Method for excavating large-diameter and super-deep cyclone shaft double-reverse suspended body solid rock mass

Abstract

The application discloses a kind of super-large-caliber super-deep cyclone shaft double-reverse suspension body solid wall rock mass excavation methods, belong to shaft excavation technical field.This method is based on the construction of pilot hole of rotary drilling rig, constructs annular blasting free face, uses top blasting+bottom guide well slag discharge double-reverse construction mode, simultaneously combines system anchor rod+spraying concrete suspension body solid wall technology, through cyclic development excavation-reinforcement operation, realize the safe, efficient excavation of super-large-caliber super-deep cyclone shaft.The application effectively solves the technical problems, such as the difficulty in constructing free face, poor blasting effect, poor surrounding rock stability and low slag discharge efficiency, during the excavation of super-large-caliber super-deep shaft, significantly improves the safety, economy and construction efficiency of excavation operation, reduces the influence of blasting vibration on the surrounding environment and surrounding rock, ensures that the shaft excavation quality meets the design requirements, and is suitable for super-large-caliber super-deep cyclone shaft excavation engineering under various surrounding rock conditions.

Description

Technical Field

[0001] This invention relates to the field of shaft excavation technology, specifically to a method for excavating ultra-large diameter, ultra-deep vortex shafts with dual-reverse suspended solid rock walls. Background Technology

[0002] The application of ultra-large diameter and ultra-deep vortex shafts is becoming increasingly widespread in engineering fields such as water conservancy and hydropower, mining, and urban underground space development. These shafts are characterized by large diameter, deep depth, and complex geological conditions. Their excavation and construction face many technical challenges, including difficulties in constructing the free face, challenges in controlling blasting vibration, poor surrounding rock stability, low muck removal efficiency, and high construction safety risks.

[0003] Traditional shaft excavation methods mostly employ a forward excavation model, where excavation, muck removal, and support operations are carried out sequentially from top to bottom. This model suffers from problems such as long muck removal paths, low efficiency, and increasing difficulty in controlling the stability of the surrounding rock as the excavation depth increases. Furthermore, the improper construction of the free face in traditional blasting operations leads to low blasting energy utilization, uneven rock fragmentation, severe over- and under-excavation, and the potential for cumulative blasting vibrations to adversely affect the surrounding environment and the shaft's surrounding rock. In addition, traditional support methods often lag behind excavation operations, failing to provide timely reinforcement of the excavated surrounding rock, which can easily lead to safety accidents such as rockfalls. These factors severely restrict the construction efficiency and safety quality of ultra-large diameter, ultra-deep vortex shafts.

[0004] Therefore, there is an urgent need for a construction method that can effectively solve the above-mentioned technical problems and achieve safe and efficient excavation of ultra-large diameter and ultra-deep vortex shafts. Summary of the Invention

[0005] The purpose of this invention is to provide a method for excavating ultra-large diameter, ultra-deep vortex vertical shafts with dual-reverse suspended solid rock walls.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for excavating ultra-large diameter, ultra-deep vortex vertical shafts using a dual-reverse suspended wall stabilization technique is proposed. Based on pilot hole construction with a rotary drilling rig, it employs a dual-reverse construction mode of top blasting and bottom pilot shaft muck removal, simultaneously combining system anchor bolts and shotcrete suspended wall stabilization to complete the excavation-reinforcement operation in a cyclical manner. The method includes the following steps: 1. Pre-construction preparation The construction site was cleaned, leveled, and compacted to ensure that the transportation and working space for drilling equipment and blasting materials met the requirements; construction machinery and equipment such as the YT-28 pneumatic leg drill, ventilator, loader, and rotary drilling rig were inspected and repaired to ensure their normal operation; the air supply, water supply, and power supply systems were improved to ensure the smooth progress of drilling, charging, slag removal, and support operations; a detailed geological survey was conducted on the shaft excavation area to determine the type and geological structure of the surrounding rock and collect rock physical and mechanical parameters to provide an accurate basis for blasting parameter design and support parameter selection; blasting design documents, including blasting parameters, charge structure, detonation network, and safety measures, were prepared and submitted to the supervisor for approval before implementation; blasting tests were conducted as required to collect blasting construction parameters, verify and adjust the blasting design.

