Vertical shaft excavation construction method

Abstract

The invention discloses a vertical shaft excavation construction method, a vertical shaft to be excavated is divided into a first vertical shaft to be excavated and a second vertical shaft to be excavated, and the construction method comprises the following construction steps that S1, an upper flat tunnel is excavated and constructed to the bottom of the first vertical shaft to be excavated to form a first cross section, the lower flat tunnel is excavated to the bottom of the second vertical shaft to be excavated to form a second cross section; s2, a section of the lower portion of the first shaft to be excavated serves as a protection section to be reserved, and construction is conducted on the top of the first shaft to be excavated to the top of the protection section through a normal well method; a slag sliding pilot shaft is constructed downwards along the axis of the second vertical shaft to be excavated through a raise-boring method; s3, after the slag sliding pilot shaft construction is completed, the protection section continues to be constructed to the first cross section through the normal well method; and S4, a second vertical shaft is planned to be excavated to a second cross section through inverse well construction by adopting construction equipment of a normal well method. According to the vertical shaft excavation construction method, the technical problem that the construction difficulty of the deep and large vertical shaft is high is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of vertical shaft construction of pumped storage power stations, and particularly relates to a vertical shaft excavation construction method. Background Art

[0002] With the continuous construction of pumped-storage power stations, which are moving toward higher heads and larger-capacity units, the number of pumped-storage power stations with deep, large vertical shafts is increasing. Deep, large diversion shafts are a key component of power generation, requiring a high construction schedule. Due to limitations in construction equipment, the construction of deep, large shafts exceeding 500 meters in depth and 10 to 16 meters in diameter is extremely difficult, resulting in slow progress and, in particular, the difficulty in ensuring construction safety, which has become a limiting factor in project construction. Currently, there is a lack of practical experience with deep, large-diameter shafts in the hydropower industry. Therefore, the optimal selection of a shaft excavation plan is a crucial prerequisite for ensuring the safety, quality, and progress of shaft construction.

[0003] In the existing technology, vertical shaft construction can be done in two ways: the upright method and the reverse method. Hydropower project vertical shafts generally use the reverse method to construct a slag guide shaft, followed by expansion from top to bottom. When conditions permit, this construction method offers significant advantages over the upright method in terms of drainage, slag removal, and ventilation. However, the reverse method also has its shortcomings. First, the upper and lower construction channels of the vertical shaft must be in place before reverse construction can proceed. In particular, the lower construction channel must be in place before reverse construction can proceed. Second, the upper and lower channels of the vertical shaft cannot be located on the main transportation route, otherwise they will affect each other and extend the construction period. Third, after the reverse shaft is opened, the upright excavation is still required. A set of lifting and hanging facilities and equipment must be installed at the upper entrance, requiring the work surface to be shifted, increasing the preparation time and the investment in reverse construction equipment. As the depth and diameter of the vertical shaft continue to increase, reverse construction becomes increasingly difficult and the speed becomes slower. During reverse excavation, the blockage accident rate is high, and blockage treatment is difficult, increasing the difficulty of construction organization and management. Furthermore, when the shaft depth exceeds 500 meters, the reverse shaft method cannot be directly used for construction. While the vertical shaft method is widely used in the mining and transportation industries and has exceeded the kilometer level in depth, its diameter is generally less than 7-8 meters. Moreover, if the vertical shaft method is used for the entire deep and large diameter shaft, it requires a lot of equipment, especially ventilation and drainage problems, long construction period, low slag removal efficiency, and huge costs. Summary of the Invention

[0004] In response to the current technical problems, the present invention aims to provide a shaft excavation construction method, which can solve the technical problem of the great difficulty in constructing deep and large shafts in the existing technology.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A vertical shaft excavation construction method comprises dividing a planned vertical shaft into a planned first vertical shaft and a planned second vertical shaft located at the bottom of the planned first vertical shaft, wherein the axes of the planned first vertical shaft and the planned second vertical shaft are both collinear with the axis of the planned vertical shaft, and the height of the planned second vertical shaft is no greater than 500 m; selecting a tunnel around the bottom of the planned first vertical shaft as an upper horizontal tunnel, and selecting a tunnel around the bottom of the planned second vertical shaft as a lower horizontal tunnel; and the construction method comprises the following construction steps:

[0007] Step S1: excavating the upper horizontal tunnel to the bottom of the first vertical shaft to be excavated to form a first intersection section, and excavating the lower horizontal tunnel to the bottom of the second vertical shaft to be excavated to form a second intersection section;

[0008] Step S2: A section at the lower portion of the first vertical shaft to be excavated is reserved as a protection section, the protection section being located at the top of the first intersection section. A vertical well method is used to construct the top of the protection section at the top of the first vertical shaft to be excavated. A slag guide shaft is constructed downwardly along the axis of the second vertical shaft to be excavated at the first intersection section using the reverse well method. The upper horizontal tunnel is connected to the lower horizontal tunnel through the slag guide shaft.

[0009] Step S3: After the construction of the slag guide shaft is completed, the protection section to the first intersection section is constructed using the vertical well method. The slag in the protection section is discharged to the lower level tunnel through the slag guide shaft and discharged outside the tunnel.

[0010] Step S4: using the construction equipment of the vertical shaft method in step S2 to excavate the second vertical shaft to the second intersection section through the reverse shaft method.

[0011] When the upper horizontal tunnel is excavated to the bottom of the first vertical shaft to be excavated, the section where the upper horizontal tunnel intersects with the first vertical shaft to be excavated is the first intersection section. When the lower horizontal tunnel is excavated to the bottom of the second vertical shaft to be excavated, the section where the lower horizontal tunnel intersects with the second vertical shaft to be excavated is the second intersection section. A section is reserved at the bottom of the first vertical shaft to be excavated as a protection section, and the protection section is located at the top of the first intersection section. The vertical shaft excavation construction method of the present application is mainly aimed at deep and large vertical shafts. Before construction, the vertical shaft to be excavated is divided into the first vertical shaft to be excavated and the second vertical shaft to be excavated, and the cross-sectional dimensions of the first vertical shaft to be excavated and the second vertical shaft to be excavated are the same as the cross-sectional dimensions of the corresponding positions of the vertical shaft to be excavated. In view of the advantages of the vertical shaft method for rapid lifting system and the reverse shaft method for slag discharge to the lower part, the vertical shaft method is used for the first vertical shaft to be excavated located above, and the reverse shaft method is used for the second vertical shaft to be excavated located below. During construction, when constructing the first vertical shaft to be excavated, a slag guide shaft is constructed at the same time. During the construction of the protection section, the slag can be discharged directly through the slag guide shaft. When the reverse shaft method is used for the construction of the second vertical shaft to be excavated, the construction equipment of the upright shaft method is used for construction excavation, and the slag is discharged along the slag guide shaft. The vertical shaft excavation construction method of the present application fully absorbs the advantages of the upright shaft method and the reverse shaft method. By adopting a construction method that combines the upright shaft method and the reverse shaft method, it can achieve the purpose of facilitating construction organization, shortening construction period, and ensuring safe and reliable construction. The vertical shaft excavation construction method of the present application can effectively overcome the disadvantages of the upright shaft method, such as low slag discharge efficiency, difficulty in ventilation and smoke dispersion, and difficulty in water gushing control, which is conducive to reducing construction safety risks and improving the construction period guarantee rate.

[0012] Preferably, the first vertical shaft to be excavated is divided into a first section to be excavated, a second section to be excavated, a third section to be excavated, and a protection section from top to bottom. The vertical shaft construction method in step S2 specifically includes the following construction steps:

[0013] Step S201: Excavate the top of the first vertical shaft to perform the locking section excavation and cast the locking ring beam. After the locking ring beam, wellhead water retaining sill, and temporary guardrail are completed, the entire section is excavated downwards, and the foundations of the wellhead frame, hoisting system, and vehicle stabilization system are constructed simultaneously.

