A tunnel construction method that helps control settlement

Abstract

The invention relates to the technical field of tunnel construction, and discloses a tunnel construction method that is helpful for controlling settlement, comprising the following steps: S1 upper step construction: the steps include upper step excavation, initial spraying, erecting a frame, a temporary invert, locking feet, locking feet grouting, an advance small conduit, re-spraying, and concrete curing; S2 middle step construction: the steps include dismantling the temporary invert, middle step excavation, initial spraying, erecting a frame, a temporary invert, locking feet, locking feet grouting, an advance small conduit, re-spraying, and concrete curing; S3 lower step construction: the steps include dismantling the temporary invert, middle step excavation, initial spraying, erecting a frame, a temporary invert, locking feet, locking feet grouting, an advance small conduit, re-spraying, and concrete curing; the erecting frame is an arch frame, the locking feet are locking feet anchor pipes of a φ89mm large steel pipe, the locking feet anchor pipes are arranged at 6 locations on each arch frame, two locking feet anchor pipes are arranged at each location, the length of the locking feet anchor pipes is 6m, the angle of the locking feet anchor pipes is controlled at 45°, and an I-beam is connected between the two locking feet anchor pipes at each location.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel construction, and in particular to a tunnel construction method which is helpful for controlling settlement. Background Art

[0002] The three-bench and seven-step tunnel excavation method is a tunnel construction method that uses arc-shaped pilot pit excavation to retain core soil as the basic mode. It is divided into three steps and seven excavation surfaces: upper, middle and lower. The excavation and support of each part are staggered and advanced in parallel along the longitudinal direction of the tunnel.

[0003] The three-bench seven-step excavation method can be divided into the following main steps:

[0004] A. Excavate the upper arc-shaped pilot pit in a circular direction and provide initial support for the arch;

[0005] B. The middle and lower steps are staggered to excavate and provide initial wall support:

[0006] C. Excavate the reserved core soil in the center and the tunnel bottom, and provide initial support for the tunnel bottom.

[0007] Each section should be supported promptly after excavation. After the initial support of the tunnel bottom, an invert should be constructed in time to close the tunnel into a ring as soon as possible.

[0008] At present, a Chinese patent with publication number CN113417646 and publication date September 21, 2021 discloses a large-section tunnel support structure and construction method suitable for the Xigeda formation, including a large-section tunnel support structure including a double-layer steel arch frame and an anchor bracket. The Xigeda formation adopts a three-step seven-step excavation method for tunnel excavation construction to form an excavation section with an upper step, a middle step and a lower step. A double-layer steel arch frame is erected on the top of the excavated tunnel, and anchor brackets are arranged on the horizontal sections of the upper step, the middle step and the lower step. The anchor brackets of each step are welded to the double-layer steel arch frame so that the entire support system forms a longitudinal connection system to support the tunnel.

[0009] The construction method includes the following steps:

[0010] 1. Pipe shed advance reinforcement, using large pipe shed and advance small guide tube for pipe shed advance reinforcement to form initial support;

[0011] 2. Use the three-step seven-step excavation method to excavate the tunnel and gradually release the surrounding rock stress;

[0012] 3. To install the large-section tunnel support structure, first excavate the upper arc-shaped pilot pit in the tunnel ring, reserve the core soil and spray concrete immediately after excavation. After the concrete is sprayed, install the large-section tunnel support structure in time;

[0013] 4. The large-section tunnel support structure includes a double-layer steel arch frame and anchor bracket;

[0014] 5. After the excavation of the upper arc-shaped pilot pit is completed, the left and right sides of the middle step and the left and right sides of the lower step are excavated in turn. The core soil excavation of the upper step, the middle step and the lower step is reserved. After each step is excavated, shotcrete and step support construction should be carried out in time. Anchor brackets are installed on each step, and the anchor brackets of each step are welded to the double-layer steel arch frame so that the entire support system forms a longitudinal connection system to support the tunnel.

[0015] Among them, the anchoring bracket of the large-section tunnel support structure suitable for the Xigeda formation includes locking foot anchor rods and large locking foot anchor rods. During the construction of each step support, 2 φ42mm locking foot anchor rods and 2 φ76mm large locking foot anchor rods are set on both sides of the arch foot of the upper step, and 2 φ42mm locking foot anchor rods and 2 φ76mm large locking foot anchor rods are also set on both sides of the arch foot of the middle step and the lower step.

