Shaft construction method under environmentally sensitive areas or space-constrained conditions

Abstract

The present invention provides a method for constructing a vertical shaft under environmentally sensitive areas or space - restricted conditions, comprising the following steps: Excavate the first inclined shaft to the first depth according to the position of the inclined - shaft wellhead, then switch to horizontal excavation of a maintenance and construction auxiliary passage, and excavate the upper area of the vertical - shaft operation area; Continue to excavate the second inclined shaft obliquely downward from the bottom of the first inclined shaft, and then switch to horizontal excavation to successively excavate a drift, the lower area of the vertical - shaft operation area, and the cross - tunnel operation area; Drill a rope - winding inclined hole obliquely downward from the side wall of the upper area of the vertical - shaft operation area to the cross - tunnel operation area; Drill a temporary slag - chute hole downward from the bottom of the upper area of the vertical - shaft operation area to the lower area of the vertical - shaft operation area; Excavate downward from the upper area of the vertical - shaft operation area to the lower area; The vertical - shaft operation area is excavated in an upright dumbbell shape; Excavate the vertical - shaft section downward from the lower area of the vertical - shaft operation area to connect with the underground tunnel. The present invention can solve the problem of difficult construction of a vertical shaft to connect the ground and the underground tunnel under environmentally sensitive areas and space - restricted conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel construction, and particularly to a method for constructing a vertical shaft under environmentally sensitive areas or space-limited conditions. Background Art

[0002] For extra-long mountain tunnels in related industries such as expressways and railways, during the construction process, construction auxiliary channels need to be set up to increase the working face, or ventilation and smoke exhaust channels need to be set up for ventilation and smoke exhaust during the subsequent operation of the tunnel. This type of channel generally excavates a vertical shaft above the tunnel to connect the ground with the underground highway or railway tunnel to form a channel. During the process of excavating the vertical shaft, when constructing the site at the wellhead, it is easy to cause large-scale environmental damage to the surrounding surface of the wellhead, and there is also a need to build access roads several kilometers or even dozens of kilometers long, which will also damage the surface environment along the way.

[0003] In recent years, with the improvement of national environmental protection and the intensification of land resource utilization, for some environmentally sensitive areas, such as natural ecological reserves, when the ideal vertical shaft wellhead position is calculated according to the mountain topography and geomorphology conditions and is exactly located within the natural reserve, directly excavating the vertical shaft will cause large-scale environmental damage within the natural reserve. Another example is that the terrain above the vertical shaft wellhead position is steep and space-limited, and there is a fault fracture zone in the rock mass below the vertical shaft wellhead position. In such special environmental conditions, it is difficult to directly excavate the vertical shaft for construction.

[0004] Therefore, there is an urgent need for a method for constructing a vertical shaft and connecting the ground with the underground tunnel under environmentally sensitive areas and space-limited conditions. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention provides a method for constructing a vertical shaft under environmentally sensitive areas or space-limited conditions to solve the technical problem of difficult construction of connecting the ground with the underground tunnel by constructing a vertical shaft under environmentally sensitive areas and space-limited conditions in the prior art.

[0006] The technical solution adopted by the present invention is as follows: In the first aspect, a method for constructing a vertical shaft under environmentally sensitive areas or space-limited conditions is provided.

[0007] In a first implementable manner, it includes the following steps:

[0008] Excavate the first inclined shaft according to the inclined shaft wellhead position and excavate to the first depth;

[0009] Connect the first inclined shaft and turn to horizontal excavation of the maintenance and construction auxiliary channel at the first depth and excavate to the preset position of the vertical shaft operation area;

[0010] Connect to the maintenance and construction auxiliary passage, and carry out the excavation and support of the upper area of the shaft operation area at the preset position in the shaft operation area;

[0011] Continue to excavate the second inclined shaft obliquely downward from the bottom of the first inclined shaft until the second depth, which is the same as the floor elevation of the lower area of the shaft operation area;

[0012] Connect to the second inclined shaft, and at the second depth, turn to the horizontal direction and sequentially excavate the adit, the lower area of the shaft operation area, and the cross tunnel operation area;

[0013] Drill the rope winding inclined hole obliquely downward from the side wall of the upper area of the shaft operation area to the cross tunnel operation area;

[0014] Drill the temporary slag chute hole downward from the bottom of the upper area of the shaft operation area to the lower area of the shaft operation area;

[0015] Excavate downward from the upper area of the shaft operation area to the lower area of the shaft operation area; the muck generated during the excavation process falls to the lower area of the shaft operation area through the temporary slag chute hole, and then is discharged through the adit, the second inclined shaft, and the first inclined shaft;

[0016] Arrange the auxiliary devices and equipment required for the construction of the shaft section in the shaft operation area;

[0017] Excavate the shaft section downward from the bottom of the lower area of the shaft operation area until it is connected to the underground tunnel.

