Steel mesh formwork cast-in-place pile structure suitable for high-rise building in karst area, and construction method

Abstract

Disclosed in the present invention are a steel mesh formwork cast-in-place pile structure suitable for a high-rise building in a karst area, and a construction method. A pile hole is drilled in a construction position; a cylindrical mesh formwork assembly is mounted in the pile hole and comprises a cylindrical reinforcement cage and a steel mesh formwork, and the steel mesh formwork surrounds the cylindrical reinforcement cage to form a vertically through-going cylindrical space which is adapted to the inner diameter of the pile hole; a grouting apparatus comprises a feeding guide pipe and a feeding device, the feeding guide pipe extends into the pile hole from the cylindrical space, the upper end of the feeding guide pipe extends out of a hole opening and is provided with a receiving hopper, and the feeding device is provided on the ground and feeds materials to the receiving hopper; and a hoisting apparatus is configured to: lower the cylindrical mesh formwork assembly into the pile hole before grouting, and dynamically adjust the vertical position of the feeding guide pipe during grouting, so as to maintain a constant embedment depth of the feeding guide pipe in the rising concrete.

Description

A steel mesh cast-in-place pile structure and construction method suitable for high-rise buildings in karst areas Technical Field

[0001] The invention relates to the technical field of construction engineering, and in particular provides a steel mesh formwork cast-in-place pile structure suitable for high-rise buildings in karst areas and a construction method. Background Art

[0002] In modern housing construction and public utility construction, pile foundations are often used to ensure the bearing capacity of the foundation. Pile foundation construction in karst areas or when encountering interconnected passages such as caves, earth holes, and goafs is difficult, requiring backfilling with stone slabs or other filler materials. During the pile pouring process, a large amount of concrete will flow into these passages, consuming a large amount of concrete. Furthermore, the wall strength of the pile hole in these areas is relatively poor. During the concrete pouring process, gravel and soil from the wall easily collapse and fall into the pile hole, mixing with the pile concrete, affecting the integrity of the pile foundation and reducing the pile's bearing capacity. Furthermore, the current method of pouring concrete from a fixed height into the pile hole makes it difficult to control the speed and pressure of concrete injection, which not only easily causes concrete to flow into the connecting passages but also affects the quality of the pile pouring.

[0003] At present, in order to solve the above problems, some new construction methods have emerged in the prior art. The most common method is to lower a continuous closed pipe column into the pile hole and then pour concrete into the pipe column from the upper end of the closed pipe column. Although the above construction method can realize the continuous pouring construction of the pile foundation, it can prevent the gravel and soil caused by the collapse of the hole wall from entering the concrete and reducing the integrity of the pile body.

[0004] However, the above-mentioned closed pipe column construction method has the following shortcomings: concrete only enters the closed pipe column, and concrete cannot enter the annulus between the surface of the continuous pipe column and the pile hole, so that concrete cannot fill the entire pile hole space. In addition, the closed pipe column is a rigid structure and cannot adapt to some elastic changes in the inner diameter of the pile hole at the connecting channel. It cannot form a fitting and tight connection with the pile hole. The pile body cannot be firmly combined with the pile hole to form an integral structure, which affects the bearing capacity and stability of the pile body.

[0005] Summary of the Invention

[0006] Based on this, the present invention provides a steel mesh mold cast-in-place pile structure and construction method suitable for high-rise buildings in karst areas, so as to avoid a large amount of concrete flowing into the connected empty pile holes, and enable the pile body to adapt to the changes in the inner diameter of the pile hole and combine into a solid overall structure, thereby improving the bearing capacity and stability of the pile body.

[0007] In order to achieve the above-mentioned objectives, in a first aspect, the present invention provides a steel mesh formwork cast-in-place pile structure suitable for high-rise buildings in karst areas, comprising: a pile hole drilled at a construction location; a cylindrical mesh formwork assembly installed in the pile hole, comprising a cylindrical steel cage and a steel mesh formwork, the steel mesh formwork being arranged outside the cylindrical steel cage to form a cylindrical space that is adapted to the inner diameter of the pile hole and vertically penetrates the pile hole; a pouring device comprising a feeding conduit and a feeding device, the feeding conduit extending from the cylindrical space into the pile hole, the upper end of the feeding conduit extending out of the hole and being provided with a material receiving funnel, the feeding device being arranged on the ground and feeding the material receiving funnel; a hoisting device being configured to: hoist the cylindrical mesh formwork assembly into the pile hole before pouring, and dynamically adjust the vertical position of the feeding conduit during the pouring process so that the feeding conduit maintains a constant sinking degree in the continuously rising concrete.

