Yield supporting structure suitable for deep shaft and construction method thereof

Abstract

The invention discloses a yielding supporting structure suitable for a deep shaft and a construction method of the yielding supporting structure. The yielding supporting structure comprises a peripheral drainage system, a shaft wall drainage system, a stress regulation and control channel and a construction channel. The peripheral drainage system is arranged on the periphery of the deep shaft, and the shaft wall drainage system is arranged on the outer edge of the shaft wall; the stress regulation and control channel is a yielding raise well formed in the direction of the maximum horizontal principal stress, and the well wall stress in the direction is reduced through surrounding rock stress redistribution; and the construction channel is used for providing an operation space for the construction of the stress regulation and control channel. A coupling structure of an advanced drainage drill hole, a well wall gridding drainage system and a directional yielding raise well is arranged; a traditional grouting and water plugging process is replaced with a double-drainage system, and the seepage water pressure is remarkably reduced; the yielding raise-boring cooperation drainage system releases surrounding rock stress, and the risk of high-pressure water burst is avoided; meanwhile, asymmetric stress distribution of surrounding rocks is transformed, and well wall stress uniformity is remarkably improved; and well wall cracking caused by local stress concentration is avoided, and the thickness of well wall concrete is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of mine construction engineering, and particularly relates to a pressure-relief supporting structure suitable for a deep vertical shaft and a construction method thereof. BACKGROUND

[0002] The vertical shaft is a common shaft engineering in the mining, water conservancy and transportation industries, and is a key passage for ventilation and transportation. The vertical shaft, especially the deep vertical shaft, needs to face the double difficulties of high surrounding rock pressure and high permeable water pressure when the design and construction of the vertical shaft meet the high-pressure and high-yield water stratum in the deep part. In the high-permeable water pressure environment of the deep vertical shaft, the construction operation environment of the vertical shaft is poor, the pouring quality of the concrete shaft wall is difficult to guarantee, and the risk of sudden gushing water is high. Therefore, the grouting and water plugging technology is often used when the vertical shaft meets the strong water-bearing stratum.

[0003] The construction technology of the shaft lining grouting mainly includes three types of ground pre-grouting, working face pre-grouting and wall back grouting. The working face pre-grouting is carried out when the vertical shaft is excavated to a certain distance away from the water-bearing stratum or the water-bearing stratum is exposed, and the protective measures need to be taken when there is high-pressure water.

[0004] In the working face pre-grouting process, in order to ensure that the slurry can effectively diffuse along the fissure under pressure and prevent the slurry from running on the working face, the method of reserving a grouting-stopping rock cap or pouring a concrete grouting-stopping pad on the working face is often used. When there is a dense impermeable layer above the water-bearing stratum, the shaft excavation is stopped after reaching a certain distance above the grouting section, and a grouting-stopping rock cap is reserved for the water-bearing stratum. If the working face of the shaft cannot reserve the grouting-stopping rock cap, an artificial grouting-stopping pad needs to be built. Under high surrounding rock pressure, especially in strong rock burst sections, stress release measures such as increasing the thickness of the concrete shaft wall, using high-grade concrete shaft wall, using high-section high-shotcrete anchor net primary support or constructing advanced pressure-relief boreholes near the working face are often used.

[0005] The grouting and water plugging, thickening of the shaft wall and high-grade concrete support have the following problems:

[0006] 1. Grouting and water plugging: the grouting construction period is long, the cost is high, and the slurry diffusion is difficult to control under high-pressure environment, and the water control effect is unstable;

[0007] 2. Rigid support: thickening the shaft wall or using high-grade concrete significantly increases the material cost and construction difficulty;

[0008] 3. Local pressure relief: advanced pressure-relief boreholes and high-section high-shotcrete anchor net primary support can only release stress near the working face, the range is limited and needs to be constructed in stages, and the process is complex. SUMMARY

[0009] The main purpose of the present application is to provide a pressure-relief supporting structure suitable for a deep vertical shaft by replacing grouting and water plugging with water drainage and pressure reduction, and a construction method thereof.

