Foundation pit support pile construction method

Abstract

The application discloses a foundation pit support pile construction method, and relates to the field of pile foundation construction technology, which comprises the following steps: step one, foundation pit support pile construction, a pile body of a foundation pit support pile is arranged in a soil body, a pre-pulling hole is arranged along the length direction of the pile body, a pre-pulling rope is arranged in the pre-pulling hole, and the lower end of the pre-pulling rope is fixedly arranged on the pile body; and step two, pre-stress is applied to the pile body, the upper end of the pre-pulling rope is pulled, and the upper end of the pre-pulling rope is fixed after the pre-pulling rope is pulled to a set position to maintain the pre-stress of the pre-pulling rope. The application has the effect of preventing the pile body of the foundation pit support pile from being bent, the ability of the pile body to resist lateral earth pressure is enhanced, the deformation of the pile body can be effectively reduced, and the safety of a foundation pit project is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of pile foundation construction technology, in particular to a foundation pit support pile construction method. BACKGROUND

[0002] Foundation pit support is a supporting method for developing and utilizing underground space, constructing various underground buildings such as multi-storey basement, underground railway, underground commercial street, etc. Foundation pit support pile is a pile foundation structure pre-buried around the foundation pit to be excavated to support the soil around the foundation pit.

[0003] Reference Figure 1 After the foundation pit 1 is excavated, the foundation pit support pile 2 is mainly subjected to the extrusion force from one side of the soil 3, which is easy to cause the foundation pit support pile 2 to bend and deform; and the bending and deformation of the foundation pit support pile 2 will cause the soil 3 around the foundation pit 1 to sink, extruding the pre-buried pipelines and other structures in the soil 3, affecting the construction quality.

[0004] In pile foundation construction, two foundation pit support piles are set in some constructions to enhance the strength of the pile structure, so as to reduce the deformation of the foundation pit support pile in the foundation pit excavation process and reduce the influence of soil collapse on construction. However, this construction method greatly increases the construction amount and prolongs the construction period.

[0005] In view of the above related technologies, the inventor designs a new foundation pit support pile construction method. SUMMARY

[0006] In a first aspect, the present application provides a foundation pit support pile construction method, which adopts the following technical scheme:

[0007] A foundation pit support pile construction method, characterized in that it comprises:

[0008] Step one, foundation pit support pile construction, setting a pile body of the foundation pit support pile in the soil, setting a pre-pulling hole along the length direction of the pile body, and threading a pre-pulling rope in the pre-pulling hole, and fixing the lower end of the pre-pulling rope with the pile body;

[0009] Step two: pre-stress is applied to the pile body, the upper end of the pre-pulling rope is pulled out, and the upper end of the pre-pulling rope is fixed after the pre-pulling rope is pulled out to a set position to maintain the pre-stress of the pre-pulling rope.

[0010] By adopting the technical scheme, the pre-tensioned rope with pre-tension is arranged in the pile body of the foundation pit support pile, when the foundation pit is excavated, the pile body is subjected to unilateral pressure from the soil side, the pile body tends to bend to the side of the foundation pit, the bending tendency of the pile body generates a tension force of the pre-tensioned rope in the pile body, the pre-tensioned rope with pre-tension can effectively offset the force without deformation, thereby maintaining the shape of the pile body and preventing the deformation of the pile body. After the pile body construction of the foundation pit support pile is completed, the pre-stress is applied to the pile body, the soil structure is stabilized, and the overall structure of the pile body can be prevented from being damaged during the pre-stress application.

[0011] Optionally, the foundation pit support pile in step one is a bored pile;

[0012] Step one comprises: S11, hole forming of the support pile, excavating a pouring hole on the ground; S12, pre-embedded part installation, lowering a reinforcement cage, a pre-tensioned rope and a pre-tensioning pipeline forming a pre-tension hole into the pouring hole, the pre-tensioned rope is arranged in the pre-tensioning pipeline, and a bottom end limiting part is fixed to the lower end of the pre-tensioned rope; S13, pile body pouring, pouring concrete slurry into the pouring hole, and waiting for the pile body to solidify.

[0013] By adopting the technical scheme, in the process of bored pile construction, the pre-tensioning pipeline is pre-embedded into the pouring hole to form a pre-tension hole in the pile body. Meanwhile, the pre-tensioned rope is pre-arranged in the pre-tensioning pipeline, and the lower end of the pre-tensioned rope is fixed to the lower end of the pile body by the bottom end limiting part to form a fixed connection. Without interfering with the construction of the bored pile body, the pre-tension hole is reserved and the pre-tensioned rope is fixed, which facilitates the construction of the bored pile and the application of pre-stress.

