Tbm receiving shaft construction method

Abstract

The application discloses a TBM receiving vertical shaft construction method, aiming at solving the problems of construction disturbance, low efficiency of serial process, high cost of design redundancy, easy instability of surrounding rock and poor long-term structural stability in the traditional method. Through the pre-construction through main hole of the mucking shaft of the reverse shaft drilling machine, the vibration-free excavation process of mechanical crushing and static blasting is matched, synchronous operation of excavation and slag discharge is realized, construction efficiency is greatly improved, construction period is shortened, surrounding rock exposure time is reduced, and construction safety risk is reduced; the process of TBM split disassembly machine cooperating with vertical shaft construction is adopted, the vertical shaft only needs to meet the lifting demand of the core large machine such as the cutter head, the vertical shaft design section is greatly reduced, the functional redundancy of the traditional method is eliminated, the engineering quantity and construction cost of the vertical shaft excavation, support and lining are significantly reduced, the construction difficulty and safety risk of the large-section shallow-buried vertical shaft are reduced, and the use demand of the TBM temporary disassembly machine is perfectly matched; the special surrounding rock control measures of intersection slag body counter pressure and lock port anchor rod reinforcement are adopted, the lining structure formed by one-time continuous pouring by the slip-form process is matched, and the vertical shaft sealing mode of grading backfilling not only guarantees the structural safety during construction, but also eliminates the safety hidden danger of long-term operation of the tunnel.

Description

Technical Field

[0001] This invention relates to the field of TBM construction technology for water conservancy engineering tunnels, and specifically to a method for constructing a TBM receiving shaft. Background Technology

[0002] With the large-scale construction of long-distance inter-basin water conveyance and urban water diversion tunnel projects in my country, open-face hard rock TBMs have become the core equipment for long-distance deep-buried hard rock tunnel construction due to their technical advantages of high continuous tunneling efficiency, good tunnel quality, and controllable disturbance to the surrounding strata. After the TBM completes its designated tunneling task, a dedicated dismantling space needs to be set up to dismantle and transport the equipment. When the dismantling section is near residential areas or ecologically sensitive areas, the traditional drill-and-blast method's in-tunnel dismantling tunnel can cause environmental disturbance and disputes due to blasting vibration and construction noise, becoming a key bottleneck restricting the smooth progress of the project. Replacing the in-tunnel drill-and-blast dismantling tunnel with a surface receiving shaft has become the mainstream solution for this type of work.

[0003] For the construction of TBM receiving shafts, the current industry practice is to follow the mature construction method of permanent shafts. The core of this method is to adopt a serial construction mode of drilling and blasting excavation with the shaft opening and bucket removal of slag. The shaft cross-section is designed according to the hoisting requirements of the entire TBM. After the excavation is completed, the shaft lining is constructed using a segmented formwork and cast-in-place process. Finally, the entire TBM is dismantled and transported out through the formed shaft. For temporary shafts, the entire backfill is filled with plain soil or slag after dismantling.

[0004] However, when the inventors applied the aforementioned traditional construction methods in engineering practice, they discovered the following core technical defects: First, conventional drill-and-blast excavation cannot eliminate blasting vibration and noise pollution at the source, and construction in sensitive areas still poses a serious risk of disturbing residents. Furthermore, the sequential operation of shaft excavation and muck removal results in severe cross-interference between procedures and low muck removal efficiency, significantly extending the construction period and leaving shallowly buried, fractured surrounding rock exposed for extended periods, leading to high construction safety risks. Second, conventional vertical shafts are designed with cross-sections based on the requirements for TBM hoisting, resulting in significant… The functional redundancy significantly increases the amount of work and construction cost of shaft excavation, support and lining. The construction difficulty and safety risks of large-section shallow buried shafts are increased simultaneously, and the adaptability to the use needs of temporary dismantling is extremely poor. Furthermore, the existing construction method lacks specific surrounding rock stability control measures at the intersection of shafts and existing tunnels. Excavation at the intersection is prone to causing the surrounding rock of the completed tunnel section to collapse. The segmented lining process has many construction joints and poor structural integrity. The overall backfilling of temporary shafts is prone to causing uneven settlement of the strata in the later stage, which poses a safety hazard to the long-term operation of the tunnel.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the background technology of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] In view of at least one of the above technical problems, this disclosure provides a TBM receiving shaft construction method, which aims to solve the problems of construction disturbance and low efficiency due to sequential procedures, high cost of design redundancy, easy instability of surrounding rock and poor long-term structural stability in traditional methods.

