device 4 is used to connect the flexible cloth bag casings 1 of different lengths, and through a unique rotating buckle design, it can achieve fast and stable splicing, so that the flexible cloth bag casing 1 can be infinitely extended according to the actual pile length requirements. This connection relationship and functional design of the flexible casing of the present invention effectively solves the adverse effects of geological conditions such as caves and fissures in karst areas on pile foundation construction, increases adaptability, improves pile quality, reduces construction costs, and improves construction efficiency.

[0040] Among them, the flexible bag casing 1 is made of high-strength geotextile, has excellent tensile strength and durability, can withstand complex geological stress, can restrain aggregate flow during concrete pouring, and can expand radially under pressure (expansion rate 150%-250%) to adaptively fill cavities and cracks, etc., forming a sealed space to prevent concrete leakage; the flexible bag casing 1 is sleeved on the outer periphery of the welded steel cage 2, and is tied with retractable hoops at intervals to ensure that the flexible bag casing 1 does not slide relative to the steel cage 2 when lowered. When the flexible bag casing 1 expands, the hoops are freely expanded to adapt to filling the cavities, and the hoops can limit the maximum expansion amount to prevent the flexible bag casing 1 from being damaged. During construction, according to different needs, the flexible bag can be segmented into cylindrical flexible casings of different diameters and lengths; for extra-long pile foundations, the flexible bag casing 1 is prefabricated in sections, and its end wall surface is evenly spaced along the circumference with first circular holes for connecting the splicing device 4. The high expansion rate design of the flexible bag casing enables it to adapt to the complex geological conditions in karst areas. Even in the case of caves of different sizes and irregular shapes, it can effectively fill and form a sealed space to ensure the integrity of the concrete piles.

[0041] The steel cage 2, serving as the skeletal structure of the pile foundation and providing support for the flexible bag casing 1, is prefabricated according to design requirements, with diameters and lengths strictly meeting construction standards. The main reinforcements are evenly spaced to ensure the structure's load-bearing capacity. The surface of the steel cage 2 is treated with an anti-corrosion treatment to adapt to the complex geological environment of karst areas and extend its service life.

[0042] The fixing device 3 includes a clamping washer 31 and a fixing bolt 32, which are used to fix the splicing device 4 to the end of the flexible casing to facilitate the extension of the flexible casing. The design of the fixing device not only ensures the tight fixation of the splicing device 4 and the flexible bag casing 1, but also facilitates installation and removal, improves construction efficiency and facilitates the reuse of components.

[0043] The splicing device 4 is composed of an aluminum alloy annular plate, including a first splicing plate 41 and a second splicing plate 42. The upper part of the first splicing plate 41 and the lower part of the second splicing plate 42 are circumferentially provided with second circular holes with the same diameter and corresponding to the first circular hole spacing at the end of the flexible cloth bag casing 1. The first circular hole of the flexible cloth bag casing 1 is aligned with the second circular hole of the first splicing plate 41 or the second splicing plate 42 and clamped in the two clamping gaskets 31. The fixing bolts 32 are passed through the circular holes, the first circular holes and the second circular holes of the clamping gaskets 31 to fix the two. In this embodiment, six groups of the fixing devices 3 are provided at one end of each flexible casing.

[0044] Furthermore, if Figure 3As shown, the lower diameter of the first splicing plate 41 is relatively small and can be inserted into the second splicing plate 42. The surface of the first splicing plate 41 is processed with a raised rotating snap buckle 411 along the circumferential direction. The wall of the second splicing plate 42 is provided with a female groove 421 corresponding to the rotating snap buckle 411 of the first splicing plate 41. The female groove 421 is an L-shaped groove with a circular groove at the end. The rotating snap buckle 411 is inserted into the female groove 421 and rotated until the rotating snap buckle 411 is inserted into the circular groove at the end of the female groove 421, thereby achieving a firm connection between the first splicing plate 41 and the second splicing plate 42, thereby achieving unlimited extension of the flexible casing. The splicing process is fast and stable, greatly improving construction efficiency. In this embodiment, a total of six groups of the above-mentioned snap-in methods are provided to ensure the strength and sealing of the flexible casing at the connection. Even under the complex geological conditions of karst areas, it can effectively prevent concrete leakage and ensure the quality of pile formation.