[0014] Step S202: After the first vertical shaft is excavated from the top to a certain height, the excavation operation is stopped and mechanized operation equipment is installed;

[0015] Step S203: Continue excavating downwards, and the slag and rock are lifted and transported upwards by mechanized equipment until the first excavation section is completed; install the lifting plate, sealing plate, and auxiliary production system to form a comprehensive mechanized operation system;

[0016] Step S204: sequentially carry out the construction of the second and third sections to be excavated, and lift the slag upwards and transport them out.

[0017] In step S202, the height of the first vertical shaft to be excavated downwards depends on the installation height requirement of the mechanized operation equipment. In step S203, the height of the further excavation downwards depends on the height of the hoisting platform used.

[0018] Preferably, in step S202, the mechanized group operation equipment includes a drilling rig, a slag discharge platform mounted on the drilling rig, a sheave platform mounted on top of the drilling rig, a first hoisting system, a second hoisting system, and two stabilization systems arranged around the drilling rig. The first hoisting system is connected to the bucket via the sheave platform, and the second hoisting system is connected to the cage via the sheave platform. The drilling rig serves as the primary support for construction, the sheave platform primarily facilitates the arrangement of the sheaves of the first hoisting system, the second hoisting system, and the stabilization system. The slag discharge platform is used for surface slag removal and for the translation and trenching of the umbrella drill. The bucket is primarily used to lift slag, and the cage is primarily used to facilitate personnel ascending and descending the well.

[0019] Specifically, in step S203, a double-layered lifting platform is used, which is connected to the first lifting system and / or the second lifting system. An umbrella drill and an integrated drilling, anchoring, and shotcreting device are installed at the bottom of the lifting platform. The integrated drilling, anchoring, and shotcreting device is a commercially available product. The integrated drilling, anchoring, and shotcreting device is integrated into the lifting platform to drill anchor holes in the shaft wall and perform shotcrete construction, thereby facilitating the reinforcement of the shaft wall.

[0020] Preferably, in step S4, an umbrella drill drilling and blasting method is adopted to construct the second vertical shaft to be excavated. When the umbrella drill is drilling, the protective plate is placed at the center of the top of the slag guide shaft as a support plate for the umbrella drill. During blasting, the protective plate is lifted to the bottom of the lifting plate, and the protective plate is raised and lowered by the umbrella drill hook rope.

[0021] Preferably, in step S204, both the second and third sections to be excavated are constructed using an umbrella drill drilling and blasting method. During construction, the single drilling depth and charge amount of the third section to be excavated are both smaller than those of the second section to be excavated, and the construction speed of the third section to be excavated is slower than that of the second section to be excavated. Because the protection section is located below the third section to be excavated, the construction speed of the third section to be excavated is slower than that of the second section to be excavated in order to avoid damaging the protection section.

[0022] Preferably, in step S204, before excavating the second and third planned sections, an active protective net is deployed on the roof of the upper level tunnel for protection, and a convergence deformation meter is installed on the roof to monitor changes in the surrounding rock at the roof. Since vertical shaft excavation primarily utilizes blasting, protective nets and monitoring instruments are deployed to monitor changes in the surrounding rock at the upper level tunnel roof based on deformation.

[0023] Specifically, the proposed first vertical shaft will be excavated at a height of 85 to 115 meters, the proposed first section at a height of 15 to 20 meters, the proposed second section at a height of 50 to 65 meters, the proposed third section at a height of 15 to 20 meters, and the proposed protection section at a height of 5 to 10 meters. After the proposed first section is completed, comprehensive mechanized operations can begin.

[0024] Specifically, in step S1, a first construction auxiliary passage is constructed in the upper horizontal tunnel, and a second construction auxiliary passage is constructed in the lower horizontal tunnel. By providing the first and second construction auxiliary passages, during shaft construction, the first and second intersection sections can be quickly reached, improving construction convenience.

