Foundation pit retaining pile communication channel entry hole support system and construction method

Abstract

The invention relates to the technical field of support for excavation of foundation pit tunnel sections, and specifically to a foundation pit retaining pile communication channel entry hole support system and a construction method. A steel cage assembly is placed between the outer wall of a grouting pipe and the inner wall of a pipe shed. The steel cage assembly includes four groups of main bars distributed in a circumferential array and three groups of fixed rings distributed linearly. The fixed ring is provided with a sleeve ring that is sleeved and fixed with the main bars. An arc plate is pressed onto the main bars. The beneficial effects are as follows: by arranging the steel cage assembly between a traditional pipe shed and a grouting pipe, the strength of the pipe shed after grouting solidifies is improved to avoid fracture. A pressure plate and an arc plate are inserted into the grouting hole, and the main bars in the steel cage are squeezed and inserted, so that the pressure plate squeezes the soil layer and extends to the outside of the pipe shed, forming a dislocation between the pipe shed, the pressure plate and the inner wall of the cross-section soil layer. After concrete grouting, the inner wall of the cross-section soil layer solidifies to form a dislocation clamping connection with the pressure plate, thereby achieving the purpose of stable installation support.

Description

Technical Field

[0001] The invention relates to the technical field of support for excavation of foundation pit tunnel sections, and in particular to a foundation pit retaining pile communication channel entry hole support system and a construction method. Background Art

[0002] In the construction of urban subway entrances and exits, the open excavation method is adopted. Although the excavation depth of the foundation pit is not large, due to the influence of complex conditions such as pipelines and traffic, the relocation involves many units, coordination is difficult, and safety is difficult to ensure, which often seriously delays the construction period, causes serious interference to traffic, and damages the operating pipelines.

[0003] In the prior art, an advance support method is usually adopted to perform grouting support on the upper end of the excavation section, thereby reducing its settlement and improving the continuity and safety of excavation.

[0004] In a tunnel high-strength pipe-roof advance support construction method with application number: CN201510766852.6, a technical solution is described for achieving grouting diffusion by inserting pipe-roofs and grouting pipes to achieve the support purpose.

[0005] However, in actual use, drilling and plugging are required before the pipe roof is installed. After plugging, the grouting pipe is inserted into the pipe roof to realize pressure grouting. Since the inner diameter of the grouting hole is limited, and the viscosity of the grouting liquid is reduced to facilitate diffusion, the connection between the pipe roof and the cross-section soil layer is unstable, which can easily cause the pipe roof to fall off during the excavation vibration process. In addition, the existing pipe roof is not strong enough and is prone to breakage. Summary of the invention

[0006] The purpose of the present invention is to provide a foundation pit retaining pile communication channel entry hole support system and a construction method to solve the installation problem of the pipe shed during the advance support process.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A foundation pit retaining pile communication channel entry hole support system, the support system comprising:

[0009] The support frame includes a base frame located at the bottom of the foundation pit, a pair of upright posts symmetrically distributed on both sides, and an arch-shaped frame spanning the upper ends of the upright posts, and a cross-intersecting steel frame is arranged between an adjacent pair of upright posts and the arch-shaped frame;

[0010] Small conduits, wherein a plurality of groups of the small conduits are distributed at intervals along the outside of the arch frame, and the small conduits are obliquely inserted into the side wall of the foundation pit;

[0011] An advance support component, the advance support component comprises a plurality of groups of spaced-apart pipe racks distributed along the outer side of the arch frame, a plurality of spaced-apart grouting holes are arranged on the arc outer wall of the pipe rack, the inner cavity of the pipe rack is arranged as the support inner cavity, a grouting pipe coaxially sleeved with the pipe rack is inserted and installed in the support inner cavity, an end plate is arranged between the ends of the grouting pipe and the pipe rack, one end of the end plate is externally connected to the feed interface, the other end of the end plate is connected to the inner cavity of the grouting pipe, the grouting pipe is provided with a plurality of spaced-apart through holes connected to the support inner cavity, an enlarged-diameter elongated circular groove is arranged on the inner wall of the outer port of the grouting hole, a connecting rod is slidably inserted in the grouting hole, one end of the connecting rod extends into the enlarged-diameter elongated circular groove, and a pressure plate is fixedly connected to the end of the connecting rod, the other end of the connecting rod extends into the support inner cavity, and an arc plate is connected to the end of the connecting rod;

[0012] A steel cage assembly is placed between the outer wall of the grouting pipe and the inner wall of the pipe shed. The steel cage assembly includes four groups of main bars distributed in a circular array and three groups of fixed rings distributed linearly. The fixed rings are provided with rings that are sleeved and fixed with the main bars. The arc plate is pressed onto the main bars.