[0008] Optionally, the reinforcement cage is provided with a plurality of steel plate clamps at intervals along the vertical direction, each of the steel plate clamps is arranged outside the reinforcement cage, and the steel mesh mold is fixedly connected to the steel plate clamp.

[0009] Optionally, the steel mesh mold is vertically segmented, and the upper and lower ends of each segment of the steel mesh mold are respectively provided with the steel plate clamping ring, and two adjacent steel plate clamping rings are fixedly connected by a bayonet structure.

[0010] Optionally, the steel plate clamp includes a plurality of arc-shaped clamp units equally divided along the circumference, and adjacent arc-shaped clamp units are connected by elastic clamp sleeve joints to adapt to expansion and deformation during concrete pouring, so that the arc-shaped clamp is pressed against the inner wall of the pile hole.

[0011] Optionally, each of the arc-shaped clamping ring units is welded to the main reinforcement of the steel cage through a support reinforcement, and the support reinforcement is a vertically bent structure, including a horizontal middle section, a first vertical section extending vertically from the front end of the horizontal middle section, and a second vertical section extending vertically from the rear end of the horizontal middle section. The first vertical section of the support reinforcement is welded and fixed to the vertical main reinforcement of the steel cage, and the second vertical section is welded and fixed to the vertical surface of the steel plate clamping ring.

[0012] Optionally, the radial cross-section of the ring body of the steel plate clamp is an L-shaped structure, the outer edge circumferential array of the L-shaped structure is provided with protruding teeth, the outer periphery of the steel plate clamp is provided with a plurality of bayonet holes between the protruding teeth, and the inner side of the steel mesh mold is provided with V-shaped vertical ribs that are fixedly engaged with the bayonet holes.

[0013] Optionally, the steel mesh mold includes a plurality of arc-shaped mesh mold units equally divided along the circumference, each arc-shaped mesh mold unit is adapted one by one to the arc-shaped clamping ring unit, and adjacent arc-shaped mesh mold units are overlapped and loosely tied by interface binding wires, so that the steel mesh mold forms a closed cylindrical space and can adapt to radial expansion and deformation during the concrete pouring process.

[0014] Optionally, the steel mesh mold is composed of three arc-shaped mesh mold units of equal arc length, and the steel plate clamping ring is composed of three arc-shaped clamping ring units of equal arc length. The interface of the arc-shaped clamping ring unit on the same side is located on the same normal line as the interface of the arc-shaped mesh mold unit. The overlap length at the interface of each adjacent arc-shaped mesh mold unit is equal to the clamping distance between the two adjacent arc-shaped clamping rings. The overlap is loosely tied with interface binding wire to adapt to radial expansion during the concrete pouring process.

[0015] In order to achieve the above object, in a second aspect, the present invention provides a method for constructing steel mesh formwork cast-in-place piles suitable for high-rise buildings in karst areas, comprising the steps of:

[0016] S100. Select the pile hole location and drill the pile hole to the set depth using a drilling machine;

[0017] S200. A wire rope is connected to the bottom of the lifting hook of the lifting equipment. A lifting pole is connected to the bottom of the wire rope. The lifting pole is connected to the top of the cylindrical steel cage through the lifting rod. The cylindrical mesh mold assembly is hoisted down into the pile hole.

[0018] S300. The feed conduit is hoisted by a hoisting device, and is lowered into the pile hole by the center of the cylindrical space of the cylindrical mesh mold assembly. The lower end of the feed conduit extends near the bottom of the hole and the upper end extends outside the hole;

[0019] S400. The feeding device delivers concrete from the receiving hopper through the feeding conduit to the pile hole;

[0020] S500. As the concrete in the pile hole rises, the hoisting equipment dynamically feeds the feed conduit so that the sinking degree of the feed conduit in the concrete remains unchanged until the pile foundation construction is completed.

[0021] Optionally, the cylindrical mesh mold assembly includes a steel plate clamp and a steel mesh mold, the steel plate clamp is composed of a plurality of equal-length arc-shaped clamp units, and adjacent arc-shaped clamp units are connected by elastic clamp sleeve joints; the steel mesh mold is composed of a plurality of equal-length arc-shaped mesh membrane units, adjacent edges of adjacent steel mesh mold structural units are overlapped and tied by interface binding wires, and each arc-shaped clamp unit is adapted to each arc-shaped mesh mold unit one by one; the construction method includes:

[0022] Before pouring concrete, the steel plate clamp and the steel mesh form of the steel mesh form assembly are in a contracted state and are inserted into the pile hole in a state smaller than the pile hole size;

[0023] During the concrete pouring process, due to the outward expansion force of the concrete, the steel plate clamping ring and the steel mesh formwork of the steel mesh formwork assembly expand outwards and are pressed against the inner wall of the pile hole.

