A construction method for excavation and support of a tunnel anchor with a large dip angle

Abstract

The present application discloses a construction method for the excavation and support of a large dip tunnel anchor, which includes the steps of portal slope excavation, advanced pipe shed construction, arrangement of an automatic slag discharging device, and sectional excavation of the anchor hole. The anchor hole is divided into upper, middle, and lower sections for construction. The lower section of the anchor hole is divided into an upper excavation area and a lower excavation area. The upper section of the anchor hole, the middle section of the anchor hole, and the upper excavation area of the lower section of the anchor hole are all excavated by bench blasting, and muck trucks are used to transport the muck out of the anchor hole. The lower excavation area of the lower section of the anchor hole is first continuously blasted, and after the blasting is completed, an excavator is used for excavation, and a retaining structure and a muck transportation device are constructed. The muck transportation device transports the muck in the lower excavation area to the automatic slag discharging device for unloading. The present application has the effect of improving the construction efficiency of the excavation of the anchor hole of the large dip tunnel anchor.

Description

Technical Field

[0001] The present invention relates to the field of tunnel anchors, and more particularly to a construction method for excavation and support of a large-inclination tunnel anchor. Background Art

[0002] As a long-span bridge type, a suspension bridge needs to adopt tunnel anchors to ensure the safety of project construction. For a tunnel-type anchor block, it is necessary to excavate an anchor hole in bedrock. Different from the tunnels in highway construction, the anchor hole of a tunnel anchor needs to achieve large-inclination and large-section excavation, and it is necessary to ensure the stability of surrounding rock, which puts forward high requirements for mucking and support during the excavation construction of the anchor hole. After the construction of the tunnel anchor is completed, the surrounding rock and the anchor plug body jointly bear the main cable load. Therefore, during the excavation process of the anchor hole, it is necessary to minimize the disturbance to the surrounding rock.

[0003] In related technologies, the anchor hole of a tunnel anchor is constructed by controlled blasting, and a combination of drill-and-blast excavation and manual excavation is used. In parts that cannot be reached by an excavator, such as at the corners, manual excavation is used. The anchor hole is constructed according to the bench method. When the tunneling is relatively deep, a mucking system is set up, and a small excavator is used to cooperate with a mine car for mucking. However, in this construction method, for each completed cycle of advance, it is necessary to use a winch and a steel cable to lift the excavator out of the anchor hole, and then carry out the blasting for the next cycle. After the blasting is completed, the excavator is assisted by the winch and the steel cable to enter the anchor hole for the next cycle of excavation. For each cycle of advance, the excavator needs to enter and exit the anchor hole once, which is troublesome to operate and time-consuming, reducing the construction efficiency.

[0004] In view of the above related technologies, the applicant believes that there are the following defects: during the construction of the anchor hole of a large-inclination tunnel anchor, the excavator needs to enter and exit the anchor hole once for each cycle of advance, resulting in low construction efficiency. Summary of the Invention

[0005] In order to improve the construction efficiency of the excavation of the anchor hole of a large-inclination tunnel anchor, the present application provides a construction method for excavation and support of a large-inclination tunnel anchor.

[0006] The construction method for excavation and support of a large-inclination tunnel anchor provided by the present application adopts the following technical solutions:

[0007] A construction method for excavation and support of a large-inclination tunnel anchor includes the following steps:

[0008] Excavation of the entrance slope: According to the design drawings, determine the position of the entrance of the anchor hole, and then use an excavator to excavate the entrance slope until it stops at a set position from the tunnel anchor foundation;

[0009] Construction of the advanced pipe shed: After the excavation of the entrance slope is completed, construct a concrete lagging arch at the entrance position of the anchor hole. After the strength of the concrete lagging arch reaches the design requirements, use the concrete lagging arch as a fixed wall to construct the advanced support pipe shed;

[0010] Arrangement of automatic slag discharging device: Utilize the muck excavated from the portal slope to form a platform outside the portal, and then arrange the automatic slag discharging device on the platform;