[0014] Optionally, S12 further comprises lowering a grouting pipe into the pouring hole, and the lower end of the grouting pipe is in communication with the lower end of the pre-tensioning pipeline;

[0015] Step two comprises: S21, tensioning the pre-tensioned rope, after the concrete pile body is solidified, a hollow jack is used to tension the upper end of the pre-tensioned rope, the upper end of the pre-tensioned rope is fixed after being tensioned to a set position, and the jack is removed; S22, gap pouring, high-strength slurry is poured from the grouting pipe, and the pouring is stopped when the high-strength slurry comes out of the upper end of the pre-tensioning pipeline.

[0016] By adopting the technical scheme, the gap in the pile body is filled after the construction is completed to ensure the structural strength of the pile body. The pre-tension hole is filled from the bottom of the pre-tension hole through the grouting pipe, and the top of the pre-tension hole serves as an exhaust hole, which helps to ensure the compactness of the grouting and avoid the hollow structure in the pile body.

[0017] Optionally, the foundation pit support pile in step one is a precast pile, and the pre-tension hole is arranged in the pile body of the precast pile along the length direction;

[0018] The step one comprises: S11, customizing the precast pile; S12, installing the pre-tensioning rope, threading the pre-tensioning rope into the pre-tensioning hole of the precast pile, and fixing the end of the pre-tensioning rope with the lower end of the precast pile; S13, precast pile installation, driving the precast pile into the ground.

[0019] By adopting the above technical scheme, when the precast pile is used for the construction of the foundation pit support pile, the pre-tensioning hole is pre-set in the pile body to provide space for the installation of the pre-tensioning rope, without increasing the preparation difficulty of the precast pile.

[0020] Optionally, the precast pile is further provided with a grouting hole, the lower end of the grouting hole is communicated with the lower end of the pre-tensioning hole, and the upper end of the grouting hole penetrates through the precast pile.

[0021] The step two comprises: S21, pulling the pre-tensioning rope, after the pile body is driven into the soil body, the upper end of the pre-tensioning rope is pulled by using the hollow jack, the upper end of the pre-tensioning rope is fixed after the pre-tensioning rope is pulled to the set position, and the jack is removed; S22, gap grouting, high-strength slurry is grouted from the grouting hole, and the grouting is stopped when the high-strength slurry emerges from the upper end of the pre-tensioning hole.

[0022] By adopting the above technical scheme, the gap in the precast pile body is filled after the construction is completed, so as to guarantee the structural strength of the pile body. The grouting is started from the bottom of the pre-tensioning hole, and the top of the pre-tensioning hole is used as an exhaust hole, which helps to guarantee the compactness of the grouting and avoid the hollow structure in the pile body.

[0023] Optionally, the precast pile comprises a pile body and a pointed pile head, the pointed pile head comprises a pile head body and an enlarged shell wrapped outside the pile head body, and a pressing hole is pre-set in the pile head and communicated with the grouting hole and the inner cavity of the enlarged shell.

[0024] The step two further comprises: S23, pressure injection of slurry, the upper end of the pre-tensioning hole is blocked by a plug, the grouting pressure is controlled at 1-40 MPa and gradually increased, and the pressure is maintained for 1-5 days after the pressure reaches 40 MPa.

[0025] By adopting the above technical scheme, after the grouting hole and the pre-tensioning hole are filled, the top of the pre-tensioning hole is blocked, the slurry is pressed into the space between the enlarged shell and the pile head body, and the enlarged shell is expanded by using the high-pressure liquid slurry, so as to form an enlarged head at the bottom of the foundation pit support pile, increase the contact area between the bottom of the foundation pit support pile and the soil body, further enhance the fixation of the pile body to the soil body, and better prevent the lower limit of the soil body.

[0026] Optionally, the grouting hole and the pre-tension hole both pass through the pile body of the precast pile; the pointed pile head is further provided with a feeding hole communicating with the bottom end of the grouting hole and a discharging hole communicating with the bottom end of the pre-tension hole, the feeding hole and the discharging hole both communicate with the pressing hole; the grouting hole and the pre-tension hole communicate with the bottom through the feeding hole, the pressing hole and the discharging hole.