[0045] like Figure 4 As shown, an embodiment of the present invention provides a construction method of a splicable flexible casing structure for a karst pile foundation, which is implemented using the above-mentioned splicable flexible casing structure for a karst pile foundation, and includes the following specific steps:

[0046] S100: Pile foundation positioning and setting out, drilling and cleaning the holes according to the designed pile foundation dimensions, and conducting detailed surveys inside the holes using advanced equipment such as geological radar and ultrasonic detectors to accurately locate the location, size, and shape of the caves. This survey data will be used to adjust subsequent construction plans to ensure targeted and effective construction.

[0047] S200: The steel cage 2 is welded and tied in sections on site. A splicing device 4 is manufactured according to the size of the steel cage 2. The flexible cloth bag casing 1 is manufactured in sections. The splicing device 4 is fixed to the end of the flexible cloth bag casing 1 using a fixing device 3. The first circular hole of the flexible cloth bag casing is aligned with the first splicing plate 41 or the second circular hole of the second splicing plate 42 of the splicing device 4. The flexible cloth bag casing is clamped between two clamping gaskets 31 and fixed by passing a fixing bolt 32 through the circular holes.

[0048] S300: The flexible bag casing 1 of each segment fixed with the splicing device 4 is put on the outer periphery of the steel cage 2 of the corresponding segment until the steel cage 2 is completely covered, and is fixed at intervals with a retractable hoop, and the bottom of the first segment of the flexible bag casing 1 is turned inside out and inserted into the inner side of the first segment of the steel cage 2 and fixed;

[0049] S400: Using a crane or other lifting equipment, slowly lower the first section of the steel cage 2 along with the attached flexible bag casing 1. Once it reaches the orifice, temporarily secure it at the orifice. Then, hoist the upper section of the steel cage 2, with the attached flexible bag casing 1, so that the steel cage 2 is aligned with the first section before welding. After welding the steel cage 2, precisely align the first splicing plate 41 at the bottom of the upper section of the flexible bag casing 1 with the second splicing plate 42 fixed at the top of the lower section of the flexible bag casing 1. Engage the male swivel buckle 411 of the first splicing plate 41 in the female groove 421 of the second splicing plate 42. Rotate until the male swivel buckle 411 engages the circular groove at the end of the female groove 421, completing the connection between the upper and lower flexible bag casings 1. After the splicing device is connected, inspect the connection to ensure it is secure and reliable. The rotation angle can be tested to ensure compliance with design requirements. During the installation of the flexible bag casing 1, the flexible casing should be kept intact to avoid damage and ensure its waterproofness and impermeability; during the lowering of the steel cage, it should be kept stable to avoid impact or damage to the hole wall and the position and posture of the steel cage should be monitored in real time;

[0050] In order to achieve precise docking of the first splicing plate 41 and the second splicing plate 42, laser guidance + servo closed-loop control is adopted, and the positioning error compensation formula is as follows:

[0051]

[0052] Where: Δθ is the allowable angular deviation (≤0.5°), Δy is the radial offset detected by the laser rangefinder (mm), D is the diameter of the splicing plate (mm), Δx is the compensation displacement of the hydraulic leveling system (mm), e x is the position error (target position - actual position), k p 、k i 、k d are PID control parameters (calibrated according to experiments).

[0053] The rotation makes the male buckle completely enter the circular groove at the end of the female groove and lock it. The rotation locking control algorithm is as follows:

[0054] Rotation angle error:

[0055] e(θ)=θ target -θ

[0056] The control output angle increment is:

[0057]

[0058] Among them, θ0 is the initial rotation angle, θ is the current rotation angle, θ target is the target rotation angle, k p 、k i 、kd is the PID control parameter,

[0059] The final rotation angle is updated as:

[0060] θ new =θ+Δθ

[0061] When the rotation angle satisfies:

[0062] θ∈[θ min ,θ max ]

[0063] And if a mechanical locking signal is detected or the torque reaches a set threshold, it is determined that the connection is completed.

[0064] Among them, [θ min ,θ max ] is the locking angle range.

