Construction methods for large-section, ultra-deep vertical shafts in water conveyance tunnels

Abstract

This invention discloses a construction method for an ultra-deep vertical shaft with a large cross-section in a water conveyance tunnel. The construction method includes: S1. Vertically drilling a pilot hole from the excavated section of the shaft to the conveying tunnel, and enlarging the hole to form a funnel-shaped chute; S2. Excavating the shaft opening area, performing lock-in construction, and then blasting the shaft in sections; S3. Evaluating geological parameters for the excavated section, calculating blasting parameters, and drilling and placing explosives according to the calculated blasting parameters for section blasting; S4. After the shaft opening section blasting is completed, the blasted debris is cleared through the chute into the water conveyance tunnel at the bottom of the shaft and discharged; S5. Initial support of the shaft wall with wire mesh and shotcrete reinforcement, followed by installation of slipform and pouring of phosphorus tailings powder-steel fiber reinforced concrete for secondary lining of the shaft wall; S6. After the strength reaches the design requirements, demolding is performed, and then steps S3 to S5 are repeated for the construction of the next section of the shaft. This invention shortens the construction period and reduces construction safety risks during actual construction, thereby creating certain economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy engineering construction, and more specifically relates to the construction method of ultra-deep vertical shafts with irregular large cross sections in water conservancy projects. This method optimizes the construction of ultra-deep vertical shafts from multiple aspects such as blasting layout, secondary lining of the shaft wall with new materials, safety verification, and optimization of waste rock disposal, thereby improving construction efficiency while ensuring construction safety. Background Technology

[0002] In water conservancy projects, water conveyance tunnels often involve the construction of irregularly shaped, large-section, ultra-deep vertical shafts as surge tanks, gate shafts, etc. The excavation of these shafts is a critical and challenging aspect of the project, particularly the design and construction of the blasting system, which directly impacts the project's progress. Shaft lining is an indispensable part of the construction process, playing a crucial role in ensuring construction safety, especially in areas where the shaft traverses complex geological fault zones and regions prone to rockbursts due to unbalanced ground stress. Therefore, the blasting design incorporates optimization of waste rock removal, internal water seepage, and secondary lining as supplementary considerations. Key parameters include blasting efficiency, initiation method, blast hole layout, charge structure, and the safe distance of the air shock wave from the blast point. A comprehensive evaluation is conducted to design the optimal construction scheme, thereby optimizing the excavation efficiency of large-diameter, ultra-deep vertical shafts.

[0003] Traditional shaft construction methods are typically suitable for small-diameter, medium- to low-depth circular shafts. However, when the shaft cross-section is large and irregular, the following problems will arise:

[0004] (1) As the cross-sectional area increases, the trajectory line of the charge in the traditional blasting method will not be able to cover the entire cross-section, thus making it impossible to blast the cross-section completely in one go. It cannot guarantee the blasting efficiency of the surrounding holes on the blasting trajectory line, and there may be under-blasting or over-blasting on the outer ring of the cross-section, which will affect the accuracy of the cross-sectional area.

[0005] (2) Most existing blasting methods rely on empirical formulas to set up blasting trajectories, and some calculations lack practical theoretical support. The blasting trajectory and charge amount are dynamically adjusted according to the actual field test section.

[0006] (3) Traditional blasting only provides calculations of safety parameters such as the safe distance of the air shock wave at the blast point for regular cross sections, but does not provide explanations for irregular large cross sections;

[0007] (4) Applying the small-section vertical shaft waste removal method to large-diameter, ultra-deep, irregularly shaped vertical shafts will seriously affect waste removal efficiency and construction period;

[0008] (5) Traditional shaft lining material uses ordinary concrete. When the shaft depth and construction cross section are too large, the water pressure increases further with the increase in depth. Using ordinary concrete lining will not be able to guarantee water inrush and leakage. Therefore, ordinary materials are no longer applicable.

[0009] (4) The charging and blasting time of large-diameter ultra-deep irregular cross-section vertical shafts are longer than those of small cross-section vertical shafts. Therefore, the working face is exposed to the outside for a long time after blasting. As the depth gradually increases, the large well wall area is more likely to experience ground stress imbalance, resulting in rock bursts, which greatly increases the construction risk.

[0010] In light of the above issues, it is currently necessary to study a construction scheme for irregularly shaped, large-section, ultra-deep vertical shafts to improve construction efficiency. Summary of the Invention

[0011] To address the aforementioned problems, this invention provides an efficient construction method for ultra-deep vertical shafts with irregular large cross-sections. This construction method combines existing technologies with improvements, addressing current issues in terms of blasting efficiency, slag removal, seepage resistance, safety, and providing theoretical calculations. This improves construction efficiency and guides subsequent construction, thus improving the construction method for this type of vertical shaft project and forming a new construction technology.

[0012] To achieve the above objectives, this invention provides an efficient construction method for ultra-deep vertical shafts with irregular large cross-sections. The ultra-deep vertical shaft is constructed vertically above the water conveyance tunnel, facing the water conveyance tunnel, after the water conveyance tunnel has been constructed. The bottom of the ultra-deep vertical shaft is connected to the top of the water conveyance tunnel. The specific construction steps are as follows:

[0013] S1: The soil on the surface of the vertical shaft excavation section is removed, and the surrounding rock is destroyed first. Then, a guide hole is drilled vertically from the vertical shaft excavation section to the conveying tunnel. The opening of the guide hole is then enlarged to 2-3m to form a funnel-shaped slag chute.

[0014] S2. Excavate the area of ​​the upper shaft opening and carry out the locking construction; then begin blasting construction in sections of the shaft, with each section being 4.5 to 5 meters high;

[0015] S3. Conduct geological parameter assessments for the entire cross-section of the vertical shaft in the wellhead area and calculate blasting parameters. Based on the calculated blasting parameters, drill holes in the excavated upper wellhead area and load explosives into the holes. Perform cross-sectional blasting on the wellhead section according to the designed detonation sequence. The blasting parameters include hole depth, hole filling, hole spacing, explosive consumption, number of holes, charging structure, and blasting safety distance.

[0016] The blast holes are divided into peripheral blast holes, cut holes, and auxiliary holes. The charging structure of the peripheral blast holes adopts a segmented charging method using blast hole filling and explosive intervals. Furthermore, the peripheral blast holes employ a "single-hole multi-angle drilling" method, where auxiliary holes are drilled again at an angle by expanding the angle and reducing the depth from the original peripheral blast hole. The main hole angle of the peripheral blast hole is β°, and the angle of the inclined drilling is (0.4-0.6)β°, thereby better ensuring blasting efficiency and accuracy. The inclined drilling and charging of the peripheral holes meets the requirements for underground cavern drilling and blasting in the "Technical Specification for Blasting in Water Conservancy and Hydropower Engineering" (DL / T5135-2001).

[0017] The vertical shaft cross-section is divided into rectangular and circular areas, and the blasting network is connected between the areas. During the detonation process, the circular areas are detonated from the inside out along the outer contour of the cross-section, while the rectangular areas are detonated in a V-shaped detonation sequence. The detonation arrangement method meets the detonation requirements of the "Technical Specification for Blasting in Water Conservancy and Hydropower Engineering" (DL / T5135-2001).

[0018] S4: After the blasting of the wellhead section is completed, the blasted debris is cleared through the chute constructed in step S1 to the water conveyance tunnel at the bottom of the well, and the debris is transported from the water conveyance tunnel for waste removal.

[0019] S5: For the wellhead section, the initial structural support is carried out by using anchor bolts, wire mesh spraying and arch support. Then, the secondary lining of the well wall is carried out by installing slipform and pouring phosphorus tailings powder-steel fiber concrete.

[0020] S6: After the strength meets the design requirements, the formwork is removed, and then steps S3 to S5 are repeated to construct the next section of the shaft. This cycle continues until the shaft construction is completely completed.