[0025] Specifically, the construction of the slag guide well using the reverse well method in step S2 includes the following construction steps: the directional drilling rig is brought in and installed, the directional correction system is debugged, and the directional reaming drill bit is installed to carry out the initial expansion and brushing construction of the slag guide well pilot hole; the slag guide well pilot hole expansion hole is constructed, and the directional drilling rig is withdrawn after the slag guide well pilot hole expansion hole is penetrated; the reverse well drilling rig is brought in and the slag guide well construction is carried out from bottom to top.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The shaft excavation construction method of this application fully absorbs the advantages of the vertical shaft method's rapid lifting system, the advantages of the umbrella drilling and hole-making construction equipment, and the advantages of the reverse shaft method's slag sliding to the bottom for slag discharge. By adopting a construction method that combines the vertical shaft method and the reverse shaft method, the purpose of facilitating construction organization, shortening construction period, and ensuring safe and reliable construction is achieved.

[0028] 2. The shaft excavation construction method of this application effectively overcomes the disadvantages of low slag discharge efficiency, ventilation and smoke dispersion, and water gushing control of the vertical shaft method, which is conducive to reducing construction safety risks and improving the construction period guarantee rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the overall structure of the construction equipment used in the shaft excavation construction method of the present invention;

[0030] Figure 2 This is a schematic diagram of the segmented excavation structure of the shaft excavation construction method of the present invention;

[0031] Figure 3 yes Figure 1 Schematic diagram of the well drilling derrick structure;

[0032] Figure 4 yes Figure 1 Schematic diagram of the integrated drilling, anchoring and shotcreting equipment structure under the middle lifting platform.

[0033] In the figure

[0034] 1—upper horizontal tunnel, 2—lower horizontal tunnel, 3—first construction auxiliary passage, 4—planned excavation of the first vertical shaft, 401—planned excavation of the first section, 402—planned excavation of the second section, 403—planned excavation of the third section, 404—protection section, 5—first intersection section, 6—planned excavation of the second vertical shaft, 7—second intersection section, 8—second construction auxiliary passage, 9—excavator, 10—ladder, 11—slag guide shaft pilot hole, 12—slag guide shaft pilot hole expansion hole, 13—slag guide shaft, 14—first lifting system, 15—second lifting system, 16—vehicle stabilization system, 17—drilling derrick, 18—bucket, 19—cage, 20—hoisting platform, 21—umbrella drill, 22—protective plate, 23—integrated drilling, anchoring and spraying equipment, 24—sealing plate, 25—head pulley platform, 26—slag discharge platform. DETAILED DESCRIPTION

[0035] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments. It should be noted that the embodiments and features of the embodiments may be combined unless they conflict. For ease of description, the words "upper," "lower," "left," and "right" appear below merely to indicate the directions of upper, lower, left, and right in the accompanying drawings and do not limit the structure.

[0036] This embodiment provides a shaft excavation construction method, such as Figure 1 As shown, the vertical shaft to be excavated is divided into a first vertical shaft 4 to be excavated and a second vertical shaft 6 to be excavated at the bottom of the first vertical shaft 4 to be excavated. The axes of the first vertical shaft 4 to be excavated and the second vertical shaft 6 to be excavated are both collinear with the axis of the vertical shaft to be excavated, and the cross-sectional dimensions of the first vertical shaft 4 to be excavated and the second vertical shaft 6 to be excavated are both the same as the cross-sectional dimensions of the corresponding positions of the vertical shaft to be excavated. The depth of the first vertical shaft 4 to be excavated is 105m, and the depth of the second vertical shaft 6 to be excavated is 460m. A tunnel around the bottom of the first vertical shaft 4 to be excavated is selected as the upper horizontal tunnel 1, and a tunnel around the bottom of the second vertical shaft 6 to be excavated is selected as the lower horizontal tunnel 2. The construction method specifically includes the following construction steps:

[0037] Step S1: excavating the upper horizontal tunnel 1 to the bottom of the planned first vertical shaft 4 to form a first intersection section 5, and excavating the lower horizontal tunnel 2 to the bottom of the planned second vertical shaft 6 to form a second intersection section 7; constructing a first construction auxiliary passage 3 in the upper horizontal tunnel 1, and constructing a second construction auxiliary passage 8 in the lower horizontal tunnel 2;

[0038] Step S2: Figure 2As shown, the first vertical shaft 4 to be excavated is divided from top to bottom into a first section 401 to be excavated, a second section 402 to be excavated, a third section 403 to be excavated, and a protection section 404. The depth of the first section 401 to be excavated is 20m, the depth of the second section 402 to be excavated is 60m, the depth of the third section 403 to be excavated is 15m, and the depth of the protection section 404 is 10m. The protection section 404 is located at the top of the first intersection section 5. The vertical well method is used at the top of the first vertical shaft 4 to be excavated to the top of the protection section 404; at the first intersection section 5, the reverse well method is used to construct the slag guide shaft 13 downward along the axis of the second vertical shaft 6 to be excavated, and the upper level tunnel 1 It is connected to the lower horizontal tunnel 2 through the slag pilot shaft 13. When the reverse well method is used for construction, a directional drilling rig is brought in and installed, the directional correction system is debugged, and a directional reaming drill bit is installed to carry out the initial expansion and brushing of the slag pilot shaft pilot hole 11. The diameter of the slag pilot shaft pilot hole 11 is 216 mm. The slag pilot shaft pilot hole expansion hole 12 is constructed from top to bottom. The diameter of the slag pilot shaft pilot hole expansion hole 12 is 360 mm. After the slag pilot shaft pilot hole expansion hole 12 is penetrated, the directional drilling rig is withdrawn from the site, and the reverse well drilling rig is brought in to carry out the construction of the slag pilot shaft 13 from bottom to top. The diameter of the slag pilot shaft 13 is 2.5 m. Among them, the construction using the upright well method specifically includes the following construction steps:

[0039] Step S201: Excavate the top of the first vertical shaft 4 to perform the locking section excavation and cast the locking ring beam. After the locking ring beam, wellhead water retaining sill, and temporary guardrail are completed, the entire section is excavated downwards, and the foundations of the wellhead frame 17, the first hoisting system 14, the second hoisting system 15, and the two vehicle stabilization systems 16 are simultaneously constructed.

[0040] Step S202: After the first vertical shaft 4 is excavated 8 meters downward from the top, the excavation operation is stopped and the mechanized operation equipment such as the well drilling frame 17, the first lifting system 14, the second lifting system 15 and the two stabilizing systems 16 are installed; Figure 1 and Figure 3 As shown, the mechanized group operation equipment includes a V-shaped well drilling frame 17, a slag discharge platform 26 arranged on the well drilling frame 17, a sheave platform 25 arranged on the top of the well drilling frame 17, a first hoisting system 14, a second hoisting system 15 and two stabilizing car systems 16 arranged around the well drilling frame 17. The first hoisting system 14 is connected to the bucket 18 through the sheave platform 25, and the second hoisting system 15 is connected to the cage 19 through the sheave platform 25; the sheave platform 25 is mainly used to meet the arrangement of the sheaves of the first hoisting system 14, the second hoisting system 15 and the stabilizing car system 16. The slag discharge platform 26 is set at a height of 10.5m from the ground, and its main function is to meet the needs of ground slag turning and the translation and hook grabbing of the umbrella drill 21; the first hoisting system 14 uses a JKZ-3.2 mine hoist, the second hoisting system 15 uses a JKZ-2.8 mine hoist, and the bucket 18 has a volume of 5m 3; In addition to lifting the bucket 18, the first lifting system 14 is also used to lift the umbrella drill 21 and the excavator 9 up and down the well. The second lifting system 15 is mainly used to lift personnel up and down the well.

