A vortex shaft construction method suitable for high ground stress hard rock area

Abstract

The application relates to the technical field of vortex shafts, and discloses a vortex shaft construction method suitable for high ground stress hard rock areas. In order to solve the problems of easy rock burst and spalling, low safety, time and labor consumption of slag transportation, and low work efficiency during construction of a vortex shaft in a high ground stress hard rock area, a pilot hole is arranged at the dome position of the upper horizontal section of the pressureless tunnel, the dome is excavated and supported clockwise or counterclockwise from the pilot hole as a starting point, a load-bearing rock column is reserved during excavation, the load-bearing rock column is excavated after the dome is excavated and supported, the load-bearing rock column part of the dome is anchored and supported, the vortex chamber section, the vortex shaft section, the gradual change section, the vortex shaft section and the blind shaft section are sequentially excavated and constructed in layers, and a slag chute is arranged during construction of the vortex shaft section. The stability of the vortex shaft dome excavation stage can be improved, the rock burst risk in the high ground stress area can be effectively reduced, and the large equipment used for transporting slag from the upper horizontal section of the pressureless tunnel in the existing shaft is replaced, so that the work efficiency can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of vortex shaft technology, specifically, a method for constructing vortex shafts suitable for hard rock areas with high ground stress. Background Technology

[0002] In my country's hydropower engineering field, most underground hydropower stations are built in the deep mountain and canyon areas of southwest China, where internal and external dynamic geological processes are intense. To ensure the smooth construction of hydropower stations, construction is often carried out in hard rock areas. However, the surrounding rock in hard rock areas under strong unloading exhibits brittle failure characteristics. The principle is that the tangential stress brought about by the initial high ground stress and the stress concentration in multiple chambers jointly lead to local spalling, slab cracking, and rock bursts in the spillway chamber. The spillway system is an important component of water conservancy projects, playing a crucial role in ensuring dam safety, regulating water levels, and ensuring stable power generation. For the construction of high-head, high-flow-rate dams in high mountain and canyon areas, vortex vertical shaft spillway tunnels are suitable. This energy dissipation structure is not only simple in structure and has a high energy dissipation rate, but it can also meet the flood discharge conditions of "high head, large discharge volume, and fast flow velocity." In particular, the dome structure of the vortex vertical shaft, due to its narrow excavation face, high ground stress, and large vortex chamber diameter, is prone to rock bursts and spalling during the excavation stage when using conventional construction methods, making it difficult to guarantee the construction safety of the vortex vertical shaft. Meanwhile, the slag produced after excavation in the lower section of the unpressurized tunnel is discharged from the air replenishment shaft or the upper section of the unpressurized tunnel. Due to the high overall height of the shaft, large equipment is needed to lift the slag, which is time-consuming, labor-intensive, and inefficient. Summary of the Invention

[0003] The purpose of this invention is to provide a method for constructing vortex shafts in hard rock areas with high ground stress. The method involves excavating the shaft in layers and zones in an orderly manner, and using different excavation techniques for each level and zone of surrounding rock stress to gradually release the surrounding rock stress and avoid phenomena such as rock bursts and spalling.

[0004] This invention is achieved through the following technical solution: a method for constructing vortex shafts suitable for high-stress hard rock zones, specifically including the following steps:

[0005] Step 1: Dome excavation construction; specifically, after the upper level of the unpressurized tunnel is excavated, a pilot tunnel is excavated longitudinally towards the dome. The entrance of the pilot tunnel is located on the upper level of the unpressurized tunnel, and the exit of the pilot tunnel is located near the inner wall of the dome. The load-bearing rock pillar is retained in the center of the dome. Smooth blasting is carried out layer by layer and section by section around the load-bearing rock pillar. The dome is divided into N layers from top to bottom, where N≥3 and N is an integer. Anchor bolts are inserted and steel mesh is installed and shotcreted on the inner wall of the dome according to the layer. Steel mesh is installed and shotcreted on the load-bearing rock pillar.

[0006] Step 2: Excavation of the load-bearing rock column; specifically, the load-bearing rock column is divided into at least three layers from top to bottom, and excavation is carried out from top to bottom. After the first layer of the load-bearing rock column is excavated, it serves as a construction platform for the excavation of the second layer of the load-bearing rock column. After the excavation of the second layer of the load-bearing rock column is completed, anchor bolts are inserted and steel mesh is installed and shotcrete is applied to the dome above the load-bearing rock column. Then, the excavation of the next layer of the load-bearing rock column is carried out until the entire load-bearing rock column is completely excavated and removed.

[0007] Step 3: Excavation of the vortex chamber section; specifically, this refers to dividing the vortex chamber section into the main vortex chamber section and the vortex chamber well section. The main vortex chamber section includes the upper section, middle section, and lower section of the main vortex chamber. The upper section of the main vortex chamber is divided into annular sections from the inside out. The central annular section is excavated using vertical blasting, while the annular sections outside the central annular section are excavated radially. The middle section of the main vortex chamber is excavated in layers, with each layer divided into annular sections. The central annular section is excavated using vertical blasting, while the annular sections outside the central annular section are excavated radially. After the excavation of the middle section of the main vortex chamber is completed, the lower layer of the upper horizontal section of the vertical shaft and the bottom protective layer are excavated and supported. The lower section of the main vortex chamber is excavated in layers, with each layer divided into annular sections. The central annular section is excavated using vertical blasting, while the annular sections outside the central annular section are excavated radially.

