A soft cover end bearing rock-socketed pile forming system and construction method

Abstract

The application provides a soft cover layer end bearing rock-embedded pile forming system and a construction method, the soft cover layer end bearing rock-embedded pile forming system comprises a thick soft clay cover layer retaining and water stopping curtain body, a strong weathered rock stratum rock wall supporting ring wall body and a medium weathered rock stratum bottom expansion cavity body; firstly, a group construction micro-inclined SMW method pile ring, a reinforced concrete pile top ring beam and a soft clay partition excavation are used to form the thick soft clay cover layer retaining and water stopping curtain body in the thick soft clay cover layer; then, the strong weathered rock stratum is excavated and constructed to form the strong weathered rock stratum rock wall supporting ring wall body; then, the medium weathered rock stratum is excavated and constructed to form the weathered rock stratum bottom expansion cavity body; finally, the bottom virtual soil is cleaned, a steel reinforcement cage is placed and concrete is poured to form a pile. The thick soft clay cover layer retaining and water stopping curtain body is formed by using multiple groups of micro-inclined SMW method pile rings and multiple groups of reinforced concrete ring beams, the pile hole wall is effectively formed, the water stopping effect is good, and the negative friction resistance after pile forming is avoided.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of pile foundation construction, and particularly relates to a soft overburden end-bearing rock-socketed pile forming system and a construction method. BACKGROUND

[0002] Pile foundation is a long-standing construction method, and its image can be seen everywhere in the long history of Chinese architecture. A perfect system has been formed through long-term development. In pile foundation engineering, different pile types have different characteristics to adapt to the requirements of different environments as the pile foundation develops continuously. According to the stress conditions in the soil, the pile foundation can be divided into end-bearing piles and friction piles. The end-bearing pile is a pile that penetrates through the soft soil layer to reach the deep and solid rock layer, and the upper structure load is mainly borne by the pile tip resistance. The friction pile is a pile that is completely set in the soft soil layer to a certain depth, and the upper structure load is borne by the pile tip resistance and the friction between the pile body side and the soil. The rock-socketed pile is a special type of end-bearing or friction end-bearing pile, and the lower end is embedded in the moderately weathered, slightly weathered or fresh bedrock. The axial ultimate bearing capacity standard value is composed of the total side resistance of the soil around the pile, the total side resistance of the rock-socketed section and the total end resistance. The large-diameter rock-socketed pile has the advantages of simple construction, large diameter, deep soil penetration and high bearing capacity, and is now widely used in the construction industry, such as in the foundation of high-rise, super high-rise buildings, bridges, port engineering and heavy structures, which has brought about a rapid development of the construction industry.

[0003] The traditional pile foundation construction method usually adopts a casing and mud slurry protection wall for excavation construction. China has a vast territory and complex geological conditions. Under the condition that the geological soil layer is thick soft clay overburden, strongly weathered rock layer, moderately weathered rock layer and slightly / unweathered rock layer from top to bottom, the pile foundation is often long and will generate negative friction. In this case, waterproofing and anti-collapsing hole enclosure need to be done during construction, and the traditional pile foundation construction method cannot be used.

[0004] Therefore, it is very important to seek a thick soft overburden end-bearing rock-socketed pile forming system and construction method with reasonable structure, which solves the problems of large-diameter soft overburden hole forming and force transmission, and has good bearing capacity. SUMMARY

[0005] The first object of the present application is to provide a soft overburden end-bearing rock-socketed pile forming system to solve the problems in the prior art.

[0006] To this end, the above object of the present application is achieved by the following technical solutions:

[0007] A soft overburden end-bearing rock-socketed pile forming system, characterized in that the soft overburden end-bearing rock-socketed pile forming system comprises, from top to bottom, a plurality of groups of thick soft clay overburden retaining and waterproof curtain bodies, a strong weathered rock stratum rock wall support ring wall body, and a medium weathered rock stratum bottom expansion cavity body.