[0021] The preferred technical solution of the present invention is as follows: the vertical shaft excavation section in step S1 is an irregular cross-section composed of rectangles and semicircles, with the semicircular area and the rectangular area connected as one. The guide hole is drilled from the center of the semicircular area of ​​the vertical shaft excavation section, and the diameter of the hole is 30-40cm. The surface soil and surrounding rock at the wellhead are excavated and broken by a backhoe excavator, and the slag is transported by a loader.

[0022] The preferred technical solution of the present invention is as follows: In step S2, the lock construction adopts an integral suspended hydraulic single-seam metal formwork wall construction. The well neck section is reinforced with double layers of steel bars. When the well is excavated to 2.8m, the working surface is leveled, the outer layer of steel bars is tied, 1m is reserved at the temporary lock, the cutting edge is assembled, the inner layer of steel bars is tied, the lower thread ends of the outer layer of steel bars are buried with yellow sand, and the inner layer of steel bars are inserted into the pre-reserved holes of the cutting edge to leave room for the connection thread ends of the next section. After the steel bars are tied, the well wall formwork is lowered and corrected, and concrete is poured.

[0023] A further technical solution of the present invention: The verification calculation for the blasting safety distance in step S3 is as follows:

[0024] (1) Calculate the blasting vibration velocity V. Based on the upper and lower limits of K, the corresponding upper and lower limits of ￡ are 1.5-1.8. Substitute the above coefficients into the following formula V=K×(Q / 3 / R)￡ for verification. Compare the result with the range of V values ​​of 0.7-1.2cm / s in the "National Blasting Safety Regulations" (GB6722-2022) to verify that the blasting vibration velocity V is controlled within the above range. In the above formula: K is the vibration propagation coefficient; Q is the charge amount in the blasting stage; R is the distance from the blast source center to the protected building, in meters; ￡ is the blasting attenuation coefficient.

[0025] (2) Calculate the safe distance Rf for blasting flyrock, in meters. Flyrock protection measures are required within the Rf range of the detonation. The calculation of the safe distance Rf for blasting flyrock is as follows:

[0026] Rf = 20 × n² × W × K;

[0027] In the formula: n is the blasting action index, which is 1 for standard throwing; W is the minimum resistance line; K is the safety factor, which is 2; the values ​​of the blasting action index n and the safety factor K are taken with reference to the "National Blasting Safety Regulations" (GB6722-2022);

[0028] (3) Calculate the safe distance Rk of the air shock wave from the blast point. When the air shock wave is outside the Rk range, it does not pose a hazard to surrounding buildings; and the blasting direction is not towards surrounding villages and buildings, protective measures are required within the Rk range of the blast point; the calculation of the safe distance Rk of the air shock wave from the blast point is as follows:

[0029] Rk = Kk × Q / 2;

[0030] In the above formula: Q is the total explosive charge, in kg; Kk is the safety factor, which is 2; the values ​​of the factors are all based on the "National Regulations for Blasting Safety" (GB6722-2022).

[0031] The preferred technical solution of this invention is as follows: When arranging blast holes in step S3, a hydraulic umbrella drill is used in conjunction with a rock drill to drill the holes. When the well casing passes through unfavorable strata during excavation, the blasting adopts a shallow-hole multi-cycle method. The total amount of explosives per cycle is reduced by adjusting the height of the construction section to reduce the vibration effect on the well wall. Specifically, the step height I (in meters) of the excavation section is reduced to 1 / 2 of the original step height, and the side is shaped by a pneumatic pick. Then, temporary support is provided by anchor mesh and shotcrete. Mortar anchors are used, and shotcrete is applied. If necessary, H-shaped steel arch frames are added for composite support. Then, the next small section of high excavation, anchor mesh and shotcrete support, and other cycles are carried out.

[0032] A further technical solution of the present invention: The calculation process of the blasting parameters in step S3 is as follows, and the same parameters appearing in the following calculation formulas have the same meaning:

[0033] (1) Calculation of borehole depth L: The boreholes are arranged vertically and inclined;

[0034] When the blast holes are arranged vertically, the blast hole depth L = I + Δh;

[0035] When the blast holes are arranged at an angle, the blast hole depth L = I / sinα + Δh;

[0036] In the above formula: I is the step height, I = M / v × n × y × η; Δh is the borehole over-depth, Δh = (8~12)d; α is the borehole drilling inclination angle, M is the total planned well depth for the month, v is the number of days of tunneling in the month, d is the borehole diameter; n is the number of daily cycles, y is the regular cycle rate, taken as 85%, η is the borehole utilization rate, taken as 85%; the step height is determined according to the cycle advance, so the step height can be determined according to the template height, which is a known value; the borehole depth calculation complies with the provisions of the "Design Code for Open-Pit Blasting Engineering" (T / CSEB0011-2020) and the "Safety Standard for Design of Civil Explosives Engineering" (GB 50089-2018). The borehole filling height L2 = (20~30)d complies with the provisions of the "Design Code for Nonferrous Metal Mine Shaft and Tunnel Engineering" and the "Design Code for Open-Pit Blasting Engineering" (T / CSEB0011-2020).

[0037] (2) Hole filling height L2: Hole filling height L2 = (20~30)d;

[0038] (3) Calculation of borehole spacing a: a = m·W;

[0039] In the above formula: m is the borehole density coefficient, which is taken as 0.9 to 1.5;

[0040] W represents the minimum resistance line. When the shaft geology is hard rock with a hardness coefficient f = 3 to 6, the formula for calculating the minimum resistance line is W = (15-25)d. When the shaft geology is hard or extremely hard rock with a hardness coefficient f = 8 to 20, the formula for calculating the minimum resistance line is W = (25-35)d. The calculation of the minimum resistance line conforms to the "Code for Design of Open-Pit Blasting Engineering" (T / CSEB0011-2020), and the rock hardness coefficient conforms to the "Soil and Rock (Protodactyly) Classification Table".

[0041] (4) Total explosive charge for a single mine collapse Q: Q = V·q;

[0042] In the above formula: q is the unit consumption of explosives for shaft excavation (kg / m³) 3 ), where v is the volume of each ore collapse: V=(S1+S2)×I; S1 is the semi-circular area of ​​the vertical shaft cross-section, S1=1 / 2(π×r 2 ), where r is the radius of the semi-circular section of the shaft;

[0043] S2 is the rectangular area of ​​the vertical shaft cross-section, S2 = a × b; a is the length of the rectangular vertical shaft cross-section; b is the width of the rectangular vertical shaft cross-section.

[0044] (5) Number of blast holes N: The blast holes are arranged on the design outline of the cross-section, and the bottom of the blast hole is controlled within 50mm outside the outline; the blast hole arrangement meets the requirement of a blast hole spacing of 550-700mm and a blast hole density coefficient of 0.8-1.2; the number of blast holes N is calculated as follows:

[0045] In the above formula: f is the rock firmness coefficient, S is the blasting cross-sectional area, S=S1+S2; referenced from the DuPont Blasting Handbook translated and published by Metallurgical Industry Press.

[0046] (6) The peripheral blast hole charging is to divide the blast hole depth L into n equal parts at equal intervals, and the filling height and filling height of each part are L / n (mm). n is determined according to the filling amount and filling height, and n is not greater than 4.

[0047] Single-hole charge p = Q / N; Q is the total amount of explosives in a single blasting operation, and N is the number of blast holes;

[0048] If the borehole is cylindrical, then the charge structure is also cylindrical. The total height of the charge per borehole = charge amount per borehole / borehole area; borehole area = π·d 2 / 4; where n parts are set according to the actual situation, and n is no greater than 4;

[0049] The top elevation of the charge structure in the slotted hole and auxiliary hole is L-L2 (mm), and the bottom elevation is L-L2-L3 (mm). The charge height L3 = Q·π·d 2 / 4N; Where: Q is the total amount of explosives in a single blasting operation, N is the total number of blast holes, and d is the diameter of the blast hole. The above charging structure and calculation comply with the technical requirements of the "Safety Regulations for Blasting" (GB6722-2014).

