Construction method and device for backfilling foundation pile foundation

Abstract

The invention relates to the technical field of foundation construction, and particularly discloses a construction method and device for backfilling a foundation pile foundation, and the construction method comprises the following steps: forming a hole to a certain depth by an impact hammer, and fixedly burying a steel casing; the impact hammer is lifted to a certain height, freely falls and continuously impacts and penetrates through the backfill soil layer to the preset depth of the pile end bearing layer, and pile hole construction is completed; and a plain concrete pile or a reinforced concrete pile or a precast pile or a concrete filled steel tube pile is formed through dado pouring by using a long spiral drilling tool or a steel sleeve. The impact hammer is used for compacting to form holes, negative friction resistance is eliminated, and the compactness of soil around the pile and pile side friction resistance are improved; soil and slurry are not discharged during impact hole forming; the long spiral drilling tool or the steel sleeve dado is poured with concrete, so that hole collapse and hole shrinkage are avoided; during precast pile construction, static pressure or a pile hammering machine is not needed, equipment investment is low, efficiency is high, and noise and pollution are avoided.

Description

Technical Field

[0001] The invention relates to the technical field of backfill foundation pile construction, and in particular to a construction method and device for a backfill foundation pile foundation. Background Art

[0002] As more and more "cut mountains to build cities" projects are located in mountainous areas, mountains are dug to fill ditches and pits; more and more high fill foundations are created, and the backfill foundations of construction waste, domestic waste, large blocks of stone, etc. are deep, with a large void ratio and complex composition; and the stratigraphic structure is mostly distributed with complex geological soil layers such as pebble layers, round gravel layers, strongly weathered rocks, sand layers and caves. Since these soil layers have been under alluvial and flood conditions for a long time, the distribution regularity of each soil layer is not strong and the uniformity is poor. In high fill areas, due to the loose foundation, rotary drills, impact drills, rotary drilling drills and down-the-hole hammers have problems such as leakage, hole collapse, drill sticking, deviated holes and thick sediment at the bottom of the piles, and static pressure or hammer precast piles cannot be formed when encountering block stone, pebble interlayers, round gravel interlayers and sand interlayers.

[0003] In addition, land reclamation is one of the important ways to solve the contradiction between land supply and demand in my country's coastal areas. The scale of land reclamation in my country is increasing day by day. With the increasing depth of reclamation, riprap reclamation has the characteristics of thick stone filling layer, large local particle size of blocks, high water content, and low silt strength. Moreover, the difficulty of foundation treatment is increasing, and it is subject to different degrees of restrictions in engineering applications. Foundation treatment often adopts foundation treatment such as strong tamping method, vibroflotation method, vacuum drainage consolidation preloading method, and various construction methods such as rotary drilling, long spiral, impact drilling, column hammer expansion and down-the-hole hammer, and static pressure or hammer precast piles. Especially in the construction of precast piles, encountering large boulders in the backfill soil will cause the bottom of the pile to deviate, the top of the pile to break, the pile body to break, the pile body to shift and tilt, resulting in large differences in pile length, insufficient bearing capacity and construction difficulties. Summary of the invention

[0004] The object of the present invention is to provide a construction method and device for backfill pile foundation to solve the above-mentioned background problems.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A construction method for backfilling a pile foundation comprises the following steps:

[0007] Step A: Bury the casing: Use an impact hammer to drill a hole to a certain depth and fix the buried steel casing.

[0008] Step B: Pile Hole Construction

[0009] B1: Compacting and drilling: lift the impact hammer to a certain height, let it fall freely, and continuously impact and penetrate the backfill soil to the preset depth of the bearing layer at the pile end to complete the impact compacting and drilling;

[0010] B2: Casing wall protection: Use a hollow hydraulic vibration hammer and an impact hammer inside the steel casing to sink the pipe while impacting or sink the pipe while impacting to the preset depth of the bearing layer at the pile end to complete the steel casing wall protection hole forming;