[0018] As can be seen from the technical solution of the first implementable manner, the beneficial technical effects of the present invention are as follows: It is possible to bypass the environmentally sensitive area and the space-limited conditions, and directly carry out shaft construction in the underground space mountain body to connect the ground and the underground tunnel.

[0019] Combined with the first implementable manner, in the second implementable manner, the support of the upper area of the shaft operation area includes:

[0020] Bind the rock anchor steel bars and cast the concrete in accordance with the designed rock anchor shape. After the concrete reaches the designed strength, drill holes to install the mortar anchor bars to fix the rock anchor.

[0021] Combined with the first implementable manner, in the third implementable manner, the cross tunnel operation area serves as the fixing and operation work area for the hoisting equipment, and the adit serves as the feeding and muck discharging channel.

[0022] Combined with the first implementable manner, in the fourth implementable manner, tapered rock anchors are provided at the side wall position of the upper area of the shaft operation area;

[0023] The reinforced concrete cross beam is connected to the tapered rock anchor, and guide rails are provided on the reinforced concrete cross beam;

[0024] The walking truss and the guide rail are slidably connected through rollers, and a skywheel is provided in the middle of the walking truss.

[0025] The skywheel is used in cooperation with a winch to lift and lower the working suspension platform through a steel wire rope.

[0026] Combined with the first implementation method, in the fifth implementation method, an excavation shaft section is excavated downward from the bottom of the shaft operation area until it communicates with the underground tunnel, including:

[0027] At the bottom of the shaft operation area and at the central position of the shaft, a pilot hole is drilled vertically downward until it communicates with the underground tunnel.

[0028] Then, the pilot hole is reamed from bottom to top until the top of the shaft to form a shaft slag chute.

[0029] At the bottom of the shaft operation area, drilling and blasting are carried out according to the designed shaft contour line, and the slag is discharged through the shaft slag chute and the underground tunnel.

[0030] The outer layer of the shaft wall is supported, and corrugated steel plates are assembled, hung and fixed on the shaft wall.

[0031] According to the cyclic operation sequence of drilling, blasting, slag discharging and outer layer support, the excavation is gradually carried out towards the bottom of the shaft; when excavating to a preset unit depth, precast wall seats are installed on the shaft wall.

[0032] When the excavation reaches the bottom of the shaft and communicates with the underground tunnel, precast reinforced concrete segments are installed from bottom to top in a splicing manner close to the corrugated steel plates until the top of the shaft.

[0033] It can be seen from the technical solution of the fifth implementation method that the beneficial technical effects of the present invention are as follows: adopting the structure of double-layer support of corrugated steel plates and precast reinforced concrete segments plus an intermediate buffer layer, it can be directly and quickly assembled during construction, with fast speed, safety and controllable quality.

[0034] Combined with the fifth implementation method, in the sixth implementation method, the bottom edge of the upper corrugated steel plate and the top edge of the lower corrugated steel plate are connected by threaded anchor bolts, and the gap between the corrugated steel plate and the surrounding rock is filled and compacted by grouting.

[0035] Combined with the fifth implementation method, in the seventh implementation method, the precast wall seat is provided with reserved holes, the trapezoidal wall seat cross-section of the precast wall seat has the same thickness as the precast reinforced concrete segment, and the bottom cross-section width of the precast wall seat extends towards the periphery;

[0036] The precast wall seat is provided with circumferential connection holes at both ends close to the precast reinforced concrete segment; a plurality of precast wall seats are connected and closed into a ring by threaded anchor bolts, and anchor rods are driven in along the peripheral circumference.

[0037] Combined with the fifth implementation method, in the eighth implementation method, the precast reinforced concrete segment is a cavity structure, with an inner edge in an arc shape and an outer edge in a wavy shape, which matches the wave height of the corrugated steel plate;

[0038] The precast reinforced concrete segments are provided with circumferential and vertical connection holes in the horizontal and vertical directions respectively, and are connected into a ring by threaded anchor bolts, and an elastic gasket is provided at the end.