[0024] The technical advantages of the steel mesh formwork cast-in-place pile structure and construction method for high-rise buildings in karst areas provided by the present invention are at least reflected in:

[0025] Firstly, by setting up a steel mesh formwork in the cylindrical steel cage as a barrier, it can effectively prevent the large-scale loss of slurry containing stones into the connecting channel, and also prevent impurities such as gravel and soil on the hole wall from entering the concrete pile body, thus avoiding material waste and improving the overall quality of the pile body.

[0026] Secondly, during the concrete pouring process, the steel mesh mold deforms and sticks to the side wall of the pile hole, which not only increases the friction resistance on the pile side, but also allows the concrete slurry to penetrate through the steel mesh mold into the space between the hole wall and the steel mesh mold. After solidification, the pile body and the hole wall of the pile hole form a solid integrated structure, thereby improving the bearing capacity.

[0027] Thirdly, during the concrete pouring process, the vertical position of the feed pipe is dynamically adjusted through the lifting equipment, so that the feed pipe maintains a constant sinking degree, effectively controlling the speed and pressure of concrete input, avoiding excessive concrete pressure and large-scale loss to the connecting channel, and maintaining the quality of pile pouring. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0029] FIG1 is an elevation view of an embodiment of a steel mesh formwork cast-in-place pile structure suitable for high-rise buildings in karst areas;

[0030] FIG2 is a schematic structural diagram of an embodiment of the connection between the provided steel mesh form and the steel cage;

[0031] FIG3 is a schematic diagram of the structure of the provided steel mesh mold and the steel plate clamping ring;

[0032] FIG4 is a schematic diagram of the connection structure of the main reinforcement cage, steel plate clamp and steel mesh mold provided;

[0033] FIG5 is a schematic structural diagram of an embodiment of a support bar provided;

[0034] FIG6 is a schematic structural diagram of an embodiment of a provided steel cage hoisting sling;

[0035] FIG7 is a schematic diagram showing the state of the pouring construction process of the provided high-rise building steel mesh formwork cast-in-place pile.

[0036] FIG8 is a flowchart of an embodiment of a method for constructing steel mesh formwork cast-in-place piles for high-rise buildings in karst areas.

[0037] Explanation of the accompanying symbols: 1-pile hole, 11-steel casing, 12-karst hole; 2-cylindrical mesh formwork assembly, 21-vertical main reinforcement, 22-support reinforcement, 23-steel plate clamping ring, 24-clamping ring sleeve joint, 25-steel mesh formwork, 26-bayonet, 27-interface binding wire; 3-hoisting equipment, 31-steel wire rope, 32-hoisting shoulder pole, 33-hoisting reinforcement; 4-feeding device, 41-material receiving funnel, 42-feeding conduit. DETAILED DESCRIPTION

[0038] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0039] As shown in FIG1 to FIG7, the present invention provides an embodiment of a steel mesh formwork cast-in-place pile structure suitable for high-rise buildings in karst areas, comprising a pile hole, a cylindrical mesh formwork assembly, a casting device and a hoisting device.

[0040] The pile hole 1 is drilled at the construction location. Before drilling, a steel casing is buried at the hole mouth of the pile hole to maintain the hole mouth structure near the ground stable, creating basic conditions for subsequent construction such as lowering the cylindrical mesh formwork component 2 and pouring concrete.

[0041] The cylindrical mesh mold assembly 2 is installed in the pile hole 1, and includes a cylindrical steel cage and a steel mesh mold 25. The steel mesh mold 25 is arranged outside the cylindrical steel cage to form a cylindrical space that is adapted to the inner diameter of the pile hole 1 and vertically penetrates. The steel mesh mold is affected by the expansion of concrete during the pouring process, and can produce a small range of elastic deformation and adhere to the wall of the pile hole 1.

[0042] The grouting equipment includes a feeding conduit 42 and a feeding device 4. The feeding conduit 42 extends into the pile hole 1 from the cylindrical space. The upper end of the feeding conduit 42 extends out of the hole and is provided with a receiving funnel 41. The feeding device 4 is set on the ground and feeds the receiving funnel 41. The feeding conduit is movably connected to the hook of the lifting equipment and can be adjusted up and down by driving the lifting equipment 3.