[0008] Step 4: Excavation of the vortex chamber section; specifically, the vortex chamber section is divided into the upper section, middle section, and lower section, and is excavated layer by layer from top to bottom. After the main vortex chamber section is excavated, the slag at the center of the main vortex chamber section is cleared, and a well ring is set at the center. The well ring is used to excavate the slag chute. Inside the well ring, a reverse drilling rig is used to pull the guide shaft to the lower horizontal section of the unpressurized tunnel. The excavation angle of each layer is reduced by no more than 5°. Figure 6 , Figure 7 , Figure 8 As shown;

[0009] Step 5: Gradual section excavation construction; specifically, the gradual section is excavated in layers, with each advance being a cycle, and the excavation diameter is reduced to within 25cm.

[0010] Step 6; Excavation and construction of the vortex shaft section and blind shaft section; Specifically, the vortex shaft section is divided into the upper section, the middle section, and the blind shaft section. The upper and middle sections are excavated and supported in layers. The side walls on both sides of the section connecting the middle section of the vortex shaft to the lower horizontal section of the unpressurized tunnel, as well as the area on both sides above the arching line of the lower horizontal section of the unpressurized tunnel, are expanded and supported in a secondary manner. The blind shaft section is excavated and supported in layers.

[0011] To better realize the present invention, further, in step 1, the dome is divided into a first dome, a second dome, a third dome and a fourth dome from top to bottom. The first dome is excavated in a counterclockwise ring manner while retaining the load-bearing rock pillar, starting from the entrance of the pilot tunnel. First, the inner ring is excavated. After the inner ring is excavated, the outer ring is excavated. A protective layer is reserved during the excavation process.

[0012] The second dome was excavated in a clockwise ring from the entrance of the pilot tunnel. Each ring was evenly divided into several areas for excavation. After the excavation of the first and second domes was completed, 6m anchor bolts were installed using manual labor and hand-held pneumatic drills. After the support was completed, steel mesh was hung on the first and second domes and the exposed load-bearing rock columns and shotcrete was applied.

[0013] The third dome was excavated in a clockwise ring-shaped manner, starting from the entrance of the pilot tunnel. Each ring was evenly divided into several areas for excavation. The first and second domes were supported by 9m anchor bolts using manual labor and hand-held pneumatic drills. The third dome was supported by 6m and / or 9m anchor bolts using down-the-hole drills. Steel mesh was hung on the third dome and the exposed load-bearing rock columns, and shotcrete was applied.

[0014] The fourth dome was excavated in a clockwise ring pattern, starting from the entrance of the pilot tunnel. Each ring was evenly divided into several areas for excavation. Down-the-hole drills were used to provide staggered support for the fourth dome with 6m and / or 9m anchor bolts. Steel mesh was installed on the fourth dome and the exposed load-bearing rock columns, and shotcrete was applied.

[0015] To better realize the present invention, the dome is further divided into four layers and the load-bearing rock pillars are divided into three layers.

[0016] To better realize the present invention, further, in step 3, the central ring of the upper section of the main vortex chamber is excavated in one go, the middle ring of the upper section of the main vortex chamber is excavated by zonal radial vertical blasting, and the outer ring of the upper section of the main vortex chamber is excavated by step-by-step vertical blasting; a full-span scaffold is erected in the upper section of the main vortex chamber, and after 12m anchor bolts are installed at the dome position, the full-span scaffold is dismantled; 6m locking anchor bolts and / or 9m locking anchor bolts are staggered above the connection between the middle section of the main vortex chamber and the upper flat section of the pressureless tunnel.

[0017] To better realize the present invention, further, in step 4, the well ring is a reinforced concrete well ring. Inner and outer ring reinforcement bars are inserted at the center of the lower section of the main vortex chamber. Circumferential reinforcement bars are tied to the exposed inner and outer ring reinforcement bars. A two-way double-layer steel mesh is set within the well ring. Templates are installed along the inner and outer ring reinforcement bars. Concrete is poured within the well ring. After the concrete solidifies, the templates are removed, and concrete is poured inside the well ring. The circumferential construction joint between the two is filled with foam board. A trench is excavated outside the well ring, and the trench is divided into several circulating water settling pools. A guide hole for the vertical shaft is excavated using a reverse drilling rig. A guide drill rod is added every 2-3 drill rod sections. After the guide hole is completed, the reverse drill bit is replaced, and a chute is formed from bottom to top. The chute connects the upper section of the vortex chamber well and the lower horizontal section of the unpressurized tunnel.

[0018] To better realize the present invention, further, in step 4, the shrinkage section is located in the middle section of the vortex chamber well, and the shrinkage section is blasted in layers and sections from top to bottom, with each advance being a cycle, and the excavation diameter is reduced to within 25cm.

[0019] To better realize the present invention, furthermore, after the excavation of the dome, the upper section of the main vortex chamber and the middle section of the main vortex chamber, the slag is transported to the upper flat section of the pressureless tunnel through the guide tunnel; the slag in the lower section of the main vortex chamber is loaded into dump trucks by excavators for slag transportation; the slag in the vortex chamber section falls by its own weight through the slag chute and is transported out through the lower flat section of the pressureless tunnel.

[0020] To better realize the present invention, further, the inner diameter of the lower opening of the contraction section is smaller than the inner diameter of the vortex section, and the inner diameter of the lower opening of the contraction section is smaller than or equal to the inner diameter of the blind well section.