[0016] However, the connection between the two locking anchor rods at the arch foot position is often not stable enough, which may affect the overall force of the arch frame, and ultimately affect the settlement when the next step is excavated. Summary of the invention

[0017] The purpose of the present invention is to provide a tunnel construction method that helps to control settlement, which can help to increase the structural strength between two locking foot anchor pipes, thereby enhancing the overall force of the arch frame.

[0018] The above technical objectives of the present invention are achieved through the following technical solutions: A tunnel construction method that helps control settlement, including the following steps: S1 upper step construction: the steps include upper step excavation, initial spraying, erecting a frame, temporary invert, locking feet, locking foot grouting, advanced small pipe, re-spraying, and concrete curing; S2 middle step construction: the steps include dismantling the temporary invert, middle step excavation, initial spraying, erecting a frame, temporary invert, locking feet, locking foot grouting, advanced small pipe, re-spraying, and concrete curing. Concrete maintenance; S3 lower step construction: the steps include dismantling the temporary invert, excavating the middle step, initial spraying, erecting a frame, temporary invert, locking feet, locking foot grouting, advancing small guide tubes, re-spraying, and concrete maintenance; the frame is an arch frame, and the locking feet are locking foot anchor pipes made of φ89mm large steel pipes. The locking foot anchor pipes are set at 6 locations on each arch frame, and two locking foot anchor pipes are set at each location. The length of the locking foot anchor pipe is 6m, and the angle of the locking foot anchor pipe is controlled at 45°. An I-beam is connected between the two locking foot anchor pipes at each location.

[0019] The present invention is further configured as follows: an annular connecting rib is sleeved on the upper end between the two locking foot anchor pipes at each location, the upper side of the I-beam is welded to the annular connecting rib, and the inner wall of the annular connecting rib is welded to the locking foot anchor pipe.

[0020] The present invention is further configured as follows: two steel bars are arranged between each of the two locking foot anchor pipes; a through hole for the steel bars to pass through is opened on the I-beam; and two ends of the steel bars are respectively welded to the outer walls of the locking foot anchor pipes on both sides.

[0021] The present invention is further configured as follows: a positioning assembly for positioning the I-beam is also provided between the two locking foot anchor tubes at each location, the positioning assembly comprising two buckles respectively arranged on the outsides of the two locking foot anchor tubes and used to engage with the locking foot anchor tubes, clamping arms arranged on the upper and lower sides of the buckles and respectively located at the upper and lower surface positions of the lower side of the I-beam, a rubber pad arranged on the inner wall of the buckle and used to press against the outer wall of the locking foot anchor tube, and a driving member arranged between the two buckles and used to drive the two buckles to move away from or closer to each other.

[0022] The present invention is further configured as follows: the driving member includes a fixed arm arranged on the side wall of the buckle, an open groove opened on the side of the fixed arm away from the buckle, a threaded shaft located between the two fixed arms, a block embedded in the open groove of one side of the fixed arm and having a rectangular cross-section, a threaded hole opened on one end of the block and for threaded connection of the threaded shaft, a first chuck arranged at the end of the block away from the threaded hole and having an outer diameter greater than the width of the open groove, a second chuck arranged at the end of the threaded shaft away from the block and having an outer diameter greater than the width of the open groove, and a handle arranged at the end of the threaded shaft away from the block.

[0023] The present invention is further configured as follows: the buckle is provided with a first elastic plate which extends obliquely upward toward the side close to the locking foot anchor tube and whose rear end abuts against the outer wall of the locking foot anchor tube, and a locking column abuts against the steel bar is provided on the side of the first elastic plate.

[0024] The present invention is further configured as follows: a second elastic plate extending obliquely upward toward a side away from the locking foot anchor tube is integrally provided at one end of the first elastic plate away from the buckle; the first elastic plate and the second elastic plate are combined to form a V-shape; an arc-shaped elastic clamping rod for embedding annular connecting ribs is integrally provided at one end of the second elastic plate away from the first elastic plate; when the rubber pad is flattened and the second elastic plate moves up, the annular connecting ribs embedded in the arc-shaped elastic clamping rod are pressed against the upper side of the I-beam.