[0007] According to one aspect of this disclosure, a method for constructing a TBM receiving shaft is provided, characterized by comprising the following steps: S1. Based on the TBM dismantling space requirements, determine the location of the receiving shaft, and complete the construction site layout, topsoil treatment, and supporting system installation. S2. The slag chute is constructed using a reverse drilling rig. First, a pilot hole is drilled from top to bottom and connected to the main tunnel. Then, the hole is enlarged from bottom to top to form the slag chute. S3. Construction shaft lock and lock ring structure; S4. The shaft body is excavated in layers. The overburden layer is excavated mechanically, and the rock section is excavated by mechanical crushing or static blasting without vibration. The excavated slag is discharged into the main tunnel through the slag chute and transported out. Initial support is carried out in a timely manner after each cycle of excavation. S5. Construct the structure of the intersection between the vertical shaft and the main tunnel, as well as the step tunnel, and complete the reinforcement support of the intersection; S6. After the shaft excavation is completed, the shaft lining is constructed from bottom to top using the slipform process; S7. Utilize the existing receiving shaft to dismantle the TBM in a modular manner, hoisting the TBM cutterhead out of the shaft and transporting it outside, while the remaining components are transported and dismantled by trailers inside the tunnel; S8. After dismantling the machine, the shaft will be backfilled and sealed in layers, and the construction site will be reclaimed and restored.

[0008] In some embodiments of this disclosure, in step S2, the slag chute is located inside the vertical shaft. The pilot hole is aligned with the axis of the main tunnel throughout the drilling process. After the pilot hole is connected to the main tunnel, the reaming drill bit is replaced inside the main tunnel to ream the hole from bottom to top.

[0009] In some embodiments of this disclosure, in step S4, the rock section adopts a vibration-free excavation process with hydraulic breakers for main excavation and static blasting for auxiliary excavation. The excavated slag is discharged into the main tunnel in real time through a chute, realizing simultaneous excavation and slag removal operations.

[0010] In some embodiments of this disclosure, in step S5, when excavation reaches near the top of the main tunnel, the height of the slag pile in the slag chute is controlled to connect with the top of the tunnel. The original arch frame at the intersection is dismantled in a segmented manner, and anchor bolts are added to the arch tops upstream and downstream of the intersection for reinforcement.

[0011] In some embodiments of this disclosure, in step S5, after the tunnel construction is completed, the tunnel floor slab concrete is poured, and a TBM step guide groove is reserved in the floor slab.

[0012] In some embodiments of this disclosure, in step S6, during the slipform lining construction process, the three processes of rebar tying, concrete pouring, and formwork slipforming are carried out in parallel and continuously, and are poured continuously from the bottom of the shaft to the shaft opening in one go.

[0013] In some embodiments of this disclosure, during S7, when the TBM is dismantled in a split manner, only the cutter head and the main core components are hoisted and transported out through a vertical shaft. The remaining components are separated from the main unit and transported to a pre-designated maintenance chamber for dismantling and transport out via a trailer inside the tunnel.

[0014] In some embodiments of this disclosure, in step S8, the backfilling of the shaft adopts a graded backfilling structure with the lower layer of slag filling, the middle layer of concrete partition, and the top layer of topsoil covering.

[0015] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages: 1. By pre-constructing the chute through the main tunnel using a reverse drilling rig, and combining it with a vibration-free excavation process using mechanical crushing and static blasting, simultaneous excavation and slag removal operations were achieved. This eliminated the problems of blasting vibration and noise pollution at the source, and solved the pain points of sequential procedures and cross-interference of working faces in the traditional direct shaft method. This significantly improved construction efficiency, shortened the construction cycle, reduced the exposure time of the surrounding rock, and lowered construction safety risks.

[0016] 2. The TBM split-type dismantling and shaft construction process is adopted. The shaft only needs to meet the hoisting requirements of core large components such as the cutterhead, which greatly reduces the design cross-section of the shaft, eliminates the functional redundancy of traditional construction methods, significantly reduces the amount of work and construction cost of shaft excavation, support and lining, and at the same time reduces the construction difficulty and safety risks of large cross-section shallow buried shafts, perfectly adapting to the use requirements of temporary TBM dismantling.

