A pile foundation construction device for soft soil subgrade treatment

Abstract

The present invention relates to the technical field of subgrade construction, and specifically relates to a pile foundation construction device for treating soft soil subgrade, including a pile press and a foundation pile. The foundation pile includes a settlement pile and a cast-in-place pipe pile. The lower end surface of the cast-in-place pipe pile is fixedly welded with the settlement pile, and the settlement pile is pressed into the soft soil subgrade through the pile press. The cast-in-place pipe pile is exposed in the cast-in-place foundation hole opened on the surface of the soft soil subgrade. An elastic block is fixed in each installation groove. The end surfaces of a plurality of elastic blocks arranged in a circumferential array above are elastically hinged with first insertion strips. The plurality of first insertion strips are arranged in a circumferential array on the outer circumferential surface of the cast-in-place pipe pile in an inclined downward manner. The end surfaces of a plurality of elastic blocks arranged in a circumferential array below are elastically hinged with second insertion strips, and the plurality of second insertion strips are arranged in a circumferential array on the outer circumferential surface of the cast-in-place pipe pile in an inclined upward manner. The plurality of first insertion strips and the plurality of second insertion strips are arranged in a staggered manner; the present invention can enable the foundation pile to be safely supported on a large area on the soft soil subgrade, and thus will not affect the safe use of the soft soil subgrade.

Description

Technical Field

[0001] The present invention relates to the technical field of subgrade construction, and particularly to a pile foundation construction device for treating soft soil subgrade. Background Technique

[0002] At present, due to the complex and diverse geological conditions in China, when building railways, subgrades are sometimes built on soft soil foundations. Especially in the southeast coastal areas dominated by marine soft soil with deep soft foundations, the insufficient bearing capacity of the foundation and large settlement and deformation of the subgrade have always been difficult problems in the construction of high-speed railways in this area. Therefore, effective engineering measures must be taken to reinforce and treat the low-strength soft soil foundation.

[0003] When it is necessary to drive pile foundations into the soft soil subgrade so that the pile foundations can reinforce and treat the soft soil subgrade, because the foundation of the soft soil subgrade is relatively soft, therefore, if the existing conventional pile foundations are pressed into the soft soil subgrade by a pile press, since the pressed pile foundations are only inserted into the foundation by being wrapped by the soft soil layer, they cannot play a role in hardening and supporting the upper surface of the soft soil subgrade. Furthermore, when the subgrade around the pile foundation undergoes lateral water flow sliding, it will cause the pressed pile foundation to tilt or shift, which will affect the safety support of the pressed pile foundation for the soft soil subgrade and is also prone to causing potential safety hazards. Summary of the Invention

[0004] The purpose of the present invention is to provide a pile foundation construction device for treating soft soil subgrade to solve the problems raised in the above background technique.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A pile foundation construction device for treating soft soil subgrade, including a pile press and a pile foundation. The pile foundation includes a settlement pile and a casting pipe pile. The lower end surface of the casting pipe pile is welded and fixed with the settlement pile, and the settlement pile is pressed into the soft soil subgrade by the pile press. The casting pipe pile is exposed in the casting base hole opened on the surface of the soft soil subgrade. A limit settlement mechanism is arranged on the casting pipe pile. The limit settlement mechanism is used to perform settlement limit on the pile foundation pressed into the soft soil subgrade, thereby improving the stability of the pile foundation when used in the soft soil subgrade.