[0025] The present invention is further configured as follows: a guide portion is provided at one end of the arc-shaped elastic clamping rod away from the second elastic plate and extends obliquely upward toward a side away from the locking foot anchor pipe.

[0026] The present invention is further configured as follows: a connecting spring with two ends respectively fixed to the clamping arms is provided between the two buckles.

[0027] In summary, the present invention has the following beneficial effects:

[0028] 1. When the locking foot anchor pipe is embedded in the surrounding rock and provided for the welding support of the arch frame, the locking foot anchor pipe is set at 6 locations on each arch frame, with two locking foot anchor pipes at each location, and the length of the locking foot anchor pipe is 6m, and the locking foot anchor pipe angle is controlled at 45°. At the same time, the two locking foot anchor pipes at each location are connected with an I-beam. After the two locking foot anchor pipes are reinforced by the middle I-beam, the structural strength between the two locking foot anchor pipes can be increased, thereby enhancing the overall force of the arch frame, reducing the settlement during the excavation of the next step, and ultimately helping to control the settlement;

[0029] 2. After the I-beam is embedded between the two locking foot anchor pipes, the annular connecting rib is set on the upper end between the two locking foot anchor pipes, and then the annular connecting rib is welded to the upper side of the I-beam, and the inner wall of the annular connecting rib is welded to the locking foot anchor pipe, which is conducive to the connection and fixation of the I-beam between the two locking foot anchor pipes;

[0030] 3. At the same time, two steel bars are passed through the through holes on the I-beam and the two ends are welded to the outer walls of the locking foot anchor pipes on both sides. At this time, the I-beam and the two locking foot anchor pipes can be stably connected through the steel bars and the annular connecting ribs;

[0031] 4. When welding the I-beam, the annular connecting ribs and the steel bars, it is necessary to locate the positions of the I-beam, the annular connecting ribs and the steel bars, so as to facilitate the operator to perform fast and accurate welding; at this time, two buckles are respectively engaged on the two locking foot anchor pipes, and then the clamping arms on the upper and lower sides of the buckle are respectively embedded in the upper and lower surface positions of the lower side of the I-beam, and the rubber pad is pressed against the outer wall of the locking foot anchor pipe; at the same time, after the two buckles are driven by the driving member to move toward the side close to each other, the buckles can be locked on the locking foot anchor pipe, so that the position of the I-beam on the locking foot anchor pipe is located by the two buckles;

[0032] 5. The clamping block is embedded in the open groove on one side of the fixed arm, and one end of the threaded shaft is threadedly connected to the threaded hole on the clamping block, and the threaded shaft is embedded in the open groove on the other side of the fixed arm. Then, the handle is turned to drive the threaded shaft to rotate in the threaded hole, thereby shortening the distance between the first chuck and the second chuck. Then, the first chuck and the second chuck can be pressed against the fixed arm, and finally, the clamping blocks on both sides can be driven to move toward the side close to each other;

[0033] If the threaded shaft is rotated in the reverse direction, the distance between the first chuck and the second chuck becomes longer, and then the first chuck and the second chuck can be loosened from the fixed arm, and then the clamping blocks on both sides can be separated from the locking foot anchor pipe;

[0034] 6. When the two buckles move toward the side close to each other and press against the locking foot anchor tube, the rubber pad can be flattened, and at the same time, the first elastic plate on the buckle can move toward the side close to the locking foot anchor tube. Since the rear end of the first elastic plate extends upward obliquely toward the side close to the locking foot anchor tube and presses against the outer wall of the locking foot anchor tube, when the first elastic plate moves toward the side close to the locking foot anchor tube, the first elastic plate undergoes elastic deformation, and at the same time, the locking column on the first elastic plate can rise a short distance. At this time, the locking column originally pressing against the steel bar can press against the steel bar, thereby positioning the steel bar passing through the through hole, which is conducive to fast and accurate welding between the steel bar and the outer wall of the locking foot anchor tube.