[0011] Segmented excavation of the anchor hole: Divide the anchor hole into upper, middle, and lower sections. The inclination angles of the three sections of the anchor hole increase in sequence. The inclination angles of the upper and middle sections of the anchor hole satisfy the entry and exit of muck transport vehicles; the lower section of the anchor hole is divided into an upper excavation area and a lower excavation area. The inclination angle of the upper excavation area satisfies the entry and exit of muck transport vehicles. The upper section of the anchor hole, the middle section of the anchor hole, and the upper excavation area of the lower section of the anchor hole are all excavated by bench blasting. Use muck transport vehicles to transport the muck out of the anchor hole. During excavation, blast and excavate from top to bottom according to the construction section, with a cyclic footage. After each cycle is completed, construct a section of the retaining structure; the lower excavation area of the lower section of the anchor hole is first continuously blasted, and then an excavator is used for excavation after blasting. During excavation, push from outside to inside and build a muck transport device. The muck transport device is connected to the automatic slag discharging device. The muck transport device transports the muck in the lower excavation area to the automatic slag discharging device for unloading. For each section advanced in the lower excavation area, construct a section of the retaining structure and lengthen a section of the muck transport device until the lower excavation area is advanced to the elevation, completing the excavation and support of the tunnel anchor.

[0012] By adopting the above technical solutions, the inclination angles of the upper and middle sections of the anchor hole in this application satisfy the entry and exit of muck transport vehicles. The excavated muck can be directly transported out by muck transport vehicles, which is convenient for muck removal and has high muck removal efficiency; the lower section of the anchor hole is divided into an upper excavation area and a lower excavation area. The excavation of the upper excavation area is directly transported out by muck transport vehicles, which is convenient for muck removal. The excavation of the upper excavation area provides space for the advanced support and continuous blasting of the lower excavation area. After the blasting of the lower excavation area is completed, an excavator is used for excavation. The excavator does not need to repeatedly enter and exit the anchor hole during the excavation process and can continuously excavate the lower excavation area, with high construction efficiency.

[0013] Preferably, after each cycle is completed in the upper excavation area, drill multiple pipe holes on both sides of the lower excavation area. Install a support pipe in each pipe hole. After the support pipe is installed, grout is injected. The support pipe is connected to the retaining structure of the upper excavation area to form an integral structure, forming the advanced support of the lower excavation area.

[0014] By adopting the above technical solutions, the support pipes are inserted in advance on both sides of the lower excavation area, which can form advanced support for the lower excavation area and reduce the disturbance of the surrounding rock during the blasting excavation of the lower excavation area; and the support pipe is connected to the retaining structure of the upper excavation area to form an integral structure, making the subsequent connection between the retaining structure of the lower excavation area and the retaining structure of the upper excavation area closer and more firm.

[0015] Preferably, after the blasting of the lower excavation area is completed, first use an excavator to dig out the muck on both sides of the anchor hole and pile it up in the middle of the anchor hole, exposing the rock surfaces on both sides of the anchor hole. Then spray 3 - 5 cm of concrete on the rock surfaces on both sides of the anchor hole to form the initial sprayed concrete.

[0016] By adopting the above technical solution, first spray 3 - 5 cm of concrete on the rock surfaces on both sides of the anchor hole to form the primary sprayed concrete, which can provide preliminary protection for the rock surfaces on both sides of the anchor hole.

[0017] Preferably, the muck transportation device includes a bracket, a slide rail, a loading truck, and a winch. There are multiple slide rails, and the multiple slide rails are connected in sequence. The slide rails extend into the anchor hole. The slide rails are fixedly connected to the retaining structure in the lower excavation area through connecting rods. The bracket is arranged below the slide rails and forms a vertical support for the slide rails. The loading truck is installed on the slide rails, and the winch is installed outside the anchor hole. The winch is connected to the loading truck through a cable and drives the loading truck to move along the slide rails.

[0018] By adopting the above technical solution, after the slide rails are connected to the retaining structure, the retaining structure can limit the axial direction of the slide rails, and the bracket can support the slide rails vertically. The winch pulls the loading truck full of muck to the automatic slag - discharging device outside the anchor hole to unload the muck, and then returns to the anchor hole to transport muck.