[0039] Combined with the fifth implementation method, in the ninth implementation method, a non-woven fabric is laid between the precast reinforced concrete segment and the corrugated steel plate.

[0040] In the second aspect, a shaft is provided, which is used to connect the ground and the underground tunnel, and is constructed by using any one of the shaft construction methods in the first to ninth implementation methods under environmentally sensitive areas or space-limited conditions. Brief Description of the Drawings

[0041] In order to more clearly illustrate the specific implementation manners of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required to be used in the description of the specific implementation manners or the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to actual scale.

[0042] Figure 1 It is a schematic plan view of the shaft construction in Embodiment 1 of the present invention;

[0043] Figure 2 It is a schematic view of the excavation of the shaft operation area in Embodiment 1 of the present invention in an upright dumbbell shape;

[0044] Figure 3 It is a schematic plan view of the shaft operation area in Embodiment 1 of the present invention;

[0045] Figure 4 It is a schematic layout diagram of the shaft construction equipment in Embodiment 1 of the present invention;

[0046] Figure 5 It is a schematic view of the excavation of the shaft section in Embodiment 1 of the present invention;

[0047] Figure 6 It is a schematic view of the outer lining structure of the shaft in Embodiment 1 of the present invention;

[0048] Figure 7 It is a schematic view of the assembly of the corrugated steel plate of the outer lining of the shaft in Embodiment 1 of the present invention;

[0049] Figure 8 It is a schematic view of installing a precast wall seat on the shaft wall in Embodiment 1 of the present invention;

[0050] Reference Numerals:

[0051] 1 - First inclined shaft, 2 - Maintenance and construction auxiliary passage, 3 - Shaft operation area, 31 - Upper area of the shaft operation area, 32 - Middle area of the shaft operation area, 33 - Lower area of the shaft operation area, 4 - Second inclined shaft, 5 - Adit, 6 - Cross - tunnel operation area, 7 - Rope - winding inclined hole, 8 - Temporary slag - chute hole, 9 - Shaft section, 11 - Ground surface, 12 - Underground tunnel, h1 - First depth, h1 - Second depth, h1 - Third depth;

[0052] 311 - Conical rock anchor, 312 - Reinforced concrete cross - beam, 313 - Walking truss, 314 - Guide rail, 315 - Roller, 316 - Sheave, 317 - Winch, 318 - Steel rope, 319 - Working platform;

[0053] 911 - Reinforcement mesh, 912 - Concrete filling layer, 913 - Anchor rod, 914 - Threaded anchor bolt, 915 - Prefabricated wall seat, 916 - Corrugated steel plate, 917 - Prefabricated reinforced concrete segment, 918 - Elastic gasket. Detailed implementation mode

[0054] The embodiments of the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solutions of the present invention more clearly, so they are only examples and cannot be used to limit the protection scope of the present invention.

[0055] It should be noted that unless otherwise specified, the technical terms or scientific terms used in this application should have the ordinary meanings understood by those skilled in the art to which the present invention belongs.

[0056] Embodiment 1

[0057] Before the shaft construction excavation, it is necessary to determine the connection position between the shaft and the underground tunnel, and the inclined - shaft excavation wellhead position according to the design construction documents and the on - site geological exploration situation. The inclined - shaft excavation wellhead position can be selected outside the environmentally sensitive area and avoid special environmental conditions with limited space at the same time. For determining the connection position between the shaft and the underground tunnel and the inclined - shaft excavation wellhead position, any implementable method in the prior art can be used.

[0058] When the position is determined, during the actual construction of the shaft construction, it is also necessary to set up a shaft operation area above the downward excavation area of the shaft in the underground rock and soil layer to provide working and turnover space for construction equipment, and operation space for feeding and slag discharging. Currently, according to the needs of the actual project, the height of the shaft operation area is usually 15 - 30m, and the area of the shaft operation area is larger than the cross - sectional area of the shaft.

[0059] Combined with the above description, as Figure 1 shown, the shaft construction method includes the following steps:

[0060] S1. Excavate the first inclined shaft according to the position of the inclined shaft wellhead until the first depth is reached.