[0007] 2. Construction of large-diameter pilot holes A Shanhe-330 rotary drilling rig was used to pre-construct a large-diameter pilot hole in the central area of ​​the shaft. The diameter of the pilot hole was determined based on the shaft excavation diameter to ensure the formation of a ring-shaped blasting face and improve the utilization rate of blasting energy. The specific construction process is as follows: S1. Drilling Rig Positioning: Move the rotary drilling rig to the designated position, adjust the rig level, and ensure the rig is stable. S2. Mast inversion operation: Invert the mast according to the standard procedure to ensure that the mast is vertical and accurately positioned; S3. Lower casing: The casing is made of steel plate with a thickness of 10-12mm. Its inner diameter is 20-30cm larger than the diameter of the guide hole. It is buried at least 30cm above the ground to ensure the stability of the upper opening of the guide hole and prevent the hole from collapsing. S4. Drilling operation: Rotary drilling rigs are used for drilling. The pressure and rotation speed of the drill rod are controlled. The pressure parameters are gradually adjusted as the drilling depth increases to avoid problems such as hole inclination and hole shrinkage. The verticality deviation of the pilot hole is no more than 1%. No additional wall protection is required during the drilling process. The hole is formed in one go and the pilot hole runs through the entire vertical shaft excavation depth.

[0008] 3. Measurement, layout, and hole arrangement Using a total station, the positions of the blast holes are accurately laid out on the excavation face of the shaft. Markings are made with paint or steel frames according to the design requirements, and the deviation of the hole positions is no more than 5cm. The hole layout scheme adopts a wide hole spacing + small resistance line, and the hole row spacing ratio is controlled at 2-3, that is, the hole spacing is 2-3 times the resistance line, to ensure uniform distribution of blasting energy, uniform rock fragmentation, and reduce over-excavation and under-excavation. Taking a 10m diameter shaft as an example, 199 blast holes are arranged according to the design hole layout diagram, divided into 5 sections, including peripheral holes, auxiliary holes, etc., to ensure that the blast holes cover the entire excavation section.

[0009] 4. Drilling operations Drilling operations were carried out using YT-28 pneumatic leg drills, with skilled technicians and pneumatic drill operators assigned to specific areas and locations for drilling. Before drilling, steel pipes were used to temporarily protect the area around the guide tunnel to prevent falls. During the drilling process, the hole direction was strictly controlled to ensure that the parallelism of each borehole met the design requirements and the hole depth deviation was no more than 50mm. After drilling was completed, holes with large deviations in hole direction and position were treated as waste holes and re-drilled.

[0010] 5. Top blasting operation The explosives are manually loaded according to the designed loading structure. Wooden or bamboo rams are used for loading; metal rods are strictly prohibited to avoid accidents. Peripheral holes use smooth-surface blasting with intermittent decoupled charges, employing φ32mm×100g type No. 3 rock emulsion explosive, detonated by detonating cord. Auxiliary holes use continuous decoupled charges, employing φ32mm×150g type No. 3 rock emulsion explosive. Bottom holes and holes with seepage from mountain fissures use the same type of water-resistant explosive. Holes are plugged with sticky soil rolls, with a plugging length of not less than 25-30cm; blasting without plugging is strictly prohibited. After loading, digital electronic detonators are connected to the explosives to form a millisecond-delay step blasting network. After completion, conduct a comprehensive inspection. Once confirmed to be correct, evacuate all personnel and machinery to a safe area at least 200 meters away. Set up blasting warnings at designated locations and intersections, with personnel wearing armbands or flags and carrying whistles. Issue blasting signals as required: Pre-warning signal: three intermittent long blasts, each lasting 30 seconds, with a 30-second interval; Preparation signal: issued 20 minutes after the pre-warning signal, three intermittent blasts, one long and one short, each lasting 20 seconds and 10 seconds, with a 30-second interval; Detonation signal: issued 10 minutes after the preparation signal, three consecutive short blasts, each lasting 10 seconds, with a 10-second interval; After the detonation signal is issued, activate the detonator to initiate the detonation.