[0035] 7. At the same time, after the first elastic plate drives the locking column to rise, it also drives the second elastic plate to rise. At this time, the arc-shaped elastic clamping rod on the second elastic plate can be moved to the position on the upper side of the I-beam, and then the annular connecting rib can be embedded in the arc-shaped elastic clamping rod. After the arc-shaped elastic clamping rod is elastically deformed, the annular connecting rib can be clamped and positioned, so that the annular connecting rib is kept in a position close to the upper side of the I-beam, which is conducive to the rapid and accurate welding between the annular connecting rib, the I-beam and the locking foot anchor pipe;

[0036] 8. When the annular connecting rib needs to be embedded in the arc-shaped elastic clamping rod, the guide portion on the end of the arc-shaped elastic clamping rod can be used to guide the annular connecting rib, so that the annular connecting rib can be smoothly embedded in the arc-shaped elastic clamping rod;

[0037] 9. A connecting spring, whose two ends are respectively fixed to the clamping arms and is arranged between the two buckles, can be used to connect the two buckles, thereby avoiding the loss of the two buckles; at the same time, the elastic restoring force of the connecting spring is used to drive the buckle to be locked on the locking foot anchor tube, thereby pre-locking the buckle on the locking foot anchor tube, making it convenient to drive the buckle to be locked on the locking foot anchor tube through the threaded shaft in the driving member in the subsequent process. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a cross-sectional view of the connection relationship between two locking foot anchor pipes at a single location on the arch frame of the present invention and the I-beam, the annular connecting ribs and the steel bars;

[0039] Figure 2 It is a schematic diagram of the connection relationship between two locking foot anchor pipes at a single location on the arch frame of the present invention and the I-beam, the annular connecting ribs and the steel bars;

[0040] Figure 3 It is a schematic diagram of the connection relationship between the locking foot anchor pipe, the I-beam, the annular connecting rib, the steel bar, the positioning assembly, the first elastic plate, the second elastic plate and the arc-shaped elastic clamping rod in the present invention;

[0041] Figure 4It is a schematic diagram of the connection relationship between the positioning assembly, the first elastic plate, the second elastic plate and the arc-shaped elastic clamping rod in the present invention;

[0042] Figure 5 It is a schematic diagram of the connection relationship between the locking foot anchor pipe, I-beam, annular connecting ribs, steel bars, the first elastic plate, the second elastic plate and the arc-shaped elastic clamping rod in the present invention. At this time, the rubber pad is flattened and the first elastic plate is represented by a solid line, wherein the first elastic plate, the second elastic plate and the arc-shaped elastic clamping rod in the initial position state are represented by dotted lines.

[0043] Figure numerals: 1. locking foot anchor pipe; 2. I-beam; 21. through hole; 3. annular connecting rib; 4. steel bar; 5. positioning assembly; 51. buckle; 52. clamping arm; 53. rubber pad; 54. driving member; 541. fixed arm; 542. open groove; 543. threaded shaft; 544. clamping block; 545. threaded hole; 546. first chuck; 547. second chuck; 548. handle; 6. first elastic plate; 61. locking column; 62. second elastic plate; 63. arc-shaped elastic clamping rod; 64. guide part; 7. connecting spring. DETAILED DESCRIPTION

[0044] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0045] A tunnel construction method that helps control settlement, referring to Figure 1 , the tunnel construction method that helps control settlement includes the following steps:

[0046] S1 upper step construction: the steps include upper step excavation, initial spraying, erection of frames, temporary invert, foot locking, foot locking grouting, advance small guide tube, re-spraying, and concrete curing;

[0047] S2 middle step construction: the steps include dismantling temporary invert, middle step excavation, initial spraying, erecting frame, temporary invert, locking foot, locking foot grouting, advanced small guide tube, re-spraying, and concrete curing;

[0048] S3 lower step construction: the steps include dismantling temporary invert, excavation of middle step, initial spraying, erection of frame, temporary invert, foot locking, foot locking grouting, advance small guide tube, re-spraying, and concrete curing;