[0061] Excavate the first inclined shaft at the selected inclined shaft wellhead position until the first depth is reached, such as Figure 1 the first inclined shaft 1 in Figure 1 . In a specific implementation, the first depth is at the elevation h1 position. Preferably, h1 is the position 7 - 15 m downward from the crown of the vertical shaft operation area 3, leaving a construction operation space for the excavation of the vertical shaft operation area.

[0062] S2. Connect to the first inclined shaft and start horizontal excavation of the maintenance and construction auxiliary passage at the first depth until the preset position of the vertical shaft operation area is reached.

[0063] As shown in Figure 1 , at the first depth elevation h1, connect to the first inclined shaft and excavate the maintenance and construction auxiliary passage 2 horizontally until the preset position where the vertical shaft operation area is located in the design construction documents is reached.

[0064] The excavated maintenance and construction auxiliary passage can, in the next step, provide a passage for feeding and mucking when the upper area of the vertical shaft operation area is under excavation construction.

[0065] S3. Connect to the maintenance and construction auxiliary passage and carry out the excavation and support of the upper area of the vertical shaft operation area at the preset position of the vertical shaft operation area.

[0066] Connect to the first inclined shaft and excavate the upper area 31 of the vertical shaft operation area at the preset position where the vertical shaft operation area should be set. As shown in Figure 1 , the bottom plate of the excavated upper area of the vertical shaft operation area is at the third depth, that is, the h3 elevation position, and the top of the upper area of the vertical shaft operation area is preferably a circular crown.

[0067] Since a reinforced concrete cross beam needs to be installed in the upper area of the vertical shaft operation area, the following support method is adopted for the upper area of the vertical shaft operation area: Tie the rock anchor steel bars and cast concrete according to the designed rock anchor shape. After the concrete reaches the designed strength, drill holes to install mortar bolts to fix the rock anchor. Preferably, the length of the mortar bolts is selected as 12 m.

[0068] S4. Connect to the bottom of the first inclined shaft and continue to excavate the second inclined shaft obliquely downward until the second depth is reached, and the second depth is the same as the bottom plate elevation of the lower area of the vertical shaft operation area.

[0069] The first inclined shaft continues to be excavated obliquely downward from the first depth elevation h1 position until the second depth elevation h2 position is reached, and h2 is the same as the bottom plate elevation of the lower area of the vertical shaft operation area, forming the second inclined shaft 4.

[0070] S5. Connect to the second inclined shaft, and at the second depth, turn horizontally and sequentially excavate the adit, the lower area of the vertical shaft operation area, and the cross tunnel operation area.

[0071] After the second inclined shaft is excavated, at the elevation h2 of the second depth, connect to the second inclined shaft and turn horizontally to excavate the adit 5. After the adit is excavated, continue to excavate the lower area 33 of the vertical shaft operation area forward horizontally. After the lower area 33 of the vertical shaft operation area is excavated, continue to excavate the cross tunnel operation area 6 forward horizontally. As Figure 1 shown, the excavated cross tunnel operation area 6, the lower area 33 of the vertical shaft operation area, and the adit 5 are sequentially connected. In a specific implementation manner, the width of the adit and the cross tunnel operation area is not less than 5 m to facilitate the entry and exit of engineering equipment.

[0072] S6. Drill a rope winding inclined hole obliquely downward from the side wall of the upper area of the vertical shaft operation area to the cross tunnel operation area.

[0073] To the upper area 31 of the vertical shaft operation area, as Figure 1 shown, drill an inclined hole obliquely downward at the side wall position from the elevation h3 of the floor of this area. This hole is the rope winding inclined hole, which is used for the rope winding routing between the winch and the sheave during the subsequent excavation of the vertical shaft. The rope winding inclined hole connects the upper area of the vertical shaft operation area and the cross tunnel operation area. In a specific implementation manner, the diameter of the rope winding inclined hole is 0.8 - 1 m.

[0074] S7. Drill a temporary slag chute hole downward from the bottom of the upper area of the vertical shaft operation area to the lower area of the vertical shaft operation area.

[0075] Drill a hole at the elevation h3 of the floor of the upper area of the vertical shaft operation area. This hole is the temporary slag chute hole 8. The temporary slag chute hole connects the upper area of the vertical shaft operation area and the lower area of the vertical shaft operation area. In a specific implementation manner, the diameter of the temporary slag chute hole is 1 - 1.2 m. The drilled temporary slag chute hole can provide a channel for feeding and discharging slag during the excavation construction of the middle area of the vertical shaft operation area in the next step.