[0010] The application provides a pressure-releasing supporting structure suitable for a deep vertical shaft, which comprises a peripheral drainage system, a shaft wall drainage system, a stress regulation channel and a construction channel; the peripheral drainage system is arranged on the periphery of the deep vertical shaft, and the shaft wall drainage system is arranged on the outer edge of the shaft wall; the stress regulation channel is a pressure-releasing counter shaft formed in the direction of the maximum horizontal principal stress, and the stress of the shaft wall in this direction is reduced through stress redistribution of the surrounding rock; and the construction channel provides an operation space for construction of the stress regulation channel.

[0011] In an embodiment of the above structure, the peripheral drainage system comprises advanced drainage boreholes arranged along the circumferential direction of the deep vertical shaft, and the advanced drainage boreholes extend to below the aquifer, and drainage equipment is arranged in the boreholes.

[0012] In an embodiment of the above structure, the shaft wall drainage system comprises radial anchor rods, vertical drainage blind pipes and annular drainage blind pipes; the radial anchor rods are arranged at intervals along the radial direction of the shaft wall, and the end portions thereof penetrate the shaft wall and contact the surrounding rock; the vertical drainage blind pipes are arranged along the vertical direction of the shaft wall and are connected with the radial anchor rods; and the annular drainage blind pipes are arranged at intervals around the shaft wall, and are connected with the radial anchor rods and the vertical drainage blind pipes through connecting members.

[0013] In an embodiment of the above structure, the annular drainage blind pipes are wrapped with permeable geotextiles, and together with the vertical drainage blind pipes and the radial anchor rods, form a grid drainage network.

[0014] In an embodiment of the above structure, the pressure-releasing counter shaft is formed by upwardly pulling from the lower horizontal portal through a raise drill.

[0015] In an embodiment of the above structure, the pressure-releasing counter shaft is filled with permeable crushed stone or kept as a cavity, and the diameter thereof is smaller than the diameter of the deep vertical shaft.

[0016] In an embodiment of the above structure, the construction channel comprises an upper horizontal portal, a lower horizontal portal arranged in the deep vertical shaft, and an upper horizontal shaft bypass and a lower horizontal shaft bypass respectively connected with the two.

[0017] A method for constructing the above pressure-releasing supporting structure, comprising the following steps:

[0018] Step 1: Advanced drainage construction

[0019] The advanced drainage boreholes are constructed through the upper horizontal portal, and the advanced drainage boreholes are arranged along the circumferential direction of the deep vertical shaft at an interval of 0.1-0.8 times the diameter of the vertical shaft, and the borehole depth extends to 5-10 m below the aquifer; a deep well pump and a drainage pipeline are installed in the borehole, and the surrounding rock seepage water pressure of the vertical shaft is continuously reduced through continuous pumping and drainage until the water inflow of the vertical shaft is reduced to below the safety threshold;

[0020] Step 2: Shaft wall drainage system construction

[0021] In the process of excavating the deep vertical shaft from top to bottom, a 3-5m high section is simultaneously installed with a shaft wall drainage system; specifically comprising: arranging radial anchor rods at intervals outside the shaft wall, the end of the anchor rod penetrating the shaft wall and contacting the surrounding rock; arranging vertical drainage blind pipes along the shaft wall, connected with the radial anchor rods; arranging annular drainage blind pipes around the shaft wall at intervals, connected with the radial anchor rods and the vertical drainage blind pipes through tee joints to form a grid drainage network; the annular drainage blind pipes are wrapped with water permeable geotextile, and the water flow is guided to the shaft bottom drainage system through the pre-buried pipeline;

[0022] Step three, simultaneous excavation and monitoring

[0023] Pouring concrete shaft wall and monitoring the stress state of the shaft wall through stress sensors to review the direction of the maximum horizontal principal stress of the surrounding rock and calculate and determine the arrangement direction and diameter parameters of the pressure-relief counter shaft;

[0024] Step four, pressure-relief counter shaft construction

[0025] Using the upper horizontal horsehead, the lower horizontal horsehead, the upper horizontal shaft bypass and the lower horizontal shaft bypass as construction passages; installing a raise-boring machine in the upper horizontal shaft bypass and installing an underreamer in the lower horizontal shaft bypass; forming a pressure-relief counter shaft by pulling upward from the lower horizontal horsehead along the direction of the maximum horizontal principal stress determined in step three; the pressure-relief counter shaft maintains a cavity to promote stress release.