[0019] Preferably, the bracket is slidably connected to the slide rails, and the bracket can expand and contract along the length direction of the slide rails.

[0020] By adopting the above technical solution, the bracket can expand and contract, which is convenient for the bracket to extend deeper into the anchor hole. For each section of the bracket extended, then install a section of the slide rail, and repeat the process until the excavation of the anchor hole is completed. There is no need to carry the bracket from outside the hole into the anchor hole for installation and lengthening every time a cycle is completed, improving the lengthening efficiency of the muck transportation device and thus improving the construction efficiency.

[0021] Preferably, the bracket includes multiple parallel support rods. The multiple support rods are divided into two rows, and both rows of support rods extend along the anchor hole. The adjacent support rods in different rows are connected by cross bars. Two diagonal rods are installed between the adjacent support rods in the same row, and the two diagonal rods intersect. The two ends of the diagonal rods slide on the two support rods respectively.

[0022] By adopting the above technical solution, the support rods support the slide rails vertically, and the diagonal rods can enable the bracket to expand and contract along the direction of the anchor hole, realizing the extension of the bracket.

[0023] Preferably, limit pins are respectively arranged on the diagonal rods, and the limit pins limit the expansion distance between the adjacent two support rods.

[0024] By adopting the above technical solution, when the limit pin on the diagonal rod catches another diagonal rod, the diagonal rod stops sliding, and the expansion distance between the two support rods cannot be further enlarged, thus keeping the support rods stably supporting the slide rails.

[0025] Preferably, wheels are installed at both ends of the support rod. The wheels are rotatably connected to the support rod, and a part of the wheels extends outside the end face of the support rod.

[0026] By adopting the above technical solution, the wheels can reduce the resistance of the support rod to unfold, facilitating the unfolding of the support rod.

[0027] In summary, the present application includes at least one of the following beneficial technical effects:

[0028] 1. The inclination angles of the upper anchor hole and the middle anchor hole of the present application meet the requirements for the entry and exit of muck transport vehicles. The excavated muck can be directly transported out by muck transport vehicles, facilitating muck removal and with high muck removal efficiency. The lower anchor hole is divided into an upper excavation area and a lower excavation area. The excavation of the upper excavation area is directly transported out by muck transport vehicles, facilitating muck removal. The excavation of the upper excavation area provides space for the advanced support and continuous blasting of the lower excavation area. After the blasting of the lower excavation area is completed, an excavator is used for excavation. During the excavation process, the excavator does not need to repeatedly enter and exit the anchor hole and can continuously excavate the lower excavation area, with high construction efficiency;

[0029] 2. Support pipes are inserted in advance on both sides of the downward excavation area, which can form advanced support for the lower excavation area and reduce the disturbance of the surrounding rock caused by the blasting excavation of the lower excavation area. The support pipes are connected to the retaining structure of the upper excavation area as an integral structure, making the subsequent connection between the retaining structures of the lower excavation area and the upper excavation area closer and more firm. After the blasting of the lower excavation area is completed, first use an excavator to dig out the muck on both sides of the anchor hole, and then spray 3 - 5 cm of concrete on the rock surfaces on both sides of the anchor hole to form a primary protection, which can provide preliminary protection for the rock surfaces on both sides of the anchor hole;

[0030] 3. Since the muck transport device is installed after the blasting of the lower excavation area, the muck transport device is not affected by the blasting of the lower excavation area. Therefore, the support of the muck transport device does not need to be fixedly connected to the slide rail and the ground. After the slide rail is connected to the retaining structure, the retaining structure can limit the axial direction of the slide rail, and the support only needs to support the vertical direction of the slide rail, so that the support can be set as a telescopic structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a flow chart of a construction method for excavating and supporting a large - inclination tunnel anchor in Embodiment 1 of the present application.

[0032] Figure 2 is a sectional view of the anchor hole in Embodiment 1 of the present application.