[0008] The thick soft clay overburden retaining and waterproof curtain body comprises a pile top ring beam, a transfer beam, a load-bearing ground ring beam, a slightly inclined SMW method pile ring, and a transfer column, the slightly inclined SMW method pile ring is arranged around the pile hole, a plurality of groups of slightly inclined SMW method pile rings are arranged in a nested manner from top to bottom, the top of the slightly inclined SMW method pile ring in the lower one of the two adjacent groups of slightly inclined SMW method pile rings is embedded into the bottom of the slightly inclined SMW method pile ring in the upper one of the two adjacent groups of slightly inclined SMW method pile rings, the pile top ring beam is arranged at the top of the slightly inclined SMW method pile ring, the load-bearing ground ring beam is arranged at the periphery of the pile top ring beam at the ground, the transfer beam connects the pile top ring beam and the load-bearing ground ring beam at the ground, and the transfer column is arranged between the upper and lower adjacent pile top ring beams and the upper and lower ends of the transfer column are connected to the upper and lower pile top ring beams, respectively.

[0009] The strong weathered rock stratum rock wall support ring wall body comprises an anchor rod, a side wall hanging net, and a sprayed concrete layer, the anchor rod is obliquely driven into the rock wall of the strong weathered rock stratum, the side wall hanging net is arranged at the end of the anchor rod in the pile hole, the sprayed concrete layer is arranged outside the side wall hanging net, and a wall top ring beam is arranged at the top of the strong weathered rock stratum rock wall support ring wall body.

[0010] In addition to the above technical solutions, the present application can also adopt or combine the following technical solutions:

[0011] As a preferred technical solution of the present application, the width of the pile top ring beam exceeds the thickness of the top of the slightly inclined SMW method pile ring.

[0012] As a preferred technical solution of the present application, the part of the pile top ring beam that exceeds the top of the slightly inclined SMW method pile ring is provided with a pre-embedded steel plate, and the pre-embedded steel plate is used to connect the transfer column.

[0013] As a preferred technical solution of the present application, the two ends of the transfer column are provided with flange plates, and the transfer column is fixed to the pile top ring beam through the flange plates, bolts, and the pre-embedded steel plate on the pile top ring beam.

[0014] As a preferred technical solution of the present application, the medium weathered rock stratum bottom expansion cavity body is a circular truncated cone, and the medium weathered rock stratum bottom expansion cavity body is arranged at the bottom of the pile hole.

[0015] As a preferred technical solution of the present application, the medium weathered rock stratum expansion cavity body has a vertical cavity body penetrating through the top and the bottom, and the vertical cavity body forms a non-equal-length drill hole to the side wall of the medium weathered rock stratum expansion cavity body.

[0016] As a preferred technical scheme of the present application: the length of the drill hole gradually increases from the top of the medium weathered rock layer to the bottom.

[0017] As a preferred technical scheme of the present application: the bottom expansion cavity of the medium weathered rock layer is an isosceles circular table.

[0018] As a preferred technical scheme of the present application: the slightly inclined SMW method pile ring is composed of cement-soil mixture units and H-shaped steel, the cement-soil mixture units are overlapped and lapped with each other and surround the pile hole, the bottom of the cement-soil mixture unit is slightly inclined outward compared with the top, and an H-shaped steel is arranged in each cement-soil mixture unit.

[0019] The present application also has the purpose of providing a construction method of a soft overburden end-bearing rock-socketed pile forming system to overcome the shortcomings of the prior art.