[0013] Preferably, the width of the expanded elongated groove is the same as the inner diameter of the grouting hole, the length of the expanded elongated groove is greater than the inner diameter of the grouting hole, the outer contour of the pressure plate fits the inner contour of the expanded elongated groove, and the outer diameter of the connecting rod is smaller than the inner diameter of the grouting hole.

[0014] Preferably, a pair of first positioning ring and second positioning ring are sleeved between the sleeve ring and the main reinforcement, a through hole is provided in the middle of the first positioning ring and the second positioning ring, and the first positioning ring and the second positioning ring are sleeved on the outer wall of the main reinforcement through the through hole.

[0015] Preferably, the first positioning ring and the second positioning ring are rotationally connected via a thread, the outer diameter of one side where the first positioning ring and the second positioning ring are connected is set to be stepped, and the other side of the outer wall of the first positioning ring and the second positioning ring is provided with a sloped cone surface.

[0016] Preferably, the inner diameter of the collar is larger than the outer diameter of the main rib, a slot is provided at the step groove at the connection position of the first positioning ring and the second positioning ring, the slot is in the shape of a circular ring, the collar is sleeved on the outer wall of the slot, and the arc outer wall of the collar is fixedly welded to the fixing ring.

[0017] Preferably, the outer wall of one end of the pipe rack is set as a second cone head, a positioning groove is set on the inner wall of the end of the pipe rack, a mounting screw hole is set in the positioning groove, the end of the grouting pipe is inserted in the positioning groove, and a stud is set on the outer wall of the end of the grouting pipe for threaded rotation with the mounting screw hole.

[0018] Preferably, a first cone head is provided at the end of the main rib, one end of the sloped cone surface fits the outer wall of the main rib, and the other end of the sloped cone surface is flush with the outer wall of the collar.

[0019] Preferably, a feed pipe is provided at the outer end of the grouting pipe, the feed pipe is connected to the feed interface on the end plate, the inner wall of the outer port of the pipe rack is provided with an internal thread, and the end plate is provided with an external thread connected to the internal thread.

[0020] A construction method implemented according to the above foundation pit retaining pile communication channel entry hole support system, the construction method comprising:

[0021] S1: Support frame assembly: set up the support frame on the excavation end face, divide the excavation end face into sections by steel frame, and reduce the excavation section by CRD method;

[0022] S2: Installation of pipe sheds. Connect the connecting rods in the grouting holes of the pipe sheds, and install the pressure plates and arc plates at both ends of the connecting rods. Set up multiple groups of pipe sheds within the 120° range of the arch outside the bow frame. The spacing between adjacent pipe sheds is 40cm, and the distance from the supporting surface is 50cm.

[0023] S3: Small pipe support. The pipe shed is supported by a small pipe. The small pipe is made of hot-rolled seamless steel pipe with an outer diameter of 42mm and a wall thickness of 3.5mm. The small pipe is 3.5m long. The end of the small pipe is set to be conical. The tail of the small pipe is welded with a φ6.5mm steel reinforcement hoop. Four rows of 6mm grouting holes are drilled every 15cm around the pipe wall. During construction, the steel pipe is driven into the soil layer at an external insertion angle of 5-10 degrees along the outer contour line of the blind hole excavation.

[0024] S4: Grouting pipe installation: insert and install the grouting pipe in the inner cavity of the pipe shed, and inject water into the grouting pipe to achieve the purpose of flushing and cleaning the inner cavity of the pipe shed;

[0025] S5: Installation of the steel cage. Insert the steel cage composed of the fixing ring and four sets of main bars between the grouting pipe and the inner wall of the pipe shed. Under the insertion and extrusion of the main bars, the arc plate is squeezed outward, driving the pressing plate to squeeze the cross-section soil layer and extend to the outside of the pipe shed.

