Subway foundation pit secant pile shear key construction method without feet-lock anchor cable and rotary excavating drill bit

Abstract

The invention provides a metro foundation pit secant pile shear key construction method without a feet-lock anchor cable, which comprises the following steps of: S1, determining a pile position along a foundation pit sideline according to a drawing; s2, rotary digging and hole forming are carried out, and meat pile holes and shear key holes are formed; shear key holes are positioned at the bottoms of the reinforced pile holes; s3, a reinforcement cage is put in, concrete is poured, and reinforced piles and shear keys are formed; s4, holes are formed in the plain piles, the bottoms of the holes enter the bed rock surface by more than 1 m, then concrete is poured, the plain piles are formed, and the plain piles are engaged with the meat piles; s5, the steps S1 to S4 are repeated, and a closed foundation pit is formed; and S6, subway foundation pit construction is completed. According to the metro foundation pit secant pile shear key construction method without the feet-lock anchor cable and the rotary excavating drill bit, a feet-lock waist beam and the feet-lock anchor cable are omitted, external expansion of the foundation pit is not needed, earth and stone excavation is reduced, mass migration and modification of surface pipelines are avoided, the influence on the surrounding environment is reduced, land resources are intensified, and the construction efficiency is guaranteed.

Description

Technical Field

[0001] The invention relates to the field of subway foundation pits, and in particular to a subway foundation pit bite pile shear key construction method without a locking foot anchor cable and a rotary drilling drill bit. Background Art

[0002] At present, in the construction of urban rail transit subway stations or open-cut tunnels, various forms of foundation pit support are used, including underground continuous wall retaining structure, bored cast-in-place pile retaining structure, SMW method pile structure, and interlocking pile retaining structure. The specific structural form needs to be determined based on factors such as the geological conditions of the project, foundation pit depth, surrounding environmental constraints, investment intensity, and construction period.

[0003] Among them, the interlocking pile foundation pit support is to form a retaining structure with high strength, high rigidity and good waterproof performance by interlocking "cooked piles" equipped with steel bars and "plain piles" without steel bars. Compared with other support structure forms, interlocking piles have the advantages of mature construction technology, fast construction speed, good structural mechanical properties, flexible plane layout, wide stratum adaptability and good waterproof effect, and are widely used in underground space development.

[0004] During the excavation of subway foundation pits, if there is hard bedrock (such as moderately weathered to slightly weathered granite, moderately weathered to slightly weathered basalt, etc.) and the rock surface is uplifted, the construction of bored cast-in-place piles in the hard rock will result in a slow hole-making speed and high construction cost. The noise problem caused by the construction will also have a greater impact on the surrounding environment. In addition, the good mechanical properties of hard rock itself can achieve self-stability without support. The bite piles constructed below the hard rock surface are a waste.

[0005] Therefore, the self-stabilizing capacity of the rock mass in the foundation pit can be fully utilized to shorten the design length of the bored pile. The pile end only needs to be embedded in a certain depth of bedrock to carry the load from the pile body, without having to go below the bottom of the foundation pit to form a "hanging pile". This design form can greatly reduce the construction volume of the retaining structure and achieve the goal of green and low carbon. At the same time, this structural form also has strong economic benefits and saves construction time.

[0006] Nevertheless, since the bottom of the bored pile is in a "suspended state", in order to maintain the stability of the pile body, Figure 8 As shown, a locking beam ( Figure 8 201), and drive in the locking anchor cable ( Figure 8202) to "nail" the pile bottom to prevent the instability of the skirting. However, this method will produce two results. First, the retaining pile needs to be expanded outward to reserve enough space for the locking waist beam. The width of the expansion should not be less than the width of the locking waist beam. This leads to an increase in the amount of earth and stone excavated in the foundation pit, which also means more demolition of existing buildings or relocation of pipelines. In addition, the expanded part of the foundation pit needs to be backfilled. The loose backfill can easily cause the main structure of the station to float later. Second, when the waterproof structure and concrete structure of the station are constructed to the position of the locking waist beam and the locking anchor rod, the locking waist beam and the locking anchor cable need to be removed. If the internal support structure above the pile bottom is far away from the pile bottom, and the side wall of the station concrete structure has not reached the middle plate position, the station structure is still in a "U"-shaped groove. At this time, the bottom of the "hanging pile" completely loses its constraint. The constraint of the concrete structure side wall is completely insufficient to resist the thrust caused by the instability of the skirting. Therefore, a series of processes such as "replacing support" and "removing support" need to be added at this point, which greatly increases the construction time.