[0026] In step three, short-section excavation and pouring technology is adopted, and concrete shaft wall is poured in time after each section is excavated; the vertical shaft is excavated and poured from top to bottom in sections until the shaft wall is poured to the lower horizontal horsehead elevation; the excavation height of each section is 3-5m, and the pouring of each section of concrete shaft wall is completed within 24 hours after the excavation is completed.

[0027] Step three and step four are carried out simultaneously; only shotcrete and anchor netting is used as the initial support during the process of excavating the vertical shaft from top to bottom, and the radial anchor rods in the shaft wall drainage system serve as the initial support anchor rods; the concrete shaft wall is poured from bottom to top, starting from the lower horizontal horsehead elevation and ending at the upper horizontal horsehead elevation.

[0028] The beneficial effects of the present application are as follows:

[0029] 1. The coupling structure of advanced drainage boreholes, shaft wall grid drainage system and directional pressure-relief counter shaft is provided; the double drainage system replaces the traditional grouting and water plugging process, significantly reducing the seepage water pressure; the pressure-relief counter shaft cooperates with the drainage system to release the stress of the surrounding rock and avoid the risk of high-pressure gushing water;

[0030] 2. Construct a pressure relief well in the direction of maximum horizontal principal stress and fill it with permeable gravel to form a stress release channel. This will transform the asymmetric stress distribution of the surrounding rock and significantly improve the stress uniformity of the well wall. This will prevent cracking of the well wall caused by local stress concentration and reduce the thickness of the well wall concrete. At the same time, the pressure relief well can serve as an emergency escape route to avoid the risk of high-pressure water inrush.

[0031] 3. Utilize existing horse-head gates and shaft bypasses to create operating space, enabling simultaneous installation of mechanized reverse pull construction and drainage systems; eliminating the grouting process significantly shortens construction time, reduces material costs, and improves construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a cross-sectional view of a deep shaft pressure-yielding support structure along the longitudinal direction of the shaft in one embodiment of the present invention.

[0033] Figure 2 for Figure 1 Large sample image at point C in the middle.

[0034] Figure 3 For the Figure 1 AA cross-sectional view of .

[0035] Figure 4 For the Figure 1 BB cross-sectional diagram.

[0036] In the attached figure: 1. vertical shaft; 101. vertical shaft wall; 2. vertical shaft surrounding rock; 3. advanced drainage drilling; 4. shaft wall drainage system; 401. radial anchor rod; 402. vertical drainage blind pipe; 403. circumferential drainage blind pipe; 5. upper horizontal horse head gate; 6. lower horizontal horse head gate; 7. upper horizontal vertical shaft bypass; 8. lower horizontal vertical shaft bypass; 9. pressure-reversing well. DETAILED DESCRIPTION

[0037] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the relevant technical solutions. Obviously, the embodiments described are only some embodiments, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] like Figure 1 As shown, the pressure-yielding support structure for a deep vertical shaft disclosed in this embodiment includes a deep vertical shaft 1, an advanced drainage borehole 3 arranged on the periphery of the deep vertical shaft 1, and a well wall drainage system 4 arranged on the outer edge of the well wall 101.

[0039] Advanced drainage boreholes 3 are arranged circumferentially around the deep shaft 1, extending to the depth below the aquifer. Deep well pumps and drainage pipes are installed within the boreholes to continuously pump and drain water to reduce the seepage pressure in the shaft's surrounding rock 2.

[0040] As shown in Figure 2 , the shaft wall drainage system 4 includes radial anchor rods 401, vertical drainage blind pipes 402 and annular drainage blind pipes 403.

[0041] The radial anchor rods 401 are arranged along the shaft wall 101 in a radial direction and spaced apart from each other, and the ends of the anchor rods penetrate the shaft wall and contact the surrounding rock 2, which has the functions of anchoring and water guiding.

[0042] The vertical drainage blind pipes 402 are PVC drainage pipes arranged along the shaft wall 101 in a vertical direction, connected with the radial anchor rods 401, and collecting fissure water guided by the radial anchor rods.

[0043] The annular drainage blind pipes 403 are corrugated pipes arranged around the shaft wall in a spaced manner, and wrapped with water permeable geotextile.