[0011] During blasting, the charge amount per stage is controlled according to the blasting vibration calculation formula, which is: ; The blasting vibration velocity v is taken as 2.0-2.5 cm / s. K and α are selected according to the surrounding rock type: K=50-150 and α=1.3-1.5 for hard rock; K=150-250 and α=1.5-1.8 for medium-hard rock; and K=250-350 and α=1.8-2.0 for soft rock. Generally, K is taken as 200 and α is taken as 1.65 to ensure that the blasting vibration does not exceed the standard and to reduce the impact on the surrounding environment and surrounding rock.

[0012] 6. Slag removal from the bottom pilot well After detonation, ventilation fans are used to supply air to the working face to remove smoke. Construction personnel can only enter the well after about 2 hours of smoke removal. When there is still a small amount of blasting smoke and pungent gas at the working face, water mist is sprayed onto the blast pile to improve the working environment. After entering the working face, construction personnel should first check for any misfires. If misfires are found, they should be properly handled according to regulations. No one else is allowed to enter the site before the misfires are handled. Loose rocks at the working face should be cleared to prevent them from falling and injuring people. Loaders and dump trucks are used to transport the blasting debris to the designated slag yard through the bottom guide shaft and horizontal tunnel to achieve rapid slag removal from the bottom and improve construction efficiency.

[0013] 7. Suspended wall stabilization operation After blasting and muck removal, a system of anchor bolts and shotcrete is used simultaneously for suspended rock stabilization to reinforce the excavated section. The density, length, and diameter of the anchor bolts are determined based on the surrounding rock type and the shaft excavation dimensions to ensure effective anchoring of the surrounding rock. The shotcrete thickness is no less than 10cm, and the concrete strength grade is no less than C25 to ensure a tight bond between the shotcrete and the surrounding rock, forming a stable support structure and preventing deformation and collapse of the surrounding rock.

[0014] 8. Cyclic operation Repeat steps 3-7, advancing 2.5-3m per cycle to complete the full-section blasting excavation and reinforcement of the shaft until the designed excavation depth is reached. After each cycle, monitor and analyze the blasting vibration data, adjust the blasting parameters based on the monitoring results and blasting effect, and optimize the blasting design; ensure that the smooth blasting half-hole ratio is not less than 80%, the surface flatness deviation is not greater than 15cm, and guarantee the excavation quality.

[0015] The beneficial effects of this invention are as follows: This invention is based on the pilot hole construction using a rotary drilling rig. A large-diameter annular blasting face is pre-formed in the central area of ​​the shaft, significantly improving the utilization rate of blasting energy, resulting in more uniform rock fragmentation, effectively reducing over- and under-excavation, and improving the flatness of the shaft excavation cross-section. The dual reverse construction mode of top blasting + bottom pilot shaft muck removal overcomes the problems of long and inefficient muck removal paths associated with traditional forward excavation. The short muck removal path of the bottom pilot shaft allows for rapid transportation of blasted muck to the designated muck yard, greatly improving muck removal efficiency and shortening the construction cycle.

[0016] By combining the system of anchor bolts and shotcrete suspension wall reinforcement technology, the excavation section is reinforced in a timely manner after blasting and muck removal. This avoids the risk of rock instability caused by the lag of traditional support methods behind the excavation operation, effectively improves the stability of the surrounding rock, and ensures construction safety.

[0017] The blasting design was optimized, employing a wide hole spacing and small resistance line layout, coupled with a digital electronic detonator micro-delay initiation network. Scientific calculations controlled the charge amount per stage, strictly controlling blasting vibration within permissible limits, thus minimizing the adverse effects of blasting vibration on the surrounding environment and the shaft's surrounding rock, ensuring the safety of the construction area. The entire construction process utilized a cyclical operation method, with parameters adjusted and optimized based on monitoring data and blasting results after each cycle, ensuring continuous improvement in construction quality and efficiency. This approach is suitable for ultra-large diameter, ultra-deep vortex shaft excavation projects under various surrounding rock conditions, demonstrating broad practicality and widespread application value.