[0007] In addition, the prior art is to construct the plain piles first and then the steel piles. During the construction of the steel piles, it is difficult to ensure that the bottom end of the steel cage is located in the center, which makes the steel cage easily skewed. If the plain piles are constructed later, the steel cage will easily be damaged during the drilling process of the plain pile holes, affecting the stability of the bite piles. However, the strength and supporting force of the plain piles are insufficient. If the plain piles are constructed first, it is easy for the support to be unstable in the initial stage of the bite pile construction, affecting the construction and overall quality of the bite piles. Summary of the invention

[0008] The main purpose of the present invention is to provide a subway foundation pit bite pile shear key construction method without locking foot anchor cables, so as to solve the problem that locking foot waist beams and locking foot anchor cables are required to be constructed at the bottom of the pile during the existing "hanging foot pile" construction.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is: A method for constructing a shear key of a subway foundation pit bite pile without a locking foot anchor cable comprises the following steps: Step S1: determine the pile position along the foundation pit edge according to the drawing; Step S2, rotary drilling to form a pile hole and a shear key hole; The bottom of the pile hole is 1 to 2.5 meters into the bedrock surface, and the shear key hole is located at the bottom of the pile hole; The depth of the shear key hole is 1m to 2m; Pile hole diameter: shear key hole diameter = 1.2~3.0:1; Step S3, placing a steel cage and pouring concrete to form steel piles and shear keys; Step S4, forming a hole for a plain pile, the bottom of the hole enters the bedrock surface for more than 1m, and then pouring concrete to form a plain pile, which is engaged with the raw pile; Step S5, repeating steps S1 to S4, the plain piles and the meat piles are engaged with each other to form a closed foundation pit, and constructing a crown beam on the top of the plain piles and the meat piles; Step S6: Complete the subway foundation pit construction.

[0010] In a preferred solution, step S6 includes: Step S61: excavate the foundation pit according to the drawings and support it with internal supports until the foundation pit is excavated to the designed bottom; Step S62, temporarily supporting the foundation pit below the bottom of the pile by constructing anchor rods and spraying concrete layers on the surface, making full use of the self-stabilizing ability of the bedrock; Step S63: construct the station main body bottom plate, side wall, middle plate, side wall and top plate in sequence from the bottom of the foundation pit, remove the internal supports in sequence from bottom to top, and finally backfill with concrete to form a complete station structure; Among them, a bottom longitudinal beam is arranged in the bottom plate, a middle longitudinal beam is arranged in the middle plate, and a top longitudinal beam is arranged in the top plate.

[0011] In the preferred solution, the meat piles and the plain piles are in direct contact with the side walls, and there is no need to backfill the gaps later.

[0012] In a preferred solution, the steel cage includes a small-sized steel cage and a large-sized steel cage, the small-sized steel cage is located inside the shear key hole, the large-sized steel cage is located inside the pile hole, and the small-sized steel cage and the large-sized steel cage are connected by steel bars; Both ends of the small-size steel cage are provided with radially extended steel bars, and the extended steel bars are against the inner wall of the shear key hole.

[0013] In the preferred solution, both the shear key hole and the pile hole are drilled by a rotary drilling machine in cooperation with a rotary drilling drill bit.