[0043] The hoisting equipment 3 is configured to: hoist the cylindrical mesh form assembly 2 into the pile hole 1 before pouring, and dynamically adjust the vertical position of the supply conduit 42 during the pouring process so that the supply conduit 42 maintains a constant sinking degree in the continuously rising concrete.

[0044] As shown in FIG8 , based on a provided steel mesh formwork cast-in-place pile structure applicable to high-rise buildings in karst areas, an embodiment of a steel mesh formwork cast-in-place pile construction method applicable to high-rise buildings in karst areas provided by the present invention includes the following steps:

[0045] S100 selected pile hole position 1, before drilling, buried in the pile hole 1 steel casing 11, drilling machinery drill pile hole 1 to a set depth;

[0046] S200. The hook of the lifting device 3 is connected to the wire rope 31 below, the wire rope 31 is connected to the lifting pole 32 below, the lifting pole 32 is connected to the top of the cylindrical steel cage through the lifting rod 33, the cylindrical mesh mold assembly 2 is hoisted into the pile hole 1;

[0047] S300 hoisting the feed conduit 42 by the hoisting equipment 3, the cylindrical space center of the cylindrical mesh mold assembly 2 into the pile hole 1, the lower end of the feed conduit 42 extends near the bottom of the hole, the upper end extends outside the hole;

[0048] S400. The feeding device 4 is connected to the material hopper 41 through the feeding conduit 42 to transport concrete to the pile hole 1;

[0049] S500. As the concrete in the pile hole 1 rises, the hoisting device 3 dynamically supplies the feed conduit 42 so that the sinking degree of the feed conduit 42 in the concrete remains unchanged until the pile foundation construction is completed.

[0050] Based on the above-mentioned cast-in-place pile structure and construction method suitable for high-rise buildings in karst areas, a steel mesh formwork is added to the periphery of the steel cage to form a simple template for the side walls of the pile hole during concrete pouring. The steel mesh formwork effectively prevents the large-scale loss of slurry containing stones into the connecting channel, thus avoiding material waste and preventing impurities such as gravel and soil from entering the concrete pile body, thereby improving the overall quality of the pile body. At the same time, the feed conduit extends into the pile hole through the center of the cylindrical mesh formwork. During the pouring process, the vertical position of the feed conduit is dynamically adjusted by the hoisting equipment to ensure that the feed conduit remains submerged in the continuously rising concrete. This allows for the control of the speed and pressure of concrete injection, preventing excessive concrete pressure from causing large-scale loss into the connecting channel, and maintaining the quality of the pile injection.

[0051] As shown in Figures 2 and 3, in some embodiments, the steel cage is provided with a plurality of steel plate clamps 23 at vertical intervals. Each of the steel plate clamps 23 is disposed outside the steel cage, and the steel mesh mold 25 is fixedly connected to the steel plate clamps 23. Furthermore, the steel mesh mold 25 is vertically segmented, with the upper and lower ends of each segment of the steel mesh mold 25 respectively provided with the steel plate clamps 23, and adjacent steel plate clamps 23 are fixedly connected via a bayonet 26 structure. Based on this structural approach, the steel plate clamps 23 connected to the steel cage support the steel mesh mold, maintaining the structural stability and bearing capacity of the steel mesh mold, facilitating the lowering of the cylindrical mesh mold assembly into the pile hole, and being able to withstand the large impact force generated by the concrete during the pouring process.

[0052] As shown in Figure 2, in some embodiments, the steel plate collar 23 comprises a plurality of equally spaced arcuate collar units, each connected by an elastic collar sleeve 24. This allows for expansion and deformation during concrete pouring, allowing the arcuate collar units to be pressed against the inner wall of the pile hole 1. The arrangement of multiple arcuate collar units connected by an annular collar sleeve allows the steel plate collar units to undergo elastic deformation in different directions, accommodating varying gaps between the pile hole wall, the steel plate collar unit, and adjacent pile hole walls, improving adaptability to pile hole shapes.

[0053] As shown in Figures 2 and 3, in some embodiments, the steel mesh mold 25 includes a plurality of arc-shaped mesh mold units equally divided along the circumference, each arc-shaped mesh mold unit is adapted to the arc-shaped clamping ring unit one by one, and adjacent arc-shaped mesh mold units are overlapped and loosely tied by interface binding wires 27, so that the steel mesh mold 25 forms a closed cylindrical space and can adapt to radial expansion and deformation during the concrete pouring process.