[0006] Preferably, the limiting settlement mechanism includes elastic blocks, first insertion strips, second insertion strips, push connecting rods, first extrusion blocks, second extrusion blocks and a conical extrusion cylinder. A plurality of installation grooves are circumferentially arrayed on the outer circumferential surface of the cast pipe pile, and adjacent two of the installation grooves are arranged in an up-and-down staggered manner. Each installation groove is fixedly provided with an elastic block. A first insertion strip is elastically hinged to the end face of each of the plurality of elastic blocks in the circumferential array located above. The plurality of first insertion strips are circumferentially arrayed on the outer circumferential surface of the cast pipe pile in an inclined downward manner. A second insertion strip is elastically hinged to the end face of each of the plurality of elastic blocks in the circumferential array located below. The plurality of second insertion strips are circumferentially arrayed on the outer circumferential surface of the cast pipe pile in an inclined upward manner. The plurality of first insertion strips and the plurality of second insertion strips are arranged in a staggered manner. A plurality of sliding guide grooves are circumferentially arrayed on the cast pipe pile, and the sliding guide grooves are located between two symmetrically arranged installation grooves above and below. A push connecting rod is slidably inserted into each of the plurality of sliding guide grooves, and one end face of each of the plurality of push connecting rods is respectively hinged to the inner side surfaces of the plurality of first insertion strips and the plurality of second insertion strips. A first extrusion block is installed on the other end face of the push connecting rod connected to the first insertion strip, and a second extrusion block is installed on the other end face of the push rod connected to the second insertion strip. The inner side surfaces of the plurality of first extrusion blocks in the circumferential array are on the same inner circumferential surface, and the inner side surfaces of the plurality of second extrusion blocks in the circumferential array are on the same inner circumferential surface. A conical extrusion cylinder is inserted into the cast pipe pile, and the conical extrusion cylinder slides up and down in the grouting pipe pile through a sliding and pushing assembly to extrude the plurality of first extrusion blocks and the second extrusion blocks, facilitating the insertion of the first insertion strip and the second insertion strip into the inner circumferential wall of the cast foundation hole under the push of the push connecting rod.

[0007] Preferably, the sliding and pushing assembly includes a pressing rod, a guiding slide rod, a supporting disc, a supporting rod, a guiding slide cylinder and a supporting spring. The pressing rod is fixedly inserted into the conical extrusion cylinder, and a guiding slide rod is fixed to the bottom end face of the pressing rod. The connection part between the settlement pile and the cast pipe pile is fixedly supported by a plurality of supporting rods with a supporting disc, and a guiding slide cylinder is fixed to the upper surface of the supporting disc. The guiding slide rod is slidably inserted into the guiding slide cylinder, and the lower end face of the guiding slide rod is rotationally connected to the bottom end inside of the guiding slide cylinder through a supporting spring. The outer circumferential surface of the bottom end of the guiding slide rod is in the shape of a threaded rod, and a threaded groove hole is provided inside the bottom end of the guiding slide cylinder. The top end face of the pressing rod is higher than the upper surface of the conical extrusion cylinder.

[0008] Preferably, an expansion cavity is provided in each of the first insertion strip and the second insertion strip, and bentonite particles are filled in the expansion cavity. A plurality of convex tumor holes are provided on the outer side surface of the expansion cavity.

[0009] Preferably, a burr bent strip is provided in each convex tumor hole, and one end face of the burr bent strip is fixedly connected to the cavity wall of the expansion cavity. The other end face of the burr bent strip extends out of the convex tumor hole, and the size of the burr bent strip is smaller than the size of the convex tumor hole.

[0010] Preferably, the diameter of the inner circumferential surface formed by the plurality of first pressing blocks in the circumferential array is smaller than the diameter of the inner circumferential surface formed by the plurality of second pressing blocks in the circumferential array.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0012] 1. In the present invention, a plurality of first inserting strips inclined downward and a plurality of second inserting strips inclined upward are arranged on the outer circumferential surface of the cast pipe pile. When the conical extrusion cylinder slides downward in the cast pipe pile, it will drive the plurality of first inserting strips and the plurality of second inserting strips to expand and insert into the hole wall in the cast foundation hole through the plurality of first pressing blocks and the plurality of second pressing blocks. Since the plurality of first inserting strips are inserted into the hole wall of the cast foundation hole inclined downward, and the suspended ends of the plurality of second inserting strips are inserted into the hole wall of the cast foundation hole inclined upward, no matter whether partial collapse or subsidence occurs in the soft soil subgrade around the cast pipe pile, the mutual cooperation of the plurality of first inserting strips and the second inserting strips can play a triangular supporting role for the cast pipe pile, thereby increasing the stability and firmness of the installation support of the cast pipe pile in the cast foundation hole. Then, concrete is poured into the cast foundation hole. After the concrete solidifies, it will fix the plurality of first inserting strips and the second inserting strips, so that the foundation pile can be safely supported on a large area on the soft soil subgrade, and thus will not affect the safe use of the soft soil subgrade.