[0026] S6: Grouting support: close the outer port of the pipe rack through the end plate, connect the concrete pipe through the feed interface, and control the grouting pressure at 0.4MPa-0.6MPa. The grouting time and grouting amount are determined according to the first test to ensure that the grouting diffusion radius is not less than 0.25m.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention arranges a steel cage assembly between the traditional pipe roof and the grouting pipe, thereby improving the strength of the pipe roof after the grouting solidifies and avoiding breakage. At the same time, the grouting holes of the traditional pipe roof are arranged in a stepped shape, and a pressure plate and an arc plate are inserted in the grouting holes. In cooperation with the extrusion and insertion of the main reinforcement in the steel cage, the pressure plate squeezes the soil layer and extends to the outside of the pipe roof, forming a misalignment between the pipe roof, the pressure plate and the inner wall of the cross-section soil layer. After the concrete is grouted, the inner wall of the cross-section soil layer solidifies and the strength is increased, forming a misaligned connection with the pressure plate, thereby avoiding the pipe roof from falling off and achieving the purpose of stable installation and support. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the cross-sectional structure of the present invention;

[0030] Figure 2 This is a schematic diagram of the installation structure of the advanced support assembly of the present invention;

[0031] Figure 3 It is a schematic diagram of the three-dimensional structure of the steel cage assembly of the present invention;

[0032] Figure 4 It is a schematic diagram of the three-dimensional structure of the pipe shed of the present invention;

[0033] Figure 5 It is a cross-sectional view of the positioning ring structure of the present invention;

[0034] Figure 6 It is a schematic diagram of the three-dimensional structure of the grouting pipe of the present invention;

[0035] Figure 7 Schematic diagram of the three-dimensional structure of the pipe rack and grouting pipe assembly of the present invention

[0036] Figure 8 Schematic diagram of the three-dimensional structure of the connection between the pressing plate and the curved plate of the present invention

[0037] Fig. 9 It is a schematic diagram of the three-dimensional structure of the positioning ring of the present invention.

[0038] In the figure: 1. base frame; 2. column; 3. advance support assembly; 4. arch frame; 5. small guide tube; 6. steel frame; 7. pipe shed; 8. enlarged long circular groove; 9. grouting hole; 10. pressure plate; 11. connecting rod; 12. arc plate; 13. grouting pipe; 14. support inner cavity; 15. fixing ring; 16. main reinforcement; 17. first positioning ring; 18. reinforcing rib; 19. collar; 20. first cone head; 21. slot; 22. second positioning ring; 23. internal thread; 24. positioning slot; 25. mounting screw hole; 26. through hole; 27. stud; 28. feed pipe; 29. ​​second cone head; 30. external thread; 31. end plate; 32. feed interface; 33. through hole; 34. slope cone surface. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present invention are described clearly and completely below. The embodiments of the present invention and all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] See also Figures 1 to 9 , the present invention provides a technical solution:

[0041] Embodiment 1:

[0042] The foundation pit retaining pile communication channel entry hole support system includes a support frame, a small guide tube 5 and an advance support component 3, and a steel cage component.

[0043] The support frame includes a base frame 1 located at the bottom of the foundation pit, a pair of columns 2 distributed symmetrically on the left and right, and a bow frame 4 located at the upper end of the column 2. A cross-intersecting steel frame 6 is arranged between the adjacent pair of columns 2 and the bow frame 4. The support frame is arranged to support the excavation section, and the steel frame 6 is used to partition the excavation section, thereby facilitating partitioned excavation through the CRD method and reducing the excavation section.

[0044] A plurality of groups of spaced apart small conduits 5 are distributed along the outside of the arch frame 4, and the small conduits 5 are obliquely inserted into the side wall of the foundation pit. Before the excavation of the tunnel body, the small conduits 5 are used for support at the lower end of the pipe shed 7 to further enhance the support rigidity.