[0054] As shown in Figures 2 and 3, in a specific embodiment, the steel mesh mold 25 is composed of three arc-shaped mesh mold units of equal arc length, and the steel plate clamping ring 23 is composed of three arc-shaped clamping ring units of equal arc length. The interfaces of the arc-shaped clamping ring units on the same side are located on the same normal line as the interfaces of the arc-shaped mesh mold units. The overlap length at the interface of each adjacent arc-shaped mesh mold unit is equal to the distance between the clamping openings 26 of the two adjacent arc-shaped clamping rings. The overlap is loosely tied with interface binding wires 27 to accommodate radial expansion during the pouring of concrete. Based on the structure provided by the above embodiment, the construction method includes:

[0055] Before pouring concrete, the steel plate clamp ring 23 and the steel mesh mold 25 of the steel mesh mold 25 assembly are in a contracted state and are inserted into the pile hole 1 in a state smaller than the size of the pile hole 1; during the concrete pouring process, due to the external expansion force of the concrete, the steel plate clamp ring 23 and the steel mesh mold 25 of the steel mesh mold 25 assembly expand outwards and are pressed against the inner wall of the pile hole 1.

[0056] Moreover, during the concrete pouring process, the steel plate clamp and the steel mesh mold are deformed and pressed against the side wall of the pile hole, which not only increases the friction resistance on the pile side, but also allows the concrete slurry to penetrate through the mesh holes of the steel mesh mold into the space between the hole wall and the steel mesh mold. After solidification, the pile body containing the steel mesh mold and the hole wall of the pile hole form a solid integrated structure, thereby improving the bearing capacity of bored piles constructed in complex geology.

[0057] As shown in Figures 4 and 5 , in some embodiments, each of the arc-shaped collar units is welded to the main reinforcement of the steel cage via a support bar 22. The support bar 22 is a vertically bent structure comprising a horizontal middle section, a first vertical section extending perpendicularly from the front end of the horizontal middle section, and a second vertical section extending perpendicularly from the rear end of the horizontal middle section. The first vertical section of the support bar 22 is welded to the vertical main reinforcement 21 of the steel cage, and the second vertical section is welded to the vertical surface of the steel plate collar 23. The structural design of the support bar maintains the vertical rigidity of the connection between the elastic collar unit and the main reinforcement of the steel cage, and can produce radial deformation due to the external expansion force of concrete, thereby achieving the dual functions of supporting the steel mesh formwork and accommodating deformation.

[0058] As shown in Figures 2 and 3, further, in some embodiments, the radial cross-section of the ring body of the steel plate clamp 23 is an L-shaped structure, the outer edge circumferential array of the L-shaped structure is provided with convex teeth, the outer periphery of the steel plate clamp 23 is provided with a plurality of bayonet holes 26 located between the convex teeth, and the inner side of the steel mesh mold 25 is provided with V-shaped vertical ribs that are fixedly engaged with the bayonet holes 26. Through this structure, the firmness of the connection between the steel plate clamp and the steel mesh mold is improved.

[0059] The present invention provides a steel mesh formwork cast-in-place pile structure and construction method suitable for high-rise buildings in karst areas, thereby avoiding the waste of materials and reduction in pile quality caused by the large amount of concrete loss during the construction of cast-in-place piles containing connected empty passages. The structure adapts to the changes in the inner diameter of the empty passages and is combined into a solid overall structure, thereby achieving uniform distribution of concrete slurry between the pile body and the pile hole, thereby improving the bearing capacity and stability of the pile body.

[0060] The steel mesh formwork cast-in-place pile structure and construction method suitable for high-rise buildings in karst areas can be used for the construction of pile foundations of various construction projects and municipal common projects in karst development areas, and are also suitable for pile foundation construction when encountering connecting passages such as karst caves, soil caves, and goafs.

[0061] In order to further illustrate the technical solution of the present invention, the following describes the steel mesh formwork cast-in-place pile structure and construction method applicable to high-rise buildings in karst areas provided by the present invention with a specific on-site embodiment.