[0017] 3. Specialized surrounding rock control measures, such as cross-section slag back pressure and anchor bolt reinforcement, combined with a slipform process for continuous casting of the lining structure and a graded backfilling method for shaft sealing, were adopted. These measures solved the problems of easy collapse of surrounding rock at intersections, poor integrity of the lining structure, and easy settlement of the strata in the later stage, which are common in traditional construction methods. This not only ensured the structural safety during construction but also eliminated the safety hazards of long-term tunnel operation. Attached Figure Description

[0018] Figure 1 This is a flowchart of a TBM receiving shaft construction method in one embodiment of this application.

[0019] Figure 2This is a schematic diagram of the plan layout of the receiving well and slag chute in one embodiment of this application.

[0020] Figure 3 This is a schematic diagram of the construction of a riser drilling rig in one embodiment of this application.

[0021] Figure 4 This is a schematic diagram of the excavation layout of the tunnel roof section in one embodiment of this application.

[0022] Figure 5 This is a schematic cross-sectional view of the receiving well in one embodiment of this application.

[0023] In the above figures, 11 is the main tunnel axis, 12 is the vertical shaft center, 21 is the slag chute, 211 is the slag body, 22 is the surface water and electricity guide hole, 23 is the sedimentation tank, 31 is the main machine, 32 is the drill rod, 33 is the operating vehicle, 34 is the pump station, 35 is the pilot hole drill bit, 351 is the pilot hole, 36 is the reaming drill bit, 361 is the reaming, 37 is the broken rock, 38 is the working face, 41 is the step tunnel, 411 is the unexcavated section, 42 is the drill and blast hole, 51 is the lock well ring, 52 is the lock, and 53 is the well wall lining. Detailed Implementation

[0024] In the description of this application, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," "outer," "vertical," "horizontal," "clockwise," and "counterclockwise," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. The terms "first," "second," etc., used in this application are used to distinguish the described objects and do not have any sequential or technical meaning. And the terms "connection" and "linkage," unless otherwise specified, include both direct and indirect connections (linkages).

[0025] Unless otherwise specified, the unit modules or sensors involved in the following embodiments are all commercially available products.

[0026] This application provides a TBM receiving shaft construction method that pre-constructs a chute through the main tunnel using a raise boring machine, combined with a vibration-free excavation process using mechanical crushing and static blasting. It also employs a TBM split-type dismantling and shaft construction technique, along with specialized surrounding rock control measures such as cross-section back pressure and anchor bolt reinforcement. This method fundamentally eliminates the problems of blasting vibration and noise pollution, significantly reduces the amount of excavation, support, and lining work and construction costs, and solves the problems of easy collapse of surrounding rock at cross-sections, poor integrity of lining structure, and easy subsidence of strata in traditional construction methods.

[0027] To better understand the technical solution of this application, the above technical solution will be described in detail below with reference to the accompanying drawings and specific embodiments. Example

[0028] This example discloses a method for constructing a TBM receiving shaft. (See also...) Figure 1 The specific implementation steps are as follows: S1: Based on the TBM dismantling space requirements, determine the location of the receiving shaft, and complete the construction site layout, topsoil treatment, and supporting system installation.

[0029] Based on the TBM cutterhead outer diameter, hoisting operation radius, and other dismantling space requirements, combined with the on-site tunnel excavation progress and the scope of sensitive village areas, the center of the receiving shaft, station 12, was determined to be T14+371.27, corresponding to station 38, T14+370.47, of the excavated face inside the tunnel. The shaft is located at 3.2m of the excavated section and 4114.8m of the unexcavated section of the main tunnel. The shaft adopts a circular structure with an excavation diameter of 9.6m, a diameter of 9.2m after support, an inner diameter of 8m after lining, and a depth of 36.82m. Through TBM dismantling and hoisting simulation, this size meets the hoisting space requirements of core large components. Excavators were used to level the site and strip the topsoil. The stripped topsoil was transported by 20-ton dump trucks to a designated storage area for centralized stockpiling, which was protected by woven bag retaining walls. Temporary facilities were constructed, covering a total area of ​​5280.8 m², including the construction plant area, the reclaimed soil storage area, and a 168.5 m long access road. The shaft hoisting operation area was hardened with 30 cm thick C30 concrete, while the remaining areas were leveled and compacted with stone chips. The site was fully enclosed by a grid fence. Simultaneously, the construction ventilation, water supply, and power supply systems were laid out. A guide hole 22 was drilled in the completed section of the main tunnel to bring the water and electricity systems from the tunnel to the surface plant area. Two 20 m³ / min electric air compressors were installed for ventilation. The pipelines inside the shaft were fixed along the shaft wall, and a safety rope was installed at the shaft opening for secondary protection.