[0044] The annular drainage blind pipes 403 are connected with the radial anchor rods 401 and the vertical drainage blind pipes 402 through tee joints, forming a grid drainage network, and guiding water flow to the shaft bottom drainage system.

[0045] As shown in Figure 3 , the deep shaft 1 is provided with an upper horizontal manhole 5 and a lower horizontal manhole 6, which are used as construction passages and provide equipment transportation and drainage pipeline installation passages.

[0046] The upper horizontal shaft bypass 7 and the lower horizontal shaft bypass 8 are connected with the upper and lower horizontal manholes respectively, forming annular construction spaces for installation of raise boring machines and operation of reaming bits.

[0047] As shown in Figure 4 , in the direction of the maximum horizontal principal stress of the deep shaft 1, a yielding counter shaft 9 is formed by upwardly pulling from the lower horizontal manhole 6 using a raise boring machine, and the shaft wall stress in the direction of the maximum horizontal principal stress is reduced by stress redistribution of the surrounding rock, so that the shaft wall 101 tends to be uniformly compressed.

[0048] The yielding counter shaft 9 is filled with water permeable crushed stone or kept as a cavity, and has a diameter smaller than that of the deep shaft 1.

[0049] The advanced drainage borehole of the embodiment reduces water pressure from the periphery, and the shaft wall drainage system guides water to the drainage network composed of vertical blind pipes and annular blind pipes through radial anchor rods, achieving double pressure reduction; the yielding counter shaft releases the stress of the surrounding rock in the direction of the maximum horizontal principal stress, and cooperates with the drainage system to reduce the load of the shaft wall; the manhole and the shaft bypass provide mechanical operation space for construction of the yielding counter shaft.

[0050] The combination of the above components achieves the synergistic effect of drainage pressure reduction and stress regulation, and ensures the safety of the deep shaft without grouting.

[0051] The advanced hydrophobic borehole size of the embodiment needs to meet the lowering of the deep well pump in the borehole, and the diameter is φ0.2-0.8 m; the radial anchor rod adopts a diameter of 40-43 split pipe anchor rods, a length of 1.8-4 m, and a radial anchor rod spacing of 0.8-1.2 m; and the diameter of the pressure-relief counterwell is 0.67-3.0 m.

[0052] The application also provides a construction method of a deep vertical shaft pressure-relief supporting structure, and the specific steps are as follows.

[0053] Step one, advanced hydrophobic construction

[0054] The advanced hydrophobic borehole 3 is constructed through the upper horizontal horsehead 5, the borehole is arranged along the peripheral direction of the deep vertical shaft 1, the spacing is 0.1-0.8 times of the diameter of the vertical shaft, and the spacing is determined according to the calculation of the permeability coefficient of the surrounding rock; the borehole depth extends to 5-10 m below the aquifer; the deep well pump and the drainage pipeline are installed in the borehole, the seepage water pressure of the surrounding rock 2 of the vertical shaft is continuously pumped and drained, and the water inflow of the vertical shaft is reduced to below the safety threshold value;

[0055] Step two, construction of the shaft wall hydrophobic system

[0056] During the upward excavation of the deep vertical shaft 1, the shaft wall hydrophobic system 4 is synchronously installed every 3-5 m, and the shaft wall hydrophobic system 4 specifically includes the following:

[0057] The radial anchor rods 401 are arranged at intervals outside the outer edge of the shaft wall 101, the end of the anchor rod penetrates the shaft wall and contacts the surrounding rock 2; the vertical drainage blind pipe 402 is arranged vertically along the shaft wall and is connected with the radial anchor rod 401; the annular drainage blind pipe 403 is installed at intervals around the shaft wall, the radial anchor rod 401 and the vertical drainage blind pipe 402 are connected through a tee joint, and a grid drainage network is formed; the blind pipe is wrapped with a permeable geotextile, and the water flow is guided to the shaft bottom drainage system through the pre-buried pipeline;

[0058] Step three, synchronous excavation and monitoring

[0059] The shaft wall 101 is poured with concrete, the stress state of the shaft wall can be monitored through a stress sensor, the maximum horizontal principal stress direction of the surrounding rock is further reviewed, and parameters such as the arrangement direction and diameter of the pressure-relief counterwell are calculated and determined;

[0060] Step four, pressure-relief counterwell construction

[0061] The upper horizontal horsehead 5, the lower horizontal horsehead 6, the upper horizontal shaft bypass 7 and the lower horizontal shaft bypass 8 are used as construction channels: a raise boring machine is installed on the upper horizontal shaft bypass 7; an expansion drill bit is installed on the lower horizontal shaft bypass 8; the pressure-relief counterwell 9 is formed by upwardly pulling from the lower horizontal horsehead 6 along the maximum horizontal principal stress direction determined in step three; and the pressure-relief counterwell keeps a cavity to promote stress release.