[0021] To better realize the present invention, both the contraction segment and the gradient segment are cone-shaped bodies that are larger at the top and smaller at the bottom.

[0022] To better realize the present invention, further, the diameter of the entrance end connecting the pressureless tunnel lower horizontal section and the blind well section is less than or equal to the diameter of the blind well section.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] (1) The present invention provides a method for constructing a vortex shaft in a hard rock area with high ground stress. A pilot tunnel is opened at the dome position in the upper horizontal section of the unpressurized tunnel. The layered excavation and support are carried out clockwise or counterclockwise from the pilot tunnel. During the excavation, the load-bearing rock column is retained to avoid the collapse due to insufficient prestress of the dome. After the excavation and support of the dome is completed, the load-bearing rock column is excavated. Then, the load-bearing rock column part of the dome is supported by anchor bolts. The vortex chamber section, vortex chamber shaft section, transition section, vortex shaft section and blind shaft section are excavated in layers in sequence to slowly release the surrounding rock pressure and avoid rock bursts or collapses. When constructing the vortex chamber shaft section, a chute is opened to facilitate the discharge of the slag generated during the excavation process through the chute and the lower horizontal section of the unpressurized tunnel.

[0025] (2) During the excavation stage, the central load-bearing rock pillar is retained first, and the construction process is carried out in a layered excavation method with short advance and weak blasting in different areas to reduce the disturbance of the dome. In order to ensure the timely support of the dome excavation, the support anchor rod is used to support the rock pillar before the rock pillar is excavated. The anchor rod is installed after the rock pillar is excavated. The support of the load-bearing rock pillar and the anchor rod can avoid the impact force generated during the dome excavation and blasting, which can prevent the dome from collapsing. This construction technology can ensure the stability of the rock mass during the excavation construction in the high ground stress hard rock area, as well as improve the construction quality of the vortex shaft and the safety factor of the construction personnel.

[0026] (3) A chute is provided in the vortex chamber section. The slag generated during the excavation of the vortex chamber section can fall freely under gravity through the chute to the lower horizontal section of the pressureless tunnel. The slag can then be transported out through the lower horizontal section of the pressureless tunnel, which replaces the existing method of transporting the slag to the upper horizontal section of the pressureless tunnel using large equipment during the construction of the vertical shaft. This saves time and effort, effectively improves work efficiency, and saves construction time. Attached Figure Description

[0027] The technical solution will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention.

[0028] Figure 1 A schematic diagram of the structure of the vortex shaft provided by the present invention;

[0029] Figure 2 This is a partition diagram of the dome and vortex chamber sections of the present invention;

[0030] Figure 3 This is a cross-sectional view of the layered excavation of the dome and vortex chamber sections of the present invention;

[0031] Figure 4 This is a diagram of the anchor bolt support for the dome of the present invention;

[0032] Figure 5 This is a diagram showing the ring-and-zone division of the dome excavation in this invention;

[0033] Figure 6 This is a zoning diagram of the upper section of the main vortex chamber of the present invention;

[0034] Figure 7 This is a zoning diagram of the excavation section in the middle of the main vortex chamber of the present invention;

[0035] Figure 8 This is a zoning diagram of the excavation of the lower section of the main vortex chamber in this invention;

[0036] Figure 9 This is a schematic diagram of the structure of the well ring and circulating water settling tank of the reverse drilling rig of the present invention;

[0037] Figure 10 This is a cross-sectional view of the layered excavation of the vortex chamber section in this invention;

[0038] Figure 11 This is a cross-sectional view of the layered excavation of the transition section and the vortex section in this invention;

[0039] Figure 12 This is a cross-sectional view of the secondary excavation at the connection between the middle section of the vortex shaft and the lower horizontal section of the unpressurized tunnel in this invention.

[0040] Figure 13 This is a diagram showing the layout of the blasting sections in the same layer of the vortex chamber section of the present invention.

[0041] The components include: 1. Dome; 101. First-level dome; 102. Second-level dome; 103. Third-level dome; 104. Fourth-level dome; 2. Upper section of the unpressurized tunnel; 201. Upper layer of the upper section of the unpressurized tunnel; 3. Vortex section; 301. Upper section of the main vortex chamber; 302. Middle section of the main vortex chamber; 303. Lower section of the main vortex chamber; 4. Contraction section; 5. Blind well section; 6. Gradual transition section; 7. Vortex well section; 8. Lower section of the unpressurized tunnel; 9. Pilot tunnel exit; 10. Pilot tunnel entrance; 11. Slag chute; 12. Load-bearing rock pillar; 13. Pilot tunnel; 1401. 9m anchor bolt; 1402. 6m anchor bolt; 15. Raised well drilling rig; 16. Well ring; 17. Circulating water settling tank. Detailed Implementation

[0042] The following detailed description, in conjunction with specific embodiments, further illustrates the above-mentioned content created by the present invention. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following examples. Various substitutions or modifications made based on ordinary technical knowledge and conventional means in the art without departing from the above-mentioned technical concept of the present invention should be included within the scope of the present invention. In the description of the present invention, it should be noted that the terms used in the various embodiments, such as "upper," "lower," "front," "rear," "left," and "right," which indicate orientation, are only for simplifying the description of the positional relationships based on the accompanying drawings and do not mean that the elements and devices referred to must be operated according to the specific orientation and limited operation, method, or structure in the specification. Such directional terms do not constitute a limitation of the present invention.