[0011] B3: Pile end compaction: After completing step B1 or B2, continue to tamp the soil at the pile end. According to the pile bearing capacity and the quality of the impact hammer, set the impact hammer lifting height to ensure that the cumulative penetration of the last ten hits is ≤30cm, and complete the pile end compaction;

[0012] B4: Pile end bottom expansion: After completing steps B1 and B2, fill the pile hole with filling materials in batches, and tamp while filling; according to the pile bearing capacity and the quality of the impact hammer, set the impact hammer lifting height to ensure that the cumulative penetration of the last ten hits is ≤30cm, and complete the pile end bottom expansion;

[0013] Step C: Pile Construction

[0014] C1: Plain concrete pile: Use a long spiral drill to rotate and insert it into the bottom of the B1, B2, B3 or B4 pile hole, rotate for 30 seconds, and use the spiral extrusion drill to compact the soil at the pile end; start pumping and pouring concrete, rotate and lift the drill to pour concrete to the pile top elevation +50cm, stop pouring, and lift the drill to the ground to complete the construction of the plain concrete pile;

[0015] C2: Plain concrete pile: Use a hollow hydraulic vibrating hammer and the pile tip sealed at the bottom of the steel casing to be implanted at the bottom of the B1, B2, B3 or B4 pile hole. Turn on the vibrating hammer and vibrate continuously for 30 seconds to compact the soil at the pile end. Pour concrete into the steel casing at one time and overfill to a certain height. Turn on the vibrating hammer and pull out the steel casing while vibrating to the pile top elevation +50cm. Pull the steel casing to the ground to complete the construction of the plain concrete pile.

[0016] C3: Reinforced concrete pile: Use a vibrating hammer to vertically insert the steel cage into the center of the C1 or C2 plain concrete pile. When the length of the upper steel anchor bar meets the design requirements, the construction of the reinforced concrete pile is completed;

[0017] C4: Reinforced concrete pile: Repeat the steps of C2. Before pouring concrete, place a steel cage in the steel casing, pour concrete to a certain height at one time, start the vibration hammer, and pull the steel casing to the pile top elevation +50cm while vibrating. Then, pull the steel casing to the ground to complete the construction of the reinforced concrete pile.

[0018] C5: Use a long spiral drill or steel casing to pour a certain amount of fluid solidified soil or mortar or concrete or soil solidifier into the B1 or B2 or B3 or B4 pile hole, insert the precast pile vertically into the pile hole, and tap the precast pile with an impact hammer to the pile top elevation +10cm, and the construction of the precast pile is completed;

[0019] C6: Steel tube concrete pile: Use a long spiral drill or steel casing to pour a certain amount of fluid solidified soil or mortar or concrete or soil curing agent into the B1 or B2 or B3 or B4 pile hole, implant the steel tube together with the pile tip that blocks the bottom of the steel tube into the bottom of the B1 or B2 or B3 or B4 pile hole, pour concrete into the steel tube to the pile top design elevation + 10 cm, and complete the construction of the steel tube concrete pile;

[0020] Completing the above-mentioned step A and any one of step B1 or B2 or B3 or B4 and C1 or C2 or C3 or C4 or C5 or C6 means completing any construction method of a plain concrete pile or a reinforced concrete pile or a precast pile or a steel tube concrete pile in compaction hole formation or casing wall protection or pile end compaction or pile end bottom expansion.

[0021] As a further solution, it also includes secondary compaction to form holes and piles, and the construction steps are as follows:

[0022] Step D: After completing step A and step B1 or B2, fill the pile hole with filler to the pile top elevation, and then perform secondary impact drilling to the preset depth of the pile end bearing layer to complete the secondary compaction drilling;

[0023] Or complete step A, while drilling, filling, and impacting and penetrating the backfill soil layer to the preset depth of the pile end bearing layer, and also complete the secondary compaction and drilling;

[0024] Step E: completing any one of steps D or B3 or B4 and C1 or C2 or C3 or C4 or C5 or C6, that is, completing any one of the construction methods of the plain concrete pile, reinforced concrete pile, precast pile or steel tube concrete pile in secondary compaction hole forming, casing wall protection, pile end compaction or pile end bottom expansion.