[0062] The short section excavation and construction process can be used in step three, and the concrete shaft wall 101 is poured in time after each section is excavated, and the shaft is poured from top to bottom to the lower horizontal portal 7 elevation;

[0063] In steps three and four, the pouring of the concrete shaft wall 101 and the yielding counter-bore construction are carried out simultaneously; only the initial support of the spray anchor net is used in the process of excavating the shaft from top to bottom, and the radial anchor rod 601 serves as the initial support anchor rod, and the shaft wall 101 is poured from bottom to top to the upper horizontal portal 3 elevation.

[0064] The following is the engineering verification data of an embodiment of the yielding support structure suitable for deep shafts:

[0065] 1. Project overview: The shaft depth is 800 m, the diameter is 4.2 m, it passes through a sandstone aquifer, and the maximum horizontal principal stress direction is NE 30°.

[0066] 2. Advanced dewatering construction: 12 advanced dewatering boreholes are constructed using a CY-R120V raise borer from the upper horizontal portal, the borehole diameter is 280 mm, the spacing is 4 m, and the depth is 8 m below the aquifer; a deep well pump is installed to pump water for 15 days, and the shaft inflow is reduced from 25 m 3 / h to 5 m 3 / h.

[0067] 3. Installation of shaft wall dewatering system: radial anchor rods are installed every 4 m, with a spacing of 1 m x 1 m, and the anchor rod length is 3 m; the anchor rod uses MF43 threaded pipe anchor rod. The vertical drainage blind pipe uses Φ50 mm PVC pipe, and the annular blind pipe uses Φ100 mm corrugated pipe wrapped with 300 g / m 2 permeable geotextile.

[0068] 4. Shaft excavation and monitoring: The shaft uses a short section excavation and construction process, and the wall formwork height is 4 m; the concrete shaft wall is poured in time after each section is excavated, and stress sensors are embedded in the shaft wall every 50-100 m to monitor the stress state of the shaft wall; the maximum horizontal principal stress direction of the surrounding rock is further reviewed by analyzing the stress distribution of the shaft wall, and parameters such as the layout direction and diameter of the yielding counter-bore are calculated and determined.

[0069] 5. Yielding counter-bore construction: A CY-R120V raise borer is installed on the upper horizontal shaft bypass, and a yielding counter-bore with a diameter of 2 m is formed in the NE 30° direction, and the counter-bore is filled with gravel; three on each side, a total of six.

[0070] 6. Effect verification: The thickness of the shaft wall is reduced from the original design of 500 mm to 350 mm, and the cost is reduced by 28%; the shaft wall stress monitoring shows that the maximum compressive stress difference is reduced from 15 MPa to 5 MPa, and the uniformity is improved by 67%.

[0071] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the foregoing embodiments are described in detail, those skilled in the art can modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A yield support structure suitable for deep shafts, characterized by: It includes peripheral drainage system, well wall drainage system, stress control channel and construction channel; The peripheral drainage system is installed on the periphery of the deep shaft, and the wellbore drainage system is installed on the outer edge of the shaft wall. The stress control channel is a pressure-yielding reverse well formed in the direction of the maximum horizontal principal stress, which reduces the wellbore stress in this direction by redistributing the surrounding rock stress. And a construction channel that provides operating space for the construction of the stress control channel.

2. The yield support structure for deep shafts according to claim 1, characterized in that: The peripheral drainage system includes advanced drainage boreholes arranged along the circumferential direction of the deep vertical shaft. The depth of the advanced drainage boreholes extends to below the aquifer, and drainage equipment is provided in the boreholes.