[0076] S8. Excavate downward from the upper area of the vertical shaft operation area to the lower area of the vertical shaft operation area; the muck generated during the excavation process goes down to the lower area of the vertical shaft operation area through the temporary slag chute hole, and then is discharged through the adit, the second inclined shaft, and the first inclined shaft.

[0077] In this step, excavate downward from the upper area of the vertical shaft operation area to the lower area of the vertical shaft operation area to form the middle area 32 of the vertical shaft operation area. The middle area of the vertical shaft operation area connects the upper area and the lower area of the vertical shaft operation area.

[0078] With the temporary slag chute 8, the muck generated during the excavation process can easily fall through the temporary slag chute under the action of its own gravity to the lower area of the already excavated shaft operation area, and then be discharged through the adit, the second inclined shaft, and the first inclined shaft; instead of transporting the muck upward to the maintenance and construction auxiliary passage 2 for discharging, which saves construction time and cost.

[0079] Through steps S1 - S8, a shaft operation area can be excavated above the underground tunnel and below the ground surface, serving as an operation platform for the subsequent shaft section excavation construction. As Figure 3 shown, the projection of the shaft operation area and the adit on the horizontal plane forms a "cross" - shaped plane. Two pairs of rock bolts are symmetrically arranged on the side walls of the shaft operation area. The cross - tunnel operation area serves as the fixing and operation work area for the hoisting equipment, and the adit serves as the feeding and muck - discharging channel. The functional partitions on the left and right sides of the shaft operation area are clear, and the overall structure is evenly stressed.

[0080] The shaft operation area is excavated in an upright dumbbell shape. The excavation sequence of the shaft operation area is summarized as follows: First, excavate the upper area of the shaft operation area, then the lower area, and finally the middle area through the slag chutes in the upper and lower areas.

[0081] In a specific implementation manner, the structures of each part formed by the above - mentioned steps are as follows:

[0082] The first inclined shaft and the second inclined shaft: circular arch + straight wall shape;

[0083] The adit: circular arch + straight wall shape;

[0084] The cross - tunnel operation area: circular arch + straight wall shape, with hoisting winches, steady cars and other hoisting equipment and staff operation areas arranged.

[0085] The shaft operation area: three - centered circular arch + straight wall shape.

[0086] In a specific implementation manner, the first inclined shaft, the second inclined shaft, the adit, the middle area and the lower area of the cross - tunnel operation area and the shaft operation area need to be supported during the excavation process. The specific support methods are as follows: To improve the muck - discharging utilization rate of the cross - section, mainly temporary supports such as rock bolts, shotcrete, and steel mesh are used; a layer of secondary lining reinforced concrete lining structure can be added later as a permanent lining to enhance the structural safety reserve. Examples of the temporary support parameters for the inclined shaft, adit and shaft operation area are as follows:

[0087] φ8 steel mesh, @25×25cm;

[0088] 20b(18) I - shaped steel arch frame, @1m;

[0089] φ22 mortar rock bolts, L = 3.0m(4.0m), @1.5m;

[0090] 26 cm thick C30 steel fiber shotcrete.

[0091] S9. Arrange auxiliary devices and equipment required for the construction of the shaft section in the shaft operation area.

[0092] As Figure 3 shown, at the side wall position in the upper area of the shaft operation area, four conical rock bolts 311 are set. The conical rock bolts 311 provide support for the reinforced concrete cross beam 312 and the walking truss 313. The rock bolts are designed to be conical, which can increase the contact area between the conical concrete and the side wall rock surface. The inclined surface is set to be conducive to improving the vertical bearing capacity of the structure. In a specific implementation manner, the rock bolts are made of C35 reinforced concrete, and 12 m long φ36 mortar bolts are used to anchor into the deep surrounding rock so as to make full use of the deep tensile capacity of the surrounding rock. There are two reinforced concrete cross beams 312, and one guide rail 314 is respectively provided on each of the two reinforced concrete cross beams. The walking truss 313 is slidably connected with the guide rail 314 through rollers 315. A sheave 316 is provided in the middle of the walking truss 313. The sheave 316 is used in cooperation with the winch 317, and the working suspension platform 319 is lifted and lowered through the steel rope 318; in a specific implementation manner, the working suspension platform 319 is a metal circular platform.