[0025] As a further solution, it also includes compaction and expansion of the top to form a hole and compaction and expansion of the diameter to form a hole to form a pile. The construction steps are as follows:

[0026] Step F: Expanding the top and compacting the hole: After completing step A, first form a hole according to the preset compaction and expansion top height, and complete the expansion and compaction by one-time filling or multiple filling impacts, and continue to impact and penetrate the backfill soil to the preset depth of the pile end bearing layer to complete the expansion and compaction of the hole;

[0027] Step G: completing any one of steps F or B3 or B4 and C1 or C2 or C3 or C4 or C5 or C6, that is, completing any one of the construction methods of the plain concrete pile, reinforced concrete pile, precast pile or steel tube concrete pile with expanded top and compacted hole.

[0028] Step H: Expanding and compacting holes: After completing step A, first make holes to the expansion position, and then make holes according to the preset expansion height, and then complete the expansion and compaction by one-time or multiple impacts, and then continue to impact and penetrate the backfill soil to the preset depth of the pile end bearing layer to complete the expansion and compaction of holes; and the expansion can be arbitrarily achieved;

[0029] Step I: completing any one of steps H or B3 or B4 and C1 or C2 or C3 or C4 or C5 or C6, that is, completing any one of the construction methods of top expansion and compaction, diameter expansion and compaction, pile end compaction, or pile end bottom expansion and compaction to form a plain concrete pile, reinforced concrete pile, precast pile, or steel tube concrete pile in the hole.

[0030] As a further solution: the plain concrete and reinforced concrete are mixtures made of cement or low-carbon cementitious materials, sand and gravel or recycled aggregates, water and water reducing agent.

[0031] The recycled aggregate includes any one of construction waste, waste slag, waste stone, pebbles, tailings, or a mixture of coarse and fine aggregates.

[0032] As a further embodiment, the filler includes any one or a mixture of recycled aggregate, dry mortar, or dry hard concrete.

[0033] As a further described scheme: the preparation method of the low-carbon cementitious material is: use any two or more of fly ash, steel slag, slag, vaporized slag, manganese slag, carbide slag, lithium slag, industrial by-gypsum, coal gangue, tailings, red mud, aluminum ash, fly ash, sludge, alkali slag and salt mud to mix and physically activate them together with an enhancer to form a solid waste-based micro-nano ultrafine hydraulic cementitious material, and the performance indicators meet or exceed those of cement.

[0034] A construction device for backfilling a pile foundation, the device is used to execute the construction method described in any one of the above schemes.

[0035] Beneficial effects of the present invention:

[0036] (1) The impact hammer connected to the wire rope wound on the top pulley of the pile frame or crane arm forms the pile hole once or multiple times by free fall impact compaction. The device realizes wireless data connection with the central processor through the encoder, limiter, sensor and inductor set in the quick release winch and the impact hammer, accurately controls the preset depth of the hole and the cumulative penetration of the last ten hits, ensures the quality of the hole and improves the pile end resistance.

[0037] (2) The impact compaction and drilling process does not discharge soil or slurry, is pollution-free, and meets environmental protection requirements. Secondly, multiple compaction and drilling processes can effectively increase the density of the soil around the pile and the friction resistance on the pile side, eliminating negative friction resistance. In addition, the compaction and expansion of the pile end can increase the pile end resistance, reduce the pile settlement difference, avoid uneven settlement of the building, and ensure building safety.

[0038] (3) Steel casing is poured with concrete to effectively prevent hole collapse and shrinkage, thus ensuring the quality of the pile body.

[0039] (4) No static pressure or hammer pile driver is required when implanting precast piles, which reduces equipment investment, improves construction efficiency, and causes no noise or vibration during the process, with little impact on the surrounding environment.

[0040] (5) Use low-carbon cementitious materials to replace cement and recycled aggregates to replace sand and gravel, turning waste into treasure, saving resources, reducing carbon dioxide emissions, and saving costs.