[0013] 2. In the present invention, burr bent strips are arranged in the expansion cavities of the first inserting strips and the second inserting strips. When the first inserting strips and the second inserting strips are respectively inserted into the hole wall of the cast foundation hole, the burr bent strips arranged on the first inserting strips and the second inserting strips will be synchronously inserted into the hole wall at this time, thereby increasing the contact area of the first inserting strips and the second inserting strips in the hole wall. At the same time, the concrete slurry leaking out of the convex tumor holes and the expanded bentonite particles will improve the firmness and stability of the burr bent strips inserted into the hole wall, and thus can further improve the supporting effect of the first inserting strips and the second inserting strips on the foundation pile. Description of the Drawings

[0014] Figure 1 is a schematic structural diagram of the present invention;

[0015] Figure 2 is a cross-sectional view of the cast pipe pile of the present invention;

[0016] Figure 3 is a cross-sectional view of the first inserting strip of the present invention.

[0017] In the figure: 1, basic pile; 2, settlement pile; 3, cast-in-place pipe pile; 31, installation groove; 32, sliding guide groove; 4, limit settlement mechanism; 41, elastic block; 42, first insertion strip; 421, expansion cavity; 422, convex tumor hole; 43, second insertion strip; 44, push connecting rod; 45, first extrusion block; 46, second extrusion block; 47, conical extrusion cylinder; 5, sliding and pushing assembly; 51, downward pressure rod; 52, guiding slide rod; 53, support disk; 54, support rod; 55, guiding slide cylinder; 56, support spring; 6, burr bent strip. Specific implementation mode

[0018] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0019] Embodiment 1:

[0020] As Figures 1 to 3As shown in the figure, the present invention provides a technical solution for a pile foundation construction device for soft soil subgrade treatment: It includes a pile press and a foundation pile 1. The foundation pile 1 includes a settlement pile 2 and a cast-in-place pipe pile 3. The lower end surface of the cast-in-place pipe pile 3 is welded and fixed with the settlement pile 2, and the settlement pile 2 is pressed into the soft soil subgrade by the pile press. The cast-in-place pipe pile 3 is exposed in the cast-in-place foundation hole opened on the surface of the soft soil subgrade. A limit settlement mechanism 4 is provided on the cast-in-place pipe pile 3. The limit settlement mechanism 4 is used to limit the settlement of the foundation pile 1 pressed into the soft soil subgrade, thereby improving the stability of the foundation pile 1 when used in the soft soil subgrade. Designed by the present invention, when pile driving construction of the foundation pile 1 is required for the soft soil subgrade, since the foundation of the soft soil subgrade is relatively soft, therefore, if the existing conventional foundation pile 1 is pressed into the soft soil subgrade by a pile press, since the pressed foundation pile 1 is only inserted into the foundation by being wrapped by the soft soil layer, it cannot play a role in hardening and supporting the upper surface of the soft soil subgrade. Therefore, if the subgrade around the foundation pile 1 undergoes lateral sliding of water flow, it will cause the pressed foundation pile 1 to tilt or shift, which will affect the safety support of the pressed foundation pile 1 for the soft soil subgrade and is also prone to causing safety hazards. Therefore, when the construction device designed by the present invention is used to press the foundation pile 1 into the soft soil subgrade, at this time, the construction personnel need to dig a cast-in-place foundation hole with a certain depth on the subgrade surface, and then suspend the foundation pile 1 to the cast-in-place foundation hole, so that the settlement pile 2 at the lower end of the foundation pile 1 contacts the bottom of the cast-in-place foundation hole. Then, the pile press clamps the pipe orifice of the cast-in-place pipe pile 3, so that the pile press applies a downward pressure, thereby facilitating the settlement pile 2 to be pressed into the soft soil subgrade. When the cast-in-place pipe pile 3 is located in the cast-in-place foundation hole and the upper surface of the cast-in-place pipe pile 3 is higher than the rated distance of the cast-in-place foundation hole, at this time, stop the pile press from working, then disconnect the pile press from the cast-in-place pipe pile 3, and then drive the limit settlement mechanism 4 inside the cast-in-place pipe pile 3, so that the limit settlement mechanism 4 can expand outward along the outer circumference of the cast-in-place pipe pile 3 and insert into the hole wall of the cast-in-place foundation hole. Then, fill the cast-in-place foundation hole with cushion materials such as sand and gravel, and then pour concrete into the cast-in-place foundation hole. Then, after the concrete solidifies in the cast-in-place foundation hole, it will fix the expanded and inserted limit settlement mechanism 4 in the cast-in-place foundation hole, thereby increasing the support area of the foundation pile 1 in the soft soil subgrade. At the same time, it can cooperate with the cast and solidified concrete to improve the hardening and supporting effect of the foundation pile 1 on the surface of the soft soil subgrade layer, thereby improving the safety support effect of the foundation pile 1 in the soft soil subgrade.