[0043] Example 1:

[0044] The vortex shaft structure to be constructed is as follows: Figure 1 As shown, the surrounding rock of the vortex shaft spillway in the high-stress hard rock zone is a hard, porphyritic biotite-potassium feldspar granite with pegmatite veins. The rock is mainly slightly weathered to freshly weathered with occasional weathering. After considering the high stress reduction, the surrounding rock is mainly of type IIIa, with some areas of type IIIb. The failure type of this type of high-stress rock is brittle failure, and there is obvious rebound deformation when the minimum principal stress is unloaded. The failure of the rock is the relative displacement between rock mineral grains under the action of shear stress or tensile strain on the oblique section. This type of rock mass stores a large amount of elastic energy. The excavation process will cause the surrounding rock to adjust from a triaxial stress state to a biaxial stress state. When the rock is brittle, this strain energy will be released violently, causing spalling and rockburst phenomena. The rock mass excavation process can be regarded as the deterioration process of the mechanical parameters after the rock mass yields. Based on the RDM model, this process is a typical elastic-brittle-plastic model. The excavation of deep-buried structures will cause secondary stress redistribution, resulting in displacement and stress in the surrounding rock. As the fundamental cause of surrounding rock damage, its secondary stress state exhibits an elastoplastic distribution. Due to the uniformly distributed confining pressure load on all sides, blasting under deep-buried excavation conditions can be simplified to a plane strain problem in infinite space. The propagation distance of the main blast crack in the deeply buried surrounding rock is shorter, and the damage range is reduced. Hard rock blasting can be divided into four zones: the blast cavity, the pulverization zone, the fracture zone, and the vibration zone. Outside the fracture zone, the impact of blasting on the rock mass can be considered as an elastic effect. According to the hard rock blasting damage radius theory, the first three zones can be regarded as the damage zone, and the radius of the fracture zone is generally about 2.3 times the radius of the pulverization zone.

[0045] Typically, before the construction of the vortex shaft, the upper level 201 of the upper flat section of the unpressurized tunnel and the lower flat section 8 of the unpressurized tunnel have already been completed using existing technologies, and this plan will not describe them further.

[0046] This embodiment provides a method for constructing vortex shafts in hard rock areas with high ground stress, specifically including the following steps:

[0047] Step 1: Excavation of Dome 1. After the excavation of the upper level 201 of the pressureless tunnel is completed, at least one pilot tunnel is excavated longitudinally along the direction of Dome 1. The entrance 10 of the pilot tunnel is located at the upper level 201 of the pressureless tunnel, and the exit 9 of the pilot tunnel is located near the inner wall of Dome 1. The load-bearing rock column 12 is retained in the central part of Dome 1. Smooth blasting is carried out in layers and sections from top to bottom around the load-bearing rock column 12. The dome is divided into N layers, where N≥3 and N is an integer. Anchor rods are inserted and steel mesh is installed and shotcrete is applied to the inner wall of Dome 1 in layers. Steel mesh is installed and shotcrete is applied to the load-bearing rock column 12.

[0048] Taking N=4 as an example, the dome is divided into a first dome, a second dome, a third dome, and a fourth dome, as follows: Figure 2 As shown.

[0049] like Figure 5 As shown, the first layer of the dome, starting from the entrance 10 of the pilot tunnel, is excavated in a counter-clockwise ring pattern while retaining the load-bearing rock pillars 12. Figure 5 As shown, the inner ring is excavated first, followed by the outer ring. A protective layer of at least 1 meter is reserved during excavation to ensure effective blasting and control over-excavation during outer ring construction. The excavation is divided into four equal zones, each representing 1 / 4 of the ring. Before excavating the fourth zone of the first layer, the I-beams at the lower guide tunnel outlet 9 of this zone are removed, and a construction platform is erected for excavation. Each cycle requires all boreholes to be horizontal, with the azimuth angle perpendicular to the vortex chamber axis. Five blasting cycles are needed to complete the excavation for each zone and ring. Over-excavation of the inner boreholes is controlled within 16cm, and over-excavation of the outer boreholes is controlled within 26cm, i.e., short advance and weak blasting. This method is used for subsequent excavation.

[0050] The second layer of the dome is excavated clockwise in rings, starting from the entrance 10 of the pilot tunnel. Each ring is evenly divided into four areas for excavation, with each area being 1 / 4 of the ring. Before excavating the second area of ​​the second layer, depending on the remaining rock thickness above the top of the lower pilot tunnel exit 9, if the safety of the second layer excavation can be ensured, the I-beams at the lower pilot tunnel entrance 10 in this area can be temporarily left unremoved; otherwise, the lower I-beams in this area will be gradually removed during the excavation of this layer, and then a construction platform will be erected for the excavation of this area. The requirements for each cycle are: all boreholes must be horizontal, with the azimuth angle perpendicular to the axis of the vortex chamber. Each area and each ring requires 5 blasting operation cycles to complete the excavation. The over-excavation of the internal test holes should be controlled within 26cm, and the over-excavation of the external test holes should be controlled within 28m.

[0051] After the excavation of the first and second domes is completed, 6m anchor bolts are used for support by manual labor and YT-28 hand drills. After the support is completed, φ8@20*20cm or φ8@30*30cm steel mesh is hung on the first and second domes and the exposed load-bearing rock columns, and C25 concrete is sprayed with a thickness of 10cm-20cm.