[0018] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Detailed Implementation

[0019] The specific embodiments of the present invention will be described in further detail below with reference to the examples. These examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0020] Unless otherwise specified, the technical solutions described in this invention are conventional solutions in the field; unless otherwise specified, the materials described are all from commercial channels.

[0021] 1. Project Overview This embodiment addresses the excavation of an ultra-large diameter, ultra-deep vortex shaft in a water conservancy and hydropower project. The shaft is designed to have an excavation diameter of 10m and an excavation depth of 120m. The surrounding rock in the area is mainly medium-hard rock, with localized fissures and a small number of weak interlayers. The physical and mechanical parameters of the rock, as determined by investigation, are: compressive strength 35-50MPa, elastic modulus 20-30GPa, and Poisson's ratio 0.25-0.30. This project needs to solve key problems such as the construction of the free face for the excavation of the large-diameter, ultra-deep shaft, blasting vibration control, surrounding rock stability, and muck removal efficiency. The excavation method described in this invention is used for construction.

[0022] 2. Pre-construction preparation Construction site preparation: The construction site around the shaft will be cleared, removing weeds, debris and loose soil from the surface. The site will be leveled and compacted in layers using a vibratory roller, with a compaction degree of over 95%. This will ensure that the driving and working space for drilling equipment, loaders, dump trucks and other machinery meets the requirements. Drainage ditches will be set up around the site to prevent rainwater accumulation from affecting construction.

[0023] Equipment Inspection and Debugging: Conduct a comprehensive inspection and debugging of the mechanical equipment required for construction, including the Shanhe-330 rotary drilling rig, YT-28 pneumatic leg drill, ventilation fan, ZL50 loader, 15t dump truck, digital electronic detonator, etc. Check the operating status of key components, hydraulic system, power system, etc., to ensure that all equipment is in good working order and operating normally. At the same time, professional maintenance personnel and spare parts are provided to deal with possible equipment failures during construction.

[0024] The auxiliary systems are comprehensive: a temporary air supply system is set up, using two 20m³ / min air compressors to deliver compressed air to the work surface through Φ150mm high-pressure air ducts to meet the needs of drilling and shotcrete operations; a water supply system is constructed, using Φ100mm water supply pipelines to bring water from a nearby water source to the construction site, and a 50m³ water storage tank is provided to ensure water supply for drilling cooling, dust suppression after blasting, and shotcrete mixing; a temporary power supply system is set up, using a 315kVA transformer connected to the municipal power grid, with a dedicated power distribution room and a backup generator to ensure uninterrupted power supply during construction.

[0025] Geological Survey and Blasting Design: A professional geological survey team will be organized to conduct a detailed investigation of the surrounding rock type and geological structure distribution in the shaft excavation area using a combination of drilling and geophysical exploration. Key areas of fracture development and weak interlayer locations will be marked, and rock physical and mechanical parameters will be collected to provide a basis for blasting design and support parameter selection. Detailed blasting design documents will be prepared, specifying blasting parameters, charge structure, detonation network, and safety protection measures. After review and approval by the supervisor, blasting tests will be conducted in an open area around the shaft to verify the rationality of the blasting parameters. The blasting design will be adjusted and optimized based on the test results.

[0026] 3. Construction of large-diameter pilot holes Drilling rig positioning: Move the Shanhe-330 rotary drilling rig to the center of the vertical shaft and adjust the level of the drilling rig using the built-in level to ensure that the horizontal deviation of the drilling rig body is no more than 0.5% and that the body is stable without shaking.

[0027] Inverting the mast: Follow the operating procedures of the rotary drilling rig to slowly invert the mast, monitor the verticality of the mast in real time, and use a theodolite to assist in calibration to ensure that the vertical deviation of the mast is no more than 0.3% and the positioning is accurate.