[0021] As an implementation manner of the present invention, the limit settlement mechanism 4 includes an elastic block 41, a first insertion bar 42, a second insertion bar 43, a pushing connecting rod 44, a first extrusion block 45, a second extrusion block 46 and a conical extrusion cylinder 47. A plurality of installation grooves 31 are circumferentially arranged on the outer circumferential surface of the cast pipe pile 3, and two adjacent installation grooves 31 are arranged in a vertically staggered manner. An elastic block 41 is fixed in each installation groove 31. A first insertion bar 42 is elastically hinged to the end surface of each of the plurality of elastic blocks 41 in the circumferential array located above. The plurality of first insertion bars 42 are circumferentially arranged obliquely downward on the outer circumferential surface of the cast pipe pile 3. A second insertion bar 43 is elastically hinged to the end surface of each of the plurality of elastic blocks 41 in the circumferential array located below. The plurality of second insertion bars 43 are circumferentially arranged obliquely upward on the outer circumferential surface of the cast pipe pile 3. The plurality of first insertion bars 42 and the plurality of second insertion bars 43 are arranged in a staggered manner. A plurality of sliding guide grooves 32 are circumferentially arranged on the cast pipe pile 3, and the sliding guide grooves 32 are located between two vertically symmetric installation grooves 31. A pushing connecting rod 44 is slidably inserted into each of the plurality of sliding guide grooves 32, and one end surfaces of the plurality of pushing connecting rods 44 are respectively hinged to the inner side surfaces of the plurality of first insertion bars 42 and the plurality of second insertion bars 43. A first extrusion block 45 is installed on the other end surface of the pushing connecting rod 44 connected to the first insertion bar 42. A second extrusion block 46 is installed on the other end surface of the pushing rod connected to the second insertion bar 43. The inner side surfaces of the plurality of first extrusion blocks 45 in the circumferential array are on the same inner circumferential surface. The inner side surfaces of the plurality of second extrusion blocks 46 in the circumferential array are on the same inner circumferential surface. A conical extrusion cylinder 47 is inserted into the cast pipe pile 3, and the conical extrusion cylinder 47 slides up and down in the grouting pipe pile through a sliding and pushing assembly to extrude the plurality of first extrusion blocks 45 and the second extrusion blocks 46, so that the first insertion bar 42 and the second insertion bar 43 are inserted into the inner circumferential wall of the cast foundation hole under the push of the pushing connecting rod 44;In the design of the present invention, after the cast-in-place pipe pile 3 is pressed into the cast-in-place foundation hole, a plurality of first inserting strips 42 inclined downward and second inserting strips 43 inclined upward need to be inserted into the inner circumferential wall of the cast-in-place foundation hole at this time. At this time, the construction workers need to drive the conical extrusion cylinder 47 to move downward in the cast-in-place pipe pile 3 through the sliding and pushing assembly. At this time, the downward-moving conical extrusion cylinder 47 will extrude a plurality of first extrusion blocks 45 and second extrusion blocks 46 arranged in a circumferential array in the cast-in-place pipe pile 3. Therefore, the plurality of first extrusion blocks 45 and second extrusion blocks 46 subjected to extrusion will move toward the inner circumferential surface of the cast-in-place pipe pile 3, and then drive the inclined first inserting strips 42 and second inserting strips 43 to expand in the cast-in-place foundation hole through the pushing connecting rod 44. Therefore, as the first inserting strips 42 and the second inserting strips 43 continuously expand along the angle of the hinged elastic blocks 41, the suspended ends of the first inserting strips 42 and the second inserting strips 43 will be continuously inserted into the hole wall of the cast-in-place foundation hole under the push of the pushing connecting rod 44. Since a plurality of first inserting strips 42 are inserted into the hole wall of the cast-in-place foundation hole inclined downward, and the suspended ends of a plurality of second inserting strips 43 are inserted into the hole wall of the cast-in-place foundation hole inclined upward, whether there is partial collapse or subsidence in the soft soil subgrade around the cast-in-place pipe pile 3, the mutual cooperation of the plurality of first inserting strips 42 and the second inserting strips 43 can play a triangular supporting role for the cast-in-place pipe pile 3, thereby increasing the stability and firmness of the installation and support of the cast-in-place pipe pile 3 in the cast-in-place foundation hole. Then, concrete is poured into the cast-in-place foundation hole, and after the concrete solidifies, it will fix the plurality of first inserting strips 42 and the second inserting strips 43, so that the foundation pile 1 can be safely supported on a large area on the soft soil subgrade, and thus will not affect the safe use of the soft soil subgrade.;