[0041] (6) The present invention effectively solves the problems of difficulty in treating complex backfill foundations, difficulty in controlling quality, high cost, and long construction period; and has broad application prospects.

[0042] It is particularly suitable for complex backfill foundations formed by large-scale mountain cutting and city building and sea reclamation. The backfill foundation includes various types such as miscellaneous fill, construction waste, ravine block backfill or silt riprap backfill. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The present invention will be further described below in conjunction with the accompanying drawings.

[0044] Figure 1 It is a schematic diagram of the construction method of the present invention;

[0045] Figure 2 This is a schematic diagram of the cross-section of the backfill foundation pile construction in the present invention. Figure 1 ;

[0046] Figure 3 This is a schematic diagram of the cross-section of the backfill foundation pile construction in the present invention. Figure 2 . DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] Embodiment 1

[0049] like Figure 1 and Figure 2 As shown, the present invention is a construction method for backfilling foundation pile foundation, including a quick release winch on the device and an encoder, a stopper, a sensor and an inductor arranged in the impact hammer are wirelessly connected with a central processor to detect the hole depth and penetration; the impact hammer is set to lift a height, fall freely, detect the preset hole depth, and when the cumulative penetration of the last ten hits is tested to be ≦30cm, the pile hole is completed; a plain concrete pile or a reinforced concrete pile or a prefabricated pile or a steel pipe concrete pile is implanted into the pile hole, and the pile foundation construction is completed; the implementation steps are as follows:

[0050] Step A: Burying the casing: Use an impact hammer to drill a hole to a certain depth and fix the buried steel casing;

[0051] Step B: Pile Hole Construction

[0052] B1: Compacting and drilling: lift the impact hammer to a certain height, let it fall freely, and continuously impact and penetrate the backfill soil to the preset depth of the bearing layer at the pile end to complete the impact compacting and drilling;

[0053] B2: Casing wall drilling: Use a hollow hydraulic vibration hammer and an impact hammer inside the steel casing to sink the pipe while impacting or sink the pipe while impacting to the preset depth of the bearing layer at the pile end to complete the steel casing wall drilling;

[0054] B3: Pile end compaction: After completing step B1 or B2, continue to tamp the soil at the pile end. According to the pile bearing capacity and the quality of the impact hammer, set the impact hammer lifting height to ensure that the cumulative penetration of the last ten hits is ≤30cm, and complete the pile end compaction;

[0055] B4: Pile end bottom expansion: After completing steps B1 and B2, fill the pile hole with filling materials in batches, and tamp while filling; according to the pile bearing capacity and the quality of the impact hammer, set the impact hammer lifting height to ensure that the cumulative penetration of the last ten hits is ≤30cm, and complete the pile end bottom expansion;

[0056] Step C: Pile Construction

[0057] C1: Plain concrete pile: Use a long spiral drill to rotate and insert it into the bottom of the B1, B2, B3 or B4 pile hole, rotate for 30 seconds, and use the spiral extrusion drill to compact the soil at the pile end; start pumping and pouring concrete, rotate and lift the drill to pour concrete to the pile top elevation +50cm, stop pouring, and lift the drill to the ground to complete the construction of the plain concrete pile;

[0058] C2: Plain concrete pile: Use a hollow hydraulic vibrating hammer and the pile tip sealed at the bottom of the steel casing to be implanted at the bottom of the B1, B2, B3 or B4 pile hole, turn on the vibrating hammer, vibrate continuously for 30 seconds, and compact the soil at the pile end; pour concrete into the steel casing at one time and overfill to a certain height, turn on the vibrating hammer, and pull out the steel casing while vibrating to the pile top elevation +50cm, and then pull the steel casing to the ground to complete the construction of the plain concrete pile;

[0059] C3: Reinforced concrete pile: Use a vibrating hammer to vertically insert the steel cage into the center of the C1 or C2 plain concrete pile. When the length of the upper steel anchor bar meets the design requirements, the construction of the reinforced concrete pile is completed;