[0065] S500: repeat steps S300 to S400, lower other segments of the steel cage 2 with the flexible bag casing 1, weld the steel cages and connect them through the splicing device 4, and extend the length of the flexible casing pile.

[0066] S600: Start pouring concrete from bottom to top, and adjust the grouting pressure and flow rate in real time according to the location, size and shape of the cave located in step S100. The concrete will expand freely into the cave or crack under the pressure of the concrete. The height of the concrete liquid level will be monitored at all times during the process. When the concrete liquid level reaches the elevation, the pouring will be stopped to form a closed pile body.

[0067] S700: After the pile foundation is maintained and tested to meet the requirements, the superstructure construction is carried out.

[0068] Example 3

[0069] In a large bridge foundation project, the pile foundation needs to pass through multiple karst cave layers, and the caves vary in size and depth. The pile foundation is designed to be more than 50 meters long. Traditional construction methods are difficult to meet construction requirements and have high construction risks. The present invention adopts a splicable flexible casing structure construction method for karst pile foundations, which includes the following steps:

[0070] The first step: using a large rotary drilling rig to drill and clean the hole to the design depth. Geological radar and ultrasonic detectors were used to precisely locate the location, size, and shape of the cave. The results revealed the presence of multiple caves of varying sizes within the hole, with the largest reaching a diameter of 3 meters and a depth of approximately 10 meters.

[0071] Step 2: Prefabricate multiple sections of flexible casing and splicing devices. Each section of flexible casing is 10 meters long, and the splicing device is fixed to the end of the flexible casing with a fixing device to ensure the firmness and reliability of the connection.

[0072] Step 3: Put the flexible casing on the corresponding tied and welded steel cage segment, and the bottom of the first segment flexible casing is turned inward and fixed to the bottom of the first segment steel cage. Use a crane to slowly lower the first section of steel cage together with the flexible casing. After reaching the hole position, temporarily fix it at the hole mouth, hoist the second section casing so that its steel cage is aligned with the first section steel cage and then weld it. After welding is completed, the rotating buckle male buckle and female groove of the splicing device are used to achieve quick connection. Repeat the operation, lower the subsequent steel cage segments with flexible cloth bag casing in turn and complete the connection of the entire pile body.

[0073] Step 4: Begin pouring concrete, using a high-precision level gauge to monitor the concrete level in real time. During the pouring process, adjust the pouring speed and grouting pressure based on the cave conditions to ensure that the concrete evenly fills the cave.

[0074] Step 5: When the concrete level reaches the design elevation, stop pouring immediately. Maintain and monitor the poured pile foundation to ensure construction quality.

[0075] The embodiment of the present invention realizes the construction of ultra-long pile foundations through segmented prefabricated flexible casing and splicing device, breaking through the length limitation of traditional construction methods and enabling rapid splicing; the high expansion rate of the flexible casing can effectively adapt to complex karst geological conditions and ensure the quality of pile formation; the quick connection method of the splicing device greatly shortens the construction time and improves construction efficiency.

[0076] It will be easily understood by those skilled in the art that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A splicable flexible casing structure for karst pile foundation, characterized in that: The invention comprises a flexible cloth bag casing (1), a steel cage (2), a fixing device (3) and a splicing device (4), wherein the flexible cloth bag casing (1) is prefabricated in sections, the fixing device fixes the splicing device (4) to both ends of the flexible cloth bag casing (1), and the flexible cloth bag casing (1) is extended by the splicing devices (4) fixed at both ends and wrapped around the outer periphery of the steel cage (2) to form a closed space, wherein: The splicing device (4) comprises a second splicing plate (42) and a first splicing plate (41) that can be sleeved in the second splicing plate (42); a protruding rotating snap buckle male buckle (411) is provided on the surface of one end portion of the first splicing plate (41) along the circumferential direction; a female groove (421) corresponding to the rotating snap buckle male buckle (411) of the first splicing plate (41) is provided on the plate wall of one end portion of the second splicing plate (42); the rotating snap buckle male buckle (411) is embedded in the female groove (421) and is rotated to snap together and firmly connect the first splicing plate (41) and the second splicing plate (42), thereby realizing the extension of the flexible bag casing (1).