[0014] A rotary drilling bit for a subway foundation pit bite pile shear key construction method without a locking foot anchor cable, characterized in that it comprises a main drill bit, a connecting seat is provided on one side of the main drill bit, an extension drill bit is provided on the other side of the main drill bit, and the extension drill bit is connected to the main drill bit; The connecting seat is used to connect the rotary drilling rig, the main drill bit is used to drill pile holes, and the extension drill bit is used to drill shear key holes.

[0015] In the preferred scheme, a plurality of first cutting edges are fixedly connected to the side of the main drill bit away from the connecting seat, the first cutting edges are arranged in an arc shape and tilted, and a plurality of first feed holes are opened on the side of the main drill bit away from the connecting seat, the first cutting edges are arranged in an inclined manner, and the first feed holes are close to the inner side of the first cutting edge.

[0016] In a preferred embodiment, a plurality of second cutting edges are fixedly connected to the side of the extended drill bit away from the connecting seat, the second cutting edges are arranged in an arc shape and tilted, a plurality of second feed holes are opened on the side of the extended drill bit away from the connecting seat, the second cutting edges are arranged in an tilted manner, and the second feed holes are close to the inner side of the second cutting edges.

[0017] In a preferred solution, the extension drill bit is connected to the main drill bit via a connecting mechanism; The connecting mechanism includes a connecting sleeve fixedly connected to the main drill bit, the connecting sleeve has the same diameter as the extension drill bit, a plurality of plug-in columns are fixed on the side of the connecting sleeve away from the main drill bit, the plug-in columns are plugged into the interior of the extension drill bit, a plurality of fixing blocks are fixed on the outer periphery of the connecting sleeve, a plurality of connecting blocks are fixed on the outer periphery of the extension drill bit, and the connecting blocks and the fixing blocks are connected by bolts.

[0018] In a preferred embodiment, the length of the extended drill bit is 0.1 m to 2 m.

[0019] In the preferred solution, the connection seat is connected to a spare drill bit, the top of the spare drill bit is fixedly connected to the connection seat, and the other structures are the same as those of the extended drill bit, and a plurality of reinforcing ribs are fixed between the spare drill bit and the connection seat; A fixing sleeve is arranged at the top of the main drill bit, and the fixing sleeve is sleeved on the outside of the spare drill bit. A plurality of pin shaft holes are arranged inside the spare drill bit and the fixing sleeve, and the pin shafts pass through the pin shaft holes.

[0020] In a preferred solution, the extension drill bit includes a fixed cylinder connected to the main drill bit, a connecting cylinder is fixed to the bottom of the fixed cylinder, and a crushing head is fixed to the bottom of the connecting cylinder; The connecting tube is in a truncated cone shape, and the top diameter is larger than the bottom diameter. A plurality of crushing teeth are fixed on the outer wall of the connecting tube. A plurality of second cutting edges are fixedly connected to the side of the crushing head away from the connecting seat, and the second cutting edges are arranged in an arc shape and tilted. A plurality of second feed holes are opened on the side of the extended drill bit away from the connecting seat, and the second cutting edges are arranged in an inclined manner, and the second feed holes are close to the inner side of the second cutting edges.

[0021] The present invention provides a subway foundation pit bite pile shear key construction method without a locking foot anchor cable and a rotary drilling drill bit. By adopting the above scheme, the following beneficial effects are achieved: 1. The locking foot waist beam and locking foot anchor cable are cancelled, and there is no need to expand the foundation pit, which reduces earthwork excavation, avoids the large-scale relocation of surface pipelines, reduces the impact on the surrounding environment, and intensifies land resources.

[0022] 2. There is no need to remove the shear keys during construction, and there is no need to replace the support at the bottom of the pile, which ensures construction efficiency.

[0023] 3. The bite piles are constructed by first constructing meat piles and then constructing plain piles, which ensures the support force and strength of the bite piles in the initial stage of construction, thereby ensuring the smooth construction of the bite piles and the overall quality of the bite piles.