[0022] As an embodiment of the present invention, the sliding and pushing assembly includes a downward pressing rod 51, a guiding slide rod 52, a supporting disc 53, a supporting rod 54, a guiding slide cylinder 55 and a supporting spring 56. The downward pressing rod 51 is fixedly inserted into the conical extrusion cylinder 47, and a guiding slide rod 52 is fixed to the bottom end surface of the downward pressing rod 51. The connection between the settlement pile and the cast-in-place pipe pile 3 is fixedly supported by a plurality of supporting rods 54 with a supporting disc 53, and a guiding slide cylinder 55 is fixed to the upper surface of the supporting disc 53. The guiding slide rod 52 is slidably inserted into the guiding slide cylinder 55, and the lower end surface of the guiding slide rod 52 is rotationally connected to the bottom inside of the guiding slide cylinder 55 through the supporting spring 56. The outer circumferential surface of the bottom end of the guiding slide rod 52 is in the shape of a threaded rod, and a threaded groove hole is provided inside the bottom end of the guiding slide cylinder 55. The top surface of the downward pressing rod 51 is higher than the upper surface of the conical extrusion cylinder 47. In the design of the present invention, when it is necessary for the conical extrusion cylinder 47 to move downward in the cast-in-place pipe pile 3, at this time, the construction worker needs to connect the handheld hydraulic cylinder to the top surface of the downward pressing rod 51, and then activate the hydraulic cylinder, so that the piston rod of the hydraulic cylinder extends to push the downward pressing rod 51 to move downward. Furthermore, the downward pressing rod 51 will drive the conical extrusion cylinder 47 to move downward in the cast-in-place pipe pile 3. Therefore, the conical extrusion cylinder 47 will extrude a plurality of first extrusion blocks 45 and second extrusion blocks 46 arranged in a circumferential array. When the conical extrusion cylinder 47 moves downward, at this time, the guiding slide rod 52 will move downward in the guiding slide cylinder 55, and the supporting spring 56 inside the guiding slide cylinder 55 will be compressed, and the supporting disc 53 will support the guiding slide cylinder 55. When the threaded rod at the bottom end of the guiding slide rod 52 contacts the threaded groove, at this time, the piston rod of the hydraulic cylinder will not extend any further. Then the construction worker can rotate the hydraulic cylinder, so that it drives the guiding slide rod 52 to rotate through the downward pressing rod 51. Furthermore, the threaded rod at the bottom end of the downward pressing rod 51 will be threadedly connected to the threaded groove hole at the bottom end of the guiding slide cylinder 55, which is convenient for fixing the downward moving conical extrusion cylinder 47. At this time, the first insert 42 and the second insert 43 expand to the limit position under the push of the push rod, which is convenient for inserting the suspended end faces of the first insert 42 and the second insert 43 into the hole wall of the cast-in-place foundation hole. Then the construction worker disconnects the piston rod of the hydraulic cylinder from the end face of the downward pressing rod 51, which is convenient for the limit settlement mechanism 4 to safely and stably support the foundation pile 1 in the soft soil subgrade.