[0050] The preferred technical solution of the present invention is as follows: In step S4, the blasted rock is pushed into the slag chute with a funnel-shaped cross section by a backhoe excavator.

[0051] The preferred technical solution of this invention is as follows: For the initial structural support of the well wall in step S5 (for wells less than 300m), anchor bolts, wire mesh, and sprayed plain concrete are used; or anchor bolts, wire mesh, and sprayed plain concrete are used combined with an I-beam arch support. The steel arch is I20, the anchor bolts are mortar anchors or self-drilling hollow anchors, the wire mesh is steel mesh, and plain concrete is used for the spraying. For the initial structural support of the well wall in wells deeper than 300m but less than 600m, I22a steel arches are used, and self-drilling hollow anchors or prestressed hollow anchors are used. The remaining construction methods are the same as for the section with a well depth less than 300m. For the initial structural support of the well wall in wells deeper than 600m, prestressed hollow anchors are used, and the remaining construction methods are the same as for the section with a well depth less than 300m.

[0052] The preferred technical solution of the present invention is as follows: the mix proportion of phosphorus tailings powder-steel fiber concrete in step S5 is 1350-1580 parts of coarse aggregate, 810-1010 parts of fine aggregate, 475-590 parts of cement aggregate, 200-300 parts of water, 75-113 parts of phosphorus tailings powder, 45-84 parts of expansion agent, and 3-7 parts of water-reducing agent; wherein, the steel fiber accounts for 1.5-2% of the total volume of the above-mentioned mixed materials, and the pouring thickness is 45cm.

[0053] The preferred technical solution of the present invention is as follows: In step S5, the anchor bolt construction adopts an anchor bolt trolley and a pneumatic drill to drill holes. After the hole is formed, the rock debris inside the hole is blown away with high-pressure air. Then, the early-strength cement mortar is injected into the anchor hole using a grouting machine. The anchor bolt is then inserted into the hole. After the mortar strength reaches the design requirements, the pad plate is installed and the nut is tightened. For downward anchor bolts, the grouting pipe should be inserted into the bottom of the hole. Then, the grouting pipe is pulled outward while grouting until it is full. The self-drilling central control anchor bolt and the prestressed anchor bolt are driven to a depth of 4.5m to 6m and are arranged in a quincunx pattern.

[0054] The steel arch frame is processed on the work platform designed on site. The steel frame is bent using a steel bending machine in combination with the dimensions of the vertical shaft. Each steel arch frame is divided into several units. The steel arch frame joints use Q235 connecting steel plates. Bolt holes are drilled on the steel plates, and the hole diameter meets the requirements of M20 bolts. The connecting parts are fully and densely welded, and the width and length of the weld are fully welded.

[0055] This invention addresses the entire cross-section process, from charging and detonation to construction completion, requiring geological parameter assessment, explosive quantity calculation, minimum resistance line determination, borehole depth, borehole filling, borehole spacing, explosive consumption, number of boreholes (cut-out holes, auxiliary holes, peripheral holes), charging structure and blasting network connection, and blasting safety distance calculation. The shaft excavation cross-section is an irregular shape, specifically a rectangle circumscribed by a semicircle; geological fault zones, soil and rock unit weight (t / m³) 3 The hardness coefficient (f), looseness coefficient (k), and moisture content (%) were obtained by referring to the "Engineering Geological Survey Report of the Main and Auxiliary Shaft Site Selection and Research Project". The explosive consumption per unit volume for shaft excavation (kg / m³) was also calculated.3 The reference value is obtained by referring to the hardness coefficient (f) of the corresponding geology in the "Engineering Geological Survey Report of Main and Auxiliary Shaft Site Selection Research and Development Project" and then consulting the "Classification of Geological Types of Underground Coal Mines" (MT / 1197-2020) to obtain the corresponding explosive consumption q (kg / m³). 3 The drilling depth h (mm) and hole diameter d (mm) were determined by referring to the rated parameters of the selected machinery. Due to the irregular cross-section, drilling was completed using a combination of pneumatic drills and machinery.

[0056] The secondary masonry shotcrete of this invention meets the requirements of the "Technical Specification for Rock and Soil Anchor and Shotcrete Support Engineering" (GB50086-2015). The mix design of phosphorus tailings powder-steel fiber concrete is detailed in CN20221138969. The steel arch frame is selected in accordance with the "General Specification for Steel Structures" (GB55006-2021).

[0057] This invention improves the blasting performance by employing a shallow-hole, multi-cycle blasting method during well excavation and lining, which may involve blasting through several unfavorable strata. This reduces the distance between peripheral holes and the resistance distance. It utilizes decoupled charges or intermittent charges between peripheral holes to minimize damage to the surrounding rock, maintain its integrity, and fully utilize its inherent resistance. Adjusting the construction section height reduces the total charge per cycle, thus minimizing vibration to the well wall and reducing construction risk while increasing efficiency. The traditional single-hole, single-aperture blasting method is replaced with "single-hole, multi-angle drilling," allowing explosives to be loaded into multiple filling holes from a single hole. The drilling angle is calculated using the spacing between the lower peripheral holes, thus resolving the "under-blasting" or "over-blasting" phenomena caused by excessive distance between the bottom of the peripheral holes and auxiliary holes during blasting, ensuring the accuracy of the blast cross-section.

[0058] The optimization of the blasting trajectory is achieved by breaking down the irregular cross-section, such as into a combination of rectangles and semicircles. The blasting trajectory in the semicircular part is drilled with an umbrella drill to form the entire circular blasting trajectory. The rectangular part is drilled manually with a pneumatic drill. The blasting trajectory is tangent to or circumscribed with the circle, thus completing the layout of the blasting trajectory for the entire excavation section. The detonation sequence is optimized by adopting a combined sequential detonation method for the blasting network connection. For the detonation arrangement, the blasting holes of rectangular and semi-circular blasting sections are arranged row by row from the inside out along the outer contour of the section according to the aforementioned spacing. Circular sections are detonated sequentially, while rectangular sections have blasting holes arranged in a rectangular pattern, using a V-shaped detonation sequence. The advantage of this combined detonation sequence lies in the obstructing effect of the loose medium (ore). The compensation space relies on the kinetic energy of the fragmented ore to impact and compress the blast pile, thus extending the expansion and work time of the high-pressure blasting gas products, which is beneficial for fracture development and can improve the effective utilization rate of the explosion energy. The blasting operation uses emulsion explosives and digital electronic detonators, with reverse loading, series and parallel connection, and detonation by a dedicated detonator. The design and optimization of blasting parameters, including the calculation of explosive quantity, minimum resistance line, borehole depth, borehole filling, hole spacing, explosive consumption, number of boreholes (cut holes, auxiliary holes, peripheral holes), charging structure and blasting network connection, and calculation of blasting safety distance, are all detailed in this invention and conform to industry standards, providing a theoretical basis for blasting design and construction.

[0059] This invention addresses the secondary lining construction of well walls. For large-section, irregularly shaped well walls, a "blasting and lining section by section" approach is adopted. The process involves manually using pneumatic picks to brush and trim the edges, followed by spraying with a mesh. Different types and depths of anchor bolts are driven into the well according to different strata and depths. Slipform construction is used for pouring, and steel arch frames are employed for support. This construction method can quickly seal the exposed surface of the well wall, reducing the risks of water inrush and rock bursts, and increasing construction safety.