[0045] The advance support assembly 3 includes a plurality of groups of spaced-apart pipe racks 7 distributed along the outer side of the arch frame 4, a plurality of groups of spaced-apart grouting holes 9 are arranged on the arc outer wall of the pipe rack 7, the inner cavity of the pipe rack 7 is arranged as a support inner cavity 14, a grouting pipe 13 coaxially sleeved with the pipe rack 7 is inserted and installed in the support inner cavity 14, an end plate 31 is arranged between the grouting pipe 13 and the end of the pipe rack 7, one end of the end plate 31 is connected to the feed interface 32, and the other end of the end plate 31 is connected to the inner cavity of the grouting pipe 13, and a plurality of groups of spaced-apart through holes 26 connected to the support inner cavity 14 are arranged on the grouting pipe 13.

[0046] By providing the grouting pipe 13, the pipe shelf 7 and the connection interface 32 on the end plate 31, the grouting pipeline is connected to achieve the purpose of pressure grouting.

[0047] An enlarged diameter elongated circular groove 8 is provided on the inner wall of the outer port of the grouting hole 9, and a connecting rod 11 is slidably inserted in the grouting hole 9. One end of the connecting rod 11 extends into the enlarged diameter elongated circular groove 8, and the end of the connecting rod 11 is fixedly connected to a pressure plate 10, and the other end of the connecting rod 11 extends into the support inner cavity 14, and the end of the connecting rod 11 is connected to an arc plate 12.

[0048] The outer wall of the pipe rack 7 is sealed by providing a pressing plate 10 , and the sliding plug-in installation of the connecting rod 11 is achieved by utilizing the cooperation of the stepped enlarged diameter long circular groove 8 and the grouting hole 9 .

[0049] The steel cage assembly is placed between the outer wall of the grouting pipe 13 and the inner wall of the pipe shed 7. The steel cage assembly includes four groups of main bars 16 distributed in a circular array and three groups of fixed rings 15 distributed linearly. The fixed rings 15 are provided with rings 19 that are sleeved and fixed with the main bars 16. The arc plate 12 is pressed onto the main bars 16.

[0050] By setting up a steel cage assembly and utilizing the extrusion and insertion of the main reinforcement 16 in the steel cage, the arc plate 12 is squeezed and moved outward, and the pressing plate 10 is driven by the connecting rod 11 to squeeze the cross-section soil layer and extend to the outside of the pipe shed 7, thereby forming a misalignment between the pipe shed 7, the pressing plate 10 and the inner wall of the cross-section soil layer. After the concrete is grouted, the inner wall of the cross-section soil layer solidifies and increases in strength, forming a misaligned connection with the pressing plate 10, thereby preventing the pipe shed 7 from falling off and achieving the purpose of stable installation and support.

[0051] Embodiment 2:

[0052] On the basis of Example 1, in order to prevent the connecting rod 11 from causing blockage of grouting, the width of the expanded elongated circular groove 8 is the same as the inner diameter of the grouting hole 9, the length of the expanded elongated circular groove 8 is greater than the inner diameter of the grouting hole 9, the outer contour of the pressure plate 10 fits the inner contour of the expanded elongated circular groove 8, and the outer diameter of the connecting rod 11 is smaller than the inner diameter of the grouting hole 9.

[0053] By limiting the size between the connecting rod 11 and the grouting hole 9 , the gap insertion of the connecting rod 11 is achieved, so that the concrete slurry overflows and grouts along the gap between the connecting rod 11 and the grouting hole 9 .

[0054] Embodiment 3:

[0055] On the basis of Example 2, in order to achieve smooth insertion of the ring 19 and the arc plate 12 during the insertion process of the main reinforcement 16, a pair of first positioning rings 17 and second positioning rings 22 are sleeved between the ring 19 and the main reinforcement 16, and a through hole 33 is provided in the middle of the first positioning ring 17 and the second positioning ring 22. The first positioning ring 17 and the second positioning ring 22 are sleeved on the outer wall of the main reinforcement 16 through the through hole 33. The inner diameter of the ring 19 is greater than the outer diameter of the main reinforcement 16. A slot 21 is provided at the step groove at the connection position of the first positioning ring 17 and the second positioning ring 22. The slot 21 is in a circular ring shape, and the ring 19 is sleeved on the outer wall of the slot 21. The arc outer wall of the ring 19 is fixedly welded to the fixing ring 15.