[0024] 4. The rotary drilling bit can simultaneously drill the shear key hole when drilling the pile hole, without the need to replace the drill bit, which increases the construction efficiency.

[0025] 5. Start with small-diameter rotary drilling and then large-diameter rotary drilling. There is no need to replace the drill bit during the process, which reduces the difficulty of rotary drilling and increases the efficiency of rotary drilling.

[0026] 6. The rotary drilling bit can replace the rotary drilling shear key hole according to construction requirements, and has better adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 It is a structural schematic diagram of the present invention after construction is completed; Figure 2 It is a structural schematic diagram of the meat pile and shear key hole forming of the present invention; Figure 3 It is a schematic diagram of the structure after the foundation pit of the present invention is formed; Figure 4 It is a structural schematic diagram of the rotary drilling drill bit of the present invention; Figure 5 It is a structural schematic diagram of the rotary drilling drill bit of the present invention; Figure 6 It is a schematic cross-sectional structural diagram of a rotary drilling drill bit of the present invention; Figure 7 The present invention Figure 6 Schematic diagram of the structure at A in FIG. Figure 8 It is a structural schematic diagram of the hanging pile after the locking waist beam is applied in the prior art; Fig. 9 It is a schematic structural diagram of an embodiment of a rotary drilling drill bit of the present invention; Fig.10 It is a schematic structural diagram of an embodiment of a rotary drilling drill bit of the present invention.

[0028] In the figure: bottom plate 101, side wall 102, middle plate 103, top plate 104, hanging pile 2, locking waist beam 201, anchor cable 202, anchor rod 3, concrete layer 4, meat pile 501, shear key 502, crown beam 503, inner support 504, main drill bit 6, first feed hole 601, first cutting edge 602, protective sleeve 603, fixed sleeve 604, pin 605, reinforcing rib 606, extension drill bit 7, spare drill bit 71, fixed cylinder 721, connecting cylinder 722, crushing head 723, crushing teeth 724, second feed hole 701, second cutting edge 702, connecting seat 8, connecting mechanism 9, connecting sleeve 901, plug-in column 902, fixing block 903, connecting block 904, bolt 905. DETAILED DESCRIPTION

[0029] Embodiment 1: like Figure 1 , 2 As shown in 3, a method for constructing a shear key of a subway foundation pit bite pile without a locking foot anchor cable comprises the following steps: Step S1: determine the pile position along the foundation pit edge according to the drawing; Step S2, rotary drilling to form a pile hole and a shear key hole; The bottom of the pile hole is 1.5m into the bedrock surface, and the shear key hole is located at the bottom of the pile hole; The shear key hole depth is 1.1m; Pile hole diameter: shear key hole diameter = 2:1; Step S3, placing a steel cage and pouring concrete to form a steel pile 501 and a shear key 502; Step S4, the plain pile is bored, the bottom of the hole enters the bedrock surface by 1.5m, and then concrete is poured to form the plain pile, which is engaged with the meat pile 501; Step S5, repeating steps S1 to S4, the plain piles and the meat piles are engaged with each other to form a closed foundation pit, and constructing a crown beam 503 on the top of the plain piles and the meat piles 501; Step S6: Complete the subway foundation pit construction.

[0030] During the whole process, there is no need to redundantly construct locking foot waist beams and locking foot anchor cables, so there is no need to carry out foundation pit expansion construction, which reduces earth and stone excavation, avoids large-scale relocation of surface pipelines, reduces the impact on the surrounding environment, and concentrates land resources; and during construction, there is no need to remove the shear key 502, and there is no need to carry out the processes of "changing supports" and "removing supports", which ensures the continuous progress of construction and construction efficiency.

[0031] The shear key 502 penetrates deep into the bedrock, which can effectively prevent the base of the retaining structure from becoming unstable. The design length of the shear key 502 can also be dynamically designed according to the fluctuation of the bedrock surface.