[0060] The secondary lining material for the well wall is phosphorus tailings powder-steel fiber reinforced concrete. This material is being used for the first time in vertical shaft construction. The appropriate amount of phosphorus tailings powder increases the material's impermeability, raising the impermeability grade from P6 to P10. The addition of steel fibers improves the material's bending toughness, thus better resisting the stress of large-section irregular well walls.

[0061] This invention involves first drilling small holes in the waste rock discharge chute to facilitate construction and test the safety and stability of the rock strata. Then, the holes are enlarged to increase the diameter, and the slag discharge surface on the cross-section is arranged in a funnel shape to increase the waste rock loading capacity and flow velocity. Slag is discharged from the bottom through a connecting channel, increasing discharge efficiency and reducing economic costs. This method combines manual and mechanical construction, resulting in significantly higher efficiency than traditional methods using only manual drilling for irregular cross-sections, thus increasing overall construction efficiency.

[0062] The gain effect achieved by this invention:

[0063] (1) This invention solves the problem that the outer ring of the cross section may be under-exploded or over-exploded when the detonation efficiency cannot be guaranteed when the detonation is performed on a large cross section with irregular shape, by optimizing the layout of the blasting trajectory line, the new construction method of the peripheral eye, and the secondary calculation of the blasting charge, thereby affecting the accuracy of the cross section area.

[0064] (2) Based on the existing blasting methods for various cross-section vertical shafts, this invention summarizes, optimizes, and promotes detailed calculation methods for various blasting parameters in irregularly shaped large-section ultra-deep vertical shafts, providing a theoretical basis for future construction.

[0065] (3) This invention proposes a method for discharging gangue in a funnel-shaped cross section, which solves the problem that the slow gangue discharge in ultra-deep vertical shafts with irregular large cross sections leads to the inability to carry out subsequent construction procedures and affects the overall construction progress.

[0066] (4) This invention proposes to use phosphorus tailings-steel fiber concrete for secondary lining of the well wall, and provides detailed construction methods for secondary lining. It provides corresponding technical support for the construction of ultra-deep vertical shafts with large cross sections. It solves the risk of leakage and water inrush that may occur when using ordinary concrete lining as the well depth increases when the construction cross section is too large. At the same time, the phosphorus tailings-steel fiber concrete improves the tensile strength of the well wall, which solves the probability of rock bursts that may occur due to unbalanced ground stress, thereby reducing construction safety risks. Attached Figure Description

[0067] Figure 1 This is a flowchart illustrating the implementation of this invention;

[0068] Figure 2 These are on-site photos of an embodiment of the present invention;

[0069] Figure 3 This is a diagram showing the blasting trajectory and detonation method arrangement in an embodiment of the present invention;

[0070] Figure 4 This is a schematic diagram of the slotted eye loading structure in this invention;

[0071] Figure 5 This is a schematic diagram of the auxiliary eye structure in this invention;

[0072] Figure 6This is a schematic diagram of the peripheral eye medication loading structure in this invention;

[0073] Figure 7 This is a schematic diagram of the peripheral eye structure arrangement in this invention;

[0074] Figure 8 This is a schematic diagram of the secondary lining structure in this invention;

[0075] Figure 9 This is an example diagram of the steel arch frame in the secondary lining structure of this invention;

[0076] Figure 10 This is a schematic diagram of the cross-section of the slag chute in this invention;

[0077] Figure 11 This is a planar structural layout diagram of Embodiment 1 of the present invention. Detailed Implementation

[0078] The present invention will be further clearly and completely described below with reference to the embodiments. Unless otherwise specified, the materials described in the embodiments can be obtained from conventional commercial channels. The embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0079] The ultra-deep shaft in the following embodiments is constructed vertically above the water conveyance tunnel, facing the water conveyance tunnel, after the water conveyance tunnel construction is completed. The bottom of the ultra-deep shaft is connected to the top of the water conveyance tunnel. The shaft excavation cross-section is an irregular cross-section composed of rectangles and semicircles. The specific construction steps are as follows:

[0080] S1: The surface soil of the shaft excavation section is removed, and the surrounding rock is damaged first. Then, a pilot hole with a diameter of 30-40cm is vertically drilled from the center of the semi-circular area of ​​the shaft excavation section to the conveying tunnel. The opening of the pilot hole is then enlarged to 2-3m to form a funnel-shaped slag chute. The surface soil and surrounding rock at the shaft opening are excavated and broken using a backhoe excavator, and the slag is transported by a loader. In the embodiment, the slag discharge shaft structure is as follows: Figure 10 As shown.

[0081] S2. Excavate the area of ​​the upper shaft opening and carry out the locking construction; then begin blasting construction in sections of the shaft. The height of each section can be determined according to the step height I plus the over-depth of the blast hole, and the blasting section height is generally 4.5-5m; the locking construction adopts the overall suspended hydraulic single-seam metal formwork wall construction. The shaft neck section is reinforced with double layers of steel bars. When the shaft is excavated to 2.8m, level the working face, tie the outer layer of steel bars, leave 1m at the temporary locking point, assemble the cutting edge, tie the inner layer of steel bars, bury the lower thread of the outer layer of steel bars with yellow sand, and insert the inner layer of steel bars into the pre-reserved hole of the cutting edge to leave room for the connection thread of the next section height; after the steel bars are tied, lower and correct the shaft wall formwork, and pour concrete.

[0082] S3. Geological parameters are assessed for the entire cross-section of the vertical shaft in the wellhead area, and blasting parameters are calculated. Based on the calculated blasting parameters, boreholes are drilled and blasted in the excavated upper wellhead area. Explosives are loaded into the blastholes, and blasting is carried out on the wellhead section according to the designed detonation sequence. The blasting parameters include blast hole depth, borehole filling, hole spacing, explosive consumption, number of blast holes, charging structure, and blasting safety distance. The blast holes are divided into peripheral blast holes, cut holes, and auxiliary holes. Considering that the charging method of peripheral holes cannot guarantee the blasting efficiency of peripheral holes along the blasting trajectory, there may be under-blasting or over-blasting on the outer edge of the cross-section, thus affecting the accuracy of the cross-sectional area, the drilling of peripheral holes is optimized by adopting a "single-hole multi-angle drilling" method. Auxiliary holes are drilled again at an angle by expanding the angle and reducing the depth from the original peripheral hole. Specifically, as follows... Figure 6 As shown, the main borehole angle β (°) of the peripheral holes is taken as (0.4-0.6)β (°), thus better ensuring blasting efficiency and accuracy. The inclined drill charge of the peripheral holes meets the requirements for drilling and blasting of underground caverns in the "Technical Specification for Blasting in Water Conservancy and Hydropower Engineering" (DL / T5135-2001).

[0083] (1) The depth of the blast hole is determined by a combination of the step height I, the over-depth Δh of the blast hole, and the borehole inclination angle. The over-depth Δh of the blast hole is related to geological conditions, rock properties, blast hole diameter d, hole spacing, and row spacing. A larger blast hole diameter, hole spacing, and row spacing result in a larger over-depth, while a smaller blast hole diameter, hole spacing, and row spacing result in a smaller over-depth. The blast hole depth L is divided into two categories: ① vertical hole depth, ② inclined hole depth.

[0084] When the blast holes are arranged vertically, the blast hole depth L = I + Δh;

[0085] When the blast holes are arranged at an angle, the blast hole depth L = I / sinα + Δh;

[0086] In the above formula: I is the step height, I = M / v × n × y × η; Δh is the borehole over-depth, Δh = (8~12)d; α is the borehole drilling inclination angle, M is the total planned well depth for the month, v is the number of days of tunneling in the month, d is the borehole diameter; n is the number of daily cycles; y is the regular cycle rate, taken as 85%; η is the borehole utilization rate, taken as 85%; the step height is determined according to the cycle advance, so the step height can be determined according to the template height, which is a known value; the calculation of the borehole depth complies with the provisions of the "Code for Design of Open-Pit Blasting Engineering" (T / CSEB0011-2020) and the "Safety Standard for Design of Civil Explosives Engineering" (GB 50089-2018).