[0033] Figure 3 is a schematic view of the working face of the lower anchor hole in Embodiment 1 of the present application.

[0034] Figure 4 is a schematic view of muck transport in the lower excavation area in Embodiment 1 of the present application.

[0035] Figure 5 It is a schematic diagram of the excavation of the muck transportation device in the lower excavation area of the second embodiment of the present application.

[0036] Explanation of reference numerals:

[0037] 1. Upper anchor hole; 2. Middle anchor hole; 3. Lower anchor hole; 31. Upper excavation area; 32. Lower excavation area; 4. Automatic slag discharging device; 5. Muck transportation device; 51. Slide rail; 52. Connecting rod; 53. Support; 531. Support rod; 532. Diagonal rod; 533. Wheel; 534. Cross bar; 6. Enclosure structure; 7. Support pipe. Specific implementation manners

[0038] The following further elaborates on the present application in conjunction with the attached Figures 1-5 drawings.

[0039] The embodiment of the present application discloses a construction method for the excavation and support of a large - dip tunnel anchor.

[0040] Embodiment 1

[0041] Referring to Figure 1 , a construction method for the excavation and support of a large - dip tunnel anchor includes the following steps:

[0042] Excavation of the entrance slope: According to the design drawings, determine the position of the entrance of the anchor hole, and then use an excavator to excavate the entrance slope of the tunnel. Stop excavation when it reaches 30 cm above the foundation of the tunnel anchor. During the excavation process, it is necessary to ensure that the slope is smooth, without fragmentation or vibration, and promptly remove convex overhanging rocks, floating rocks, and muck pile debris. To ensure the safety of on - site construction during the rainy season and prevent surface water from flowing into the anchor hole during construction, a catch - water ditch and a retaining wall are set along the top of the surrounding slope of the entrance according to the terrain. The longitudinal slope of the bottom of the catch - water ditch is not less than 0.5%.

[0043] Advance pipe shed construction: After the excavation of the portal slope is completed, a concrete collar arch is poured at the portal position. The longitudinal length of the concrete collar arch is 1 m. The concrete collar arch is provided with two steel I-beam arch frames. According to the construction drawing, the spacing is 0.2 m, 0.6 m, and 0.2 m. The two steel I-beam arch frames are welded and fixed with steel bars. After the steel I-beam arch frames are processed in the steel bar processing factory, they are transported to the site for installation. During installation, they are accurately positioned according to the elevation measured by the surveyors and the installation control line of the arch frames, and the verticality of the arch frames is strictly checked to strictly control the arch frames in the same plane. After the installation of the steel I-beam arch frames is completed, the guide pipes are constructed. The guide pipes are positioned using the inclination angle of the steel I-beams. The plane position is lofted by the surveyors and spot-welded and fixed on the steel I-beams. The guide pipes are made of Φ127×4 mm hot-rolled steel pipes with a length of 1 m, a circumferential spacing of 40 cm, and an external insertion angle of 1°. The orifices of the guide pipes are blocked with gunny bags and other materials to prevent concrete from entering the guide pipes during concrete pouring and causing blockage. When the installation of the steel I-beam arch frames is completed and the positioning of the guide pipes is completed, the formwork installation of the collar arch is carried out. The formwork installation sequence is: bottom formwork installation → end formwork installation → collar arch formwork reinforcement → pump pipe installation. When installing the formwork, the firmness and tightness of the formwork must be controlled. After the installation of the formwork and pump pipes is completed and inspected and qualified, concrete pouring can be carried out. The concrete is poured symmetrically from the bottom upwards to prevent the formwork from deforming due to eccentric pressure. The concrete pouring must be vibrated in time to ensure the compactness of the concrete, and there shall be no phenomena of missed vibration or insufficient vibration. After pouring concrete in winter, geotextiles should be covered. After the concrete pouring is completed, watering and curing should be carried out in time. After the concrete has hardened, the formwork can be removed. After the strength of the concrete collar arch reaches the design requirements, the construction of the concrete collar arch is completed. After the construction of the concrete collar arch is completed, the concrete collar arch is used as a fixed wall to construct the advance support pipe shed 7. When constructing the advance support pipe shed 7, within the 120° range of the arch, advance steel pipes are arranged at a circumferential spacing of 40 cm. Φ108×6 mm hot-rolled seamless steel pipes are used and installed in sections, and the two sections are connected with screw threads. After the pipe shed construction is completed, the pipe shed grouting process is carried out.