[0049] Reference Figure 1 , Figure 2The upright frame is an arch frame, and the locking foot is a locking foot anchor pipe 1 of a φ89mm large steel pipe. The locking foot anchor pipe 1 is arranged at 6 locations on each arch frame, and two locking foot anchor pipes 1 are arranged at each location, wherein the length of the locking foot anchor pipe 1 is 6m, and the angle of the locking foot anchor pipe 1 is controlled at 45°; at the same time, an I-beam 2 is connected between the two locking foot anchor pipes 1 at each location, and an annular connecting rib 3 is sleeved on the upper end between the two locking foot anchor pipes 1 at each location, and the upper side of the I-beam 2 is welded to the annular connecting rib 3, wherein the inner wall of the annular connecting rib 3 is welded to the locking foot anchor pipe 1; wherein two steel bars 4 are also arranged between the two locking foot anchor pipes 1 at each location, and a through hole 21 for the steel bars 4 to pass through is opened on the I-beam 2, and at the same time, the two ends of the steel bars 4 are respectively welded to the outer walls of the locking foot anchor pipes 1 on both sides.

[0050] Reference Figure 3 , Figure 4 A positioning assembly 5 is also provided between the two locking foot anchor tubes 1 at each location, and the positioning assembly 5 can be used to position the I-beam 2. The positioning assembly 5 includes a buckle 51, a clamping arm 52, a rubber pad 53 and a driving member 54, wherein two buckles 51 are provided and the cross-section is semicircular for clamping on the locking foot anchor tube 1, and the two buckles 51 can be respectively clamped on the outside of the two locking foot anchor tubes 1, and the clamping arm 52 is integrally arranged on the upper and lower sides of the buckle 51 and is respectively located at the upper and lower surface positions of the lower side of the I-beam 2, while the rubber pad 53 is bonded to the inner wall of the buckle 51 and is used to press against the outer wall of the locking foot anchor tube 1, and a connecting spring 7 with both ends respectively welded and fixed to the clamping arm 52 is provided between the two buckles 51.

[0051] Reference Figure 3 , Figure 4 The driving member 54 is arranged between the two buckles 51 and is used to drive the two buckles 51 to move away from or towards each other. The driving member 54 includes a fixed arm 541, an opening groove 542, a threaded shaft 543, a block 544, a threaded hole 545, a first chuck 546, a second chuck 547 and a handle 548. The fixed arm 541 is welded on the side walls of the two buckles 51, and the opening groove 542 is opened on the side of the fixed arm 541 away from the buckle 51. At the same time, the threaded shaft 543 is arranged between the two fixed arms 541, and the block 544 is embedded in The cross-section of the clamping block 544 is rectangular in the open groove 542 of the fixed arm 541 on one side, and the width of the cross-section is equal to the width of the open groove 542; wherein the threaded hole 545 is opened on one end of the clamping block 544 and is threadedly connected to the threaded shaft 543, and the first chuck 546 is integrally arranged at the end of the clamping block 544 away from the threaded hole 545 and has an outer diameter greater than the width of the open groove 542, and the second chuck 547 is welded at the end of the threaded shaft 543 away from the clamping block 544 and has an outer diameter greater than the width of the open groove 542, and the handle 548 is welded at the end of the threaded shaft 543 away from the clamping block 544.

[0052] Reference Figure 3 , Figure 4 A first elastic plate 6 is provided on the buckle 51, wherein the lower end of the first elastic plate 6 is welded on the buckle 51 and the upper end extends upwardly obliquely toward the side close to the locking foot anchor tube 1, and the upper end of the first elastic plate 6 abuts against the outer wall of the locking foot anchor tube 1, and the first elastic plate 6 is made of spring steel, and a locking column 61 is welded on the side of the first elastic plate 6 to abut against the lower outer wall of the steel bar 4.

[0053] Reference Figure 3 , Figure 4 , Figure 5 A second elastic plate 62 is integrally provided at one end of the first elastic plate 6 away from the buckle 51, and an end of the second elastic plate 62 away from the first elastic plate 6 extends obliquely upward toward the side away from the locking foot anchor tube 1, and the first elastic plate 6 and the second elastic plate 62 are combined to form a V-shape, wherein an arc-shaped elastic clamping rod 63 is integrally provided at one end of the second elastic plate 62 away from the first elastic plate 6, and the arc-shaped elastic clamping rod 63 can be embedded and clamped for the annular connecting rib 3; when the rubber pad 53 is flattened and the second elastic plate 62 moves upward, the arc-shaped elastic clamping rod 63 can move to the position on the upper side of the I-beam 2, and the annular connecting rib 3 embedded in the arc-shaped elastic clamping rod 63 can be pressed against the upper side of the I-beam 2; at the same time, a guide portion 64 is also integrally provided at one end of the arc-shaped elastic clamping rod 63 away from the second elastic plate 62, and the guide portion 64 extends obliquely upward toward the side away from the locking foot anchor tube 1.