[0060] C4: Reinforced concrete pile: Repeat the steps of C2. Before pouring concrete, place the steel cage in the steel casing first, then pour concrete into the steel casing at one time and over-pour to a certain height, start the vibration hammer, and pull the steel casing to the pile top elevation +50cm while vibrating, and then lift the steel casing to the ground to complete the construction of the reinforced concrete pile;

[0061] C5: Precast piles: Use a long spiral drill or steel casing to pour a certain amount of fluid solidified soil or mortar or concrete or soil solidifier into the B1, B2, B3 or B4 pile holes, insert the precast pile vertically into the pile hole, and tap the precast pile with an impact hammer to the pile top elevation +10cm to complete the construction of the precast pile;

[0062] C6: Steel tube concrete pile: Use a long spiral drill or steel casing to pour a certain amount of fluid solidified soil or mortar or concrete or soil solidifier into the B1 or B2 or B3 or B4 pile hole, implant the steel tube together with the pile tip that blocks the bottom of the steel tube into the bottom of the B1 or B2 or B3 or B4 pile hole, pour concrete into the steel tube to the pile top design elevation + 10cm, and complete the construction of the steel tube concrete pile;

[0063] Completing any one of the above steps A and B1 or B2 or B3 or B4 and C1 or C2 or C3 or C4 or C5 or C6, any one of the construction methods of the plain concrete pile, reinforced concrete pile, precast pile or steel tube concrete pile in the process of compaction hole formation, casing wall protection, pile end compaction or pile end bottom expansion is completed.

[0064] The hole is formed by impact compaction, without soil or slurry discharge, and pollution-free, which has an environmentally friendly effect. In addition, the compaction hole can improve the density of the soil around the pile, and in addition to eliminating negative friction resistance, the friction resistance on the pile side can be increased by ≧2.0 times;

[0065] Through pile end compaction and pile end bottom expansion, the pile end resistance can be increased by 3-5 times; the pile settlement is small, the pile settlement difference is reduced, uneven settlement of the building is avoided, and the safety of the building is ensured.

[0066] The concrete is poured with casing protection wall, which prevents hole collapse and diameter shrinkage. No static pressure or hammer pile driver is required when precast piles are implanted. During the entire construction process, the equipment investment is small, the efficiency is high, there is no noise, and there is no ground vibration during the construction process, ensuring the safety and stability of the ground during the construction process.

[0067] Example 2: Secondary compaction and pore formation

[0068] Step D: After completing step A and step B1, fill the pile hole with a one-time filling material to the pile top elevation, and then perform a secondary impact to form a hole to a preset depth of the pile end bearing layer, thereby completing the secondary compaction and forming of the hole;

[0069] Or complete step A, while drilling, filling, and impacting and penetrating the backfill soil layer to the preset depth of the pile end bearing layer, and also complete the secondary compaction and drilling;

[0070] Compared with the compaction and hole-forming in step B1 or B2, the secondary compaction and hole-forming can further improve the density of the soil around the pile, and the friction resistance on the pile side can be increased by ≥3.0 times, while also further improving the stability of the pile body.

[0071] Embodiment 3: Expanding the top and expanding the diameter to form a dense hole

[0072] Step F: After completing step A, firstly form a hole according to the preset compaction and expansion height, and then use one-time or multiple fillings to impact and penetrate the backfill soil to the preset depth of the pile end bearing layer to complete the expansion and compaction of the hole;

[0073] Step H: Expanding and compacting holes: After completing step A, first make holes to the expansion position, and then make holes according to the preset expansion height, and then use one-time or multiple fillings to impact and penetrate the backfill soil to the preset depth of the bearing layer at the pile end to complete the compaction and expansion of holes; and the diameter can be expanded arbitrarily;

[0074] Compared with steps B1 and B2, steps F and H have a small top area of ​​the pile body, a low replacement rate, and a relatively large pile-soil stress due to the limitation of the pile body diameter of C1-C6, which can easily lead to the piercing damage of the pile, and the small constraint of the pile body, resulting in shear damage. The top expansion on the pile can disperse the load of the raft slab on the pile or the pile cap and the soil between the piles, avoid the damage of the pile top due to the small pile diameter and stress concentration, and increase the pile body surrounding area, improve the pile side friction resistance and horizontal bearing capacity, and increase the stability of the pile body.