[0023] As an embodiment of the present invention, expansion cavities 421 are formed in both the first insert 42 and the second insert 43, and bentonite particles are filled in the expansion cavities 421. A plurality of convex tumor holes 422 are formed on the outer side surface of the expansion cavity 421. In the design of the present invention, since the expansion of the first insert 42 and the second insert 43 is partially inserted into the hole wall of the casting base hole, and the part close to the casting pipe pile 3 is exposed in the casting base hole. When the construction worker pours the concrete slurry into the casting base hole, at this time, part of the concrete slurry will enter the expansion cavity 421 through the convex tumor holes 422. When the bentonite particles encounter the concrete slurry, they will expand in the expansion cavity 421. At the same time, part of the expanded bentonite particles will be squeezed into the hole wall of the casting base hole through the convex tumor holes 422 on the inserted first insert 42 and second insert 43, so that the inserted first insert 42 and second insert 43 can be inserted into the soft soil subgrade in a root-like convex tumor shape, thereby improving the stable support effect of the plurality of first inserts 42 and second inserts 43 on the pressed-in foundation pile 1, and thus improving the safety of the foundation pile 1 in the soft soil subgrade support.

[0024] As an embodiment of the present invention, a burr bent bar 6 is arranged in each convex tumor hole 422, and one end surface of the burr bent bar 6 is fixedly connected to the cavity wall of the expansion cavity 421. The other end surface of the burr bent bar 6 extends out of the convex tumor hole 422, and the size of the burr bent bar 6 is smaller than the size of the convex tumor hole 422. In the design of the present invention, when the first insert 42 and the second insert 43 are respectively inserted into the hole wall of the casting base hole, at this time, the burr bent bars 6 arranged on the first insert 42 and the second insert 43 will be synchronously inserted into the hole wall, thereby increasing the contact area of the first insert 42 and the second insert 43 in the hole wall. At the same time, the concrete slurry leaking out of the convex tumor holes 422 and the expanded bentonite particles will improve the firmness and stability of the burr bent bars 6 inserted in the hole wall, thereby further improving the support effect of the first insert 42 and the second insert 43 on the foundation pile 1.

[0025] As an embodiment of the present invention, the diameter of the inner circumferential surface formed by the plurality of the first extrusion blocks 45 in the circumferential array is smaller than the diameter of the inner circumferential surface formed by the plurality of the second extrusion blocks 46 in the circumferential array; designed by the present invention, the distance from the first extrusion block 45 designed by the present invention to the inner circumferential surface of the cast-in-place pipe pile 3 is greater than the distance from the second extrusion block 46 to the inner circumferential surface of the cast-in-place pipe pile 3. Then, when the conical extrusion cylinder 47 slides downward in the cast-in-place pipe pile 3, at this time, the conical extrusion cylinder 47 will first contact the plurality of the first extrusion blocks 45 in the circumferential array. Then, the first extrusion block 45 will drive the first insert 42 to expand outward and insert into the hole wall of the cast-in-place foundation hole by pushing the connecting rod 44. As the conical extrusion cylinder 47 continues to move downward, at this time, it contacts the second extrusion block 46, so that the second insert 43 is inserted into the hole wall of the cast-in-place foundation hole later. Then, after the plurality of the first inserts 42 and the plurality of the second inserts 43 are inserted into the hole wall, they are not on the same circumferential surface, so that the insertion support area of the first insert 42 and the second insert 43 in the hole wall of the cast-in-place foundation hole can be further increased, and the support stability of the foundation pile 1 designed by the present invention in the soft soil subgrade can be further improved.