[0032] At the same time, this application constructs the interlocking piles by first constructing the raw piles and then constructing the plain piles. Constructing the raw piles first can ensure the strength and supporting force of the pile body after construction, that is, to ensure the supporting strength in the initial stage of construction, which not only facilitates subsequent construction, but also ensures the overall quality of the interlocking piles.

[0033] In a preferred solution, step S6 includes: Step S61, excavate the foundation pit according to the drawing and support it through the internal support 504, and excavate the foundation pit to the designed bottom; Step S62, temporarily supporting the foundation pit below the bottom of the pile 501 by constructing anchor rods 3 and spraying a concrete layer 4 on the surface, making full use of the self-stabilizing ability of the bedrock; Step S63, construct the station main body bottom plate 101, side wall 102, middle plate 103, side wall 102 and top plate 104 in sequence from the bottom of the foundation pit, and remove the inner support 504 in sequence from bottom to top, and finally backfill with concrete to form a complete station structure; Among them, the bottom plate 101 is provided with a bottom longitudinal beam, the middle plate 103 is provided with a middle longitudinal beam, and the top plate 104 is provided with a top longitudinal beam. The station structure is supported and reinforced by the bottom longitudinal beam, the middle longitudinal beam and the top longitudinal beam.

[0034] In the preferred solution, the meat piles 501 and the plain piles are in direct contact with the side wall 102, and there is no need to backfill the gap later, which reduces the process and avoids the problem of loose backfill.

[0035] In the preferred scheme, the steel cage includes a small-sized steel cage and a large-sized steel cage. The small-sized steel cage is located inside the shear key hole, and the large-sized steel cage is located inside the raw pile hole. The small-sized steel cage and the large-sized steel cage are connected by steel bars. The steel cage is formed in one piece to ensure the connection strength between the raw pile and the shear key. The large-sized steel cage must be guaranteed not to touch the plain pile. Both ends of the small-sized steel cage are provided with radially extended steel bars, and the radially extended steel bars are against the inner wall of the shear key hole. Through the support of the extended steel bars, the entire steel cage can be relatively vertical, and the bottom of the steel cage can be close to the center position. The top of the steel cage is located on the ground, which is convenient for construction personnel to adjust and fix the position of the top of the steel cage at any time, thereby avoiding the steel cage from tilting, and will not affect the subsequent raw pile drilling, ensuring the normal progress of construction, that is, it can ensure that the scheme of constructing raw piles first and then constructing plain piles in this application can proceed smoothly.

[0036] In the preferred solution, both the shear key hole and the pile hole are drilled by a rotary drilling machine in cooperation with a rotary drilling drill bit.

[0037] Embodiment 2: like Figure 4 , 5As shown in , 6 and 7, a rotary drilling bit for the construction method of shear key of subway foundation pit interlocking piles without locking foot anchor cables is characterized in that: it includes a main drill bit 6, a connecting seat 8 is provided on one side of the main drill bit 6, and an extended drill bit 7 is provided on the other side of the main drill bit 6. The size of the extended drill bit 7 is adapted to the size of the shear key hole. The extended drill bit 7 is connected to the main drill bit 6, and the connecting seat 8 is used to connect to a rotary drilling machine. The connecting seat 8 is adapted to the crushing head of the existing rotary drilling machine. In the process of rotary drilling, small-diameter excavation is first performed by the extended drill bit 7, and then large-diameter excavation is performed by the main drill bit 6. A two-stage rotary drilling method is adopted, which makes rotary drilling easier; and when the main drill bit 6 has excavated the pile hole, the shear key hole is synchronously excavated by the extended drill bit 7, and there is no need to excavate the shear key hole separately, which is more efficient.