[0020] To this end, the above-mentioned purposes of the present application are achieved by the following technical scheme:

[0021] According to the construction method of the soft overburden end-bearing rock-socketed pile forming system described above, characterized in that: the construction method comprises the following steps:

[0022] S1, construction of the first group of thick soft clay overburden retaining and waterproof curtain

[0023] S101, around the pile hole, a triaxial type drilling and mixing machine is used to drill and mix to a certain depth with slight outward inclination, and a cement-based reinforcing agent is sprayed at the drill bit to repeatedly mix and stir with the thick soft clay overburden soil to form cement-soil mixture units, the cement-soil mixture units are overlapped and lapped with each other, then an H-shaped steel is inserted before the cement-soil mixture units harden, until the cement hardens, forming the first group of slightly inclined SMW method pile ring;

[0024] S102, welding and binding the steel bars of the pile top ring beam at the top of the first group of slightly inclined SMW method pile ring, installing a pre-embedded steel plate at the bottom of the pile top ring beam when binding the steel bars of the pile top ring beam, then pouring the first group of reinforced concrete pile top ring beam, transfer beam and bearing ground ring beam to form the first group of thick soft clay overburden retaining and waterproof curtain;

[0025] S2, excavate the first soft clay excavation area: use a hydraulic grab combined with manual labor to excavate the soft clay in the first group of thick soft clay overburden retaining and waterproof curtain to a certain distance from the bottom of the first group of thick soft clay overburden retaining and waterproof curtain;

[0026] S3, fill a certain thickness of gravel layer at the bottom of the first soft clay excavation area, facilitate the construction equipment to enter the pile hole to carry out the construction of the second group of slightly inclined SMW method pile ring and the second group of reinforced concrete pile top ring beam, install embedded steel plates at the top and bottom of the second group of pile top ring beam respectively when binding the second group of pile top ring beam reinforcement, and form the second group of thick soft clay covering layer supporting and waterproof curtain body after pouring;

[0027] S4, excavate the second soft clay excavation area: before excavation, install multiple force transmission columns between the upper and lower adjacent two pile top ring beams, then use hydraulic grabber to cooperate with manual work to excavate and pile the filled gravel layer near the pile hole for the next bottom filling of the excavation area, and excavate the soft clay body in the second group of thick soft clay covering layer supporting and waterproof curtain body to a certain distance from the bottom of the second group of thick soft clay covering layer supporting and waterproof curtain body;

[0028] S5, repeat the above steps to form the third group, fourth group, …, and nth group of thick soft clay covering layer supporting and waterproof curtain body in turn, until the bottom of the thick soft clay covering layer, thereby forming the overall thick soft clay covering layer supporting and waterproof curtain body;

[0029] S6, excavate the last soft clay excavation area: before excavation, install multiple force transmission columns between the upper and lower adjacent two pile top ring beams, then use hydraulic grabber to cooperate with manual work to excavate and transport away the filled gravel layer, and excavate the soft clay body in the last group of thick soft clay covering layer supporting and waterproof curtain body to the top of the strongly weathered rock layer;

[0030] S7, carry out the ring-shaped drill construction of the down-the-hole hammer in the circumferential circle of the pile hole at the top of the strongly weathered rock layer; after the ring-shaped drill construction is completed, carry out the vertical drilling blasting and strongly weathered rock layer block excavation construction in the strongly weathered rock layer in the middle of the pile hole;

[0031] S8, drill anchor rods in the sidewall of the pile hole in the strongly weathered rock layer, then install sidewall hanging nets at the end of the anchor rods in the pile hole, and then spray concrete to form the strongly weathered rock wall supporting ring wall body, the end of the anchor rod in the pile hole exceeds the thickness of the strongly weathered rock wall supporting ring wall body by a certain distance, which facilitates the pouring of the end bearing pile concrete in the later stage, enhances the integrity of the strongly weathered rock wall supporting ring wall body and the pile body, at the same time, the strongly weathered rock wall supporting ring wall body and the thick soft clay covering layer supporting and waterproof curtain body form partial overlap, and the wall top ring beam is constructed at the top of the strongly weathered rock wall supporting ring wall body to enhance the integrity and waterproof capacity;

[0032] S9, a pile hole around the top of the weathered rock layer is drilled by a down-the-hole hammer, and a vertical cavity capable of lateral drilling is formed by drilling to the top of the slightly weathered rock layer; a vertical cavity is formed by drilling on the side wall of the vertical cavity, and then a blast hole of different lengths is formed, and then the blast hole is blasted and the slightly weathered rock layer is removed to form a bottom expansion cavity of the slightly weathered rock layer;

[0033] S10, the bottom virtual soil is cleaned, the steel reinforcement cage is placed in the pile hole from top to bottom, and the concrete is poured to form a pile, and the construction of the soft overburden end-bearing rock-embedded pile forming system is completed.