[0044] Arrangement of the automatic slag discharging device 4: Utilize the muck excavated from the portal slope to form a platform outside the portal, and then arrange the automatic slag discharging device 4 on the platform. The automatic slag discharging device 4 is a conventional technology and is the same as the slag discharging method of the mine tunnel.

[0045] Segmental excavation of the anchor hole: Refer to Figure 2 and Figure 3, the anchor hole is divided into three sections: upper, middle and lower. The inclination angles of the three sections of the anchor hole are gradually increased. The inclination angles of the upper anchor hole 1 and the middle anchor hole 2 meet the requirements for the entry and exit of slag transportation vehicles. The inclination angle of the upper anchor hole 1 in this embodiment is 5°, and the inclination angle of the middle anchor hole 2 is 15°. The lower anchor hole 3 is divided into an upper excavation area 31 and a lower excavation area 32. The inclination angle of the upper excavation area 31 meets the requirements for the entry and exit of slag transportation vehicles. The inclination angle of the upper excavation area 31 in this embodiment is 15°. The upper excavation area 31 of the upper anchor hole 1, the middle anchor hole 2 and the lower anchor hole 3 are all excavated by step blasting. Excavators are used to remove, collect and load slag. Slag transportation vehicles are used to transport the slag out of the anchor hole. During excavation, blasting is carried out from top to bottom according to the construction section, and the advance is cyclic. After each cycle is completed, a section of the enclosure structure 6 is constructed. The lower excavation area 32 of the lower anchor hole 3 is first blasted continuously, and then an excavator is used for excavation after the blasting is completed. The excavation is advanced from the outside to the inside, and a slag transportation device 5 is built. The slag transportation device 5 is connected to the automatic slag unloading device 4. The slag transportation device 5 transports the soil and slag in the lower excavation area 32 to the automatic slag unloading device 4 for unloading, and the slag is loaded by a dump truck and transported to a designated dump site. A retaining structure 6 is constructed every time the lower excavation area 32 is advanced a certain distance, and the slag transportation device 5 is lengthened until the lower excavation area 32 is advanced to the elevation, completing the tunnel anchor excavation and support.

[0046] Reference Figure 4 The construction process of the upper anchor hole 1, the middle anchor hole 2 and the retaining structure 6 of the upper excavation area 31 is the same, and the construction sequence is: initial spraying of concrete → anchor drilling → anchor installation → grouting → hanging steel mesh → erecting steel frame → spraying of concrete to the designed thickness. In order to ensure the strong pre-supporting capacity of the steel frame, each steel frame must be connected as a whole through anchors and longitudinal connecting rods 52, and at the same time tightly supported by the surrounding rock. After each cycle of the upper excavation area 31 is completed, multiple pipe holes are drilled on both sides of the lower excavation area 32, and a supporting pipe 7 is installed in each pipe hole. The supporting pipe 7 is an anchor rod, and the lower end of the supporting pipe 7 is more than 1m lower than the elevation of the lower excavation area 32. After the supporting pipe 7 is installed, grouting is performed, and the grouting pressure is not less than the set value. The upper end of the supporting pipe 7 is fixedly connected to the steel frame of the upper excavation area 31, so that the retaining structure 6 of the upper excavation area 31 and the retaining structure 6 of the lower excavation area 32 are connected as an integrated structure. Inserting support pipes 7 in advance on both sides of the lower excavation area 32 before blasting can reduce the disturbance of the surrounding rock caused by blasting and excavation in the lower excavation area 32. The construction sequence of the retaining structure 6 of the lower excavation area 32 is the same as that of the retaining structure 6 of the upper excavation area 31, and the anchor drilling of the lower excavation area 32 needs to avoid the support pipes 7.