[0027] By using the above technical solution, the bottom of the grouting hole and the pre-tension hole is communicated through the feeding hole, the pressing hole and the discharging hole in the pile head body, the grouting pipe first grouts the feeding hole, the pressing hole and the discharging hole in the pile head body, and the air in the pile head body can be discharged through the discharging hole, effectively preventing air retention in the pile head body and ensuring the structural strength.

[0028] Optionally, the precast pile is a steel pipe concrete precast pile, the pile body includes a steel pipe and a concrete core arranged in the steel pipe, and a plug-in cavity formed by not filling the concrete core is reserved at the lower end of the steel pipe; the pile head body is provided with a plug-in part near one end of the pile body, and the edge of the enlarged shell is wrapped on the side wall of the plug-in part, and the plug-in part wrapped with the enlarged shell is plugged into the plug-in cavity.

[0029] By using the above technical solution, the plug-in cavity is reserved at the bottom of the pile body, and the plug-in part is arranged on the pointed pile head, which facilitates the combination of the pile body and the pointed pile head, and the steel pipe of the pile body cooperates with the plug-in part on the pile head body to clamp and fix the edge of the enlarged shell, which eliminates the need for special fixing of the edge of the enlarged shell.

[0030] Optionally, the upper end of the pre-tensioning rope is fixed to the end of the pile body through a tensioning end anchor; a grout hole communicating with the pre-tension hole is arranged through the anchor pad of the tensioning end anchor.

[0031] By using the above technical solution, the existing tensioning end anchor is used as the end fixing component of the pre-tensioning rope, which is convenient to obtain and has a mature construction scheme; the grout hole of the existing anchor pad with a grout hole of the tensioning end anchor can be directly used as the feeding hole.

[0032] Optionally, the pre-tension hole is arranged on the side close to the foundation pit.

[0033] By using the above technical solution, when the pile body of the precast pile deforms, the pile body close to the side of the foundation pit has the largest length deformation, so the deformation trend of the pile body close to the side of the foundation pit is more obvious, the pre-tension hole is arranged on the side close to the foundation pit, the pre-tensioning rope is more obviously subjected to the pulling force of the pile body, and the pre-tensioning rope in the pre-tension hole can more effectively offset the load received by the pile body, thereby better preventing the deformation of the pile body.

[0034] In summary, the present application has at least one of the following beneficial technical effects:

[0035] 1. A foundation retaining pile construction method provided by the present application, after the pile body construction of the foundation retaining pile is completed, pre-tensioning ropes are used to apply pre-stress to the pile body along the length direction of the pile body to limit the deformation trend of the pile body, thereby preventing the deformation of the pile body caused by the earth pressure after the foundation pit is excavated, pre-tensioning holes and pre-tensioning ropes are reserved in the pile body in advance, the pre-tensioning ropes are pulled out to apply pre-stress to the precast pile after the pile body is arranged in the earth, the pre-stress is applied after the earth surrounds the pile body structure, in the case of using the precast pile, the pre-tensioning affecting the strength of the pile body or the transportation of the precast pile is prevented;

[0036] 2. The grouting pipe or grouting hole is arranged, after the pre-tensioning ropes are stretched and fixed, the structure of the pre-tensioning hole is grouted and filled from the bottom, the top of the pre-tensioning hole is used as an exhaust port, the hole structure in the foundation retaining pile is effectively ensured to be dense and filled, the hollow structure is prevented from occurring, and the strength of the foundation retaining pile is ensured;

[0037] 3. In the case of using the precast pile for the foundation retaining pile, the pointed pile head is arranged at the bottom of the pile body, the pile head body with the enlarged shell can be expanded by using high-pressure slurry in the process of grouting the hole, the enlarged head is formed at the bottom of the foundation retaining pile, the bearing capacity of the bottom of the foundation retaining pile is improved, and the blocking effect of the foundation retaining pile on the earth is further optimized. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a force schematic diagram of the foundation retaining pile in the related art of the present application;

[0039] Figure 2 is a construction structure schematic diagram of embodiment 1 of the present application;

[0040] Figure 3 is Figure 2 is an enlarged view of area A in

[0041] Figure 4 is a precast pile structure schematic diagram of embodiment 2 of the present application;

[0042] Figure 5 is Figure 4 is an enlarged view of area B in

[0043] Figure 6 is a schematic diagram of the expanded state of the enlarged shell in embodiment 2 of the present application.