[0034] The present application provides a soft overburden end-bearing rock-embedded pile forming system and a construction method, which comprises a thick soft clay overburden retaining and waterproof curtain body, a strong weathered rock wall supporting ring wall body and a slightly weathered rock layer bottom expansion cavity.

[0035] The present application is particularly suitable for the construction of an end-bearing rock-embedded pile pier in a thick soft clay overburden with a super large diameter, and is particularly suitable for the construction of an end-bearing rock-embedded pile pier in a thick soft clay overburden with a diameter greater than 5m or more.

[0036] The present application provides a soft overburden end-bearing rock-embedded pile forming system and a construction method, which has the following beneficial effects:

[0037] 1) Compared with the traditional technology, the present application uses multiple groups of slightly inclined SMW method pile rings and multiple groups of reinforced concrete ring beams to form a thick soft clay overburden retaining and waterproof curtain body, which effectively forms a pile hole wall, has good waterproof effect, and avoids negative friction after pile forming.

[0038] 2) The present application uses down-the-hole hammer ring drilling + middle vertical drilling and blasting + side wall anchor rod setting, side wall net hanging and shotcrete to form a strong weathered rock wall supporting ring wall body, which is reasonable in structure, fast in construction, effectively strengthens the strength and integrity of the strong weathered rock layer around the pile hole, and prevents hole collapse.

[0039] 3) The present application uses down-the-hole hammer middle drilling + lateral unequal length drilling and blasting to form a slightly weathered rock layer bottom expansion cavity, which has a fast hole forming speed and does not affect the stability of the surrounding rock mass.

[0040] 4), The present application sets ground pile top ring beam, force transmission beam, bearing ground ring beam and force transmission column, forms load reduction system, effectively transfers thick soft clay covering layer retaining water curtain body and other construction load to ground, reduces load on various strata, prevents hole collapse, and ensures safe and smooth construction. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 The cross section schematic view of the soft covering layer end bearing rock-socketed pile forming system provided by the present application;

[0042] Figure 2 The schematic view of the first group of thick soft clay covering layer retaining water curtain body;

[0043] Figure 3 The layout schematic view of the ground pile top ring beam, force transmission beam and bearing ground ring beam;

[0044] Figure 4 The top view of the slightly inclined SMW method pile ring;

[0045] Figure 5 The schematic view of the first soft clay excavation area;

[0046] Figure 6 The schematic view of the second group of thick soft clay covering layer retaining water curtain body;

[0047] Figure 7 The installation layout of the force transmission column;

[0048] Figure 8 The connection detail view of the force transmission column and the pile top ring beam;

[0049] Figure 9 The schematic view of the overall thick soft clay covering layer retaining water curtain body;

[0050] Figure 10 The structural layout of the strong weathered rock stratum rock wall support ring wall body;

[0051] Figure 11 The construction layout of the medium weathered rock stratum bottom expansion cavity;

[0052] Figure 12 The schematic view of the pile hole forming;

[0053] Figure 13 The construction method flow chart of the soft covering layer end bearing rock-socketed pile forming system;

[0054] In the figure: 1-thick soft clay covering layer retaining and waterproof curtain body; 2-strongly weathered rock wall supporting ring wall body; 3-mid-weathered rock layer bottom expansion cavity; 4-micro / unweathered rock layer; 5-pile hole; 6-pile top ring beam; 7-force transmission beam; 8-bearing ground ring beam; 9-micro-inclined SMW method pile ring; 10-force transmission column; 11-anchor rod; 12-side wall hanging net; 13-sprayed concrete layer; 14-cement-soil mixture unit; 15-H-shaped steel; 16-flange plate; 17-pre-embedded steel plate; 18-bolt; 19-wall top ring beam; 20-vertical cavity; 21-unequal-length blast hole; 22-reinforcing cage; 23-concrete; 24-thick soft clay covering layer; 25-strongly weathered rock layer; 26-mid-weathered rock layer; 27-first soft clay excavation area; 28-gravel layer. DETAILED DESCRIPTION