[0047] In another embodiment, after the blasting of the lower excavation area 32 is completed, an excavator is first used to dig out the debris on both sides of the anchor hole and pile it in the middle of the anchor hole to expose the rock surface on both sides of the anchor hole, and then 3-5 cm of concrete is sprayed on the rock surface on both sides of the anchor hole to form the initial sprayed concrete of the lower excavation area 32 to prevent water seepage and falling rocks from the rock wall.

[0048] In another embodiment, after the excavation of the upper excavation area 31 is completed, a lateral support can be erected on the retaining structure 6 of the upper excavation area 31 to improve the stability of the retaining structure 6 of the upper excavation area 31 during the blasting of the lower excavation area 32, and the lateral support is removed after the blasting of the lower excavation area 32 is completed.

[0049] The implementation principle of the construction method for the excavation and support of a large dip tunnel anchor in the embodiment of the present application is as follows: The dips of the upper anchor hole 1 and the middle anchor hole 2 of the present application meet the entry and exit of the muck transport vehicle, and the excavated muck can be directly transported out by the muck transport vehicle, which is convenient for muck removal and has a high muck removal efficiency. The lower anchor hole 3 is divided into an upper excavation area 31 and a lower excavation area 32. The excavation of the upper excavation area 31 is directly transported out by the muck transport vehicle, which is convenient for muck removal. The excavation of the upper excavation area 31 provides space for the advanced support and continuous blasting of the lower excavation area 32. After the blasting of the lower excavation area 32 is completed, an excavator is used for excavation. The excavator can continuously dig the soil and does not need to repeatedly enter and exit the anchor hole during the excavation process, and can continuously excavate the lower excavation area 32, with high construction efficiency.

[0050] Embodiment 2

[0051] Refer to Figure 5, A construction method for excavation and support of a large - dip tunnel anchor, which is different from the first embodiment, is that the muck transportation device 5 includes a bracket 53, a slide rail 51, a soil loading vehicle, and a winch. There are multiple slide rails 51, and the multiple slide rails 51 are connected in sequence. The slide rail 51 extends into the anchor hole. The slide rail 51 is fixedly connected to the retaining structure 6 of the lower excavation area 32 through a connecting rod 52. When each section of the retaining structure 6 in the lower excavation area 32 is constructed, a row of embedded bolts is pre - embedded. The connecting rod 52 is fixedly connected to the embedded bolts by bolts. The bracket 53 is arranged below the slide rail 51 and forms a vertical support for the slide rail 51. The soil loading vehicle is installed on the slide rail 51, and the winch is installed outside the anchor hole. The winch drives the soil loading vehicle to move along the slide rail 51 through a winding rope. The bracket 53 includes multiple parallel support rods 531. The multiple support rods 531 are divided into two rows, and both rows of support rods 531 extend along the anchor hole. Two adjacent support rods 531 in different rows are fixedly connected by a cross bar 534. Two diagonal rods 532 are installed between two adjacent support rods 531 in the same row. The two diagonal rods 532 intersect. Chutes along the length direction of the support rod 531 are respectively arranged on both sides of the support rod 531. The two ends of the diagonal rod 532 are respectively slidably installed in the chutes of two adjacent support rods 531 and can slide along the chutes. The two adjacent support rods 531 in the same row can be expanded and contracted. A limit pin is arranged in the middle of the diagonal rod 532. The limit pin is arranged on the opposite side of the two diagonal rods 532, and the limit pin is perpendicular to the diagonal rod 532. The limit pin restricts the expansion distance between two adjacent support rods 531 in the same row. Grooves are respectively arranged at both ends of the support rod 531, and wheels 533 are installed in the grooves. The wheels 533 are rotatably connected to the support rod 531, and a part of the wheels 533 extends outside the end face of the support rod 531. The upper end of the bracket 53 is slidably connected to the slide rail 51, and the bracket 53 can be telescoped along the length direction of the slide rail 51. During the process of using an excavator to excavate the blasted soil, a rope is used to tie the retracted bracket 53 to prevent the retracted bracket 53 from automatically expanding. When the bracket 53 needs to be expanded, the rope is untied. After the bracket 53 is fully expanded, the retracted bracket 53 is tied up with a rope again.