[0087] (2) Hole filling height L2: The hole filling height L2 = (20~30)d, which complies with the provisions of the "Design Code for Tunnel Engineering of Nonferrous Metal Mines" and the "Design Code for Open-pit Blasting Engineering" (T / CSEB0011-2020).

[0088] (3) Calculation of borehole spacing a: a = m·W;

[0089] In the above formula: m is the borehole density coefficient, which is taken as 0.9 to 1.5;

[0090] W represents the minimum resistance line. When the shaft geology is hard rock with a hardness coefficient f = 3 to 6, the formula for calculating the minimum resistance line is W = (15-25)d. When the shaft geology is hard or extremely hard rock with a hardness coefficient f = 8 to 20, the formula for calculating the minimum resistance line is W = (25-35)d. The calculation of the minimum resistance line conforms to the "Code for Design of Open-Pit Blasting Engineering" (T / CSEB0011-2020), and the rock hardness coefficient conforms to the "Soil and Rock (Protodactyly) Classification Table".

[0091] (4) Total explosive charge for a single mine collapse Q: Q = V·q;

[0092] In the above formula: q is the unit consumption of explosives for shaft excavation (kg / m³) 3 ), where v is the volume of each ore collapse: V=(S1+S2)×I; S1 is the semi-circular area of ​​the vertical shaft cross-section, S1=1 / 2(π×r 2 ), where r is the radius of the semi-circular section of the shaft;

[0093] S2 is the rectangular area of ​​the vertical shaft cross-section, S2 = a × b; a is the length of the rectangular vertical shaft cross-section; b is the width of the rectangular vertical shaft cross-section.

[0094] (5) Number of blast holes N: The number of blast holes is determined based on the rock type (medium-hard or hard) and the cutting method (cylindrical). Reasonable cutting blasting parameters include a diameter of 1-1.2m and a hole spacing of 500-700m. Smooth blasting should be used around the shaft. Blasting holes should be arranged along the cross-sectional design outline, with the bottom of the hole controlled within 50mm outside the outline. Reasonable smooth blasting parameters are: hole spacing 550-700mm, blast hole density coefficient 0.8-1.2, taking 1.0, which meets the technical requirements of "Technical Requirements for Smooth Blasting with Air Column Charge in Rock Tunneling in Coal Mines" (NB / T10377-2019).

[0095] The number of blast holes N is calculated as follows:

[0096] In the above formula: f is the rock firmness coefficient, S is the blasting cross-sectional area, S=S1+S2; referenced from the DuPont Blasting Handbook translated and published by Metallurgical Industry Press.

[0097] (6) The drug loading structure of the peripheral eye, such as Figure 6As shown, a segmented charging method is adopted, using a structure of borehole filling / explosive / borehole filling / explosive. Specifically, the charging of the peripheral boreholes involves dividing the borehole depth L into n equal parts at intervals. The filling height of each part is L / n (in mm), where n is determined based on the amount of explosive and the filling height, and n is not greater than 4. The charge amount per borehole is p = Q / N, where Q is the total amount of explosive in a single blasting operation, and N is the number of boreholes.

[0098] If the borehole is cylindrical, then the charge structure is also cylindrical. The total height of the charge per borehole = charge amount per borehole / borehole area; borehole area = π·d 2 / 4; where n parts are set according to the actual situation, and n is no greater than 4;

[0099] The loading structure of the slotted eye and the auxiliary eye is as follows: Figure 4 and Figure 5 As shown, the elevation of the top of the drug is L-L2, in mm;

[0100] The charge level is L-L2-L3, in mm; the charge height L3 = Q·π·d 2 / 4N;

[0101] In the formula: Q is the total amount of explosives in a single blasting operation, N is the total number of blast holes, and d is the diameter of the blast hole.

[0102] (7) The blasting network connection arrangement of this invention adopts a combined sequential detonation; such as... Figure 3 As shown, the detonation arrangement is as follows: for rectangular and semi-circular blasting sections, the blasting holes are arranged row by row from the inside to the outside along the outer contour of the section according to the above-mentioned row spacing. For circular sections, sequential detonation is adopted, and for rectangular sections, the blasting holes are arranged in a rectangular pattern, and a V-shaped detonation sequence is selected. This detonation arrangement method meets the detonation requirements of the "Technical Specification for Blasting in Water Conservancy and Hydropower Engineering" (DL / T5135-2001).

[0103] (8) Calculation of blasting safety distance:

[0104] ① Calculate the blasting vibration velocity V = K × (Q / 3 / R)￡; where: K is the vibration propagation coefficient; Q is the charge amount in one blasting stage; R is the distance (m) from the blast source center to the protected building; ￡ is the blasting attenuation coefficient; based on the upper and lower limits of K, the corresponding upper and lower limits of ￡ are 1.5-1.8. Substitute the above coefficients into the verification and compare the results with the range of V (0.7-1.2 cm / s) in the "National Blasting Safety Regulations" (GB6722-2022).

[0105] ② Calculate the safe distance for flying rocks during blasting: Rf = 20 × n² × W × K; where: n is the blasting action index, taken as 1 for standard throwing; W is the minimum resistance line; K is the safety factor, taken as 2; the calculation shows that flying rock protection measures are required within the detonation Rf (m) range. The values ​​of the blasting action index n and the safety factor K are both based on the "National Blasting Safety Regulations" (GB6722-2022).

[0106] ③ Calculate the safe distance Rk from the blast point air shock wave: Rk = Kk × Q / 2; where Q is the total explosive charge (kg), and Kk is the safety factor, taken as 2; the calculated Rk (m) shows that the air shock wave outside the Rk (m) range does not pose a hazard to surrounding buildings. Furthermore, since the blasting direction does not face surrounding villages and buildings, protective measures are required within the Rk (m) range of the detonation. The coefficient values ​​are all based on the "National Blasting Safety Regulations" (GB6722-2022).

[0107] S4: After the blasting of the wellhead section is completed, the blasted debris is cleared through the chute constructed in step S1 to the water conveyance tunnel at the bottom of the well, and the debris is transported from the water conveyance tunnel for waste disposal; during the actual construction, manual labor is used in conjunction with excavators to clear the bottom of the section, push the waste into the funnel-shaped diffusion guide hole to flow into the bottom of the well, load it onto trucks, and transport it to the waste disposal point through the bottom connecting tunnel.

[0108] S5: For the wellhead section, the initial structural support of the well wall is carried out using anchor bolts, wire mesh, shotcrete, and arch support. Then, slipform construction and pouring of phosphorus tailings powder-steel fiber reinforced concrete are performed for the secondary lining of the well wall. For well sections with a depth of less than 300m, the initial structural support of the well wall is achieved using anchor bolts, wire mesh, and shotcrete, or a combination of anchor bolts, wire mesh, shotcrete, and I-beam arch support. The steel arch is of I20 type, and the anchor bolts are either mortar anchors or self-drilling anchors. Hollow anchor bolts are used, with steel mesh as the anchor bolts and plain concrete as the shotcrete. For the initial structural support of the well wall in sections with a depth greater than 300m and less than 600m, I22a steel arches are selected, and self-drilling hollow anchor bolts or prestressed hollow anchor bolts are used. The remaining construction methods are the same as those for sections with a depth less than 300m. For the initial structural support of the well wall in sections with a depth greater than 600m, prestressed hollow anchor bolts are used, and the remaining construction methods are the same as those for sections with a depth less than 300m.