[0056] The through hole 33 is provided to realize the plug-in installation of the positioning ring.

[0057] The first positioning ring 17 and the second positioning ring 22 are rotationally connected by threads. The outer diameter of one side where the first positioning ring 17 and the second positioning ring 22 are connected is set to be stepped. A sloped conical surface 34 is provided on the other side of the outer wall of the first positioning ring 17 and the second positioning ring 22. A first cone head 20 is provided at the end of the main rib 16. One end of the sloped conical surface 34 fits the outer wall of the main rib 16, and the other end of the sloped conical surface 34 is flush with the outer wall of the ring 19.

[0058] By setting the first cone head 20, the main rib 16 can be conveniently plugged in to avoid being stuck on the side wall of the arc plate 12. By setting the slope cone surface 34, the main rib 16 can be smoothly extruded and plugged in when contacting the arc plate 12 to avoid the arc plate 12 being pressed on the side wall of the ring 19.

[0059] Embodiment 4:

[0060] On the basis of Example 3, in order to realize the positioning and installation of the grouting pipe 13, a second cone head 29 is also set on the outer wall of one end of the pipe rack 7, a positioning groove 24 is set on the inner wall of the end of the pipe rack 7, and a mounting screw hole 25 is set in the positioning groove 24. The end of the grouting pipe 13 is inserted into the positioning groove 24, and a stud 27 threadedly connected to the mounting screw hole 25 is set on the outer wall of the end of the grouting pipe 13.

[0061] The grouting pipe 13 is positioned by providing the positioning groove 24 , and the grouting pipe 13 is fixedly installed by providing the stud 27 and cooperating with the mounting screw hole 25 .

[0062] Embodiment 5:

[0063] On the basis of Example 4, in order to achieve the sealing of the port of the pipe rack 7, a feed pipe 28 is provided at the outer end of the grouting pipe 13, the feed pipe 28 is connected to the feed interface 32 on the end plate 31, and the inner wall of the outer port of the pipe rack 7 is provided with an internal thread 23, and the end plate 31 is provided with an external thread 30 connected to the internal thread 23.

[0064] The front end port of the pipe rack 7 is sealed by providing the internal thread 23 to cooperate with the external thread 30 on the end plate 31 .

[0065] A construction method implemented according to the above foundation pit retaining pile communication channel entry hole support system, the construction method comprising:

[0066] S1: Support frame assembly, support frame is set on the excavation end face, the excavation end face is divided into sections by steel frame 6, and the excavation section is reduced by CRD method;

[0067] S2: Installation of pipe sheds, inserting connecting rods 11 into the grouting holes 9 of pipe sheds 7, and installing pressing plates 10 and arc plates 12 at both ends of connecting rods 11, respectively, and setting up multiple groups of pipe sheds 7 within 120° of the outer arch of the bow frame 4, with the spacing between adjacent pipe sheds 7 being 40 cm and 50 cm from the supporting surface;

[0068] S3: Small pipe support. The small pipe 5 is used to strengthen the support under the pipe shed 7. The small pipe 5 is made of hot-rolled seamless steel pipe with an outer diameter of 42mm and a wall thickness of 3.5mm. The small pipe 5 is 3.5m long. The end of the small pipe 5 is set to be conical. The tail of the small pipe 5 is welded with a φ6.5mm steel reinforcement hoop. Four rows of 6mm grouting holes are drilled every 15cm around the pipe wall. During construction, the steel pipe is driven into the soil layer at an external insertion angle of 5-10 degrees around the outer contour line of the dark hole excavation;

[0069] S4: installing the grouting pipe, inserting and installing the grouting pipe 13 in the inner cavity of the pipe shed 7, and injecting water into the grouting pipe 13 to achieve the purpose of flushing and cleaning the inner cavity of the pipe shed 7;

[0070] S5: Installation of the steel cage. Insert the steel cage composed of the fixing ring 15 and four sets of main bars 16 between the grouting pipe 13 and the inner wall of the pipe shed 7. Under the insertion and extrusion of the main bars 16, the arc plate 12 is squeezed outward, driving the pressing plate 10 to squeeze the cross-section soil layer and extend to the outside of the pipe shed 7.