[0052] In another embodiment, according to the height of the lower excavation area 32, the lower excavation area 32 is divided into multiple areas from top to bottom for blasting excavation. Blasting excavation is carried out from top to bottom in sequence. Each time, only one area is excavated. After each area is excavated, the muck transportation device 5 is removed, and then blasting is carried out on the next area, and then the muck transportation device 5 is excavated and installed. Since the bracket 53 can be telescoped, the installation and disassembly of the muck transportation device 5 are relatively convenient, and the time required for both installation and disassembly is less.

[0053] In another embodiment, during the excavation of the lower excavation area 32, the muck transportation device 5 of the third embodiment of the present application is installed in the lower anchor hole 3, while conventional muck transportation devices 5 are installed in the upper anchor hole 1 and the middle anchor hole 2, and the muck transportation devices 5 in the lower excavation area 32, the middle anchor hole 2 and the upper anchor hole 1 are connected into a whole.

[0054] The implementation principle of the above embodiment is as follows: Since the muck transportation device 5 is installed after the blasting of the lower excavation area 32 is completed, the muck transportation device 5 is not affected by the vibration generated by the blasting of the lower excavation area 32. Therefore, the bracket 53 of the muck transportation device 5 does not need to be fixedly connected to the slide rail 51 and the ground. After the slide rail 51 is connected to the retaining structure 6, the retaining structure 6 can limit the axial and radial directions of the slide rail 51, and the bracket 53 only needs to support the vertical direction of the slide rail 51, so that the bracket 53 can be set as a telescopic structure. The ability of the bracket 53 to be telescopic enables the muck transportation device 5 to be quickly installed and disassembled. When installing the muck transportation device 5, the bracket 53 is sequentially unfolded from outside the hole to inside the hole, and the end close to the hole is unfolded to the maximum distance, while the ends far from the hole are contracted and overlapped together. When lengthening the muck transportation device 5, first, the support rods 531 of the part where the bracket 53 is contracted and overlapped together and close to the hole are sequentially unfolded, then the lengthened slide rail 51 is installed on the upper part of the bracket 53, and then the slide rail 51 is fixed to the embedded bolts of the retaining structure 6 by connection. The lengthening of the muck transportation device 5 is convenient and fast, and the bracket 53 does not need to be transported into the anchor hole for installation in a loose part manner, saving the time for transporting and assembling the bracket 53 and improving the installation efficiency of the bracket 53. In addition, the bracket 53 does not need to be fixed to the floor, which does not damage the floor of the anchor hole and is beneficial to the subsequent hoisting of the dispersion saddle.

[0055] The above are all the preferred embodiments of the present application. Without restricting the protection scope of the present application accordingly, therefore: Any equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A construction method for excavation and support of a large - dip tunnel anchor, characterized in that, it includes the following steps: Excavation of the entrance slope: According to the design drawings, determine the entrance position of the anchor hole, and then use an excavator to excavate the entrance slope until it stops at a set position from the tunnel anchor foundation; Construction of the advanced pipe shed: After the excavation of the entrance slope is completed, construct a concrete socket arch at the entrance position of the anchor hole. After the strength of the concrete socket arch reaches the design requirements, use the concrete socket arch as a fixed wall to construct the advanced support pipe (7) shed; Arrangement of the automatic slag - discharging device (4): Use the muck from the excavation of the entrance slope to form a platform outside the entrance, and then install the automatic slag - discharging device (4) on the platform; Segmented excavation of the anchor hole: Divide the anchor hole into upper, middle, and lower sections. The inclination angles of the three sections of the anchor hole increase in sequence. The inclination angles of the upper - section anchor hole (1) and the middle - section anchor hole (2) are suitable for the entry and exit of muck - transporting vehicles; the lower - section anchor hole (3) is divided into an upper excavation area (31) and a lower excavation area (32). The inclination angle of the upper excavation area (31) is suitable for the entry and exit of muck - transporting vehicles. The upper - section anchor hole (1), the middle - section anchor hole (2), and the upper excavation area (31) of the lower - section anchor hole (3) are all excavated by bench - cut blasting. Use muck - transporting vehicles to transport the muck out of the anchor hole. During excavation, blast and excavate from top to bottom according to the construction section, with a cyclic footage. After each cycle is completed, construct a section of the retaining structure (6); the lower excavation area (32) of the lower - section anchor hole (3) is first continuously blasted, and after blasting is completed, use an excavator to excavate, and construct the retaining structure (6) and the muck - transporting device (5). The muck - transporting device (5) is connected to the automatic slag - discharging device (4). The muck - transporting device (5) transports the muck in the lower excavation area (32) to the automatic slag - discharging device (4) for unloading until the lower excavation area (32) is advanced to the elevation, completing the excavation and support of the tunnel anchor.