[0055] The technical solutions of the present application will be described in detail below with reference to the accompanying drawings, as Figures 1 to 13 The technical solutions of the present application will be described in detail below with reference to the accompanying drawings, as

[0056] A soft covering layer end-bearing rock-embedded pile forming system, comprising a plurality of thick soft clay covering layer retaining and waterproof curtain bodies 1, strongly weathered rock wall supporting ring wall bodies 2 and mid-weathered rock layer bottom expansion cavities 3.

[0057] The thick soft clay covering layer retaining and waterproof curtain body 1 comprises a pile top ring beam 6, a force transmission beam 7, a bearing ground ring beam 8, a micro-inclined SMW method pile ring 9 and a force transmission column 10. The micro-inclined SMW method pile ring 9 is arranged around the pile hole 5, the pile top ring beam 6 is arranged on the top of the micro-inclined SMW method pile ring 9, the bearing ground ring beam 8 is arranged on the periphery of the pile top ring beam 6 at the ground surface, the force transmission beam 7 connects the pile top ring beam 6 and the bearing ground ring beam 8 at the ground surface, and the force transmission column 10 is arranged between two adjacent pile top ring beams 6.

[0058] The width of the pile top ring beam 6 exceeds the thickness of the micro-inclined SMW method pile ring 9, and the excess part is provided with a pre-embedded steel plate 17. The force transmission column 10 is provided with a flange plate 16 at both ends, and is fastened and connected with the pile top ring beam 6 through the bolt 18 and the pre-embedded steel plate 17 on the pile top ring beam 6.

[0059] The mid-weathered rock layer bottom expansion cavity 3 is an isosceles circular truncated cone, and is arranged at the bottom of the pile hole 5.

[0060] The micro-inclined SMW method pile ring 9 is composed of a cement-soil mixture unit 14 and an H-shaped steel 15. The cement-soil mixture unit 14 is arranged around the pile hole 5, overlaps and laps each other and is slightly outwardly inclined at the bottom, and the H-shaped steel 15 is arranged in the cement-soil mixture unit 14.

[0061] The construction method of the soft cover layer end bearing rock-socketed pile forming system comprises the following steps:

[0062] S1, construction of the first group of thick soft clay cover layer retaining and waterproof curtain body

[0063] S101, around the position of the pile hole 5, a triaxial type drilling and mixing machine is used to drill and mix slightly outwardly at a certain depth, while a cement-based reinforcing agent is sprayed at the drill bit to repeatedly mix and stir the thick soft clay cover layer 24 soil body to form a cement-soil mixture unit 14, the cement-soil mixture units 14 are overlapped and connected, and then the H-shaped steel 15 is inserted before the cement-soil mixture unit 14 is hardened, until the cement is hardened to form the first group of slightly inclined SMW method pile rings 9;

[0064] S102, welding and binding steel bars at the top of the first group of slightly inclined SMW method pile rings 9, installing embedded steel plates 17 at the bottom when binding the ring beam steel bars, and then pouring and constructing the first group of reinforced concrete pile top ring beams 6, transfer beams 7 and bearing ground ring beams 8 to form the first group of thick soft clay cover layer retaining and waterproof curtain bodies 1;

[0065] S2, excavating the first soft clay excavation area 27: using a hydraulic grab bucket combined with manual work to excavate the soft clay body in the first group of thick soft clay cover layer retaining and waterproof curtain bodies 1 to a certain distance from the bottom of the first group of thick soft clay cover layer retaining and waterproof curtain bodies 1;