[0026] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A pile foundation construction device for soft soil subgrade treatment, comprising a pile press and a foundation pile (1), characterized in that, The foundation pile (1) includes a settlement pile (2) and a cast-in-place pipe pile (3). The settlement pile (2) is fixedly welded to the lower end surface of the cast-in-place pipe pile (3), and the settlement pile (2) is pressed into the soft soil subgrade by a pile press. The cast-in-place pipe pile (3) is exposed in a cast-in-place foundation hole opened on the surface of the soft soil subgrade. A limit settlement mechanism (4) is arranged on the cast-in-place pipe pile (3). The limit settlement mechanism (4) is used to limit the settlement of the foundation pile (1) pressed into the soft soil subgrade, thereby improving the stability of the foundation pile (1) when used in the soft soil subgrade; The limit settlement mechanism (4) includes an elastic block (41), a first insertion bar (42), a second insertion bar (43), a push connecting rod (44), a first extrusion block (45), a second extrusion block (46) and a conical extrusion cylinder (47). A plurality of installation grooves (31) are circumferentially arranged on the outer circumferential surface of the cast-in-place pipe pile (3), and two adjacent installation grooves (31) are arranged in a vertical offset manner. An elastic block (41) is fixed in each installation groove (31). The end surfaces of a plurality of elastic blocks (41) arranged in a circumferential array above are elastically hinged with first insertion bars (42). A plurality of first insertion bars (42) are arranged in a circumferential array on the outer circumferential surface of the cast-in-place pipe pile (3) in an inclined downward manner. The end surfaces of a plurality of elastic blocks (41) arranged in a circumferential array below are elastically hinged with second insertion bars (43). A plurality of second insertion bars (43) are arranged in a circumferential array on the outer circumferential surface of the cast-in-place pipe pile (3) in an inclined upward manner. A plurality of first insertion bars (42) and a plurality of second insertion bars (43) are arranged in a staggered manner. A plurality of sliding guide grooves (32) are circumferentially arranged on the cast-in-place pipe pile (3), and the sliding guide grooves (32) are located between two vertically symmetric installation grooves (31). A push connecting rod (44) is slidably inserted into each of the plurality of sliding guide grooves (32), and one end surfaces of a plurality of push connecting rods (44) are respectively hinged to the inner side surfaces of a plurality of first insertion bars (42) and a plurality of second insertion bars (43). The other end surface of the push connecting rod (44) connected to the first insertion bar (42) is provided with a first extrusion block (45), and the other end surface of the push rod connected to the second insertion bar (43) is provided with a second extrusion block (46). The inner side surfaces of a plurality of first extrusion blocks (45) arranged in a circumferential array are on the same inner circumferential surface, and the inner side surfaces of a plurality of second extrusion blocks (46) arranged in a circumferential array are on the same inner circumferential surface. A conical extrusion cylinder (47) is inserted into the cast-in-place pipe pile (3), and the conical extrusion cylinder (47) slides up and down in the grouting pipe pile through a sliding and pushing assembly (5) to extrude a plurality of first extrusion blocks (45) and second extrusion blocks (46), facilitating the insertion of the first insertion bar (42) and the second insertion bar (43) into the inner circumferential wall of the cast-in-place foundation hole under the push of the push connecting rod (44); An expansion cavity (421) is arranged in each of the first insertion bar (42) and the second insertion bar (43), and bentonite particles are filled in the expansion cavity (421). A plurality of convex tumor holes (422) are arranged on the outer side surface of the expansion cavity (421); A burr bent bar (6) is arranged in each convex tumor hole (422), and one end face of the burr bent bar (6) is fixedly connected to the cavity wall of the expansion cavity (421). The other end face of the burr bent bar (6) extends out of the convex tumor hole (422), and the size of the burr bent bar (6) is smaller than the size of the convex tumor hole (422).

2. The pile foundation construction device for soft soil subgrade treatment according to claim 1, wherein: The sliding and pushing assembly (5) includes a pressing rod (51), a guiding slide bar (52), a supporting disc (53), a supporting rod (54), a guiding slide cylinder (55) and a supporting spring (56). The pressing rod (51) is fixedly inserted into the conical extrusion cylinder (47), and a guiding slide bar (52) is fixed to the bottom end face of the pressing rod (51). The connection part between the settlement pile and the cast-in-place pipe pile (3) is fixedly supported by a plurality of supporting rods (54) with a supporting disc (53), and a guiding slide cylinder (55) is fixed to the upper surface of the supporting disc (53). The guiding slide bar (52) is slidably inserted into the guiding slide cylinder (55), and the lower end face of the guiding slide bar (52) is rotationally connected to the bottom inside of the guiding slide cylinder (55) through the supporting spring (56). The outer peripheral surface of the bottom end of the guiding slide bar (52) is in the shape of a threaded rod, and a threaded groove hole is formed in the bottom inside of the guiding slide cylinder (55). The top end face of the pressing rod (51) is higher than the upper surface of the conical extrusion cylinder (47).

3. A pile foundation construction device for soft soil subgrade treatment according to claim 1, characterized in that: The diameter of the inner circumferential surface formed by the plurality of first extrusion blocks (45) arranged in a circumferential array is smaller than the diameter of the inner circumferential surface formed by the plurality of second extrusion blocks (46) arranged in a circumferential array.

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