[0062] As shown in Figures 1 to 7, the present invention provides a steel mesh formwork cast-in-place pile structure suitable for high-rise buildings in karst areas, comprising a pile hole system 1, a steel cage and steel mesh formwork system 2, a hoisting system 3, a concrete pouring system 4, etc.; the pile hole system comprises a pile hole 1, a steel casing 11, and a karst hole 12. The pile hole 1 is drilled by a drilling machine, and the steel casing 11 is buried at the hole mouth before drilling; the steel cage and steel mesh formwork system comprises a steel cage 2, a steel cage main reinforcement 21, a support reinforcement 22, a steel plate clamp 23, a clamp sleeve joint 24, a steel mesh formwork 25, a clamp 26, and an interface binding wire 27. A steel plate clamp 23 is arranged on the periphery of the steel cage 2, and the steel plate The clamping ring 23 is connected to the main reinforcement 21 of the steel cage by a support reinforcement 22, and both ends are welded and fixed. The steel plate clamping ring 23 is divided into three sections of equal arc length in the circumferential direction and is made into a circle shape. A retractable clamping ring joint 24 is set between the sections. The V-shaped vertical ribs of the steel mesh mold 25 are clamped in the clamping mouth around the outer edge of the steel plate clamping ring 23 to form a simple template around the pile to prevent the poured concrete from flowing into the karst hole 12. The steel mesh mold 25 is first rolled into a cylindrical shape and divided into three sections of equal arc length along the circumferential direction. Adjacent sections are overlapped, and the inner and outer molds at the overlap are tied with interface binding wire 27. They are processed in vertical sections, and double steel plate clamping rings 23 are set at the joints to form a firm clamping mouth 26 structure.

[0063] As shown in Figures 6 and 7, the lifting system includes a truck crane 3, a steel wire rope 31, a lifting pole 32, and a lifting rod 33. The truck crane 3 is supported on the ground near the hole mouth. The steel wire rope 31 is connected to the bottom of the truck crane 3 hook, and the lifting pole 32 is connected to the bottom of the steel wire rope. The lifting pole is connected to the top of the steel cage through the lifting rod 33. The truck crane lifts the steel cage 2 and the outer steel mesh mold 25 and installs them into the pile hole 1. The concrete pouring system includes a steel pipe 4, a large funnel 41, and a concrete mixer truck 42. The steel pipe 4 is lowered into the steel cage 2, with the bottom opening approximately 30 cm from the bottom of the hole and the top elevated above the ground. The large funnel 41 is installed at the top of the steel pipe 4. The concrete mixer truck 42 transports and pours concrete into the large funnel. The steel pipe is lifted section by section and concrete is poured to complete the pile foundation construction.

[0064] As shown in Figures 4 and 5, in some specific embodiments on site, the support bar 22 is made of Φ10mm steel bars, one end of which is welded to the main reinforcement 21 of the steel cage, supporting the steel plate clamp 23 outward, and the outer end is welded to the vertical edge of the "L" shape of the steel plate clamp 23. Each section of the steel plate clamp 23 is supported by two support bars 22. The steel plate clamp 23 is made of Q235 steel, with an "L"-shaped cross-section and a wall thickness of not less than 2mm, and is made into a circular shape. A convex tooth is set on the outer edge of the "L"-shaped horizontal side, and a bayonet and a barb are set in the middle of the convex tooth. The bayonet can clamp the V-shaped vertical ribs on the steel mesh mold 25.

[0065] As shown in Figures 2 and 3, the steel plate clamp 23 is divided into three sections of equal arc length along the circumference, and a retractable clamp sleeve joint 24 is set between adjacent sections, forming a circle shape after assembly; when pouring concrete, the steel plate clamp 23 can expand a small amount synchronously with the steel mesh mold.

[0066] As shown in FIG2 , in some specific embodiments on site, the steel mesh mold 25 is made of Q195A steel, which is a steel mesh made of galvanized thin steel sheets through punching, stretching, and rolling. The weight is ≥1.5 kg / m2, and V-shaped vertical ribs are arranged in parallel on the steel mesh with a spacing of 200 to 300 mm. The steel mesh mold 25 is rolled into a cylindrical shape using a plate rolling machine. The rolled diameter is the same as the designed diameter of the pile foundation. When rolled, the steel mesh mold 25 is divided into three sections of equal arc length along the circumferential direction. The three interfaces are overlapped. The interface position is on the same normal line as the clamping ring joint 24. The overlap length is the length between two adjacent clamping openings 26. The inner and outer molds of the overlap interface are tied with interface binding wire 27. Within the overlap length range, the steel mesh mold is not connected to the steel plate clamping ring 23. The steel mesh mold 25 forms a closed simple template structure and can adapt to a small amount of expansion to fill the pile hole 1. In some specific embodiments on site, each section of the steel mesh mold 25 is 2.0 m long vertically. The two sections of the steel mesh mold are aligned at the joint, and a double steel plate clamping ring 23 is provided to form a firm bayonet 26 structure, forming a continuous, cylindrical steel mesh mold 25 vertically.