[0066] S3, laying a certain thickness of gravel layer 28 at the bottom of the first soft clay excavation area 27 to facilitate the construction equipment to enter the pile hole 5 for the construction of the second group of slightly inclined SMW method pile rings 9 and the second group of reinforced concrete pile top ring beams 6, installing embedded steel plates 17 at the top and bottom of the ring beam when binding the second group of ring beam steel bars, and forming the second group of thick soft clay cover layer retaining and waterproof curtain bodies 1 after pouring;

[0067] S4, excavating the second soft clay excavation area: before excavation, a plurality of transfer columns 10 are installed by bolting between the upper and lower ring beams, then the laid gravel layer 28 is excavated separately and piled near the pile hole 5 for the next bottom laying, and the soft clay body in the second group of thick soft clay cover layer retaining and waterproof curtain bodies 1 is excavated to a certain distance from the bottom of the second group of thick soft clay cover layer retaining and waterproof curtain bodies 1;

[0068] S5, repeating the above steps to form the third group, the fourth group, the nth group of thick soft clay cover layer retaining and waterproof curtain bodies 1 in turn, until the bottom of the thick soft clay cover layer, thereby forming the overall thick soft clay cover layer retaining and waterproof curtain body 1;

[0069] S6, excavate the last soft clay excavation area: before excavation, install multiple force transmission columns 10 between the upper and lower ring beams, then use hydraulic grab buckets to manually excavate and remove the crushed stone layer 28, and excavate the soft clay in the last group of thick soft clay covering layer within the retaining and waterproof curtain body 1, to the top of the strongly weathered rock layer 25;

[0070] S7, perform ring-shaped drill pile construction on the circumference of the pile hole 5 at the top of the strongly weathered rock layer 25; after the ring-shaped drill pile construction is completed, perform vertical drilling and blasting and strongly weathered rock block removal construction in the strongly weathered rock layer 25 in the middle of the pile hole 5;

[0071] S8, drill and install anchor rods 11 on the sidewall of the pile hole 5 in the strongly weathered rock layer 25, then install sidewall hanging nets 12 at the end of the anchor rods 11, and then spray concrete to form a strongly weathered rock wall supporting ring wall body 2, the end of the anchor rod 11 extends a certain distance beyond the wall thickness, which facilitates the pouring of the end-bearing pile concrete 23 in the later stage, enhances the integrity of the strongly weathered rock wall supporting ring wall body and the pile body, at the same time, the wall body partially overlaps with the thick soft clay covering layer retaining and waterproof curtain body 1, and a wall top ring beam 19 is constructed at the top of the wall body to enhance the overall integrity and waterproof capacity;

[0072] S9, perform middle drill pile construction on the circumference of the pile hole 5 at the top of the moderately weathered rock layer 26, drill to the top of the slightly / unweathered rock layer 4 to form a vertical cavity 20 that can be drilled laterally, drill holes on the sidewall of the vertical cavity 20 to form unequal-length blast holes 21, then perform blasting and moderately weathered rock block removal to form a moderately weathered rock layer bottom expansion cavity 3;

[0073] S10, clean the virtual soil at the bottom of the moderately weathered rock layer bottom expansion cavity 3, place a steel reinforcement cage 22 and pour concrete 23 into the pile hole from top to bottom to form a pile, and complete the construction of the soft covering layer end-bearing rock-embedded pile system.

[0074] The above specific embodiments are used to explain and illustrate the present application, and are only preferred embodiments of the present application, but not a limitation on the present application, any modification, equivalent replacement, improvement, etc. made to the present application within the spirit of the present application and the protection scope of the claims, falls within the protection scope of the present application.