[0109] The anchor bolt construction employs an anchor bolt trolley and pneumatic drilling. After drilling, high-pressure air is used to blow away rock debris from the hole, and then an early-strength cement mortar is injected into the anchor hole using a grouting machine. The anchor bolt is then inserted into the hole. After the mortar strength reaches the design requirements, a backing plate is installed and the nuts are tightened. For downward-facing anchor bolts, the grouting pipe should be inserted to the bottom of the hole, and then grouting should be performed while simultaneously pulling the grouting pipe outwards until the hole is full. The self-drilling central control anchor bolts and prestressed anchor bolts are driven to a depth of 4.5m to 6m and arranged in a staggered pattern. The steel arch frame is fabricated on a work platform designed on-site, and its structure is as follows: Figure 8As shown, the steel frame is bent using a steel bending machine to combine the dimensions of the vertical shaft. Each steel arch frame is divided into several units. The steel arch frame joints use Q235 connecting steel plates, and bolt holes are drilled on the steel plates. The hole diameter meets the requirements of M20 bolts. The connecting parts are fully and densely welded, and the width and length of the weld are fully welded.

[0110] S6: After the strength meets the design requirements, the formwork is removed, and then steps S3 to S5 are repeated to construct the next section of the shaft. This cycle continues until the shaft construction is completely completed.

[0111] The secondary masonry shotcrete in the following embodiments meets the requirements of the "Technical Specification for Rock and Soil Anchor and Shotcrete Support Engineering" (GB50086-2015). The mix design of phosphorus tailings powder-steel fiber reinforced concrete is detailed in CN20221138969, and the steel arch frame is selected in accordance with the "General Specification for Steel Structures" (GB55006-2021). The selected phosphorus tailings powder-steel fiber reinforced concrete mix design is selected from CN20221138969; the plain concrete for shotcrete and anchor uses Huaxin ordinary Portland cement, and the selected cement conforms to "General Portland Cement" (GB175-2007). The selection of steel arch frames I20a and I22a in the embodiments conforms to the "Code for Acceptance of Construction Quality of Steel Structures" (GB50205-2001).

[0112] Example 1 describes the construction of a surge tank in a stone flower well; the construction plan is as follows. Figure 11 As shown, the specific dimensions of this section are a rectangle with a diameter of 22m and an outer length of 21m and a width of 19m, circumscribed by a circle; the process of blasting, waste removal, and secondary lining provides a more detailed explanation of the invention.

[0113] Blasting Specialty: Herrenknecht SJD umbrella-shaped rock drill is selected, suitable for rock formations, from medium-hard to hard rock. Specific construction process: First, determine the excavation bench height I (m). Use the SJD umbrella-shaped rock drill to drill in the inner ring. Determine the innermost ring diameter based on the blasting charge trajectory. Drill the corresponding number of holes according to the number of cut holes in the inner ring. Following this method, expand the diameter outwards sequentially according to the ring diameter. The depth of the second ring of cut holes is twice the depth of the innermost ring. After completing the cut hole drilling, construct auxiliary holes. The auxiliary hole construction method is the same as the cut hole construction process, and the depth is the same. When drilling to the outermost peripheral eye, the SJD umbrella-shaped drill rig rock drill is first used to drill holes in the peripheral eye. The drilling depth is consistent with that of the auxiliary eye. After completing the first peripheral eye drilling, the "single-eye multi-angle drilling" method is used. The hydraulic leg of the SJD umbrella-shaped drill rig rock drill is tilted at a certain angle to drill auxiliary holes from the existing holes in the peripheral eye. The angle of the main hole of the peripheral eye is β, and the angle of the tilted hole is 0.5β. Drilling continues at an angle from the already drilled peripheral eye to drill auxiliary holes at an angle. At this point, the layout of the blasting holes in the semi-circular excavation section is completed. The rectangular blasting holes are drilled using a manual pneumatic pick. Based on the distance of the blasting charge trajectory coil, the holes are drilled from the innermost circle to the outermost circle, expanding the diameter. The construction method is the same as that of the semi-circular peripheral eye, auxiliary eye, and cut hole. It is worth noting that the rectangular charge trajectory line and the semi-circular blasting trajectory line are connected tangentially or externally. The same blasting hole is used for charging at the tangential or external connection points, preferably using the blasting hole on the circular side.

[0114] When entering the fault zone, a shallow-hole, multi-cycle blasting method will be adopted. Specifically, the bench height of the excavation section (I m) will be reduced to half of the original bench height. The bench will be shaped using a pneumatic drill, followed by temporary anchor-mesh-shotcrete support. Mortar anchors will be used, along with wire mesh and shotcrete. If necessary, H-shaped steel arch frames will be added for composite support. Then, the next small section of high-level excavation will proceed, with repeated cycles of anchor-mesh-shotcrete support. Blasting and safety parameters are derived from the blasting parameter design principles, as detailed in Table 1.

[0115] Table 1. Blasting parameters for the Shihua surge tank.

[0116]

[0117] The calculated parameters in Table 1 are used to arrange the explosives in the blasting section, guiding the completion of the blasting operation.

[0118] Secondary lining: such as Figure 7 As shown, the construction of the wall of the irregular large-section ultra-deep vertical shaft follows the method of "blasting a section and lining a section". In this section of the large-section pressure regulating well, the side is brushed and trimmed with a pneumatic pick, then shotcreted. Different types and depths of anchor bolts are driven in according to different strata and depths. Slip-form construction is used for pouring, and steel arch frames are used for support.

[0119] For sections with a well depth of less than 300m, the primary support for the well body consists of anchor mesh spraying + I-beam arch support. The anchors are self-drilling hollow anchors arranged in a staggered pattern, with steel mesh attached. The steel arch is made of I20a I-beams, and the spraying is C25 plain concrete. The secondary support consists of double-layer reinforced phosphorus tailings powder-steel fiber concrete support with a concrete strength of C30.

[0120] For sections with a well depth greater than 300m but less than 600m, the primary support for the well body consists of anchor mesh spraying + I-beam arch support. The anchors are self-drilling hollow anchors arranged in a staggered pattern, with steel mesh attached. The steel arch is made of I20a I-beams, and the spraying is CF30 plain concrete. The secondary support consists of double-layer reinforced phosphorus tailings powder-steel fiber concrete support with a concrete strength of C40.

[0121] For sections with a depth greater than 600m, the secondary support of the shaft body adopts anchor mesh shotcrete + I-beam arch support. The anchors are prestressed anchors, arranged in a staggered pattern, with steel mesh hanging. The steel arch is made of I22a I-beams, and the shotcrete strength is CF30 plain concrete. The secondary support adopts double-layer steel tailings powder-steel fiber concrete support, with a concrete strength of C45.

[0122] Once the concrete pouring is completed and the concrete strength reaches the design value, the next section of the well wall lining can be constructed. The specific construction method is the same as above.