2. A splicable flexible casing structure for karst pile foundation according to claim 1, characterized in that: The female groove (421) is an L-shaped groove and a circular groove is provided at the end thereof. The rotating buckle male buckle (411) is rotated until it is embedded in the circular groove at the end of the female groove (421).

3. The splicable flexible casing structure for karst pile foundation according to claim 2, characterized in that: The flexible bag casing (1) sleeved on the outer periphery of the steel cage (2) is tied with hoops at intervals that can freely stretch as the flexible bag casing (1) expands.

4. The splicable flexible casing structure for karst pile foundation according to claim 3, characterized in that: The first splicing plate (41) and the second splicing plate (42) are both provided with second circular holes at even intervals along the circumferential direction.

5. The splicable flexible casing structure for karst pile foundation according to claim 4, characterized in that: The end of the flexible bag casing (1) is provided with a first circular hole along the circumferential direction of the wall surface, which has a corresponding spacing with the second circular holes of the first splicing plate (41) and the second splicing plate (42) and has the same diameter, and is used for connecting the splicing device (4).

6. The splicable flexible casing structure for karst pile foundation according to claim 5, characterized in that: The fixing device (3) comprises a clamping gasket (31) and a fixing bolt (32), and the first circular hole of the flexible cloth bag casing (1) is aligned with the second circular hole of the first splicing plate (41) or the second splicing plate (42) and clamped between the two clamping gaskets (31); the fixing bolt (32) passes through the circular hole, the first circular hole and the second circular hole of the clamping gasket (31), and fixes the flexible cloth bag casing (1) and the first splicing plate (41) or the second splicing plate (42).

7. The splicable flexible casing structure for karst pile foundation according to claim 6, characterized in that: Each of the flexible bag casings (1) and the first splicing plate (41) or the second splicing plate (42) is circumferentially provided with at least six sets of the fixing devices (3), and each pair of the splicing devices (4) is provided with at least six sets of the rotating buckle male buckles (411) and the female grooves (421).

8. A splicable flexible casing structure for karst pile foundation according to any one of claims 1 to 7, characterized in that: The flexible bag casing (1) is prefabricated in sections from high-strength geotextile.

9. A splicable flexible casing structure for karst pile foundation according to any one of claims 1 to 7, characterized in that: The splicing device (4) is made of an aluminum alloy annular plate.

10. A construction method for a splicable flexible casing structure for a karst pile foundation, implemented using the splicable flexible casing structure for a karst pile foundation according to any one of claims 1 to 9, characterized in that: The steps include: S100: Pile foundation layout and positioning, drilling and cleaning holes according to the designed pile foundation dimensions, and detecting and locating the location and size of karst caves; S200: Producing the steel cage (2) and the flexible bag casing (1) in sections on site, producing a splicing device (4) according to the size of the steel cage (2), and fixing the first splicing plate (41) and the second splicing plate (42) of the splicing device (4) to the end of the flexible bag casing (1) using a fixing device (3); S300: The flexible bag casing (1) is placed on the outer periphery of the steel cage (2) and is fixed at intervals with a retractable hoop, and the bottom of the first section flexible casing (1) is turned inward and fixed to the bottom of the first section steel cage (2); S400: The first section casing is gradually lowered to the hole position and temporarily fixed, the second section casing is hoisted, the steel cage is welded, and then the first splicing plate (41) at the bottom of the second section flexible bag casing (1) is rotated to fit the male buckle (411) of the snap fastener into the female groove (421) of the second splicing plate (42) at the top of the first section flexible bag casing (1), and the male buckle (411) is rotated until the male buckle (411) of the snap fastener fits into the circular groove at the end of the female groove (421), thereby completing the connection between the first section and the second section flexible bag casing (1); S500: repeating steps S300 to S400, lowering other segments of the steel cage (2) sleeved with the flexible bag casing (1), welding the steel cages and connecting them through the splicing device (4), and extending the flexible casing pile; S600: pouring concrete from bottom to top, and adjusting the grouting pressure and flow rate in real time according to the location and size of the cave located in step S100. During the process, the concrete liquid level is constantly monitored. When the concrete liquid level reaches the elevation, pouring is stopped to form a closed pile body; S700: After the pile foundation is maintained and tested to meet the requirements, the superstructure construction is carried out.

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