[0067] As shown in Figure 1 , in some specific on-site embodiments, a 25t rated load truck crane, serving as lifting equipment 3, is installed on compacted ground near the hole opening. A steel wire rope 31 is connected below the crane's hook, and a lifting pole 32 is attached below the wire rope. The lifting pole is connected to the top of the rebar cage via a lifting rod 33. The crane then lifts the rebar cage 2 and the outer steel mesh form 25 and installs them into the pile hole 1. The lifting rods 33 are made of Φ16mm HPB300 steel bars, two in total. Their lower ends are double-welded to the main cage bars 21, and their upper ends are provided with lifting rings that connect to the ear holes of the lifting pole 32.

[0068] In some specific field implementations, the steel conduit 42 is lowered into the reinforcing cage 2, with its bottom opening approximately 30 cm from the bottom of the hole. A large funnel 41 is installed above the ground at its top. A concrete mixer truck, acting as the feeding device 4, transports and pours concrete into the funnel. As the concrete surface of the pile gradually rises, the steel conduit 4 is simultaneously lifted and removed in sections, maintaining a constant depth of 4 to 6 m in the concrete. The poured concrete exceeds the designed elevation of the pile top by 0.5 to 1.0 m, completing the steel mesh cast-in-place pile construction.

[0069] The foregoing description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be readily conceived by a person skilled in the art within the technical scope disclosed herein are intended to be encompassed within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A steel mesh formwork cast-in-place pile structure applicable to high-rise buildings in karst areas, characterized in that, Comprising: A pile hole (1), drilled at the construction position; A cylindrical net formwork assembly (2), installed in the pile hole (1), including a cylindrical steel reinforcement cage and a steel net formwork (25), the steel net formwork (25) surrounding the cylindrical steel reinforcement cage to form a cylindrical space that is adapted to the inner diameter of the pile hole (1) and vertically penetrates; A pouring device, including a feeding conduit (42) and a feeding device (4), the feeding conduit (42) extending into the pile hole (1) from the cylindrical space, the upper end of the feeding conduit (42) extending out of the hole opening and provided with a receiving hopper (41), the feeding device (4) being arranged on the ground and feeding the receiving hopper (41); A hoisting device (3), configured to: hoist the cylindrical net formwork assembly (2) into the pile hole (1) before pouring, and dynamically adjust the vertical position of the feeding conduit (42) during the pouring process so that the feeding conduit (42) maintains a constant immersion depth in the continuously rising concrete.

2. The steel mesh formwork cast-in-place pile structure applicable to high-rise buildings in karst areas according to claim 1, characterized in that, A plurality of steel plate retaining rings (23) are arranged at intervals along the vertical direction of the steel reinforcement cage, each of the steel plate retaining rings (23) surrounding the steel reinforcement cage, and the steel net formwork (25) is fixedly connected to the steel plate retaining rings (23).

3. The steel mesh formwork cast-in-place pile structure applicable to high-rise buildings in karst areas according to claim 1, characterized in that, The steel net formwork (25) is vertically segmented, and the upper and lower ends of each segment of the steel net formwork (25) are respectively provided with the steel plate retaining rings (23), and adjacent two steel plate retaining rings (23) are fixedly connected through a bayonet (26) structure.

4. The steel mesh formwork cast-in-place pile structure applicable to high-rise buildings in karst areas according to claim 1, characterized in that, The steel plate retaining ring (23) includes a plurality of arc-shaped retaining ring units equally divided along the circumference, and adjacent arc-shaped retaining ring units are connected through an elastic retaining ring joint (24) to be able to adapt to expansion deformation during the pouring of concrete, so that the arc-shaped retaining ring units are pressed against the inner wall of the pile hole (1).

5. The steel mesh formwork cast-in-place pile structure applicable to high-rise buildings in karst areas according to claim 1, characterized in that, Each of the arc-shaped retaining ring units is respectively welded and connected to the main reinforcement bars of the steel reinforcement cage through a support bar (22), the support bar (22) being a bent structural steel bar, including a horizontal middle section, a first vertical section vertically extending from the front end of the horizontal middle section, and a second vertical section vertically extending from the rear end of the horizontal middle section, the first vertical section of the support bar (22) being welded and fixed to the vertical main reinforcement bar (21) of the steel reinforcement cage, and the second vertical section being welded and fixed to the vertical surface of the steel plate retaining ring (23).