[0123] Construction of slag discharge wells, such as Figure 10As shown: When the excavation face is determined, a 350mm pilot hole is constructed. During the initial drilling, a pilot hole stabilizer and drill rod are used in conjunction to slowly open the hole, while the mud pump is started to supply water. After the initial drilling is completed, normal pilot hole drilling begins. Key control points for pilot hole construction include: the pilot hole drilling speed should be higher than the initial drilling speed; low drilling pressure is used for soft and transitional strata, while high drilling pressure is used for hard rock and stable strata. After a drill rod is drilled, all rock cuttings in the hole must be removed. As the penetration distance shortens, the drilling pressure should be gradually reduced and the drilling speed slowed down until penetration is achieved. After the pilot hole is completed, mud circulation should be stopped, and clean water should be injected into the pilot hole while keeping the drilling rig rotating until the rotation is stable and the torque change is small before shutting down the drilling rig. During the pilot hole drilling process, if geological defects such as cavities or cracks are encountered and water does not return, the drill should be pulled out in time, and mud should be used for wall protection or grouting with cementing materials such as mortar, concrete, or water glass should be injected. After it solidifies, the hole should be re-drilled to avoid the drill getting stuck. Before the pilot hole is fully drilled, the reaming bit and pilot hole bit disassembly tools are transported to the lower passage of the shaft. After the pilot hole is drilled through, the drill rod is used to mark points for communication between the upper and lower parts. The pilot hole bit is then disassembled and the reaming bit is attached to form the slag removal system. Then, preparations can be made for bottom-up reaming drilling of the 3.0–3.5m slag chute. During reaming, after the reaming bit is attached, the drill string should be slowly lifted until the cutting edge begins to contact the rock. Then, stop lifting, use the lowest possible speed (5–9 r / m), and feed slowly, ensuring the cutting edge is not damaged by excessive impact. After the cutting edge breaks up the protruding rock, continue feeding until the drill bit is fully and evenly in contact with the rock before normal reaming drilling begins. To ensure the service life of the drilling rig and cutting edge, the system pressure is generally limited to 18 MPa. During reaming, if the rock hardness is high, the drilling pressure can be increased appropriately; conversely, if the rock hardness is low, the drilling pressure can be reduced. When the pilot drill bit reaches 2.5mm from the top of the shaft, reduce the drilling pressure and slow down the drilling speed, carefully observing the surrounding rock mass for any abnormalities. Near the end of the hole, enlarge the chute at the cross-section to create a funnel-shaped cross-section, allowing for larger chute discharge and increasing chute discharge efficiency.

[0124] During blasting operations, the blasted waste rock is pushed into a funnel-shaped chute when removing slag, and the waste is transported from the bottom of the chute to a designated spoil disposal site via a connecting channel.

[0125] Example 2 is for the construction of the Shihua control gate; the specific dimensions of this section are a rectangle with a diameter of 21.8m and an outer length of 22m and a width of 24.5m; the blasting parameters calculated for different strata are shown in Table 2. The remaining construction methods are in accordance with the construction of irregular large-section ultra-deep vertical shafts, and the specific methods will not be described in detail.

[0126] Table 2. Blasting parameters for the Shihua control gate

[0127]

[0128]

[0129] The parameters calculated in Table 2 are used to arrange the explosives in the blasting section, guiding the completion of the blasting operation.

[0130] To make the comparison more convincing, the construction efficiency of the same project designed using two different construction methods is compared. The comparison method controls the cross-sectional dimensions, shape, well depth, machinery, and formation parameters as fixed conditions. The construction efficiency and progress of the original construction method are denoted as Comparative Example 1 and Comparative Example 2. Examples 1 and 2 are constructed using the optimized construction design method of the present invention, which optimizes blasting parameters, secondary lining, waste rock removal, and phosphorus tailings powder-steel fiber concrete as lining material. The construction efficiency parameters obtained after construction are compared, as detailed in Table 3.

[0131] Table 3. Comparison of Construction Efficiency Parameters

[0132]

[0133] As shown in Table 3, the present invention optimizes both construction efficiency and required materials. From the perspective of material consumption, the construction method with optimized blasting parameters improves the utilization rate of blast holes by an average of 11.26%; the amount of explosives consumed per cycle is reduced by 8.12% in Example 1 and by 9.66% in Example 2; the amount of detonators consumed per unit rock mass is reduced by 9.3% in Example 1 and by 11.3% in Example 2.

[0134] From the perspective of optimizing the construction period and efficiency, the improvements in blasting layout and waste disposal have increased the number of cycles from once a day to twice a day, and the maximum single-batch push volume of the slag chute has increased by 32.8% and 32.7% respectively. This improvement effectively shortens the construction period and has significant economic value.

[0135] From the perspective of shaft construction safety, the optimization of secondary lining construction has improved the seepage resistance grade of the shaft wall from P6 to P10, and reduced the maximum possible water inflow to 1 / 4 of the original. The optimized construction method has significantly improved the safety of shaft wall construction, thereby ensuring the safety of construction personnel.

[0136] In summary, this invention optimizes the construction period, safety, and economy of excavating ultra-deep vertical shafts with irregular large cross-sections, and provides certain guidance for the construction of this type of vertical shaft.

[0137] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for constructing an ultra-deep vertical shaft with a large cross-section in a water conveyance tunnel, wherein the ultra-deep vertical shaft is constructed vertically above the water conveyance tunnel and towards the conveying tunnel after the water conveyance tunnel has been constructed, and the bottom of the ultra-deep vertical shaft is connected to the top of the water conveyance tunnel, characterized in that... The construction method specifically includes the following steps: S1: The surface soil of the shaft excavation section is excavated and the surrounding rock is damaged first. Then, a pilot hole is drilled vertically from the shaft excavation section to the conveying tunnel. The diameter of the pilot hole is then enlarged to 2-3m to form a funnel-shaped slag chute. The shaft excavation section is an irregular cross-section composed of rectangles and semicircles, with the semicircular area connected to the rectangular area. The pilot hole is drilled from the center of the semicircular area of ​​the shaft excavation section, and its diameter is 30-40cm. The surface soil and surrounding rock at the wellhead are excavated and broken up using a backhoe excavator, and the slag is transported by a loader. S2. Excavate the area of ​​the upper shaft opening and carry out the locking construction; then begin blasting construction in sections of the shaft, with each section being 4.5 to 5 meters high; S3. Conduct geological parameter assessments for the entire cross-section of the vertical shaft in the wellhead area and calculate blasting parameters. Based on the calculated blasting parameters, drill holes in the excavated upper wellhead area and load explosives into the holes. Perform cross-sectional blasting on the wellhead section according to the designed detonation sequence. The blasting parameters include hole depth, hole filling, hole spacing, explosive consumption, number of holes, charging structure, and blasting safety distance. The blast holes are divided into peripheral blast holes, slotted holes, and auxiliary holes. The charging structure of the peripheral blast holes adopts a segmented charging method using blast hole filling and explosive intervals. Furthermore, the peripheral blast holes employ a "single-hole multi-angle drilling" method, where auxiliary holes are drilled again at an angle by enlarging the angle and reducing the depth from the original peripheral blast hole. The main hole angle of the peripheral blast holes is... °, the angle of inclined drilling is taken °; The vertical shaft cross-section is divided into rectangular and circular areas, and the blasting network is connected between the areas. During the detonation process, the circular areas are detonated from the inside out along the outer contour line of the cross-section, while the rectangular areas are detonated in a V-shaped detonation sequence. S4: After the blasting of the wellhead section is completed, the blasted debris is cleared through the chute constructed in step S1 to the water conveyance tunnel at the bottom of the well, and the debris is transported from the water conveyance tunnel for waste removal. S5: For the wellhead section, the initial structural support is carried out by using anchor bolts, wire mesh spraying and arch support. Then, the secondary lining of the well wall is carried out by installing slipform and pouring phosphorus tailings powder-steel fiber concrete. S6: After the strength meets the design requirements, the formwork is removed, and then steps S3 to S5 are repeated to construct the next section of the shaft. This cycle continues until the shaft construction is completely completed.

2. The construction method for an ultra-deep vertical shaft with a large cross-section in a water conveyance tunnel according to claim 1, characterized in that: In step S2, the lock construction adopts an integral suspended hydraulic single-seam metal formwork wall construction. The well neck section has double-layer steel reinforcement. When the well is excavated to 2.8m, the working surface is leveled, the outer layer of steel reinforcement is tied, and 1m is reserved at the temporary lock. The cutting foot is assembled, the inner layer of steel reinforcement is tied, the lower thread of the outer layer of steel reinforcement is buried with yellow sand, and the inner layer of steel reinforcement is inserted into the pre-reserved hole of the cutting foot to leave room for the connection thread of the next section. After the steel reinforcement is tied, the well wall formwork is lowered and corrected, and concrete is poured.