[0028] The casing is made of 12mm thick steel plate with an inner diameter of 1.5m and a guide hole diameter of 1.2m, which meets the requirement that the inner diameter is 30cm larger than the guide hole diameter. The casing is 3m long and is buried by excavation and installation using a combination of machinery and manual labor. The casing is buried 35cm above the ground. The casing is backfilled and compacted in layers with cohesive soil around it to prevent the casing from tilting, leaking, or collapsing.

[0029] Drilling Operation: Start the rotary drilling rig to drill. Control the drill rod pressure at 15-20kN and adjust the rotation speed to 20-30r / min. As the drilling depth increases, monitor the borehole inclination every 5m and adjust the drill rod angle accordingly to ensure the verticality deviation of the pilot hole is no more than 1%. During the drilling process, utilize the rotary drilling rig's built-in mud wall protection function, eliminating the need for additional wall protection measures and achieving one-time forming. The pilot hole penetrates the entire 120m vertical shaft excavation depth. After drilling is completed, use a measuring rope to check the hole depth and diameter to ensure they meet design requirements.

[0030] 4. Measurement, layout, and hole arrangement Measurement and layout: A Leica TS06 total station was used to accurately lay out the holes on the shaft excavation face. The center of the pilot hole was used as the reference, and the positions of the blast holes were determined point by point according to the design hole layout plan. The holes were clearly marked with red paint. The layout was checked multiple times during the process to ensure that the hole position deviation was no more than 5cm.

[0031] Hole Layout Scheme: A wide hole spacing + small resistance line layout scheme is adopted, with a hole row spacing ratio controlled at 2.5, where the resistance line is set at 0.8m and the hole spacing at 2.0m. The vertical shaft of this project has a diameter of 10m, with 199 blast holes arranged in each cycle, divided into 5 sections. 60 peripheral holes are evenly distributed around the perimeter of the excavation section, with a depth of 2.8m; 139 auxiliary holes are arranged in a quincunx pattern inside the peripheral holes, with a depth of 3.0m, ensuring complete coverage of the excavation section by blast holes.

[0032] 5. Drilling operations Personnel and equipment configuration: 10 skilled technicians and pneumatic drill operators are arranged, divided into 5 work groups, with designated personnel and positions for drilling in different areas and locations. Each group is equipped with 2 YT-28 pneumatic leg drills, and the work scope and responsibilities of each group are clearly defined.

[0033] Drilling protection and control: Before drilling, temporary protective railings with a height of 1.2m are erected around the pilot hole using Φ48mm steel pipes, with two horizontal bars to prevent personnel and materials from falling. During drilling, the operators strictly follow the layout marks and hole orientation requirements, and use an angle ruler to control the angle of the blast holes to ensure that the parallelism deviation of each blast hole is no more than 0.5%, and the hole depth deviation is controlled within ±50mm.

[0034] Hole inspection: After drilling is completed, the on-duty engineer organizes the inspection. According to the requirements of "flat, straight and even", the hole depth, hole direction and hole diameter are checked with a hole inspection tool. Three holes with a hole direction deviation of more than 10° and two holes with a hole depth deviation of more than 50mm are treated as waste holes and re-layout and drilled to ensure that all holes meet the design requirements.

[0035] 6. Top blasting operation Charge Operation: Charges shall be manually carried out according to the designed charge structure, using wooden rams; metal rods are strictly prohibited. Peripheral holes shall use smooth-surface blasting with intermittent decoupled charges, employing φ32mm×100g type No. 3 rock emulsion explosive, with a charge weight controlled at 1.5-2.0kg per hole, detonated by detonating cord. Auxiliary holes shall use continuous decoupled charges, employing φ32mm×150g type No. 3 rock emulsion explosive, with a charge weight controlled at 3.0-3.5kg per hole. Boreholes in the bottom plate and areas with localized cracks and seepage shall use the same type of water-resistant explosive to ensure blasting effectiveness. All boreholes shall be plugged with sticky soil rolls, with a plugging length controlled at 28-30cm. During plugging, layers shall be compacted; blasting without plugging is strictly prohibited.