Claims

1. A soft overburden end-bearing rock-socketed pile-forming system, characterized by: The soft overburden end-bearing rock-socketed pile forming system comprises, from top to bottom, a plurality of groups of thick soft clay overburden retaining and waterproof curtain bodies, a strong weathered rock stratum rock wall supporting ring wall body, and a medium weathered rock stratum bottom expansion cavity body. The thick soft clay overburden retaining and waterproof curtain body comprises a pile top ring beam, a transfer beam, a bearing ground ring beam, a slightly inclined SMW method pile ring, and a transfer column, the slightly inclined SMW method pile ring is arranged around the pile hole, a plurality of groups of slightly inclined SMW method pile rings are arranged in a nested manner from top to bottom, the top of the slightly inclined SMW method pile ring in the lower one of the two adjacent groups of slightly inclined SMW method pile rings is embedded into the bottom of the slightly inclined SMW method pile ring in the upper one of the two adjacent groups of slightly inclined SMW method pile rings, the pile top ring beam is arranged at the top of the slightly inclined SMW method pile ring, the bearing ground ring beam is arranged at the periphery of the pile top ring beam on the ground, the transfer beam connects the pile top ring beam and the bearing ground ring beam on the ground, and the transfer column is arranged between the upper and lower pile top ring beams and the upper and lower ends of the transfer column are connected to the upper and lower pile top ring beams, respectively. The strong weathered rock stratum rock wall supporting ring wall body comprises an anchor rod, a side wall hanging net, and a sprayed concrete layer, the anchor rod is obliquely punched into the rock wall of the strong weathered rock stratum, the side wall hanging net is arranged at the end of the anchor rod in the pile hole, the sprayed concrete layer is arranged outside the side wall hanging net, and a wall top ring beam is arranged at the top of the strong weathered rock stratum rock wall supporting ring wall body. The width of the pile top ring beam exceeds the thickness of the top of the slightly inclined SMW method pile ring. The medium weathered rock stratum bottom expansion cavity body is a circular truncated cone, and is arranged at the bottom of the pile hole.

2. The soft cover end-bearing socketed pile piling system according to claim 1, wherein: The part of the pile top ring beam that exceeds the top of the slightly inclined SMW method pile ring is provided with a pre-embedded steel plate, and the pre-embedded steel plate is used to connect the transfer column.

3. The soft cover tip end-bearing socketed pile piling system according to claim 2, wherein: The transfer column is fixed to the pile top ring beam through flange plates, bolts, and the pre-embedded steel plate on the pile top ring beam.

4. The soft cover end-bearing socketed pile system of claim 1, wherein: The medium weathered rock stratum expansion cavity body has a vertical cavity that penetrates the top and the bottom, and the vertical cavity forms a non-equal-length drill hole to the side wall of the medium weathered rock stratum expansion cavity body.

5. The soft cover tip end-bearing socketed pile piling system according to claim 4, wherein: The length of the drill hole gradually increases from the top of the medium weathered rock stratum expansion cavity body downward.

6. The soft cover tip end-bearing socketed pile pile-forming system according to claim 1, wherein: The medium weathered rock stratum bottom expansion cavity body is an isosceles circular truncated cone.

7. The soft cover tip end-bearing socketed pile pile-forming system according to claim 1, wherein: The slightly inclined SMW method pile ring is composed of cement-soil mixture units and H-shaped steel, the cement-soil mixture units are overlapped and jointed with each other and surround the pile hole, the bottom of each cement-soil mixture unit is slightly inclined outward relative to the top, and one H-shaped steel is arranged in each cement-soil mixture unit.