[0071] S6: Grouting support, closing the outer port of the pipe shed 7 through the end plate 31, connecting the concrete pipe through the feed interface 32, and controlling the grouting pressure at 0.4MPa-0.6MPa. The grouting time and grouting amount are determined according to the first test to ensure that the grouting diffusion radius is not less than 0.25m. Although the embodiments of the present invention have been shown and described, it is understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. The foundation pit retaining pile communication channel entry hole support system is characterized by: The support system comprises: A support frame, the support frame comprising a base frame (1) located at the bottom surface of the foundation pit, a pair of upright posts (2) symmetrically distributed on the left and right, and an arch frame (4) located at the upper ends of the upright posts (2) and spanning, and a cross-intersecting steel frame (6) is arranged between an adjacent pair of upright posts (2) and the arch frame (4); Small conduits (5), wherein a plurality of groups of the small conduits (5) are distributed at intervals along the outer side of the arch frame (4), and the small conduits (5) are obliquely inserted into the side wall of the foundation pit; An advance support assembly (3), the advance support assembly (3) comprising a plurality of groups of spaced-apart pipe racks (7) distributed along the outer side of a bow frame (4), a plurality of groups of spaced-apart grouting holes (9) being arranged on the arc outer wall of the pipe rack (7), an inner cavity of the pipe rack (7) being arranged as a support inner cavity (14), a grouting pipe (13) coaxially sleeved with the pipe rack (7) being inserted and installed in the support inner cavity (14), an end plate (31) being arranged between the grouting pipe (13) and the end of the pipe rack (7), one end of the end plate (31) being externally connected to a feed interface (32), and the end of the end plate (31) being provided with a support inner cavity (14). The other end is connected to the inner cavity of the grouting pipe (13), and the grouting pipe (13) is provided with a plurality of through holes (26) that are spaced and connected to the supporting inner cavity (14). An enlarged diameter long circular groove (8) is provided on the inner wall of the outer port of the grouting hole (9), and a connecting rod (11) is slidably inserted in the grouting hole (9), one end of the connecting rod (11) extends into the enlarged diameter long circular groove (8), and the end of the connecting rod (11) is fixedly connected to a pressing plate (10), and the other end of the connecting rod (11) extends into the supporting inner cavity (14), and the end of the connecting rod (11) is connected to an arc plate (12); A steel cage assembly is placed between the outer wall of a grouting pipe (13) and the inner wall of a pipe shed (7), the steel cage assembly comprises four groups of main bars (16) distributed in a circular array and three groups of fixing rings (15) distributed in a linear manner, the fixing rings (15) are provided with sleeves (19) sleeved and fixed to the main bars (16), and the arc plate (12) is pressed onto the main bars (16).

2. The foundation pit retaining pile communication channel entry hole support system according to claim 1 is characterized in that: The width of the expanded diameter elongated groove (8) is the same as the inner diameter of the grouting hole (9), the length of the expanded diameter elongated groove (8) is greater than the inner diameter of the grouting hole (9), the outer contour of the pressure plate (10) fits the inner contour of the expanded diameter elongated groove (8), and the outer diameter of the connecting rod (11) is smaller than the inner diameter of the grouting hole (9).

3. The foundation pit retaining pile communication channel entry hole support system according to claim 1 is characterized in that: A pair of first positioning rings (17) and second positioning rings (22) are sleeved between the sleeve ring (19) and the main rib (16); a through hole (33) is provided in the middle of the first positioning ring (17) and the second positioning ring (22); the first positioning ring (17) and the second positioning ring (22) are sleeved on the outer wall of the main rib (16) through the through hole (33).

4. The foundation pit retaining pile communication channel entry hole support system according to claim 3 is characterized in that: The first positioning ring (17) and the second positioning ring (22) are rotatably connected via a thread; the outer diameter of one side where the first positioning ring (17) and the second positioning ring (22) are connected is arranged in a stepped shape; and the other side of the outer wall of the first positioning ring (17) and the second positioning ring (22) is arranged with a sloped conical surface (34).