2. The construction method for excavation and support of a large - dip tunnel anchor according to claim 1, characterized in that: After each cycle of the upper excavation area (31) is completed, drill a plurality of pipe holes on both sides of the lower excavation area (32). Install a support pipe (7) in each pipe hole. After the support pipe (7) is installed, grout is injected. The support pipe (7) is connected to the retaining structure (6) of the upper excavation area (31) to form an integral structure, forming the advanced support for the lower excavation area (32).

3. The construction method for excavation and support of a large - dip tunnel anchor according to claim 1, characterized in that: After the blasting of the lower excavation area (32) is completed, first use an excavator to dig out the muck on both sides of the anchor hole and pile it up in the middle of the anchor hole, exposing the rock surfaces on both sides of the anchor hole. Then spray 3 - 5 cm of concrete on the rock surfaces on both sides of the anchor hole to form the primary sprayed concrete.

4. The construction method for excavation and support of a large - dip tunnel anchor according to claim 1, characterized in that: The muck transportation device (5) includes a bracket (53), a slide rail (51), a soil loading vehicle, and a winch. A plurality of the slide rails (51) are provided, and the plurality of slide rails (51) are connected in sequence. The slide rails (51) extend into the anchor hole. The slide rails (51) are fixedly connected to the enclosure structure (6) of the lower excavation area (32) through a connecting rod (52). The bracket (53) is arranged below the slide rails (51) and forms a vertical support for the slide rails (51). The soil loading vehicle is installed on the slide rails (51). The winch is installed outside the anchor hole. The winch is connected to the soil loading vehicle through a winding rope and drives the soil loading vehicle to move along the slide rails (51).

5. A construction method for excavating and supporting a large-inclination tunnel anchor according to claim 4, characterized in that: The bracket (53) is slidably connected to the slide rail (51), and the bracket (53) can expand and contract along the length direction of the slide rail (51).

6. A construction method for excavating and supporting a large-inclination tunnel anchor according to claim 5, characterized in that: The bracket (53) includes a plurality of parallel support rods (531). The plurality of support rods (531) are divided into two rows. Both rows of support rods (531) extend along the anchor hole. Two adjacent support rods (531) in different rows are connected by a cross bar (534). Two diagonal rods (532) are installed between two adjacent support rods (531) in the same row. The two diagonal rods (532) intersect. The two ends of the diagonal rods (532) respectively slide on the two support rods (531).

7. A construction method for excavating and supporting a large-inclination tunnel anchor according to claim 6, characterized in that: Limit pins are respectively arranged on the diagonal rods (532), and the limit pins limit the expansion distance between two adjacent support rods (531).

8. A construction method for excavating and supporting a large-inclination tunnel anchor according to claim 6, characterized in that: Wheels (533) are respectively installed at both ends of the support rod (531). The wheels (533) are rotatably connected to the support rod (531), and a part of the wheels (533) extends outside the end face of the support rod (531).

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