[0075] like Figure 2 and Figure 3 As shown, equal diameter piles, upper expanded diameter piles, lower expanded diameter piles, middle expanded diameter piles, including but not limited to upper middle expanded diameter piles, upper lower expanded diameter piles, middle lower expanded diameter piles and upper middle lower expanded diameter piles;

[0076] Example 4: Low-carbon cementitious materials replace traditional cement, and recycled aggregates replace sand and gravel

[0077] The low-carbon cementitious material includes any two or more of fly ash, steel slag, slag, vaporized slag, manganese slag, carbide slag, lithium slag, industrial by-gypsum, coal gangue, tailings, red mud, aluminum ash, fly ash, sludge, alkali slag and salt mud, which are mixed and physically activated together with an enhancer to form a solid waste-based micro-nano ultrafine hydraulic cementitious material, and the performance indicators meet or exceed those of cement.

[0078] The recycled aggregate includes construction waste, waste rock, pebbles and tailings coarse and fine aggregates to replace sand and gravel;

[0079] The plain concrete and reinforced concrete adopt low-carbon cementitious materials to replace traditional cement, and recycled aggregates from construction waste, waste rocks, pebbles and coarse and fine aggregates from tailings to replace sand and gravel, which are mixed with water and water reducing agent to form low-carbon concrete, turning waste into treasure, saving resources and reducing carbon dioxide emissions.

[0080] Embodiment 5

[0081] Based on the above embodiments, this embodiment provides a construction device, characterized in that it includes a quick-release winch, an impact hammer, a hollow hydraulic vibratory hammer and a steel casing;

[0082] The quick release winch comprises a stepping motor or a hydraulic drive motor and a sensor;

[0083] The steel casing is a seamless steel pipe; the diameter of the steel casing is equal to the diameter of the cast-in-place pile or greater than the diameter of the precast pile;

[0084] The impact hammer includes a lifting ring wire rope and a hammer body; the hammer body includes a round shape or a special shape; the bottom of the hammer body includes a flat bottom shape, a semicircular arc shape, a conical shape, a flat bottom conical shape mixed shape, a cross shape, or a toothed structure; the mass of the hammer body is 3-30t; the maximum outer diameter of the hammer body is 300-2000mm;

[0085] The hollow hydraulic vibration hammer comprises a ring-free housing, a seismic-resistant motor, an eccentric gear set, a hydraulic system device, a hollow channel and a flange or a hydraulic clamp;

[0086] The impact hammer connected by the steel wire rope wound on the top pulley of the pile frame or crane arm and the steel casing with the hydraulic hollow vibrating hammer are used to form the pile hole once or multiple times by free fall impact compaction. The device realizes wireless data connection with the central processor through the encoder, limiter, sensor and inductor set in the quick release winch and the impact hammer, accurately controls the preset depth of the hole and the cumulative penetration of the last ten hits, ensures the quality of the hole and improves the pile end resistance.

[0087] Firstly, the impact compaction and drilling process does not discharge soil or slurry, is pollution-free and meets environmental protection requirements; secondly, multiple compaction and drilling processes can effectively improve the density of the soil around the pile and the friction resistance on the pile side, and eliminate negative friction resistance; in addition, the compaction of the pile end and the expansion of the pile end can increase the pile end resistance, reduce the pile settlement difference, avoid uneven settlement of the building, and ensure the safety of the building; thirdly, the steel casing wall is poured with concrete to effectively prevent the collapse of the hole and the shrinkage of the diameter, and ensure the quality of the pile body; finally, when the precast piles are implanted, no static pressure or hammer pile driver is required, the equipment investment is small, the construction efficiency is high, and there is no noise or vibration during the process, which has little impact on the surrounding environment; low-carbon cementitious materials are used to replace cement, and recycled aggregates are used to replace sand and gravel, turning waste into treasure, saving resources, reducing carbon dioxide emissions, and saving costs.