[0038] In the preferred scheme, a plurality of first cutting edges 602 are fixedly connected to the side of the main drill bit 6 away from the connecting seat 8, and the first cutting edges 602 are arranged in an arc shape and tilted. A plurality of first feed holes 601 are opened on the side of the main drill bit 6 away from the connecting seat 8, and the first cutting edges 602 are arranged tilted. The first feed holes 601 are close to the inner side of the first cutting edges 602. Through the rotary drilling of the first cutting edges 602, the excavated gravel and soil will be guided to enter the main drill bit 6 through the first feed holes 601. After the main drill bit 6 returns to the ground, it can be shaken to shake off the excavated gravel and soil, and then rotary drilling can continue.

[0039] In the preferred scheme, a plurality of second cutting edges 702 are fixedly connected to the side of the extension drill bit 7 away from the connecting seat 8, and the second cutting edges 702 are arranged in an arc shape and tilted. A plurality of second feed holes 701 are opened on the side of the extension drill bit 7 away from the connecting seat 8, and the second cutting edges 702 are arranged tilted. The second feed holes 701 are close to the inner side of the second cutting edges 702. Through the rotary drilling of the second cutting edges 702, the excavated gravel and soil will be guided to enter the extension drill bit 7 through the second feed holes 701. After the extension drill bit 7 follows the main drill bit 6 back to the ground, it can be shaken to shake off the excavated gravel and soil, and then rotary drilling can continue.

[0040] Embodiment 3: like Figure 5 , 6 As shown in 7, the extension drill bit 7 is connected to the main drill bit 6 via a connecting mechanism 9; wherein the connecting mechanism 9 includes a connecting sleeve 901 fixedly connected to the main drill bit 6, the connecting sleeve 901 has the same diameter as the extension drill bit 7, a plurality of plug-in columns 902 are fixed on the side of the connecting sleeve 901 away from the main drill bit 6, the plug-in columns 902 are plugged into the interior of the extension drill bit 7, a plurality of fixing blocks 903 are fixed on the periphery of the connecting sleeve 901, a plurality of connecting blocks 904 are fixed on the periphery of the extension drill bit 7, and the connecting blocks 904 and the fixing blocks 903 are connected via bolts 905.

[0041] When shear keys of different lengths are needed, the extension drill bits 7 of different lengths can be replaced as needed. First, the bolt 905 is unscrewed, and then the extension drill bit 7 and the connecting sleeve 901 can be separated. At this time, the plug-in column 902 leaves the extension drill bit 7, and vice versa, it can be installed. The operation is simple and the extension drill bit 7 can be easily replaced to meet different shear key hole-making requirements.

[0042] The length of the extended drill bit 7 is determined according to the actual construction requirements on site. For example, if a shear key with a length of 1 m is required, an extended drill bit 7 with a length of 1 m is used. For rotary drilling and hole turning requirements without the need for a shear key, a 0.1 m extended drill bit 7 can be replaced.

[0043] Embodiment 4: like Fig. 9 As shown, in the preferred solution, the connection seat 8 is connected to a spare drill bit 71, the top of the spare drill bit 71 is fixedly connected to the connection seat 8, and the other structures are the same as those of the extended drill bit 7, and a plurality of reinforcing ribs 606 are fixed between the spare drill bit 71 and the connection seat 8; A fixing sleeve 604 is provided at the top of the main drill bit 6, and the fixing sleeve 604 is sleeved on the outside of the spare drill bit 71. A plurality of pin holes are provided inside the spare drill bit 71 and the fixing sleeve 604, and the pins 605 pass through the pin holes.

[0044] During the rotary drilling process, if the required shear key is too long, resulting in insufficient length of the extended drill bit 7, the pin shaft 605 can be removed first, and then the spare drill bit 71 can be moved up to separate the main drill bit 6 from the spare drill bit 71, and then the spare drill bit 71 can be used alone to rotary drill the shear key hole. There is no need to replace the drill bit separately or prepare multiple drill bits. The operation is simple, easy to use, and more efficient.