[0044] Reference signs: 1, foundation pit; 2, foundation pit support pile; 3, soil body; 4, pouring hole; 51, steel reinforcement cage; 52, bottom end limiting piece; 521, communication hole; 53, pre-tensioning rope; 54, pre-tightening pipeline; 541, pre-tensioning hole; 55, grouting pipe; 551, grouting hole; 6, tensioning end anchor; 61, anchor pad; 611, slurry hole; 62, spiral rib; 63, anchor ring; 64, clamping piece; 71, steel pipe; 711, plug-in cavity; 72, concrete core; 73, concrete surface layer; 81, pile head body; 811, plug-in part; 812, feeding hole; 813, pressing hole; 814, discharging hole; 82, expanded shell. DETAILED DESCRIPTION

[0045] The application discloses a foundation pit support pile construction method.

[0046] Embodiment 1

[0047] Reference Figure 2 and Figure 3 The foundation pit support pile is a bored pile.

[0048] A foundation pit support pile construction method comprises the following steps.

[0049] Step one, foundation pit support pile construction.

[0050] S11, support pile hole forming. A rotary pile machine or a punching pile machine is used to excavate a pouring hole 4 on the ground.

[0051] S12, pre-embedded part installation. A steel reinforcement cage 51, a bottom end limiting piece 52, a pre-tensioning rope 53, a pre-tightening pipeline 54 and a grouting pipe 55 are lowered into the pouring hole 4; the pre-tensioning rope 53 is a steel strand, and the bottom end limiting piece 52 is an iron plate welded and fixed at the lower end of the pre-tensioning rope 53; the pre-tensioning rope 53 is arranged in the pre-tightening pipeline 54, and the bottom end limiting piece 52 is clamped at the end of the lower end of the pre-tightening pipeline 54; the grouting pipe 55 and the pre-tightening pipeline 54 are both stainless steel pipes 71, the lower end of the grouting pipe 55 is closed and arranged in communication with the lower end of the pre-tightening pipeline 54; the pre-tightening pipeline 54 is arranged offset to the side of the foundation pit to be excavated; the upper ends of the pre-tightening pipeline 54 and the grouting pipe 55 are fixed with the steel reinforcement cage 51 through scrap iron bars on the construction site, and the scrap iron bars are welded and fixed with other components; an anchor pad 61 and a spiral rib 62 of a tensioning end anchor 6 are installed at the upper end of the pre-tensioning rope 53, and the anchor pad 61 of the tensioning end anchor 6 is provided with a slurry hole 611 in communication with the pre-tightening pipeline 54.

[0052] S13, pile body pouring. Concrete slurry is poured into the pouring hole 4, and the pile body is allowed to solidify; the pre-tightening pipeline 54 forms a pre-tensioning hole 541 in the pile body, and the grouting pipe 55 forms a grouting hole 551 in the pile body.

[0053] Step two: Pile body prestress application.

[0054] S21, pull the pre-tensioning rope 53. After the concrete pile body is solidified, the anchor ring 63 and the clamping piece 64 of the tensioning end anchor 6 are installed, the hollow jack is used to pull the upper end of the pre-tensioning rope 53, and after the pre-tensioning rope 53 is pulled to the set position, the hollow jack is removed.

[0055] S22, gap filling. The high-strength slurry is poured from the grouting pipe 55, and the high-strength slurry is poured from the slurry hole 611 of the anchor pad 61 of the tensioning end anchor 6 to stop grouting.

[0056] The implementation principle of the embodiment 1 is that after the pile body of the cast-in-place pile is poured, the pre-tensioning rope 53 is pulled to apply a pre-tensioning force to the pre-tensioning rope 53, and the two ends of the pre-tensioning rope 53 are fixed to the end of the pile body through the bottom end limiting piece 52 and the tensioning end anchor 6; when the pile body is subjected to a compression force from a single side of the soil, the pile body will have a bending tendency, and the bending of the pile body will pull the side length of the pre-tensioning rope 53 in the pile body. The pre-tensioning rope 53 with a pre-tensioning force can provide sufficient counterforce to offset the tensioning force without deforming itself, thereby limiting the bending of the pile body and ensuring the blocking effect of the foundation pit support pile on the soil. The pre-tightening pipeline 54 and the pre-tensioning rope 53 are arranged on the side of the foundation pit, and since the pile body has a tendency to bend towards the side of the foundation pit, the deformation of the part of the pile body close to the side of the foundation pit is larger and the deformation tendency is more obvious. The pre-tensioning rope 53 can more effectively prevent the deformation of the pile body.