[0052] The third-level dome is excavated in a clockwise ring pattern, starting from the entrance 10 of the pilot tunnel. Each ring is evenly divided into several areas for excavation. Before excavating the second area of ​​the third level, the lower H-beams of the pilot tunnel exit 9 in this area are gradually removed. Then, a construction platform is erected for excavation in this area. All boreholes are horizontal, with the azimuth angle perpendicular to the axis of the vortex chamber. Over-excavation of the internal boreholes is controlled within 23cm, and over-excavation of the external boreholes is controlled within 29cm. The first and second level domes are supported by 9m anchor bolts using manual labor and YT-28 hand drills. The third level dome is supported by 6m and / or 9m anchor bolts using down-the-hole drills. φ8@20*20cm or φ8@30*30cm steel mesh is hung on the third level dome and the exposed load-bearing rock columns 12, and C25 concrete is sprayed to a thickness of 10cm-20cm.

[0053] The fourth dome is excavated in a clockwise, ring-shaped manner, starting from the entrance 10 of the pilot tunnel. Each ring is evenly divided into several areas for excavation. All boreholes are horizontal, with their azimuth angle perpendicular to the vortex chamber axis. Over-excavation of both internal and external boreholes is controlled within 29cm. Before excavating the third zone of the fourth layer, based on the remaining rock thickness above the top of the lower pilot tunnel exit 9, if the safety of the fourth layer excavation can be ensured, the H-beam at the lower pilot tunnel exit 9 in this area can be temporarily left unremoved; otherwise, the lower H-beam in this area will be gradually removed during the excavation of this layer. Then, a construction platform will be erected for the excavation of this area. Down-the-hole drills will be used to provide staggered support for the fourth dome with 6m and / or 9m anchor bolts. Figure 4 As shown, φ8@20*20cm or φ8@30*30cm steel mesh was hung on the fourth-level dome and the exposed load-bearing rock columns 12, and C25 concrete was sprayed to a thickness of 10cm-20cm.

[0054] Step 2: Excavation of Load-Bearing Rock Column 12. The load-bearing rock column 12 is divided into three layers, with the first layer being shorter than the second and third layers. Excavation proceeds from top to bottom. After the first layer is excavated, it serves as a construction platform. Over-excavation is controlled within 30cm. Excavation of the second layer is then carried out. After the second layer is completed, anchor bolts are inserted and steel mesh is installed on the dome 1 above the load-bearing rock column 12, followed by shotcreting. Excavation of the third layer continues until the entire load-bearing rock column is completely excavated and removed.

[0055] Step 3: Excavation and construction of vortex chamber section 3. Vortex chamber section 3 is divided into the main vortex chamber section and the vortex chamber well section. The main vortex chamber section includes the upper main vortex chamber section 301, the middle main vortex chamber section 302, and the lower main vortex chamber section 303, as follows... Figure 2As shown, the upper section 301 of the main vortex chamber is divided into annular sections from the inside out. The central annular section is excavated using vertical blasting, while the annular sections outside the central section are excavated radially. The middle section 302 of the main vortex chamber is excavated in layers, with each layer divided into annular sections. The central annular section is excavated using vertical blasting, while the annular sections outside the central section are excavated radially. After the middle section 302 of the main vortex chamber is excavated, the middle layer of the upper horizontal section of the shaft and the protective layer of the bottom plate are excavated and supported. The lower section 303 of the main vortex chamber is excavated in layers, with each layer divided into annular sections. The central annular section is excavated using vertical blasting, while the annular sections outside the central section are excavated radially. Specifically, as shown... Figure 10 , Figure 13 As shown. Typically, the height of the protective layer is set to 0.6m.

[0056] Step 4: Excavation of the vortex chamber section. The vortex chamber section is divided into the upper section, middle section, and lower section, and is excavated layer by layer from top to bottom. After the main vortex chamber section is excavated, the slag at the center of the main vortex chamber section is cleared, and a well ring 16 is set at the center. The well ring 16 is used to excavate the slag chute 11. Inside the well ring 16, the guide shaft is pulled back to the lower horizontal section 8 of the unpressurized tunnel using a reverse drilling rig 15. The over-excavation of the vortex chamber section is controlled within 20cm, and the excavation angle of each layer is reduced by no more than 5°. Figure 9 As shown.

[0057] Step 5: Excavation of the transition section 6. The transition section 6 is excavated in layers, with each advance consisting of one cycle, and the excavation diameter is reduced to within 25cm.

[0058] Step 6; Excavation and construction of vortex shaft section 7 and blind shaft section 5. Vortex shaft section 7 is divided into upper vortex shaft section, middle vortex shaft section, and blind shaft section 5. Layered excavation and support are carried out on both the upper and middle vortex shaft sections. Secondary excavation and support are carried out on the side walls of the section connecting the middle vortex shaft section to the lower horizontal section 8 of the unpressurized tunnel, and on both sides of the area above the arch line of the lower horizontal section 8 of the unpressurized tunnel. Blind shaft section 5 is also excavated and supported in layers, as detailed below. Figure 11 , Figure 12 As shown.

[0059] In step 2, the central load-bearing rock pillar 12 is retained during the excavation stage. During construction, a layered excavation method with short advances and weak blasting is used in different areas via a pilot tunnel to minimize disturbance to the dome 1. To ensure timely support during the excavation of the dome 1, support anchors are used to provide support in the construction space before the load-bearing rock pillar 12 is excavated. The anchors are then installed after the load-bearing rock pillar 12 is excavated. The support provided by the load-bearing rock pillar 12 and the anchors prevents the dome 1 from collapsing due to the impact force generated during blasting. This construction technique, used in high-stress hard rock areas, ensures rock mass stability during excavation and improves the construction quality and safety of the vortex shaft.