3. The construction method for an ultra-deep vertical shaft with a large cross-section in a water conveyance tunnel according to claim 1, characterized in that, The verification calculation for the blasting safety distance in step S3 is as follows: (1) Calculate the blasting vibration velocity V, based on The upper and lower limits, corresponding to The upper and lower limits are 1.5-1.8, and the above coefficients are... and Substitute into the following formula The results were verified and compared with those in the "National Blasting Safety Regulations". The value range of 0.7-1.2 cm / s was compared and verified to control the blasting vibration velocity V within the above range; in the above formula: The vibration propagation coefficient; This refers to the amount of explosive charge used in the blasting process. The distance from the blast center to the protected building, in meters (m). This is the blast attenuation coefficient; (2) Calculate the safe distance for flying rocks from blasting The unit is m, at the time of detonation. The area requires protection against flying rocks; the safe distance for flying rocks from the blasting is specified. The calculation is as follows: ； In the formula: The explosive force index is 1 for standard throwing. The line of least resistance; For safety, we set it to 2; (3) Calculate the safe distance of the air shock wave at the blast point. When the air shock wave is The explosion posed no threat to surrounding buildings outside the designated area; furthermore, the blasting direction was not directed towards surrounding villages and buildings, and the detonation... Protective measures are required for the affected area; the safe distance for the air shock wave at the blast point. The calculation is as follows: ； In the above formula: Total explosive charge, in kg; For safety, a factor of 2 is used.

4. The construction method for an ultra-deep vertical shaft with a large cross-section in a water conveyance tunnel according to claim 1, characterized in that: When arranging blast holes in step S3, a hydraulic umbrella drill is used in conjunction with a rock drill. When the well casing passes through unfavorable strata during the excavation process, the blasting adopts a shallow-hole multi-cycle method. The total amount of explosives per cycle is reduced by adjusting the height of the construction section in order to reduce the vibration effect on the well wall. Specifically, the height of the excavation section steps will be increased. The unit is m. The height of the step is reduced to half of the original height. The step is shaped by using a pneumatic hammer and then temporary support is provided by anchor mesh and spraying. Mortar anchors are used, and anchor mesh and spraying are added. H-shaped steel arch frame composite support is added. Then the next small section of high excavation is carried out, and the anchor mesh and spraying support are repeated.

5. The construction method for an ultra-deep vertical shaft with a large cross-section in a water conveyance tunnel according to claim 1, characterized in that, The calculation process for the blasting parameters in step S3 is as follows. The same parameters appearing in the following formulas have the same meaning: (1) Calculation of borehole depth L: The boreholes are arranged vertically and inclined; When the blast holes are arranged vertically, the blast hole depth is... ; When the blast holes are arranged at an angle, the blast hole depth ; In the above formula: The height of the step. ; For the excessively deep borehole, ; The drilling angle for the blast hole. The total planned well depth for the month. d represents the number of days of tunneling per month, and d represents the diameter of the blast hole. This refers to the number of daily cycles. Assuming a normal circulation rate, we take 85%. To determine the utilization rate of the blast holes, we take 85%; the step height is determined based on the cyclic advance, so the step height is determined based on the template height, which is a known value. (2) Hole filling height L2: Hole filling height ; (3) Calculation of borehole spacing a: ; In the above formula: The borehole density coefficient is taken as 0.9 to 1.5; W is the minimum resistance line; when the shaft geology consists of hard rock with a hardness coefficient f = 3 to 6, the formula for calculating the minimum resistance line is: When the geology of the shaft is hard or extremely hard rock with a hardness coefficient f = 8 to 20, the formula for calculating its minimum resistance line is: ; (4) Total amount of explosives used in a single mine collapse : ; In the above formula: q is the unit consumption of explosives for shaft excavation (kg / m³) 3 ), where v is the volume of each mining collapse: ; The area of ​​the semi-circular cross-section of the shaft. r is the radius of the semicircular section of the shaft; The area of ​​the rectangular cross-section of the shaft is given. a is the length of the vertical shaft cross-section rectangle; b is the width of the vertical shaft cross-section rectangle. (5) Number of blast holes N: The blast holes are arranged on the design outline of the cross section, and the bottom of the blast hole is controlled within 50mm outside the outline; the blast hole arrangement meets the requirement of a blast hole spacing of 550-700mm and a blast hole density coefficient of 0.8-1.2; the number of blast holes N is calculated as follows: ; In the above formula: The rock firmness coefficient, The cross-sectional area of ​​the blasting section is S = S1 + S2; (6) The peripheral blast hole charging refers to the charging of explosive charges at the blast hole depth. Equal interval Each portion has a filling height equal to the packing height. The unit is mm; n is determined based on the amount of medicine and the filling height, and n is not greater than 4. The propellant top elevation of the loading structure of the slotted eye and the auxiliary eye is: The unit is mm; Drug bottom elevation The unit is mm; Charge height ; In the formula: This refers to the total amount of explosives used in a single mine collapse. The total number of blast holes. The diameter of the borehole.

6. The construction method for an ultra-deep vertical shaft with a large cross-section in a water conveyance tunnel according to claim 1, characterized in that: In step S4, the blasted rock is pushed into a funnel-shaped slag chute using a backhoe excavator.

7. The construction method for an ultra-deep vertical shaft with a large cross-section in a water conveyance tunnel according to claim 1, characterized in that: For the initial structural support of the well wall in step S5, where the well depth is less than 300m, anchor bolts, wire mesh, and sprayed plain concrete are used, or anchor bolts, wire mesh, and sprayed plain concrete are used in conjunction with I-beam arch support. The I-beam arch is of type I20, the anchor bolts are mortar anchors or self-drilling hollow anchors, the wire mesh is steel mesh, and plain concrete is used for spraying. For the initial structural support of the well wall in well depths greater than 300m but less than 600m, I22a I-beam arches are used, and self-drilling hollow anchors or prestressed hollow anchors are used. The remaining construction methods are the same as for the section less than 300m in depth. For the initial structural support of the well wall in well depths greater than 600m, prestressed hollow anchors are used, and the remaining construction methods are the same as for the section less than 300m in depth.

8. The construction method for an ultra-deep vertical shaft with a large cross-section in a water conveyance tunnel according to claim 1, characterized in that: The mix proportion of phosphorus tailings powder-steel fiber reinforced concrete in step S5 is as follows: 1350-1580 parts coarse aggregate, 810-1010 parts fine aggregate, 475-590 parts cement aggregate, 200-300 parts water, 75-113 parts phosphorus tailings powder, 45-84 parts expansion agent, and 3-7 parts water-reducing agent; wherein, the steel fiber accounts for 1.5-2% of the total volume of the phosphorus tailings powder-steel fiber reinforced concrete mixture, and the pouring thickness is 45cm.

9. A method for constructing an ultra-deep vertical shaft with a large cross-section in a water conveyance tunnel according to claim 7, characterized in that: The anchor bolt construction in step S5 uses an anchor bolt trolley and a pneumatic drill to drill holes. After drilling, the rock debris inside the hole is blown away with high-pressure air. Then, early-strength cement mortar is injected into the anchor hole using a grouting machine. The anchor bolt is then inserted into the hole. After the mortar strength reaches the design requirements, a pad is placed and the nut is tightened. For downward anchor bolts, the grouting pipe should be inserted into the bottom of the hole. Then, the grouting pipe is pulled outward while grouting until the hole is full. The self-drilling hollow anchor bolts and prestressed anchor bolts are driven to a depth of 4.5m to 6m and are arranged in a quincunx pattern. The steel arch frame is processed on the work platform designed on site. The steel frame is bent using a steel bending machine in combination with the dimensions of the vertical shaft. Each steel arch frame is divided into several units. The steel arch frame joints use Q235 connecting steel plates. Bolt holes are drilled on the steel plates, and the hole diameter meets the requirements of M20 bolts. The connecting parts are fully and densely welded, and the width and length of the weld are fully welded.

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