[0093] S10. Excavate the shaft section downward from the bottom of the lower area of the shaft operation area until it is connected to the underground tunnel.

[0094] As Figure 4 、 Figure 5 shown, after arranging the auxiliary devices and equipment required for the construction of the shaft section, the shaft excavation is carried out next until it is connected to the underground tunnel. The specific steps are as follows:

[0095] S10-1. Drill a pilot hole vertically downward from the bottom of the shaft operation area at the center of the shaft until it communicates with the underground tunnel.

[0096] In a specific implementation manner, the pilot hole is constructed by a raiseboring machine, and the diameter of the pilot hole is 12 cm.

[0097] S10-2. Ream the pilot hole from bottom to top until the top of the shaft to form a shaft slush hole.

[0098] In a specific implementation manner, after drilling the pilot hole, the raiseboring machine is replaced with a 130 cm reaming cutter head, and the pilot hole is reamed from bottom to top until the top of the shaft to form a shaft slush hole with a diameter of 130 cm.

[0099] S10-3. Drill holes and blast according to the designed shaft contour line at the bottom of the shaft operation area, and discharge the slag through the shaft slush hole and the underground tunnel.

[0100] Move the raise boring machine at the bottom of the shaft operation area and drill and blast according to the contour line of the designed shaft excavation. After each blast, the muck in the shaft falls into the underground tunnel through the muck chute hole of the shaft, and the muck is removed by construction vehicles in the underground tunnel.

[0101] S10-4. Carry out the outer support for the shaft wall, assemble, lay and hang corrugated steel plates and fix them on the shaft wall.

[0102] In a specific implementation manner, when carrying out the outer support for the shaft wall after muck removal, as Figure 6 shown, first hang the steel mesh 911, and the steel mesh is preferably a φ6 steel mesh, @20*20cm; then spray concrete, and the concrete is preferably 8cm thick C30 steel fiber sprayed concrete; for local broken areas, use bolts 913 to strengthen the local surrounding rock, and the bolts are preferably φ22 bolts with a length of 3.5m; finally, assemble, lay and hang corrugated steel plates, drive bolts 913 to fix the corrugated steel plates 916 on the shaft wall, and the bolts are preferably φ22 bolts with a length of 1.5m.

[0103] After the support is carried out in the above manner, the outer lining of the shaft is a corrugated steel plate assembled structure. The corrugated steel plates in a circumferential circle of the shaft wall are divided into 3-5 sections, and are connected and closed into a ring by high-strength threaded bolts 914. The bottom edge of the upper corrugated steel plate and the top edge of the lower corrugated steel plate are connected by high-strength threaded bolts 914. The space between the corrugated steel plates and the surrounding rock is filled and compacted by grouting. The assembly schematic diagram of the corrugated steel plates is as Figure 7 shown. The corrugated steel plates have a wave height of 140mm, a wave pitch of 380mm, and the corrugated pipe is processed from Q345 and the surface is hot-dip galvanized.

[0104] S10-5. Repeat steps S10-3 and S10-4, and gradually drive towards the bottom of the shaft; when reaching a preset unit depth each time, install precast wall seats on the shaft wall.

[0105] On the working suspension platform, gradually drive towards the bottom of the shaft according to the cyclic operation sequence of drilling-blasting-muck removal-outer support. When driving down a preset unit depth, such as 30-50m, expand the blasting section, cut a 1.5m notch outwards, lower the precast wall seat. The precast wall seat has reserved holes. The upper cross-section of the trapezoidal wall seat of the precast wall seat has the same thickness as the precast reinforced concrete segment. The bottom cross-section width of the precast wall seat expands a certain length towards the periphery to ensure the rock-anchoring ability of the wall seat, and the expanded length is preferably 1.5m. The circumferential connection method of the wall seat is the same as that of the precast reinforced concrete segment. Circumferential connection holes are reserved at both ends of the precast reinforced concrete segment close to the ends. High-strength threaded bolts are used to connect each wall seat and close them into a ring. Bolts are driven along the circumferential direction around the periphery to fix the precast wall seat firmly to the surrounding rock of the shaft wall. The bolts are preferably φ25 bolts with a length of 3.0m. The schematic diagram of installing the precast wall seat on the shaft wall is as Figure 8 shown.