[0041] Step S203: Excavate downwards by smooth blasting. Figure 3 As shown, the excavator 9 loads the slag into the bucket 18, and the first lifting system 14 suspends the bucket 18 to lift the slag to the slag discharge platform 26, and the slag is transported out of the well until the first section 401 to be excavated is completed, that is, 20m; Figure 1 and Figure 3 As shown, the installation of the hoisting plate 20, the sealing plate 24, and various auxiliary production systems such as the air duct and the water pipes is carried out to form a comprehensive mechanized operation system. After that, the excavation of the first vertical shaft 4 is to be carried out using a regular cycle of one dig and one step. Before the formation of this comprehensive mechanized operation system, personnel ascend and descend the shaft by climbing the ladder 10 and are required to wear safety belts and fall arresters.

[0042] Step S204, the second section 402 to be excavated is carried out, the umbrella drill 21 is used for drilling and blasting, the excavator 9 loads the slag into the bucket 18 and lifts the slag to the slag discharge platform 26, and the slag is transported out of the well until the second section 402 to be excavated is completed, and a regular cycle operation is adopted; the umbrella drill 21 is continued to be used for drilling and blasting to excavate the third section 403 to be excavated, the excavator 9 loads the slag into the bucket 18 and lifts the slag to the slag discharge platform 26, and the slag is transported out of the well; the third section 403 to be excavated is carried out. The single drilling depth and charge of 03 are smaller than those of the single drilling depth and charge of the second section 402 to be excavated, and the construction speed of the third section 403 to be excavated is slower than that of the second section 402 to be excavated. During the blasting of the second section 402 to be excavated and the third section 403 to be excavated, according to the deformation of the surrounding rock at the top of the upper level tunnel 1, an active protection net will be arranged on the top of the tunnel for protection if necessary, and a set of convergence deformation meters will be installed on the top of the tunnel to monitor the changes in the surrounding rock at the top of the tunnel.

[0043] After the construction of step S3, the slag guide shaft 13 is completed, the protection section 404 to the first intersection section 5 is constructed by the vertical well method. The slag in the protection section 404 is discharged to the lower level tunnel 2 through the slag guide shaft 13 and discharged outside the tunnel.

[0044] Step S4, using the construction equipment of the upright well method in step S2 to excavate the second vertical shaft 6 to the second intersection section 7 through the reverse well method, and using the umbrella drill drilling and blasting method to excavate the second vertical shaft 6. When the umbrella drill 21 is drilling, the protective plate 22 is placed at the top center of the slag guide shaft 13 as a support plate for the umbrella drill 21. During blasting, the protective plate 22 is lifted to the bottom of the lifting plate 20, and the protective plate 22 is raised and lowered by the hook rope of the umbrella drill 21; after the umbrella drill 21 drills and blasts, the slag is slid into the lower flat tunnel 2 through the slag guide shaft 13 by the excavator 9, and is loaded onto a truck by a loader in the lower flat tunnel 2 and transported out of the tunnel.