[0054] Principle: When welding the I-beam 2, the annular connecting rib 3 and the steel bar 4, it is necessary to locate the positions of the I-beam 2, the annular connecting rib 3 and the steel bar 4, so as to facilitate the operator to perform fast and accurate welding.

[0055] First, two buckles 51 are used to clamp the two locking foot anchor pipes 1 respectively, and then the clamping arms 52 on the upper and lower sides of the buckle 51 are respectively embedded in the upper and lower surface positions of the lower side of the I-beam 2, and the rubber pad 53 is pressed against the outer wall of the locking foot anchor pipe 1; at the same time, the clamping block 544 is embedded in the open groove 542 on the fixed arm 541 on one side, and one end of the threaded shaft 543 is threadedly connected to the threaded hole 545 on the clamping block 544, and the threaded shaft 543 is embedded in the open groove 542 on the fixed arm 541 on the other side. 42, and then the threaded shaft 543 is driven to rotate in the threaded hole 545 by rotating the handle 548, thereby shortening the distance between the first chuck 546 and the second chuck 547, and then the first chuck 546 and the second chuck 547 can be pressed against the fixed arm 541, and finally the two side blocks 544 can be driven to move toward the side close to each other, and the buckle 51 can be locked on the locking foot anchor tube 1, so that the position of the I-beam 2 on the locking foot anchor tube 1 is positioned by the two buckles 51.

[0056] When the two buckles 51 move toward each other and press against the locking foot anchor tube 1, the rubber pad 53 can be flattened, and the first elastic plate 6 on the buckle 51 can move toward the side close to the locking foot anchor tube 1. Since the rear end of the first elastic plate 6 extends obliquely upward toward the side close to the locking foot anchor tube 1 and presses against the outer wall of the locking foot anchor tube 1, when the first elastic plate 6 moves toward the side close to the locking foot anchor tube 1, the first elastic plate 6 undergoes elastic deformation, and the locking column 61 on the first elastic plate 6 can rise a short distance. At this time, the locking column 61 that originally pressed against the steel bar 4 can press against the steel bar 4, thereby positioning the steel bar 4 passing through the through hole 21, which is beneficial to fast and accurate welding between the steel bar 4 and the outer wall of the locking foot anchor tube 1.

[0057] At the same time, after the first elastic plate 6 drives the locking column 61 to rise, it will also drive the second elastic plate 62 to rise. At this time, the arc-shaped elastic clamping rod 63 on the second elastic plate 62 can be moved to the position on the upper side of the I-beam 2, and then the annular connecting rib 3 can be embedded in the arc-shaped elastic clamping rod 63. After the arc-shaped elastic clamping rod 63 is elastically deformed, the annular connecting rib 3 can be clamped and positioned, so that the annular connecting rib 3 is maintained in a position close to the upper side of the I-beam 2, which is then conducive to fast and accurate welding between the annular connecting rib 3, the I-beam 2 and the locking foot anchor pipe 1.

[0058] At this time, the buckle 51, the first elastic plate 6, the second elastic plate 62, and the arc-shaped elastic clamping rod 63 will not interfere with the welding position between the locking foot anchor pipe 1, the I-beam 2, the annular connecting rib 3 and the steel bar 4, so it is conducive to the rapid welding.