[0036] Detonation network setup: Digital electronic detonators are connected to the explosives to form a millisecond-delay stepped blasting network. The detonation time differences for the five segments are set to 50ms, 100ms, 150ms, 200ms, and 250ms respectively to ensure the orderly release of blasting energy. After the connection is completed, professional technicians conduct a comprehensive inspection of the detonation network, testing the conductivity of the detonators and the reliability of the network connections. Once everything is confirmed to be correct, personnel and machinery are evacuated to a safe area at least 200m away.

[0037] Blasting Warning and Detonation: Six blasting warning points will be set up within a 500m radius of the shaft. Warning personnel will wear red armbands, carry flags, and use whistles. Unauthorized personnel and vehicles will be prohibited from entering the warning area. Blasting signals will be issued according to regulations: First, a warning signal will be issued: three intermittent long blasts, each lasting 30 seconds, with a 30-second interval. Twenty minutes after the warning signal, a preparation signal will be issued: three intermittent blasts, one long and one short, each lasting 20 seconds and 10 seconds, with a 30-second interval. Ten minutes after the preparation signal, the detonation signal will be issued: three consecutive short blasts, each lasting 10 seconds, with a 10-second interval. After the detonation signal is issued, the detonator will be activated to initiate the detonation.

[0038] Blasting vibration control: Based on the hard rock surrounding conditions in this project, the blasting vibration velocity v is taken as 2.2 cm / s, K is taken as 200, α is taken as 1.65, and the blasting vibration calculation formula is as follows: ; Where R is the distance from the blasting center to the protected object, which is 50m in this project. The calculated maximum charge per section is 80kg. During construction, the charge of each section is strictly controlled according to this to ensure that the blasting vibration does not exceed the standard.

[0039] 7. Slag removal from the bottom pilot well Ventilation and Smoke Removal & Environmental Improvement: After detonation, two high-powered ventilation fans were activated to supply air and remove smoke from the working face. The fan airflow was 15 m³ / s, and the smoke removal lasted for 2 hours. After testing, the smoke concentration at the working face was reduced to the allowable range before construction personnel could enter the well. For areas with a small amount of residual pungent gas, high-pressure water guns were used to spray water mist onto the blast pile to further improve the working environment.

[0040] Safety Inspection and Cleanup: After entering the work area, the construction personnel first checked for any misfires and used special instruments to test the detonation status of the blast holes. No misfires were found. Then, a comprehensive inspection of the work area was carried out, and loose and dangerous rocks were cleared. Crowbars were used to pry off dangerous rocks on the working face and well wall to prevent them from falling and injuring people during construction.

[0041] Slag removal operation: A ZL50 loader in conjunction with 15t dump trucks is used for slag removal. The loader loads the blasted slag into the dump trucks at the bottom guide shaft outlet, and transports it through a horizontal tunnel to a designated slag yard 800m away from the vertical shaft. During the slag removal process, dedicated personnel direct traffic to ensure unobstructed transport routes. This cycle of blasting produces approximately 235m³ of slag. Using the bottom guide shaft slag removal method, the entire slag removal operation is completed in just 8 hours, significantly improving slag removal efficiency.

[0042] 8. Suspended wall stabilization operation Immediately after blasting and muck removal, a system of anchor bolts and shotcrete was used to reinforce the surrounding rock. The anchor bolts were Φ25mm threaded steel, 3.5m long, with a spacing of 1.0m x 1.0m. A YT-28 pneumatic drill was used to drill the bolts to a depth of 3.6m. After drilling, the dust inside the holes was cleaned, and the anchor bolts were fixed with anchoring agent, leaving 10-15cm of the bolt exposed to ensure effective bonding with the shotcrete. C25 shotcrete was used, with a mix ratio of cement:sand:aggregate:water = 1:2.0:2.5:0.45, with the addition of a suitable amount of accelerator. A wet shotcrete machine was used for spraying, with a thickness controlled at 12cm, applied in two stages. The first stage was 6cm thick, followed by a second stage after initial setting, ensuring a tight bond between the shotcrete and the surrounding rock, a smooth surface, and no missed areas or hollow spots.