[0060] In step 3, a slag chute 11 is provided in the vortex chamber section. The slag generated during the excavation of the vortex chamber section 3 can fall freely under gravity through the slag chute 11 to the lower horizontal section 8 of the unpressurized tunnel. The slag can then be transported out through the lower horizontal section 8 of the unpressurized tunnel. This replaces the existing method of transporting the slag to the upper horizontal section 2 of the unpressurized tunnel or the air supply shaft during the construction of vertical shafts. This method saves time and effort, effectively improves work efficiency, and saves construction time.

[0061] Example 2:

[0062] Further, based on Example 1, such as Figures 2 to 13 As shown, during the excavation of the vortex chamber section 3 in step 3, the central ring area of ​​the upper section 301 of the main vortex chamber is excavated in one go, the middle ring area of ​​the upper section 301 of the main vortex chamber is excavated using zoned radial vertical blasting, and the outer ring of the upper section 301 of the main vortex chamber is excavated using stepped vertical blasting. A full-span scaffold is erected on the upper section 301 of the main vortex chamber, with a spacing of 2.0m x 2.0m between uprights and a floor height of 2.0m. At the edge of each floor, the bottom of one span of the scaffold is... A circumferential construction passage was set up using bamboo planks, and a safety net was installed at the bottom of the passage. Anchor holes were drilled 20cm-30cm away from the 6m anchor bolts using a 100B down-the-hole drill. 12m anchor bolts were installed at the dome 1 position. After the dome 1 was inspected and approved, the full-span scaffolding was dismantled. 6m anchor bolts and / or 9m locking anchor bolts were installed in a staggered manner against the direction of water flow above the connection between the middle section 302 of the main vortex chamber and the upper flat section 2 of the unpressurized tunnel, with a spacing of 1.0m-1.2m between rows.

[0063] The rest of this embodiment is the same as that of Embodiment 1, so it will not be described again.

[0064] Example 3:

[0065] This implementation is a further optimization based on Example 2, such as... Figures 2 to 13 As shown, in step 4, the well ring 16 is a reinforced concrete well ring. Inner and outer ring reinforcement bars are inserted at the center of the lower section 303 of the main vortex chamber. Circumferential reinforcement bars are tied to the exposed inner and outer ring reinforcement bars. A two-way, double-layer steel mesh is set within the well ring 16. Templates are installed along the inner and outer ring reinforcement bars. Concrete is poured within the well ring 16. After the concrete solidifies, the templates are removed, and concrete is poured inside the well ring 16. The circumferential construction joint between the two is filled with 5cm foam board to facilitate later C25 cement. Concrete removal is convenient and will not damage the well ring 16; a trench is excavated outside the well ring 16, and the trench is equipped with a three-stage circulating water settling tank 17; the guide hole of the vertical shaft is excavated using the reverse drilling rig 15, and a guide drill rod is added every 2 to 3 drill rods. After the guide hole is completed, the reverse drill bit is replaced, and the reverse drill bit is pulled from bottom to top to form a chute 11. The chute 11 connects the upper section of the vortex chamber well and the lower horizontal section 8 of the unpressurized tunnel. To prevent the drill bit from shaking violently and damaging the cutting tools, low drilling pressure and low speed should be used.

[0066] The rest of this embodiment is the same as that of embodiment 2, so it will not be described again.

[0067] Example 4:

[0068] Example 4 is a further optimized implementation based on Example 3, such as... Figures 2 to 13 As shown, in step 4, the contraction section 4 is located in the middle section of the vortex chamber well. The contraction section 4 is blasted layer by layer and section by section from top to bottom. Each advance is a cycle, and the excavation diameter is reduced to within 25cm.

[0069] The rest of this embodiment is the same as that of embodiment 3, so it will not be described again.

[0070] Example 5:

[0071] This embodiment is a further optimized implementation based on embodiment 4, such as... Figures 2 to 13 As shown, during the excavation of the dome 1, the upper section 301 of the main vortex chamber, and the middle section 302 of the main vortex chamber, the excavated material is transported to the upper flat section 2 of the pressureless tunnel through the guide tunnel. In the lower section 303 of the main vortex chamber, the excavated material is slid through the guide tunnel to the entrance 10 of the guide tunnel by mechanical cleaning. Then, the excavated material is loaded into 25t dump trucks in the upper flat section 2 of the pressureless tunnel by a small loader for discharge. The excavated material in the vortex chamber section falls by its own weight through the slag chute 11 and is transported out through the lower flat section 8 of the pressureless tunnel.