[0030] This step precisely matches the TBM dismantling requirements to determine the location of the vertical shaft, avoiding the construction difficulties of sensitive areas in the original drilling and blasting dismantling holes, and preventing disturbance and disputes from the source; at the same time, it completes the preparatory work for the entire construction process, solving the problems of poor adaptability between the vertical shaft layout and dismantling requirements in traditional construction methods, and poor connection between construction preparation and subsequent procedures, laying the foundation for efficient construction in the future.

[0031] S2: See also Figure 2 , Figure 3 The chute 21 is constructed using a reverse drilling rig. First, a pilot hole is drilled from top to bottom and connected to the main tunnel. Then, the hole is enlarged from bottom to top to form the chute. The chute 21 is located inside the vertical shaft. The pilot hole is aligned with the axis 11 of the main tunnel throughout the drilling process. After the pilot hole is connected to the main tunnel, the enlarged drill bit 36 ​​is replaced inside the main tunnel, and the hole is enlarged from bottom to top in reverse to form the chute.

[0032] Slag chute 21 is located inside the vertical shaft, with its center 2.27m away from the shaft center 12, and a forming diameter of 1.6m. An AT1500 type raise boring machine is used for construction. First, a 3m×3m×0.3m C25 concrete foundation platform is poured, and a mud circulation pool and cooling water tank measuring 4m long, 3m wide, and 1.0m deep are excavated. The raise boring machine is then installed, leveled, and the system is debugged. A Φ250mm pilot hole is drilled from the surface towards the main tunnel, aligned with the tunnel main shaft axis 11 throughout the drilling process. A hole-opening stabilizer is used in conjunction with the hole-opening drill rod 32 for slow hole opening. After reaching a depth of 3m, normal drilling proceeds, with adjustments made in real time according to geological conditions. Drilling pressure and rotation speed: gradually reduce drilling pressure 3m before drilling through the main tunnel. Clean up the returned rock cuttings in a timely manner throughout the process. Stop mud circulation after the pilot hole is completely penetrated. Stop drilling after the drilling rig is running smoothly. In the main tunnel, disassemble the pilot hole drill bit 36 ​​and replace it with a Φ1.6m reaming drill bit 36. Reverse reaming from bottom to top. When reaming, first slowly lift the drill bit to make the reaming drill bit 36 ​​evenly contact the rock before drilling normally. When the hole is close to the ground surface, reduce drilling pressure and drill slowly until the drill bit is exposed on the ground to complete the reaming 361. After the slag chute 21 is formed, use a 10mm thick, 3m diameter circular steel plate to make an openable and closable seal for the hole opening. Open it when slag chute operation and restore the seal immediately after the operation is completed.

[0033] This step involves the pre-construction of the chute 21, which connects to the main tunnel. This provides a dedicated slag removal channel for subsequent excavation, solving the core pain point of traditional direct shaft excavation and slag removal being carried out in sequence and with overlapping processes. The process of aligning the guide hole with the main tunnel axis 11 and expanding the hole in the opposite direction ensures the forming accuracy of the chute 21 and avoids disturbance to the surrounding rock caused by the expansion operation. At the same time, the expanded slag 211 falls directly into the main tunnel for external transportation, achieving simultaneous well completion and slag removal, which greatly improves construction efficiency.

[0034] S3: See also Figure 4 The construction shaft lock 52 and lock ring 51 structure.

[0035] The lock opening and lock opening ring 51 are constructed using C30 reinforced concrete cast-in-place structure. The specific construction sequence is as follows: surveying and setting out → rebar fabrication and installation → formwork installation → concrete pouring → formwork removal and curing. The lock opening ring 51 is made of 6m wide and 1.2m thick C30 reinforced concrete. The lock opening 52 section is 2m deep and uses double-layer Φ18@200mm rebar for binding, with a rebar protective layer thickness of 40mm. The rebar is prefabricated in the factory strictly according to the design dimensions. During on-site binding, the stirrups are set perpendicular to the main reinforcing bars, and the lap joints are staggered along the direction of the main reinforcing bars, with a considerable lap length. On day 35, after the steel reinforcement passes inspection, steel formwork is installed and reinforced with double steel pipes. Ready-mixed concrete is used, transported to the site by truck and poured into the formwork via chutes. The concrete is poured in layers using the cast-in-place method, with each layer not exceeding 30cm in thickness. During the pouring process, a Φ50 immersion vibrator is used to compact the concrete, ensuring no missed or over-vibration. After the concrete strength reaches 2.5MPa, the side formwork is removed, and the concrete is covered with geotextile and plastic film and watered for curing. The curing period is no less than 7 days. The entire lock-hole 52 structure is 1m higher than the original ground level, and a 1.5m high standardized guardrail is installed on top.