[0057] Embodiment 2

[0058] Reference Figure 4 and Figure 5 The foundation pit support pile is a steel pipe 71 concrete precast pile, and is a square pile.

[0059] A foundation pit support pile construction method, comprising:

[0060] Step one, foundation pit support pile construction.

[0061] S11, prefabricated pile customization. The prefabricated pile includes a pile body and a pointed pile head. The pile body includes a rectangular steel pipe 71, a concrete core 72 arranged in the steel pipe 71, and a concrete surface layer 73 arranged outside the steel pipe 71; the concrete core 72 is pre-buried with a pre-tightening pipe 54 and a grouting pipe 55, both of which pass through the entire concrete core 72 and form a pre-tension hole 541 and a grouting hole 551 that pass through the concrete core 72; the lower end 10-15 cm of the steel pipe 71 is not filled with the concrete core 72 and forms a splicing cavity 711. The pointed pile head includes a pile head body 81 and an enlarged shell 82 wrapped outside the pile head body 81; the pile head body 81 is a four-pyramid as a whole, and the connecting section of the pile head body 81 and the pile body is provided with a splicing part 811, the edge of the enlarged shell 82 is wrapped on the side wall of the splicing part 811, and the splicing part 811 wrapped with the enlarged shell 82 is spliced with the splicing cavity 711; the pointed pile head is provided with a feeding hole 812 corresponding to the bottom end of the grouting pipe 55 and a discharging hole 814 corresponding to the bottom end of the pre-tightening pipe 54, and a pressing hole 813 that communicates the feeding hole 812 and the discharging hole 814, the pressing hole 813 passes through the side wall of the pile head body 81 and communicates to the inner cavity of the enlarged shell 82. The upper end of the pre-tightening pipe 54 is provided with an anchor pad 61 and a spiral rib 62 of the tension end anchor 6, which are pre-buried in the concrete core 72, and the anchor pad 61 of the tension end anchor 6 is provided with a grout hole 611 that communicates with the pre-tightening pipe 54.

[0062] S12, installation of pre-tensioning rope 53. One end of the pre-tensioning rope 53 is welded to a metal plate as a bottom end limiting piece 52, the pre-tensioning rope 53 is inserted into the pre-tension hole 541 from one side of the splicing cavity 711, and the limiting plate is clamped on the end of the pre-tightening pipe 54; a communication hole 521 is provided on the plate body of the bottom end limiting piece 52 to communicate with the pre-tension hole 541, and the communication hole 521 on the bottom end limiting piece 52 corresponds to the position of the discharging hole 814 to communicate with both; the pointed pile head is spliced and fixed in the splicing cavity 711 at the lower end of the steel pipe 71.

[0063] S13, prefabricated pile installation. The prefabricated pile is driven into the ground by a practical pile driver.

[0064] Step two: prestress is applied to the pile body.

[0065] S21, drawing the pre-tensioning rope 53. The anchor ring 63 and the clamping piece 64 of the tension end anchor 6 are installed at the upper end of the pre-tensioning rope 53, the hollow jack is used to pull the upper end of the pre-tensioning rope 53, and after the pre-tensioning rope 53 is pulled to the set position, the hollow jack is removed.

[0066] S22, void grouting. High-strength grout is poured from the upper end of the grouting hole 551, and in this embodiment, epoxy resin grout is used; pouring is stopped when high-strength grout emerges from the grout hole 611 of the anchor pad 61 of the tension end anchor 6.

[0067] S23, pressure injection of the grout. The pre-tension hole 541 of the anchor pad 61 of the tensioning end anchor 6 is sealed with a plug, and a weight is placed on top to ensure that the sealing is tight. Grout is injected into the pouring hole 4 again, and the grouting pressure is controlled at 1-40 MPa, and the pressure is gradually increased. After the grouting pressure reaches 40 MPa, the pressure is stopped, and the pressure is maintained for 1-5 days to prevent the grout in the pouring hole 4 from being pressed out.

[0068] Reference Figure 6 By pressure injection of the grout, the enlarged shell 82 is expanded, and an enlarged head is formed at the bottom of the foundation pit support pile, enhancing the bearing capacity and stability of the entire foundation pit support pile.