[0045] like Figure 1 and Figure 4 As shown, the hanging platform 20 is a double-layer hanging platform connected to the first hoisting system 14 and the second hoisting system 15. The bottom of the hanging platform 20 is equipped with a SYZ8-12 umbrella drill 21 and an integrated drilling, anchoring and spraying equipment 23. The double-layer hanging platform is a double-layer steel structure with a distance of 3.6m between the upper and lower layers. Six columns (Φ219×12 steel pipes) are set between the upper and lower layers. The ring beam is made of I32b channel steel, the main beam of the hanging platform is made of I32 I-beam, and the secondary beam is made of I30 I-beam. Both the upper and lower layers are paved with 4mm thick checkered steel plates. The hanging platform 20 is suspended by four steel wire ropes, which are fixed to the hanging platform crossbeam suspension points with elevators. The suspension points are located on the upper platform. The upper platform is a protective platform, and the lower platform is a working platform. The upper and lower platforms are connected by steel pipes and U-shaped clamps. The upper and lower platforms are each equipped with a main and secondary monitoring system, and the signal system is located on the lower platform. Each hole of the hoisting plate 20 is provided with a cover plate, and the periphery and reserved holes are provided with fence poles, which are 1.2m high, and 200mm high skirting boards are added. The sealing plate 24 is a wellhead protection platform, and the main beam is made of 56b I-steel, which is covered with 5mm thick checkered steel plates. Personnel and materials go up and down the wellbore through the sealing plate 24. A fence is set around the auxiliary lifting hole / open hole (such as a wind duct) of the sealing plate 24. The fence is 1.2m high, and a skirting board is set below, which is not less than 0.5m high. The protective plate 22 is 3.5m in diameter and is made of steel sections. It serves as a protective plate for personnel entering the well and as a support plate for the umbrella drill 21. It is raised and lowered by the umbrella drill hook rope.

[0046] When drilling and blasting with an umbrella drill, a SYZ8-12 umbrella drill is used. For the first vertical shaft 4 to be excavated, if the excavation section is too large to fit within the working range of the umbrella drill 21, multiple umbrella drills 21 can be used to drill holes to complete the full-section drilling operation.

[0047] The contents described in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the invention, and are not used to limit the scope of the invention. After reading the present invention, various equivalent modifications to the embodiments made by those skilled in the art fall within the scope defined by the claims attached to the present invention.

Claims

1. A shaft excavation construction method, characterized in that: The vertical shaft to be excavated is divided into a first vertical shaft to be excavated (4) and a second vertical shaft to be excavated (6) located at the bottom of the first vertical shaft to be excavated (4). The axes of the first vertical shaft to be excavated (4) and the second vertical shaft to be excavated (6) are both collinear with the axis of the vertical shaft to be excavated. The height of the second vertical shaft to be excavated (6) is not greater than 500m. A tunnel around the bottom of the first vertical shaft to be excavated (4) is selected as an upper horizontal tunnel (1), and a tunnel around the bottom of the second vertical shaft to be excavated (6) is selected as a lower horizontal tunnel (2). The construction method includes the following construction steps: Step S1, excavating the upper horizontal tunnel (1) to the bottom of the first vertical shaft (4) to be excavated to form a first intersection section (5), and excavating the lower horizontal tunnel (2) to the bottom of the second vertical shaft (6) to be excavated to form a second intersection section (7); Step S2, a section at the lower part of the first vertical shaft (4) to be excavated is reserved as a protection section (404), the protection section (404) is located at the top of the first intersection section (5), and a vertical well method is used to construct the top of the protection section (404) at the top of the first vertical shaft (4) to be excavated; at the first intersection section (5), a reverse well method is used to construct a slag guide shaft (13) downward along the axis of the second vertical shaft (6) to be excavated, and the upper horizontal tunnel (1) is connected to the lower horizontal tunnel (2) through the slag guide shaft (13); After the construction of step S3 and the slag guide shaft (13) is completed, the protection section (404) to the first intersection section (5) is constructed by the vertical well method. The slag in the protection section (404) is slid through the slag guide shaft (13) to the lower horizontal tunnel (2) and discharged outside the tunnel. Step S4: using the construction equipment of the vertical shaft method in step S2 to excavate the second vertical shaft (6) to the second intersection section (7) through the reverse shaft method.