3. The yield support structure for deep shafts according to claim 1, characterized in that: The well wall drainage system includes radial anchor rods, vertical drainage blind pipes and annular drainage blind pipes; The radial anchor rods are arranged at intervals along the shaft wall in a radial direction, and their ends penetrate the shaft wall and contact the surrounding rock; The vertical drainage blind pipe is arranged vertically along the well wall and connected to the radial anchor rod; The annular drainage blind pipes are arranged at intervals around the well wall and are connected with the radial anchor rods and the vertical drainage blind pipes through connecting pieces.

4. The yield support structure for deep shafts according to claim 3, characterized in that: The annular drainage blind pipe is wrapped with a permeable geotextile and together with the vertical drainage blind pipe and the radial anchor rods form a grid drainage network.

5. The yield support structure for deep shafts according to claim 1, characterized in that: The pressure-releasing well is formed by pulling the well upward from the lower horizontal horse head door through a raise boring machine.

6. The yield support structure for deep shafts according to claim 1, characterized in that: The pressure relief well is filled with permeable gravel or maintained as a cavity, and its diameter is smaller than the diameter of the deep vertical well.

7. The yield support structure for deep shafts according to claim 1, characterized in that: The construction passage includes an upper horizontal horse head gate and a lower horizontal horse head gate arranged in the deep vertical shaft, and an upper horizontal vertical shaft bypass and a lower horizontal vertical shaft bypass respectively connecting the upper horizontal horse head gate and the lower horizontal vertical shaft bypass.

8. A method for constructing the yield support structure for a deep shaft according to any one of claims 1 to 7, comprising the following steps: Step 1: Advanced drainage construction Advanced drainage boreholes are constructed through the upper horizontal horse head gate. The advanced drainage boreholes are arranged along the circumference of the deep shaft, with a spacing of 0.1-0.8 times the shaft diameter, and the borehole depth extends to 5-10m below the aquifer. Deep well pumps and drainage pipelines are installed in the boreholes to continuously pump and drain to reduce the seepage water pressure in the shaft surrounding rock until the water inflow in the shaft drops below the safety threshold. Step 2: Construction of well wall drainage system During the top-down excavation of a deep vertical shaft, a wall drainage system is installed simultaneously at each 3-5m high section. Specifically, radial anchors are placed at intervals along the outer edge of the shaft wall, with the ends of the anchors penetrating the shaft wall and contacting the surrounding rock. Vertical drainage blind pipes are laid vertically along the shaft wall and connected to the radial anchors. Annular drainage blind pipes are installed at intervals around the shaft wall, connecting the radial anchors and vertical drainage blind pipes via tee joints to form a gridded drainage network. The annular drainage blind pipes are wrapped with permeable geotextiles and channel water to the bottom of the shaft through pre-buried pipes. Step 3: Simultaneous excavation and monitoring Concrete the shaft wall and monitor the stress state of the shaft wall through stress sensors, verify the direction of the maximum horizontal principal stress of the surrounding rock, and calculate and determine the layout orientation and diameter parameters of the pressure relief shaft; Step 4: Construction of pressure-reversed well The upper horizontal horse head gate, the lower horizontal horse head gate, the upper horizontal shaft bypass and the lower horizontal shaft bypass are used as construction channels; a shaft boring machine is installed in the upper horizontal shaft bypass, and a hole expansion drill bit is installed in the lower horizontal shaft bypass; along the direction of the maximum horizontal principal stress determined in step 3, the pressure relief well is formed by pulling upward from the lower horizontal horse head gate; a cavity is maintained in the pressure relief well to promote stress release.

9. A construction method according to claim 8, comprising the following steps: In step three, a short-segment excavation and masonry process is adopted, and the concrete shaft wall is poured in time after each section of excavation; the vertical shaft is excavated and poured in sections from top to bottom until the shaft wall is poured to the elevation of the lower horizontal horse head gate; the excavation height of each section is 3-5m, and the concrete shaft wall of each section is poured within 24 hours after the excavation is completed.

10. A construction method according to claim 8, comprising the following steps: Steps three and four are carried out simultaneously; during the excavation of the vertical shaft from top to bottom, only the sprayed anchor net is used as the initial support, and the radial anchor rods in the well wall drainage system also serve as the initial support anchor rods; the concrete well wall of the vertical shaft is poured from bottom to top, starting from the lower horizontal horse head gate elevation and ending at the upper horizontal horse head gate elevation.

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