[0072] The specific structure of the vortex shaft completed by the above scheme is as follows: the vortex shaft is arranged axially with a dome 1, a vortex chamber section 3, a vortex shaft section 7, and a blind shaft section 5. The dome 1 is staggered with 6m and / or 9m anchor bolts, with a spacing of 1.5m between rows. 12m anchor bolts are installed next to the already installed 6m anchor bolts for support. A 25cm reinforced concrete mesh is installed on the inner wall of the dome 1. The vortex chamber section 3 is tangent to and connected to one side of the upper horizontal section 2 of the unpressurized tunnel. The other side of the upper horizontal section 2 of the unpressurized tunnel is connected to the gate chamber. The vortex shaft section 7 is tangent to and connected to one side of the lower horizontal section 8 of the unpressurized tunnel. The other side of the lower horizontal section 8 of the tunnel is connected to the outlet flow nose sill. The upper horizontal section 2 and the lower horizontal section 8 of the unpressurized tunnel are arranged opposite each other. The middle part of the vortex chamber section 3, i.e. the middle section 302 of the main vortex chamber, is provided with a contraction section 4. The vortex chamber section 3 and the vortex shaft section 7 are connected by a transition section 6. The inner diameter of the lower opening of the contraction section 4 is smaller than the inner diameter of the vortex shaft section 7. The inner diameter of the lower opening of the contraction section 4 is smaller than or equal to the inner diameter of the blind shaft section 5. Both the contraction section 4 and the transition section 6 are cone-shaped bodies that are larger at the top and smaller at the bottom. The diameter of the entrance end of the lower horizontal section 8 of the unpressurized tunnel that connects to the blind shaft section 5 is smaller than or equal to the diameter of the blind shaft section 5.

[0073] Since the gas replenishment shaft has been eliminated, the upper part of the shaft, i.e., the inner wall of the dome 1, can be reinforced by anchor bolt support and reinforced concrete layer, which can prevent the shaft from collapsing due to cavitation erosion when the water flows at high speed in the shaft, and can increase the service life of the shaft. The upper flat section 2 of the pressureless tunnel is tangent to the vortex chamber section 3, which allows the water to generate a spiral flow motion in the shaft under the action of the vortex chamber section 3 to eliminate the energy of the water flow, and further reduce the probability of cavitation erosion.

[0074] The rest of this embodiment is the same as that of embodiment 4, so it will not be described again.

[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for constructing vortex shafts in hard rock zones with high ground stress, characterized in that, Specifically, the following steps are included: Step 1: Excavation of the dome (1); Specifically, after the excavation of the upper level (201) of the flat section of the pressureless tunnel is completed, a guide tunnel (13) is excavated longitudinally toward the dome (1). The entrance (10) of the guide tunnel is located in the upper level (201) of the flat section of the pressureless tunnel, and the exit (9) of the guide tunnel is located near the inner wall of the dome (1). The central part of the dome (1) retains the load-bearing rock column (12). Smooth blasting is carried out in layers from top to bottom around the load-bearing rock column (12). The dome (1) is divided into N layers from top to bottom, where N≥3 and N is an integer. Anchor bolts are inserted and steel mesh is hung and shotcrete is sprayed on the inner wall of the dome (1) in layers. Steel mesh is hung and shotcrete is sprayed on the load-bearing rock column (12). Step 2: Excavation of load-bearing rock column (12); Specifically, the load-bearing rock column (12) is divided into at least three layers from top to bottom, and excavation is carried out from top to bottom. After the first layer of load-bearing rock column (12) is excavated, it is used as a construction platform to carry out the excavation of the second layer of load-bearing rock column (12). After the excavation of the second layer of load-bearing rock column (12) is completed, anchor rods are inserted and steel mesh is installed and shotcrete is sprayed on the dome (1) above the load-bearing rock column (12). Then the next layer of load-bearing rock column (12) is excavated until the entire load-bearing rock column (12) is completely excavated and removed. Step 3: Excavation of the vortex chamber section (3); specifically, the vortex chamber section (3) is divided into the main vortex chamber section and the vortex chamber well section. The main vortex chamber section includes the upper section (301), the middle section (302), and the lower section (303) of the main vortex chamber. The upper section (301) of the main vortex chamber is divided into ring sections from the inside to the outside. The central ring area is excavated by vertical blasting, and the ring areas outside the central ring area are excavated radially. The middle section (302) of the main vortex chamber is excavated in layers, and each layer is divided into ring sections. The central ring area is excavated by vertical blasting, and the ring areas outside the central ring area are excavated radially. After the middle section (302) of the main vortex chamber is excavated, the lower layer of the upper horizontal section of the vertical shaft and the bottom plate protective layer are excavated and supported. The lower section (303) of the main vortex chamber is excavated in layers, and each layer is divided into ring sections. The central ring area is excavated by vertical blasting, and the ring areas outside the central ring area are excavated radially. Step 4: Excavation of the vortex chamber section; specifically, the vortex chamber section is divided into the upper section, the middle section and the lower section, and is excavated layer by layer from top to bottom. After the main vortex chamber section is excavated, the slag in the center of the main vortex chamber section is cleaned and a well ring (16) is set in the center. The well ring (16) is used to excavate the slag chute (11). The guide shaft is pulled back to the lower horizontal section (8) of the pressureless tunnel using a reverse drilling rig (15) inside the well ring (16). The excavation angle of each layer is reduced by less than 5°. Step 5: Excavation of the transition section (6); specifically, the transition section (6) is excavated in layers, with each advance being a cycle, and the excavation diameter is reduced to within 25cm. Step 6; Excavation and construction of the vortex section (7) and the blind well section (5); Specifically, the vortex section (7) is divided into the upper section of the vortex, the middle section of the vortex and the blind well section (5). The upper section and the middle section of the vortex are excavated and supported in layers. The two side walls of the middle section of the vortex and the lower horizontal section of the unpressurized tunnel (8) and the two sides above the arch line of the lower horizontal section of the unpressurized tunnel (8) are expanded and supported in a secondary manner. The blind well section (5) is excavated and supported in layers.