[0045] Embodiment 5: like Fig.10 As shown, the extension drill bit 7 includes a fixed cylinder 721 connected to the main drill bit 6, a connecting cylinder 722 is fixed to the bottom of the fixed cylinder 721, and a crushing head 723 is fixed to the bottom of the connecting cylinder 722; A plurality of second cutting edges 702 are fixedly connected to the side of the crushing head 723 away from the connecting seat 8. The second cutting edges 702 are arranged in an arc shape and tilted. A plurality of second feed holes 701 are opened on the side of the extended drill bit 7 away from the connecting seat 8. The second cutting edges 702 are arranged in an tilted manner. The second feed holes 701 are close to the inner side of the second cutting edges 702. The connecting tube 722 is in a truncated cone shape, and the top diameter is larger than the bottom diameter. A plurality of crushing teeth 724 are fixed to the outer wall of the connecting tube 722; During the rotary drilling process, the rock formation can be continuously squeezed outwards through the truncated cone-shaped connecting tube 722 to increase the efficiency of rotary drilling, facilitate the rotary drilling work of the main drill bit 6, and the rock formation is broken by the provided breaking teeth 724, thereby ensuring the rotary drilling efficiency.

[0046] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A method for constructing a shear key of a subway foundation pit bite pile without a locking anchor cable, characterized by: The steps include: Step S1: determine the pile position along the foundation pit edge according to the drawing; Step S2, forming the pile hole and the shear key hole; The shear key hole is located at the bottom of the pile hole; Step S3, placing a steel cage and pouring concrete to form a steel pile (501) and a shear key (502); Step S4, forming a pile hole, with the bottom of the hole entering the bedrock surface for more than 1m, and then pouring concrete to form a pile; Step S5, repeating steps S1 to S4, the plain piles and the meat piles are engaged with each other to form a closed foundation pit, and constructing a crown beam (503) on top of the plain piles and the meat piles (501); Step S6: Complete the subway foundation pit construction.

2. According to the method for constructing a subway foundation pit bite pile shear key without locking foot anchor cable as described in claim 1, it is characterized in that Step S6 includes: Step S61, excavate the foundation pit according to the drawings and support it through internal supports (504) to excavate the foundation pit to the designed bottom; Step S62, temporarily supporting the foundation pit below the bottom of the pile (501) by constructing anchor rods (3) and spraying a concrete layer (4) on the surface, so as to make full use of the self-stabilizing ability of the bedrock; Step S63, constructing the station main body bottom plate (101), side wall (102), middle plate (103), side wall (102) and top plate (104) in sequence from the bottom of the foundation pit, and removing the inner support (504) in sequence from bottom to top, and finally backfilling with concrete to form a complete station structure; The bottom plate (101) is provided with a bottom longitudinal beam, the middle plate (103) is provided with a middle longitudinal beam, and the top plate (104) is provided with a top longitudinal beam.

3. The construction method of the subway foundation pit bite pile shear key without locking foot anchor cable according to claim 1 is characterized by: The meat pile (501) and the plain pile are in direct contact with the side wall (102), and there is no need to backfill the gap later.

4. The method for constructing a subway foundation pit bite pile shear key without a locking foot anchor cable according to claim 1 is characterized by: The steel cage includes a small-sized steel cage and a large-sized steel cage. The small-sized steel cage is located inside the shear key hole, and the large-sized steel cage is located inside the pile hole. The small-sized steel cage and the large-sized steel cage are connected by steel bars. Both ends of the small-size steel cage are provided with radially extended steel bars, which abut against the inner wall of the shear key hole; The bottom of the pile hole penetrates into the bedrock surface more than 1 to 2.5 meters; The depth of the shear key hole is 1m to 2m; Pile hole diameter: shear key hole diameter = 1.2~3.0:

1.

5. A rotary drilling bit for the construction method of the subway foundation pit bite pile shear key of the non-locking foot anchor cable according to any one of claims 1 to 5, characterized in that: It comprises a main drill bit (6), a connecting seat (8) is provided on one side of the main drill bit (6), an extension drill bit (7) is provided on the other side of the main drill bit (6), and the extension drill bit (7) is connected to the main drill bit (6); The connecting seat (8) is used to connect to the rotary drilling machine, the main drill bit (6) is used to form a pile hole, and the extension drill bit (7) is used to form a shear key hole; The length of the extended drill bit (7) is 0.1 m to 2 m.