[0036] This step, through the cast-in-place reinforced concrete lock 52 and well ring 51 structure, solves the problems of easy wellhead collapse and difficulty in controlling surface settlement in traditional construction methods, providing a stable wellhead structure and safety protection barrier for subsequent vertical shaft excavation; at the same time, the standardized construction procedures ensure the construction quality of the lock 52 structure and avoid the impact of wellhead deformation on the accuracy of subsequent vertical shaft excavation.

[0037] S4: See also Figure 5 The shaft body is excavated in layers. The overburden layer is excavated mechanically, while the rock section is excavated using mechanical crushing or static blasting without vibration. The excavated slag 211 is discharged into the main tunnel of the tunnel through the chute 21 for external transport. Initial support is carried out in a timely manner after each cycle of excavation. The rock section adopts a vibration-free excavation process with hydraulic breaker as the main excavator and static blasting as the auxiliary excavator. The slag 211 generated during excavation is discharged into the main tunnel of the tunnel in real time through the chute 21, realizing the simultaneous operation of excavation and slag removal.

[0038] The shaft is excavated using a top-down, layered method, adhering to the principles of short advances, minimal disturbance, strong support, and frequent measurements. The standard cycle step distance is 1 meter, reduced to 50 cm when the overburden layer is unstable. The overburden layer is directly excavated using a 60-type excavator, with a 10 cm protective layer left for manual trimming to prevent over-excavation and surrounding rock collapse. The rock section employs a vibration-free process using a 75-type hydraulic breaker for main excavation and static blasting for auxiliary excavation. The hydraulic breaker is transported to the working face inside the shaft by a 50-ton crane. Excavation operations are limited to 6:00 AM to 9:00 PM daily, with work suspended at night to avoid noise. Interference occurred when the excavation reached approximately 5m from the top of the main tunnel. Inside the shaft, the excavator was secured to a 50t crane at the shaft opening with double-strand Φ28 safety anchor cables. The operator wore a double-hook safety harness throughout the process. For hard rock with poor local integrity and a uniaxial compressive strength greater than 60MPa, static blasting was used to assist excavation. Breaking parameters were first determined through on-site tests. Holes were arranged in a ring around the chute 21, with a diameter of 42mm, a spacing of 400mm, and a row spacing of 300mm. The drilling depth was consistent with the cycle advance, and the drilling direction was parallel to the free face. A hydration-expanding fracturing agent was used at a water-cement ratio of 0.3:1. The mixture is stirred into a fluid state, quickly poured into the borehole, and compacted tightly. After the hydration reaction of the agent takes 4-12 hours to induce cracks in the rock, it is then broken up using an impact hammer. The slag produced in each excavation cycle is discharged into the main tunnel through the chute 21 in real time, and transported to the designated spoil disposal site by a ZWY-120 loader in the tunnel in conjunction with 20t dump trucks, achieving simultaneous excavation and slag removal operations. Initial support is carried out immediately after each excavation cycle is completed. A8@150mm×150mm steel mesh is laid on the strongly weathered and above overburden layers, and C25 self-propelled hollow cores with an L=3200mm diameter are installed. Grouting anchors are arranged in a staggered pattern with a spacing of 1000mm between rows, with a grouting pressure of 0.1~0.2MPa. HW150 steel arch frames are erected with a spacing of 1000mm, and Φ22 connecting bars are welded circumferentially. 200mm thick C25 wet-sprayed concrete is then applied. For the weakly weathered layer, C25 cement mortar anchors with a length of L=3200mm are used, with steel arch frames randomly arranged. Other support parameters are consistent with the overburden layer. If support convergence exceeds 5mm / d or concrete cracking and spalling occur during the support process, excavation should be stopped immediately, and lining construction should proceed. Excavation can only continue after the structure has stabilized.