2. The method for constructing a vortex shaft in a high-stress hard rock zone according to claim 1, characterized in that: In step 1, the dome (1) is divided into the first dome (101), the second dome (102), the third dome (103) and the fourth dome (104) from top to bottom. The first dome (101) is excavated in a counterclockwise ring manner while retaining the load-bearing rock column (12) starting from the entrance (10) of the pilot tunnel. First, the inner ring is excavated. After the inner ring is excavated, the outer ring is excavated. A protective layer is reserved during the excavation process. The second dome (102) is excavated in a clockwise ring starting from the entrance (10) of the pilot tunnel. Each ring is evenly divided into several areas for excavation. After the excavation of the first dome (101) and the second dome (102) is completed, 6m anchor rods (1402) are used for support by manual labor and hand-held pneumatic drills. After the support is completed, steel mesh is hung on the first dome (101), the second dome (102) and the exposed load-bearing rock column (12) and shotcrete is applied. The third dome (103) is excavated in a clockwise ring-shaped manner starting from the entrance (10) of the pilot tunnel. Each ring is evenly divided into several areas for excavation. The first dome (101) and the second dome (102) are supported by 9m anchor bolts (1401) using manual labor and hand-held pneumatic drills. The third dome (103) is supported by 6m anchor bolts (1402) and / or 9m anchor bolts (1401) using down-the-hole drills. The third dome (103) and the exposed load-bearing rock column (12) are reinforced with steel mesh and shotcreted. The fourth dome (104) is excavated in a clockwise ring-shaped manner starting from the entrance (10) of the pilot tunnel. Each ring is evenly divided into several areas for excavation. The fourth dome (104) is supported by 6m anchor bolts (1402) and / or 9m anchor bolts (1401) in an alternating manner using down-the-hole drills. Steel mesh is hung on the fourth dome (104) and the exposed load-bearing rock column (12) and shotcrete is applied.

3. The method for constructing a vortex shaft in a high-stress hard rock zone according to claim 2, characterized in that: The dome (1) is divided into four layers, and the load-bearing rock pillars (12) are divided into three layers.

4. The method for constructing a vortex shaft in a high-stress hard rock zone according to claim 3, characterized in that: In step 3, the central ring of the upper section (301) of the main vortex chamber is excavated in one go, the middle ring of the upper section (301) of the main vortex chamber is excavated by zonal radial vertical blasting, and the outer ring of the upper section (301) of the main vortex chamber is excavated by step vertical blasting. A full-span scaffold is erected in the upper section (301) of the main vortex chamber. After 12m of anchor bolt support is installed at the dome (1), the full-span scaffold is dismantled. 6m anchor bolts (1402) and / or 9m anchor bolts (1401) are staggered above the connection between the middle section (302) of the main vortex chamber and the upper flat section (2) of the pressureless tunnel.

5. The method for constructing a vortex shaft in a high-stress hard rock zone according to claim 4, characterized in that: In step 4, the well ring (16) is a reinforced concrete well ring (16). Reinforcing bars are inserted into the inner and outer rings of the well ring (16) at the center of the lower section (303) of the main vortex chamber. Circumferential reinforcing bars are tied to the exposed inner and outer ring reinforcing bars. A two-way double-layer steel mesh is set in the well ring (16). Templates are installed along the inner and outer ring reinforcing bars. Concrete is poured in the well ring (16). After the concrete solidifies, the templates are removed and concrete is poured in the well ring (16). Foam board is filled in the circumferential construction joint between the two. A trench is excavated outside the well ring (16). The trench is divided into several circulating water sedimentation pools (17). The guide hole of the vertical shaft is excavated using a reverse drilling rig (15). A guide drill rod needs to be added every 2 to 3 drill rods. After the guide hole is completed, the reverse drill bit is replaced and reversed from bottom to top to form a chute well (11). The chute well (11) connects the upper section of the vortex chamber well and the lower horizontal section (8) of the unpressurized tunnel.

6. The method for constructing a vortex shaft in a high-stress hard rock zone according to claim 5, characterized in that: In step 4, a shrinkage section (4) is set in the middle section of the vortex chamber well. The shrinkage section (4) is blasted in layers and sections from top to bottom. Each advance is a cycle, and the excavation diameter is reduced to within 25cm.

7. The method for constructing a vortex shaft in a high-stress hard rock zone according to claim 6, characterized in that: After the excavation of the dome (1), the upper section (301) of the main vortex chamber and the middle section (302) of the main vortex chamber, the slag is transported to the upper flat section (2) of the pressureless tunnel through the guide tunnel (13) and then transported out. The slag in the lower section (303) of the main vortex chamber is loaded into dump trucks by an excavator for transport. The slag in the vortex chamber section falls by its own weight through the slag chute (11) and is transported out through the lower flat section (8) of the pressureless tunnel.

8. The method for constructing a vortex shaft in a high-stress hard rock zone according to claim 7, characterized in that: The inner diameter of the lower opening of the contraction section (4) is smaller than the inner diameter of the vortex section (7), and the inner diameter of the lower opening of the contraction section (4) is smaller than or equal to the inner diameter of the blind well section (5).

9. A method for constructing a vortex shaft in a high-stress hard rock zone according to claim 8, characterized in that: Both the contraction segment (4) and the transition segment (6) are cone-shaped bodies that are larger at the top and smaller at the bottom.

10. A method for constructing a vortex shaft in a high-stress hard rock zone according to claim 9, characterized in that: The diameter of the entrance end connecting the lower horizontal section (8) of the unpressurized tunnel and the blind well section (5) is less than or equal to the diameter of the blind well section (5).

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