[0106] In this step, precast wall seats are installed on the shaft wall to share the weight generated vertically by multiple precast reinforced concrete segments after the subsequent installation of precast reinforced concrete segments.

[0107] S10-6: When the excavation reaches the bottom of the shaft and is connected to the underground tunnel, the precast reinforced concrete segments are installed in a splicing manner from bottom to top against the corrugated steel plate until the top of the shaft.

[0108] The precast reinforced concrete segments are installed from bottom to top against the corrugated steel plate. The inner lining structure of the shaft is a closed annular structure assembled by precast reinforced concrete segments. The inner edge of the precast reinforced concrete segment is in an arc shape, and the outer edge is wavy, matching the wave height of the corrugated steel plate. A non-woven fabric is laid between the precast reinforced concrete segment and the corrugated steel plate as a buffer layer for the two hard shell structures.

[0109] In a specific embodiment, the thickness of the precast reinforced concrete segment is preferably 35-50 cm. The circumferential length of a single precast reinforced concrete segment is preferably 1 / 5 of the shaft circumference, and the height is 1.5 m. The precast reinforced concrete segment is a cavity structure to reduce weight. Circumferential and vertical connection holes are provided in the horizontal and vertical directions of the precast reinforced concrete segment respectively, and high-strength threaded anchor bolts are used to connect and close into a ring; an elastic gasket 918 is installed at the end of the precast reinforced concrete segment for waterproofing.

[0110] Through the above technical solutions, it is possible to bypass the environmentally sensitive area and the space-limited conditions, and directly construct a shaft in the underground space mountain body to connect the ground and the underground tunnel.

[0111] At the same time, when constructing a shaft conventionally, a composite lining structure is generally adopted for complex strata. The composite lining structure is: the primary support, including bolts, shotcrete, steel mesh and steel grid / I-beam steel frame, and the secondary lining is cast-in-place reinforced concrete by formwork. The composite lining has many problems such as many processes in the primary support shotcrete operation, long time for steel bar binding in the secondary lining, and poor control of the quality of cast-in-place concrete. For the shaft constructed by the method of step S10, the shaft structure is a permanent lining, adopting a double-layer support structure of corrugated steel plate and precast reinforced concrete segment plus an intermediate buffer layer, which can be directly and quickly assembled during construction, is fast, safe and quality controllable.

[0112] The present invention is applicable to the construction of shafts to connect the ground and the underground tunnel in the related industries such as highways and railways under the limited space conditions of environmentally sensitive areas, natural ecological protection areas, special environmental conditions or topography and geomorphology, etc., to solve the problems of tunnel ventilation and smoke exhaust, auxiliary construction or other special requirements.

[0113] Embodiment 2

[0114] This embodiment provides a shaft for connecting the ground with an underground tunnel, which is constructed by using the shaft construction method under environmentally sensitive areas or space - limited conditions provided in Embodiment 1.

[0115] For the constructed shaft, the maintenance and construction auxiliary passage formed during the shaft construction can be used as an auxiliary standby passage for the ventilation of the underground tunnel. When the adit is blocked due to an accident, the underground tunnel can still ventilate with the outside through the maintenance and construction auxiliary passage.

[0116] Finally, it should be noted that: the above - mentioned embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and the description of the present invention.

Claims

1. A method for constructing a shaft under environmentally sensitive areas or space - restricted conditions, characterized in that, It includes the following steps: Excavate the first inclined shaft according to the position of the inclined shaft wellhead and excavate to the first depth; Connect the first inclined shaft and turn to horizontal excavation of the maintenance and construction auxiliary passage at the first depth until the preset position of the shaft operation area is reached; Connect the maintenance and construction auxiliary passage and carry out excavation and support of the upper area of the shaft operation area at the preset position of the shaft operation area; Connect the bottom of the first inclined shaft and continue to excavate the second inclined shaft obliquely downward to the second depth, and the second depth is the same as the bottom elevation of the lower area of the shaft operation area; Connect the second inclined shaft and turn to horizontal excavation in sequence of the adit, the lower area of the shaft operation area, and the cross tunnel operation area at the second depth; Drill a winding rope inclined hole obliquely downward from the side wall of the upper area of the shaft operation area to the cross tunnel operation area; Drill a temporary slag chute hole downward from the bottom of the upper area of the shaft operation area to the lower area of the shaft operation area; Excavate downward from the upper area of the shaft operation area to the lower area of the shaft operation area; the muck generated during the excavation process goes down to the lower area of the shaft operation area through the temporary slag chute hole, and then is discharged through the adit, the second inclined shaft, and the first inclined shaft; Arrange auxiliary devices and equipment required for the construction of the shaft section in the shaft operation area; Excavate the shaft section downward from the bottom of the lower area of the shaft operation area until it is connected to the underground tunnel.