[0059] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A tunnel construction method that helps control settlement, comprising the following steps: S1 upper step construction: the steps include upper step excavation, initial spraying, erecting a frame, temporary invert, locking foot, locking foot grouting, advance small pipe, re-spraying, and concrete curing; S2 middle step construction: the steps include dismantling the temporary invert, middle step excavation, initial spraying, erecting a frame, temporary invert, locking foot, locking foot grouting, advance small pipe, re-spraying, and concrete curing; S3 lower step construction: the steps include dismantling the temporary invert, middle step excavation, initial spraying, erecting a frame, temporary invert, locking foot, locking foot grouting, advance small pipe, re-spraying, and concrete curing; the frame is an arch frame, characterized in that: The locking foot is a locking foot anchor pipe (1) of a φ89 mm large steel pipe. Six locking foot anchor pipes (1) are arranged on each arch frame, and two locking foot anchor pipes (1) are arranged on each arch frame. The length of the locking foot anchor pipe (1) is 6 m, and the angle of the locking foot anchor pipe (1) is controlled at 45°. An I-beam (2) is connected between the two locking foot anchor pipes (1) at each location. An annular connecting rib (3) is sleeved on the upper end between the two locking foot anchor pipes (1) at each location. The upper side of the I-beam (2) is welded to the annular connecting rib (3), and the inner wall of the annular connecting rib (3) is welded to the locking foot anchor pipe (1). Two steel bars (4) are also arranged between the two locking foot anchor pipes (1) at each location. The I-beam (2) is provided with a A through hole (21) for a steel bar (4) to pass through, the two ends of the steel bar (4) being respectively welded to the outer walls of the locking foot anchor tubes (1) on both sides; a positioning assembly (5) for positioning the I-beam (2) is also provided between the two locking foot anchor tubes (1) at each location, the positioning assembly (5) comprising two buckles (51) respectively provided on the outer sides of the two locking foot anchor tubes (1) and used to be engaged with the locking foot anchor tubes (1), a clamping arm (52) provided on the upper and lower sides of the buckle (51) and respectively located at the upper and lower surface positions of the lower side of the I-beam (2), a rubber pad (53) provided on the inner wall of the buckle (51) and used to be pressed against the outer wall of the locking foot anchor tube (1), and a rubber pad (53) provided on the inner wall of the buckle (51) and used to be pressed against the outer wall of the locking foot anchor tube (1). A driving member (54) is disposed between the two buckles (51) and is used to drive the two buckles (51) to move toward one side away from or toward each other; the driving member (54) comprises a fixed arm (541) disposed on a side wall of the buckle (51), an open groove (542) provided on a side of the fixed arm (541) away from the buckle (51), a threaded shaft (543) disposed between the two fixed arms (541), a clamping block (544) embedded in the open groove (542) of one fixed arm (541) and having a rectangular cross section, a threaded hole (545) provided on one end of the clamping block (544) and for threading the threaded shaft (543), and a threaded hole (546) disposed on the clamping block (544). (544) a first chuck (546) at one end away from the threaded hole (545) and having an outer diameter greater than the width of the opening slot (542), a second chuck (547) arranged at one end of the threaded shaft (543) away from the clamping block (544) and having an outer diameter greater than the width of the opening slot (542), and a handle (548) arranged at one end of the threaded shaft (543) away from the clamping block (544); the buckle (51) is provided with a first elastic plate (6) extending obliquely upward toward the side close to the locking foot anchor tube (1) and the rear end thereof abutting against the outer wall of the locking foot anchor tube (1); a locking column (61) abutting against the steel bar (4) is arranged on the side of the first elastic plate (6);The end of the first elastic plate (6) away from the buckle (51) is integrally provided with a second elastic plate (62) extending obliquely upward toward the side away from the locking foot anchor tube (1); the first elastic plate (6) and the second elastic plate (62) are combined to form a V-shape; the end of the second elastic plate (62) away from the first elastic plate (6) is integrally provided with an arc-shaped elastic clamping rod (63) for the annular connecting rib (3) to be embedded; when the rubber pad (53) is flattened and the second elastic plate (62) moves upward, the annular connecting rib (3) embedded in the arc-shaped elastic clamping rod (63) is pressed against the upper side of the I-beam (2); the end of the arc-shaped elastic clamping rod (63) away from the second elastic plate (62) is provided with a guide portion (64) extending obliquely upward toward the side away from the locking foot anchor tube (1); a connecting spring (7) with both ends fixed to the clamping arm (52) is also provided between the two buckles (51). ;

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