6. The steel mesh formwork cast-in-place pile structure applicable to high-rise buildings in karst areas according to claim 1, characterized in that, The radial cross-section of the ring body of the steel plate retaining ring (23) is an L-shaped structure, and convex teeth are arranged in a circumferential array on the outer edge of the L-shaped structure. A plurality of bayonets (26) are arranged between the convex teeth on the outer periphery of the steel plate retaining ring (23), and the inner side of the steel net formwork (25) is provided with V-shaped vertical ribs that are clamped and matched with the bayonets (26).

7. The steel mesh formwork cast-in-place pile structure applicable to high-rise buildings in karst areas according to claim 1, characterized in that, The steel net formwork (25) includes a plurality of arc-shaped net formwork units equally divided along the circumference, each arc-shaped net formwork unit being adapted to an arc-shaped retaining ring unit one by one, and adjacent arc-shaped net formwork units overlapping and being loosely tied through an interface binding wire (27), so that the steel net formwork (25) forms a closed cylindrical space and can adapt to radial expansion deformation during the pouring of concrete to fill the pile hole.

8. The steel mesh formwork cast-in-place pile structure applicable to high-rise buildings in karst areas according to claim 1, characterized in that, The steel mesh form (25) is composed of three arc-shaped mesh form units with equal arc lengths. The steel plate retaining ring (23) is composed of three arc-shaped retaining ring units with equal arc lengths. The interfaces of the arc-shaped retaining ring units on the same side and the interfaces of the arc-shaped mesh form units are located on the same normal line. The overlapping length at the interfaces of adjacent arc-shaped mesh form units is equal to the distance between the clamping openings (26) of two adjacent arc-shaped retaining rings. The overlapping part is loosely tied with interface binding wires (27) to adapt to radial expansion during the concrete pouring process and fill the pile hole.

9. A construction method for steel mesh formwork cast-in-place piles applicable to high-rise buildings in karst areas, characterized in that, Including steps: S100. Select the position of the pile hole (1). Before drilling, bury a steel casing (11) at the pile hole (1), and use a drilling machine to drill the pile hole (1) to the set depth. S200. Connect a steel wire rope (31) under the hook of the hoisting device (3). Connect a lifting crossbeam (32) under the steel wire rope (31). The lifting crossbeam (32) is connected to the top of the cylindrical steel reinforcement cage through a lifting bar (33), and lower the cylindrical mesh form assembly (2) into the pile hole (1) by hoisting. S300. Hoist the feeding conduit (42) by the hoisting device (3) and lower it into the pile hole (1) from the center of the cylindrical space of the cylindrical mesh form assembly (2). The lower end of the feeding conduit (42) extends near the bottom of the hole, and the upper end extends outside the hole opening. S400. The feeding device (4) conveys concrete into the pile hole (1) through the feeding conduit (42) from the receiving funnel (41). S500. As the concrete in the pile hole (1) rises, the hoisting device (3) dynamically raises the feeding conduit (42) upward so that the submersion depth of the feeding conduit (42) in the concrete remains unchanged until the pile foundation construction is completed.

10. The construction method for steel mesh formwork cast-in-place piles applicable to high-rise buildings in karst areas according to claim 9, characterized in that, The cylindrical mesh form assembly (2) includes a steel plate retaining ring (23) and a steel mesh form (25). The steel plate retaining ring (23) is composed of multiple arc-shaped retaining ring units with equal lengths. Adjacent arc-shaped retaining ring units are connected by elastic retaining ring connectors (24). The steel mesh form (25) is composed of multiple arc-shaped mesh units with equal lengths. The adjacent sides of adjacent structural units of the steel mesh form (25) overlap and are tied with interface binding wires (27). Each arc-shaped retaining ring unit is adapted to each arc-shaped mesh form unit one by one. The construction method includes: Before pouring concrete, the steel plate retaining ring (23) and the steel mesh form (25) of the steel mesh form (25) assembly are in a contracted state and are lowered into the pile hole (1) in a state smaller than the size of the pile hole (1). During the concrete pouring process, due to the outward expansion force of the concrete, the steel plate retaining ring (23) and the steel mesh form (25) of the steel mesh form (25) assembly expand outward respectively and are pressed against the inner wall of the pile hole (1).

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