[0043] 9. Cyclic Operations and Parameter Optimization The project's pre-set cycle advance was 2.8m. After completing the first cycle of excavation and reinforcement, blasting vibration data was monitored. The monitoring results showed that the blasting vibration velocity was 2.1cm / s, meeting the design and specification requirements. The shaft excavation cross-section was inspected; the smooth blasting half-hole rate was 85%, and the maximum surface flatness deviation was 12cm, meeting design requirements. Based on the blasting effect and monitoring data of the first cycle, the blasting parameters for subsequent cycles were fine-tuned, optimizing the auxiliary hole charge to 2.8-3.2kg to further improve the uniformity of rock fragmentation. The cycle operation was repeated according to the above procedure, for a total of 43 cycles, completing the excavation of the entire 120m deep shaft in 150 days. No surrounding rock collapses or blasting safety accidents occurred during the construction process, and the excavation quality and construction efficiency both met the expected goals.

[0044] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0045] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for excavating ultra-large diameter, ultra-deep vortex vertical shafts with double-reverse suspended solid rock walls, characterized in that: Based on the pilot hole construction of the rotary drilling rig, a dual reverse construction mode of top blasting + bottom pilot shaft muck removal is adopted, which is simultaneously combined with system anchor bolts + shotcrete suspension wall stabilization to complete the excavation-reinforcement operation in a cycle. The specific steps include: S1. Pre-construction preparation: Clean, level and compact the construction site, inspect and repair construction machinery and equipment and ensure their normal operation, improve the air supply, water supply and power supply system, conduct a detailed geological survey of the shaft excavation area, prepare blasting design documents and implement them after approval by the supervisor, and conduct blasting tests as required. S2. Construction of large-diameter pilot hole: A rotary drilling rig is used to pre-construct a large-diameter pilot hole in the central area of ​​the shaft to form a ring-shaped blasting free face. The pilot hole runs through the entire excavation depth of the shaft. S3. Surveying, setting out and hole layout: Using a total station, accurately set out the positions of the blast holes on the shaft excavation face and mark them, and arrange the blast holes according to the design hole layout plan; S4. Drilling operation: Use pneumatic leg drills for drilling operations, strictly control the hole direction, hole depth and hole position deviation, and inspect the hole as required after drilling is completed. S5. Top blasting operation: Charge the explosives according to the designed charge structure, and use a digital electronic detonator micro-delay initiation network to carry out top blasting. Control the amount of explosives in a single section to ensure that the blasting vibration does not exceed the standard. S6. Bottom guide shaft muck removal: A loader and dump truck are used to transport the blasting muck to the designated muck yard through the bottom guide shaft and horizontal tunnel. S7. Suspended wall reinforcement operation: After the blasting and muck removal are completed, the suspended wall reinforcement operation is carried out simultaneously using system anchor bolts and shotcrete to reinforce the excavation section. S8. Cyclic Operation: Repeat steps S3-S7 to complete the full-section blasting excavation and reinforcement of the shaft according to the preset cyclic advance until the designed excavation depth is reached.

2. The method for excavating ultra-large diameter, ultra-deep vortex vertical shafts with double-reverse suspended solid rock walls according to claim 1, characterized in that, In step S1, the geological survey needs to identify the type and structure of the surrounding rock and collect the physical and mechanical parameters of the rock. The type of surrounding rock includes hard rock, medium-hard rock, and soft rock. The geological structure includes the development of fractures and the distribution of weak interlayers.

3. The method for excavating ultra-large diameter, ultra-deep vortex vertical shafts with double-reverse suspended solid rock walls according to claim 1, characterized in that, In step S2, the rotary drilling rig selected is the Shanhe-330 model. The diameter of the pilot hole is determined to be 1-2m according to the diameter of the vertical shaft excavation, and the verticality deviation of the pilot hole is no more than 1%. During construction, the rotary drilling rig is first driven to the marked position and leveled. The mast is then erected according to the specifications to ensure that the mast is vertical. The casing is then lowered. The casing is made of steel plate with a thickness of 10-12mm, and its inner diameter is 20-30cm larger than the diameter of the pilot hole. It is buried at least 30cm above the ground. Finally, the drilling operation is carried out. No additional wall protection is required during the drilling process, and the hole is formed in one go.