[0069] The implementation principle of embodiment 2 is: by reserving a pre-tension hole 541 in the pile body of the precast pile, a pre-tensioning rope 53 is loaded into the precast pile before the precast pile is installed, and tensioning is performed after the precast pile is driven into the ground to apply prestress. The pile head body 81 covered with the enlarged shell 82 is set, and when the high-strength grout is filled into the pouring hole 551 and the pre-tension hole 541, the enlarged shell 82 in the soil is expanded to form an enlarged head, enhancing the bearing capacity and stability of the bottom of the foundation pit support pile, and further optimizing the role of the foundation pit support pile in blocking the soil.

[0070] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, so: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A method of constructing a foundation pit retaining pile, characterized by, Comprise: Step one, foundation pit support pile construction, set the pile body of the foundation pit support pile in the soil, set the pre-tensioning hole (541) along the length direction of the pile body, the pre-tensioning hole (541) is provided with a pre-tensioning rope (53) inside, the lower end of the pre-tensioning rope (53) is fixedly arranged with the pile body; Step two: prestress is applied to the pile body, the upper end of the pre-tensioning rope (53) is pulled, the pre-tensioning rope (53) is fixed after being pulled to the set position to maintain the prestress of the pre-tensioning rope (53); The foundation pit support pile in step one is a precast pile, the pre-tensioning hole (541) is arranged along the length direction in the pile body of the precast pile; The precast pile is also provided with a grouting hole (551), the lower end of the grouting hole (551) is communicated with the lower end of the pre-tensioning hole (541); The upper end of the grouting hole (551) penetrates the precast pile; The precast pile comprises a pile body and a pointed pile head, the pointed pile head comprises a pile head body (81) and an enlarged shell (82) wrapped outside the pile head body (81); The pile head body (81) is pre-provided with a pressing hole (813) communicating the grouting hole (551) and the inner cavity of the enlarged shell (82); The precast pile is a steel pipe (71) concrete precast pile, the pile body comprises a steel pipe (71) and a concrete core (72) arranged in the steel pipe (71), the lower end of the steel pipe (71) is reserved with an insertion cavity (711) formed by not filling the concrete core (72); The pile head body (81) is provided with an insertion part (811) close to one end of the pile body, the edge of the enlarged shell (82) is wrapped on the side wall of the insertion part (811), and the insertion part (811) wrapped with the enlarged shell (82) is inserted and matched with the insertion cavity (711); Step two includes: S21, pulling the pre-tensioning rope (53), after the pile body is nailed into the soil, the upper end of the pre-tensioning rope (53) is pulled using a hollow jack, the upper end of the pre-tensioning rope (53) is fixed after being pulled to the set position, and the jack is disassembled; S22, gap grouting, high-strength slurry is poured from the grouting hole (551), and the pouring is stopped when the high-strength slurry comes out of the upper end of the pre-tensioning hole (541); S23, pressure injection, the upper end of the pre-tensioning hole (541) is sealed with a plug, the grouting pressure is controlled at 1-40 MPa and gradually increased; after the pressure reaches 40 MPa, the pressure is maintained for 1-5 days.

2. The foundation pit support pile construction method according to claim 1, wherein: Step one includes: S11, precast pile customization; S12, install the pre-tensioning rope (53), pass the pre-tensioning rope (53) into the pre-tensioning hole (541) of the precast pile, and fix the end of the pre-tensioning rope (53) with the lower end of the precast pile; S13, precast pile installation, the precast pile is nailed into the ground.

3. The construction method of a retaining pile for a foundation pit according to claim 1, characterized in that: The grouting hole (551) and the pre-tension hole (541) are both through the pile body of the precast pile; the pointed pile head is further provided with a feeding hole (812) communicating with the bottom end of the grouting hole (551) and a discharging hole (814) communicating with the bottom end of the pre-tension hole (541), the feeding hole (812) and the discharging hole (814) both communicate with the pressing hole (813); the grouting hole (551) and the pre-tension hole (541) communicate with the bottom through the feeding hole (812), the pressing hole (813) and the discharging hole (814).

4. The construction method of a retaining pile for a foundation pit according to claim 1, characterized in that: The upper end of the pre-tensioning rope (53) is fixed with the end of the pile body through a tensioning end anchor (6); an anchor pad (61) of the tensioning end anchor (6) is provided with a grout hole (611) communicating with the pre-tension hole (541) through the anchor pad (61).

5. The construction method of a retaining pile for a foundation pit according to claim 1, characterized in that: The pre-tension hole (541) is arranged to be deviated from the side of the foundation pit.

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