[0088] The present invention effectively solves the problems of great difficulty in treating complex backfill foundations, difficult quality control, high cost, long construction period, etc., and has broad application prospects.

[0089] It is particularly suitable for complex backfill foundations formed by large-scale mountain cutting and city building and sea reclamation. The backfill foundation includes various types such as miscellaneous fill, construction waste, ravine block backfill or silt riprap backfill. The pile body includes plain concrete piles, reinforced concrete cast-in-place piles or precast piles or steel tube concrete piles.

[0090] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A construction method for backfill pile foundation, characterized in that: The following steps are involved: Step A: Burying the casing: Use an impact hammer to drill a hole to a certain depth and fix the buried steel casing; Step B: Pile Hole Construction B1: Compacting and drilling: lift the impact hammer to a certain height, let it fall freely, and continuously impact and penetrate the backfill soil to the preset depth of the bearing layer at the pile end to complete the impact compacting and drilling; B2: Casing wall drilling: Use a hollow hydraulic vibration hammer and an impact hammer inside the steel casing to sink the pipe while impacting or sink the pipe while impacting to the preset depth of the bearing layer at the pile end to complete the steel casing wall drilling; B3: Pile end compaction: After completing step B1 or B2, continue to tamp the soil at the pile end. According to the pile bearing capacity and the quality of the impact hammer, set the impact hammer lifting height to ensure that the cumulative penetration of the last ten hits is ≤30cm, and complete the pile end compaction; B4: Pile end bottom expansion: After completing steps B1 and B2, fill the pile hole with filling materials in batches, and tamp while filling; according to the pile bearing capacity and the quality of the impact hammer, set the impact hammer lifting height to ensure that the cumulative penetration of the last ten hits is ≤30cm, and complete the pile end bottom expansion; Step C: Pile Construction C1: Plain concrete pile: Use a long spiral drill to rotate and insert it into the bottom of the B1, B2, B3 or B4 pile hole, rotate for 30 seconds, and use the spiral extrusion drill to compact the soil at the pile end; start pumping and pouring concrete, rotate and lift the drill to pour concrete to the pile top elevation +50cm, stop pouring, and lift the drill to the ground to complete the construction of the plain concrete pile; C2: Plain concrete pile: Use a hollow hydraulic vibrating hammer and the pile tip sealed at the bottom of the steel casing to be implanted at the bottom of the B1, B2, B3 or B4 pile hole, turn on the vibrating hammer, vibrate continuously for 30 seconds, and compact the soil at the pile end; pour concrete into the steel casing at one time and overfill to a certain height, turn on the vibrating hammer, and pull out the steel casing while vibrating to the pile top elevation +50cm, and then pull the steel casing to the ground to complete the construction of the plain concrete pile; C3: Reinforced concrete pile: Use a vibrating hammer to vertically insert the steel cage into the center of the C1 or C2 plain concrete pile. When the length of the upper steel anchor bar meets the design requirements, the construction of the reinforced concrete pile is completed; C4: Reinforced concrete pile: Repeat the steps of C2. Before pouring concrete, place the steel cage in the steel casing first, then pour concrete into the steel casing at one time and over-pour to a certain height, start the vibration hammer, and pull the steel casing to the pile top elevation +50cm while vibrating, and then lift the steel casing to the ground to complete the construction of the reinforced concrete pile; C5: Precast piles: Use a long spiral drill or steel casing to pour a certain amount of fluid solidified soil or mortar or concrete or soil solidifier into the B1, B2, B3 or B4 pile holes, insert the precast pile vertically into the pile hole, and tap the precast pile with an impact hammer to the pile top elevation +10cm to complete the construction of the precast pile; C6: Steel tube concrete pile: Use a long spiral drill or steel casing to pour a certain amount of fluid solidified soil or mortar or concrete or soil solidifier into the B1 or B2 or B3 or B4 pile hole, implant the steel tube together with the pile tip that blocks the bottom of the steel tube into the bottom of the B1 or B2 or B3 or B4 pile hole, pour concrete into the steel tube to the pile top design elevation + 10cm, and complete the construction of the steel tube concrete pile; Completing any one of the above steps A and B1 or B2 or B3 or B4 and C1 or C2 or C3 or C4 or C5 or C6, any one of the construction methods of the plain concrete pile, reinforced concrete pile, precast pile or steel tube concrete pile in the process of compaction hole formation, casing wall protection, pile end compaction or pile end bottom expansion is completed.