2. The shaft excavation construction method according to claim 1, characterized in that: The first vertical shaft (4) to be excavated is divided into a first section to be excavated (401), a second section to be excavated (402), a third section to be excavated (403) and a protection section (404) from top to bottom. The vertical shaft method used in step S2 specifically includes the following construction steps: Step S201: excavate the top of the first vertical shaft (4) to be excavated, and cast the locking section and locking ring beam. After the locking ring beam, wellhead water retaining sill, and temporary guardrail are completed, the entire section is excavated downward, and the wellhead frame (17), lifting system, and vehicle stabilization system foundation are constructed simultaneously; Step S202: After the first vertical shaft (4) is excavated from the top to a certain height, the excavation operation is stopped and mechanized operation equipment is installed; Step S203: Continue excavating downwards, and the slag is lifted and transported upwards by mechanized equipment until the excavation of the first section (401) to be excavated is completed; install the lifting plate (20), the sealing plate (24) and the auxiliary production system to form a comprehensive mechanized operation system; Step S204: sequentially carry out the construction of the second section (402) to be excavated and the third section (403) to be excavated, and lift the slag upward and transport it out.

3. The shaft excavation construction method according to claim 2, characterized in that: In step S202, the mechanized group operation equipment includes a well drilling frame (17), a slag discharge platform (26) arranged on the well drilling frame (17), a sheave platform (25) arranged on the top of the well drilling frame (17), a first lifting system (14) arranged around the well drilling frame (17), a second lifting system (15) and two stabilizing systems (16), the first lifting system (14) is connected to the bucket (18) through the sheave platform (25), and the second lifting system (15) is connected to the cage (19) through the sheave platform (25).

4. The shaft excavation construction method according to claim 3, characterized in that: In step S203, the hanging plate (20) is a double-layer hanging plate, which is connected to the first lifting system (14) and / or the second lifting system (15), and an umbrella drill (21) and an integrated drilling and anchoring spraying device (23) are provided at the bottom of the hanging plate (20).

5. The shaft excavation construction method according to claim 4, characterized in that: In step S4, the second vertical shaft (6) is to be excavated by using an umbrella drill drilling and blasting method. When the umbrella drill (21) is drilling, the protective plate (22) is placed at the center of the top of the slag guide shaft (13) to serve as a support plate for the umbrella drill (21). When blasting, the protective plate (22) is hoisted to the bottom of the hoisting plate (20), and the protective plate (22) is raised and lowered by the umbrella drill (21) by grabbing the hook rope.

6. The shaft excavation construction method according to claim 2, characterized in that: In step S204, both the second section (402) to be excavated and the third section (403) to be excavated are constructed using the umbrella drill drilling and blasting method. During construction, the single drilling depth and charge amount of the third section (403) to be excavated are smaller than the single drilling depth and charge amount of the second section (402) to be excavated, and the construction speed of the third section (403) to be excavated is slower than the construction speed of the second section (402) to be excavated.

7. The shaft excavation construction method according to claim 2, characterized in that: In step S204, before the excavation of the second section (402) and the third section (403), an active protection net is arranged on the top of the upper level tunnel (1) for protection, and a convergence deformation meter is installed on the top to monitor the changes in the surrounding rock of the top.

8. The shaft excavation construction method according to claim 2, characterized in that: The height of the first vertical shaft (4) to be excavated is 85 to 115 meters, the height of the first section (401) to be excavated is 15 to 20 meters, the height of the second section (402) to be excavated is 50 to 65 meters, the height of the third section (403) to be excavated is 15 to 20 meters, and the height of the protection section (404) is 5 to 10 meters.

9. The shaft excavation construction method according to claim 1, characterized in that: In step S1, a first construction auxiliary channel (3) is constructed in the upper horizontal tunnel (1), and a second construction auxiliary channel (8) is constructed in the lower horizontal tunnel (2).

10. The shaft excavation construction method according to claim 1, characterized in that: In step S2, the reverse well method is used to construct the slag guide well (13), which includes the following construction steps: a directional drilling rig is brought in and installed, a directional deviation correction system is debugged, a directional reaming drill bit is installed to initially expand and brush the slag guide well pilot hole (11); an expansion hole (12) of the slag guide well pilot hole is constructed, and after the expansion hole (12) of the slag guide well pilot hole is penetrated, the directional drilling rig is withdrawn from the site; and a reverse well drilling rig is brought in to construct the slag guide well (13) from bottom to top.

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