6. A rotary drilling drill bit for the construction method of subway foundation pit bite pile shear key without locking foot anchor cable according to claim 5, characterized in that: A plurality of first cutting edges (602) are fixedly connected to a side of the main drill bit (6) away from the connection seat (8); the first cutting edges (602) are arranged in an arc shape and tilted; a plurality of first feed holes (601) are opened on a side of the main drill bit (6) away from the connection seat (8); the first cutting edges (602) are arranged in an tilted manner; and the first feed holes (601) are close to the inner side of the first cutting edges (602).

7. A rotary drilling drill bit for the construction method of subway foundation pit bite pile shear key without locking foot anchor cable according to claim 5, characterized in that: A plurality of second cutting edges (702) are fixedly connected to a side of the extended drill bit (7) away from the connecting seat (8); the second cutting edges (702) are arranged in an arc shape and tilted; a plurality of second feed holes (701) are opened on a side of the extended drill bit (7) away from the connecting seat (8); the second cutting edges (702) are arranged in an tilted manner; and the second feed holes (701) are close to the inner side of the second cutting edges (702).

8. The rotary drilling bit for the construction method of the subway foundation pit bite pile shear key without locking foot anchor cable according to claim 5, characterized in that: The extension drill bit (7) is connected to the main drill bit (6) via a connecting mechanism (9); The connection mechanism (9) comprises a connection sleeve (901) fixedly connected to the main drill bit (6); the connection sleeve (901) and the extension drill bit (7) have the same diameter; a plurality of plug-in posts (902) are fixed on a side of the connection sleeve (901) away from the main drill bit (6); the plug-in posts (902) are plugged into the interior of the extension drill bit (7); a plurality of fixing blocks (903) are fixed on the outer periphery of the connection sleeve (901); a plurality of connection blocks (904) are fixed on the outer periphery of the extension drill bit (7); and the connection blocks (904) and the fixing blocks (903) are connected via bolts (905).

9. A rotary drilling drill bit for the construction method of subway foundation pit bite pile shear key without locking foot anchor cable according to claim 5, characterized in that: The connecting seat (8) is connected to a spare drill bit (71), the top of the spare drill bit (71) is fixedly connected to the connecting seat (8), and the other structures are the same as those of the extended drill bit (7), and a plurality of reinforcing ribs (606) are fixed between the spare drill bit (71) and the connecting seat (8); A fixing sleeve (604) is provided at the top end of the main drill bit (6), and the fixing sleeve (604) is sleeved on the outside of the spare drill bit (71). The insides of the spare drill bit (71) and the fixing sleeve (604) are both provided with a plurality of pin holes, and the pins (605) pass through the pin holes.

10. The rotary drilling bit for the construction method of the subway foundation pit bite pile shear key without locking foot anchor cable according to claim 5, characterized in that: The extension drill bit (7) comprises a fixed cylinder (721) connected to the main drill bit (6), a connecting cylinder (722) is fixed to the bottom of the fixed cylinder (721), and a crushing head (723) is fixed to the bottom of the connecting cylinder (722); The connecting tube (722) is in a truncated cone shape, and the diameter of the top end is larger than the diameter of the bottom end. A plurality of crushing teeth (724) are fixed to the outer wall of the connecting tube (722); A plurality of second cutting edges (702) are fixedly connected to a side of the crushing head (723) away from the connecting seat (8), and the second cutting edges (702) are arranged in an arc shape and tilted. A plurality of second feed holes (701) are opened on a side of the extended drill bit (7) away from the connecting seat (8), and the second cutting edges (702) are arranged in an tilted manner, and the second feed holes (701) are close to the inner side of the second cutting edges (702).

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