2. A construction method for backfill pile foundation according to claim 1, characterized in that: It also includes secondary compaction, hole formation and pile formation. The construction steps are as follows: Step D: After completing step A and step B1 or B2, fill the pile hole with filler to the pile top elevation, and then perform secondary impact drilling to the preset depth of the pile end bearing layer to complete the secondary compaction drilling; Or complete step A, while drilling, filling, and impacting and penetrating the backfill soil layer to the preset depth of the pile end bearing layer, and also complete the secondary compaction and drilling; Step E: completing any one of steps D or B3 or B4 and C1 or C2 or C3 or C4 or C5 or C6, that is, completing any one of the construction methods of the plain concrete pile, reinforced concrete pile, precast pile or steel tube concrete pile in secondary compaction hole forming, casing wall protection, pile end compaction or pile end bottom expansion.

3. A construction method for backfill pile foundation according to claim 1, characterized in that: It also includes compaction and expansion of the top and compaction and expansion of the diameter to form holes and piles. The construction steps are as follows: Step F: Expanding the top and compacting the hole: After completing step A, first form a hole according to the preset compaction and expansion top height, and complete the expansion and compaction by one-time filling or multiple filling impacts, and continue to impact and penetrate the backfill soil to the preset depth of the pile end bearing layer to complete the expansion and compaction of the hole; Step G: completing any one of steps F or B3 or B4 and C1 or C2 or C3 or C4 or C5 or C6, that is, completing any one of the construction methods of the plain concrete pile, reinforced concrete pile, precast pile or steel tube concrete pile with expanded top and compacted hole. Step H: Expanding and compacting holes: After completing step A, first make holes to the expansion position, and then make holes according to the preset expansion height, and then complete the expansion and compaction by one-time or multiple impacts, and then continue to impact and penetrate the backfill soil to the preset depth of the pile end bearing layer to complete the expansion and compaction of holes; and the expansion can be arbitrarily achieved; Step I: completing any one of steps H or B3 or B4 and C1 or C2 or C3 or C4 or C5 or C6, that is, completing any one of the construction methods of top expansion and compaction, diameter expansion and compaction, pile end compaction, or pile end bottom expansion and compaction to form a plain concrete pile, reinforced concrete pile, precast pile, or steel tube concrete pile in the hole.

4. A construction method for backfill pile foundation according to claims 1-3, characterized in that: The plain concrete and reinforced concrete are mixtures made of cement or low-carbon cementitious materials, sandstone or recycled aggregate, water and water reducing agent. The recycled aggregate includes any one or a mixture of coarse and fine aggregates selected from construction waste, waste slag, waste stone, pebbles and tailings.

5. A construction method for backfill pile foundation according to claims 1-3, characterized in that: The filler includes any one or more mixtures of recycled aggregate, dry-mixed mortar or dry-hard concrete.

6. A construction method for backfill pile foundation according to claim 4, characterized in that: The preparation method of the low-carbon cementitious material is: any two or more of fly ash, steel slag, slag, vaporized slag, manganese slag, carbide slag, lithium slag, industrial by-gypsum, coal gangue, tailings, red mud, aluminum ash, fly ash, sludge, alkali slag and salt mud are mixed and physically activated together with a reinforcing agent to form a solid waste-based micro-nano ultrafine hydraulic cementitious material, and the performance indicators meet or exceed those of cement.

7. A construction device for backfilling pile foundation, characterized in that: The device is used to execute the construction method described in any one of claims 1 to 6.

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