2. The shaft construction method under environmentally sensitive areas or space - restricted conditions according to claim 1, characterized in that, The support of the upper area of the shaft operation area includes: Bind rock anchor steel bars, cast in-situ concrete according to the designed rock anchor shape, and drill and install mortar anchor bars to fix the rock anchor after the concrete reaches the designed strength.

3. The shaft construction method under environmentally sensitive areas or space - limited conditions according to claim 1, wherein, The cross tunnel operation area serves as the fixing and operation work area for the hoisting equipment, and the adit serves as the feeding and muck discharging channel.

4. The shaft construction method under environmentally sensitive areas or space-limited conditions according to claim 1, characterized in that, Conical rock anchors are provided at the side wall position of the upper area of the shaft operation area; The reinforced concrete cross beam is connected to the conical rock anchor, and guide rails are provided on the reinforced concrete cross beam; The walking truss is slidably connected to the guide rail through rollers, and a skywheel is provided in the middle of the walking truss; The skywheel is used in cooperation with the winch to lift the working suspension platform through the steel rope.

5. The shaft construction method under environmentally sensitive areas or space - restricted conditions according to claim 1, characterized in that, Excavating the shaft section downward from the bottom of the shaft operation area until it is connected to the underground tunnel includes: Drill a pilot hole from top to bottom at the center position of the bottom of the shaft operation area until it communicates with the underground tunnel; Then ream the pilot hole from bottom to top until the top of the shaft to form a shaft slag chute hole; Drill holes and blast according to the designed shaft contour line at the bottom of the shaft operation area, and discharge the muck through the shaft slag chute hole and the underground tunnel; Carry out outer support for the shaft wall, and assemble and hang corrugated steel plates to fix them on the shaft wall; According to the cyclic operation sequence of drilling, blasting, muck discharging, and outer support, gradually drive towards the bottom of the shaft; when tunneling to a preset unit depth, install precast wall seats on the shaft wall; When excavating to the bottom of the shaft and connecting with the underground tunnel, install precast reinforced concrete segments in a splicing manner from bottom to top close to the corrugated steel plates until the top of the shaft.

6. The shaft construction method under environmentally sensitive areas or space - restricted conditions according to claim 5, wherein The bottom edge of the upper corrugated steel plate and the top edge of the lower corrugated steel plate are connected by threaded anchor bolts, and the space between the corrugated steel plate and the surrounding rock is filled and compacted by grouting.

7. The shaft construction method under environmentally sensitive areas or space - restricted conditions according to claim 5, characterized in that, The precast wall seat is reserved with holes, the upper cross section of the trapezoidal wall seat of the precast wall seat has the same thickness as the precast reinforced concrete segment, and the bottom cross section width of the precast wall seat extends towards the periphery; The precast wall seats are provided with circumferential connection holes at both ends close to the precast reinforced concrete segments; a plurality of precast wall seats are connected and closed into a ring by threaded anchor bolts, and anchor rods are driven in along the circumferential direction of the periphery.

8. The shaft construction method under environmentally sensitive areas or space - restricted conditions according to claim 5, characterized in that, The precast reinforced concrete segment is of a cavity structure, with an inner edge in an arc shape and an outer edge in a wavy shape, which is matched with the wave height of the corrugated steel plate; The precast reinforced concrete segment is provided with circumferential and vertical connection holes in the horizontal and vertical directions respectively, and is connected and closed into a ring by threaded anchor bolts, and an elastic gasket is arranged at the end.

9. The shaft construction method under environmentally sensitive areas or space-limited conditions according to claim 5, characterized in that, A non-woven fabric is laid between the precast reinforced concrete segment and the corrugated steel plate.

10. A shaft, characterized in that, It is used to connect the ground and the underground tunnel, and is constructed by using the shaft construction method under any one of the environmental sensitive areas or space-limited conditions described in claims 1-9.

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