4. The method for excavating ultra-large diameter, ultra-deep vortex vertical shafts with double-reverse suspended solid rock walls according to claim 1, characterized in that, In step S3, the hole layout scheme adopts a wide hole spacing + small resistance line, and the hole row spacing ratio is controlled at 2-3; the hole position deviation is no more than 5cm. For a 10m diameter vertical shaft, 199 blast holes are arranged in each cycle, divided into 5 sections, including peripheral holes and auxiliary holes.

5. The method for excavating ultra-large diameter, ultra-deep vortex vertical shafts with double-reverse suspended solid rock walls according to claim 1, characterized in that, In step S4, a YT-28 pneumatic leg drill is used for drilling operations. Skilled technicians and pneumatic drill operators are assigned to specific areas and locations for drilling. Before drilling, steel pipes are used to temporarily protect the area around the guide tunnel. During the drilling process, the hole direction is controlled to ensure that the parallelism of each blast hole meets the design requirements and the hole depth deviation is no more than 50mm. Holes with large deviations in hole direction and position are treated as waste holes and re-drilled.

6. The method for excavating ultra-large diameter, ultra-deep vortex vertical shafts with double-reverse suspended solid rock walls according to claim 1, characterized in that, In step S5, wooden or bamboo rams are used for loading explosives; metal rods are strictly prohibited. Peripheral holes use smooth-surface blasting with intermittent decoupled charges, employing φ32mm×100g type No. 3 rock emulsion explosive, detonated with a detonating cord. Auxiliary holes use continuous decoupled charges, employing φ32mm×150g type No. 3 rock emulsion explosive. Bottom holes and holes with seepage from mountain fissures use the same type of water-resistant explosive. Holes are plugged with sticky soil rolls, with a plugging length of not less than 25-30cm. Before detonation, the digital electronic detonator is connected to the explosives to form a millisecond differential step blasting network, and a comprehensive inspection is conducted. Personnel and machinery are evacuated to a safe area more than 200m away. A blasting warning is set up, and after issuing the blasting signal as required, the detonator is activated to initiate the blast.

7. The method for excavating ultra-large diameter, ultra-deep vortex vertical shafts with double-reverse suspended solid rock walls according to claim 1, characterized in that, In step S5, the charge amount per stage is controlled according to the blasting vibration calculation formula, which is: ; The blasting vibration velocity v is taken as 2.0 - 2.5 cm / s; K and α are selected according to the surrounding rock type: K=50-150 for hard rock and α=1.3-1.5 for medium-hard rock; K=150-250 for medium-hard rock and α=1.5-1.8 for soft rock; K=250-350 for soft rock and α=1.8-2.0 for soft rock.

8. The method for excavating ultra-large diameter, ultra-deep vortex vertical shafts with double-reverse suspended solid rock walls according to claim 1, characterized in that, Before slag removal in step S6, a ventilation fan should be used to supply air to the working face for smoke removal for 2 hours. If there is still a small amount of blasting smoke and pungent gas at the working face, water mist should be sprayed onto the blast pile to improve the working environment. After entering the working face, the construction personnel should first check for any misfires and handle them properly according to regulations. After clearing the dangerous rocks at the working face, the slag removal operation can be carried out.

9. The method for excavating ultra-large diameter, ultra-deep vortex vertical shafts with double-reverse suspended solid rock walls according to claim 1, characterized in that, In step S7, the arrangement density, length, and diameter of the system anchor bolts are determined according to the surrounding rock type and the shaft excavation size. The thickness of the shotcrete is not less than 10cm, and the concrete strength grade is not lower than C25.

10. The method for excavating ultra-large diameter, ultra-deep vortex vertical shafts with double-reverse suspended solid rock walls according to claim 1, characterized in that, In step S8, the preset cyclic advance is 2.5-3m. After each cycle, the blasting vibration data is monitored and analyzed. Based on the monitoring results and blasting effect, the blasting parameters are adjusted and the blasting design is optimized. The half-hole rate of smooth blasting is not less than 80%, and the surface flatness deviation is not greater than 15cm.