8. The method of construction of the soft cover end-bearing socketed pile system according to claim 1, characterized in that: The construction method comprises the following steps: S1, construction of the first group of thick soft clay overburden retaining and waterproof curtain bodies S101, around the pile hole, a cement-soil mixture unit is formed by slightly inclining a triaxial type drilling and mixing machine on site to a certain depth while spraying a cement-based reinforcing agent into the soil of the thick soft clay overburden to repeatedly mix and stir the cement-soil mixture unit, the cement-soil mixture units are overlapped and jointed with each other, then an H-shaped steel is inserted into each cement-soil mixture unit before the cement-soil mixture unit hardens, and the first group of slightly inclined SMW method pile rings are formed after the cement hardens. S102, welding the reinforcement of the pile top ring beam on the top of the first group of slightly inclined SMW method pile rings, installing embedded steel plates at the bottom of the pile top ring beam when binding the reinforcement of the pile top ring beam, and then pouring the first group of reinforced concrete pile top ring beams, force transmission beams and bearing ground ring beams to form the first group of thick soft clay covering layer retaining and waterproof curtain body; S2, excavating the first soft clay excavation area: using hydraulic grab combined with manual work to excavate the soft clay body in the first group of thick soft clay covering layer retaining and waterproof curtain body to a certain distance from the bottom of the first group of thick soft clay covering layer retaining and waterproof curtain body; S3, laying a certain thickness of gravel layer at the bottom of the first soft clay excavation area to facilitate the construction equipment to enter the pile hole for the construction of the second group of slightly inclined SMW method pile rings and the second group of reinforced concrete pile top ring beams, installing embedded steel plates at the top and bottom of the pile top ring beam respectively when binding the reinforcement of the second group of pile top ring beams, and forming the second group of thick soft clay covering layer retaining and waterproof curtain body after pouring; S4, excavating the second soft clay excavation area: before excavation, a plurality of force transmission columns are bolted and installed between the upper and lower adjacent two pile top ring beams, then the laid gravel layer is excavated separately and piled near the pile hole using hydraulic grab combined with manual work for the next bottom laying, and then the soft clay body in the second group of thick soft clay covering layer retaining and waterproof curtain body is excavated to a certain distance from the bottom of the second group of thick soft clay covering layer retaining and waterproof curtain body; S5, repeating the above steps to form the third group, the fourth group, …, the nth group of thick soft clay covering layer retaining and waterproof curtain bodies in turn until the bottom of the thick soft clay covering layer, thereby forming the overall thick soft clay covering layer retaining and waterproof curtain body; S6, excavating the last soft clay excavation area: before excavation, a plurality of force transmission columns are bolted and installed between the upper and lower adjacent two pile top ring beams, then the laid gravel layer is excavated separately and removed using hydraulic grab combined with manual work, and then the soft clay body in the last group of thick soft clay covering layer retaining and waterproof curtain body is excavated to the top of the strongly weathered rock layer; S7, performing ring-shaped drill-in drilling construction around the pile hole at the top of the strongly weathered rock layer; after the ring-shaped drill-in drilling construction is completed, vertical drilling blasting and strongly weathered rock layer block excavation construction are performed in the strongly weathered rock layer in the middle of the pile hole; S8, drilling and setting anchor rods on the sidewall of the pile hole in the strongly weathered rock layer, then installing a sidewall hanging net at the end of the anchor rod in the pile hole, and then spraying concrete to form a strongly weathered rock layer rock wall supporting ring wall body, the end of the anchor rod in the pile hole exceeding the thickness of the strongly weathered rock layer rock wall supporting ring wall body by a certain distance to facilitate the pouring of the end-bearing pile concrete in the later stage, thereby enhancing the integrity of the strongly weathered rock layer rock wall supporting ring wall body and the pile body, at the same time, the strongly weathered rock layer rock wall supporting ring wall body and the thick soft clay covering layer retaining and waterproof curtain body form a partial overlap, and a wall top ring beam is constructed at the top of the strongly weathered rock layer rock wall supporting ring wall body to enhance the overall integrity and waterproof capacity; S9, in the pile hole around the top of the weathered rock, the middle of the down-the-hole hammer is stacked and drilled, and the top of the slightly / unweathered rock is drilled to form a vertical cavity that can be drilled laterally; drilling is performed on the side wall of the vertical cavity to form unequal length blast holes, and then blasting and removal of the slightly weathered rock fragments are performed to form a bottom expansion cavity of the slightly weathered rock; S10, clean the bottom virtual soil, place the steel cage in the pile hole from top to bottom, and pour concrete to form a pile, complete the construction work of the soft overburden end-bearing rock-socketed pile forming system.

Images