5. The foundation pit retaining pile communication channel entry hole support system according to claim 4 is characterized in that: The inner diameter of the collar (19) is greater than the outer diameter of the main rib (16); a clamping groove (21) is provided at the step groove at the connection position between the first positioning ring (17) and the second positioning ring (22); the clamping groove (21) is in a circular ring shape; the collar (19) is sleeved on the outer wall of the clamping groove (21); and the arc outer wall of the collar (19) is fixedly welded to the fixing ring (15).

6. The foundation pit retaining pile communication channel entry hole support system according to claim 1 is characterized in that: The outer wall of one end of the pipe rack (7) is provided with a second cone head (29), the inner wall of the end of the pipe rack (7) is provided with a positioning groove (24), a mounting screw hole (25) is provided in the positioning groove (24), the end of the grouting pipe (13) is inserted into the positioning groove (24), and a stud (27) is provided on the outer wall of the end of the grouting pipe (13) and is threadedly connected to the mounting screw hole (25).

7. The foundation pit retaining pile communication channel entry hole support system according to claim 5 is characterized in that: A first cone head (20) is provided at the end of the main rib (16), one end of the slope cone surface (34) fits the outer wall of the main rib (16), and the other end of the slope cone surface (34) is flush with the outer wall of the collar (19).

8. The foundation pit retaining pile communication channel entry hole support system according to claim 1 is characterized in that: A feed pipe (28) is provided at the outer end of the grouting pipe (13), and the feed pipe (28) is connected to a feed interface (32) on an end plate (31). An inner wall of the outer port of the pipe rack (7) is provided with an internal thread (23), and an external thread (30) connected to the internal thread (23) is provided on the end plate (31).

9. A construction method for implementing the foundation pit retaining pile communication channel entry hole support system according to any one of claims 1 to 8, characterized in that: The construction method comprises: S1: Support frame assembly, support frame is set on the excavation end face, the excavation end face is divided into sections by steel frame (6), and the excavation section is reduced by CRD method; S2: Installation of pipe sheds, inserting a connecting rod (11) into the grouting hole (9) of the pipe shed (7), and installing a pressing plate (10) and an arc plate (12) at both ends of the connecting rod (11), respectively, and setting up multiple groups of pipe sheds (7) within a 120° range of the outer arch of the bow frame (4), with the spacing between adjacent pipe sheds (7) being 40 cm and 50 cm from the support surface; S3: small conduit support, a small conduit (5) is used to strengthen the support below the pipe shed (7). The small conduit (5) is made of a hot-rolled seamless steel pipe with an outer diameter of 42 mm and a wall thickness of 3.5 mm. The small conduit (5) is 3.5 m long. The end of the small conduit (5) is set to be conical. A φ6.5 mm steel reinforcement hoop is welded at the tail of the small conduit (5). Four rows of 6 mm grouting holes are drilled every 15 cm around the pipe wall. During construction, the steel pipe is driven into the soil layer at an external insertion angle of 5-10 degrees along the outer contour line of the blind hole excavation; S4: installing a grouting pipe, inserting and installing a grouting pipe (13) in the inner cavity of the pipe shed (7), and injecting water into the grouting pipe (13) to achieve the purpose of flushing and cleaning the inner cavity of the pipe shed (7); S5: installing the steel cage, inserting the steel cage composed of the fixing ring (15) and four sets of main bars (16) between the grouting pipe (13) and the inner wall of the pipe shed (7), and under the insertion and extrusion of the main bars (16), the arc plate (12) is extruded outward, driving the pressing plate (10) to extrude the cross-section soil layer and extend to the outside of the pipe shed (7); S6: Grouting support, closing the outer port of the pipe rack (7) through the end plate (31), connecting the concrete pipe through the feed interface (32), and controlling the grouting pressure at 0.4MPa-0.6MPa. The grouting time and grouting amount are determined according to the first pipe test to ensure that the grouting diffusion radius is not less than 0.25m.

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