[0039] This step employs a vibration-free excavation process, eliminating blasting vibration and noise pollution at the source. This solves the core problems of traditional drilling and blasting methods, such as disturbing residents and causing construction delays in sensitive areas. By using the slag chute 21 for real-time slag removal, excavation and slag removal are carried out simultaneously, solving the problems of low slag removal efficiency and cross-interference between work faces in traditional shaft methods, and significantly shortening the single-cycle operation time. At the same time, the short-cut excavation and timely support process reduces the time the surrounding rock is exposed to the open air, lowering the construction safety risk of shaft collapse.

[0040] S5: Construct the structure of the intersection between the vertical shaft and the main tunnel and the stepping tunnel 41, and complete the reinforcement support of the intersection; when the excavation reaches close to the top surface of the main tunnel, control the height of the slag 211 in the slag chute 21 to connect with the top surface of the tunnel, dismantle the original arch frame of the intersection section in a segmented manner, and simultaneously add locking anchor bolts to the arch tops of the upstream and downstream of the intersection for reinforcement; after the construction of the stepping tunnel 41 is completed, pour the tunnel bottom slab concrete, and reserve the TBM stepping guide groove in the bottom slab.

[0041] When the excavation reaches 5m from the top of the main tunnel, the special construction phase for the intersection begins, with the cycle advance reduced to 50cm. After each cycle, the monitoring of surrounding rock deformation is intensified. When the excavation approaches the top of the main tunnel, the height of the slag heap 211 in the chute 21 is controlled to connect with the tunnel top. The slag heap 211 provides reverse support to the surrounding rock at the tunnel top through counter-pressure, balancing the surrounding rock pressure. A muck loader is used for slag removal, and excessive slag removal is strictly prohibited to prevent rockfall. After the tunnel top is excavated and connected, the existing HW150 steel arch frame at the intersection is dismantled in sections, with each section no longer than 1m. Support is immediately installed after each section is dismantled; complete dismantling at once is prohibited. The process is completed using an excavator in conjunction with the slag removal equipment. The remaining excavation work was completed; two rings of C25 hollow grouting anchor bolts with an L=3200mm diameter and a spacing of 1m were added to the arch tops of the upstream and downstream sections of the intersection for reinforcement, and a 5m long reinforced support section was set up simultaneously, with support parameters consistent with those of the strongly weathered layer; after the construction of the intersection section was completed, the construction of a 10m long step tunnel 41 continued. The excavation cross section of step tunnel 41 was consistent with that of the main tunnel, and the same anchor spraying support parameters as those of the main tunnel were adopted; after the excavation and support of step tunnel 41 was completed, a 40cm thick C25 tunnel floor slab concrete was poured, and the entire width was poured and vibrated to ensure compaction. A 30cm×25cm full-length TBM stepping guide groove was reserved at the center of the floor slab. The guide groove was cast using wooden formwork to provide precise guidance for subsequent TBM stepping operations.

[0042] This step, through a combination of measures including back pressure of slag body 211, segmented dismantling of the arch frame, and reinforcement with anchor bolts at the lock joint, solved the problems of rockfall and instability of existing tunnel sections that are prone to occur during excavation at intersections in traditional construction methods, thus ensuring the structural safety of intersection construction. The construction of the step tunnel 41 and the guide channel achieved a seamless connection between the vertical shaft construction and the TBM dismantling process, solving the problem of poor compatibility between the vertical shaft and dismantling process in traditional construction methods, and creating conditions for efficient TBM dismantling in the future.

[0043] S6: After the shaft excavation is completed, the shaft lining is constructed from bottom to top using the slipform process; during the slipform lining construction, the three processes of steel bar binding, concrete pouring, and formwork slip-lifting are carried out in parallel and continuously, and the shaft is continuously poured from the bottom to the opening in one go.

[0044] After the entire shaft excavation and initial support passed inspection, the shaft lining was constructed from the bottom to the shaft opening using a hydraulic slipform process. The shaft lining consisted of 60cm thick C30 reinforced concrete with double-layer Φ20@200mm steel reinforcement binding and a 40mm protective layer for the reinforcement. The slipform device employed an integrated hydraulic slipform system, including a template system made of δ6mm steel plates, a 12# channel steel ring structure, an "F"-shaped lifting frame welded from 20# I-beams, and 14 GYD-60 type... A 6-ton jack, a ZYXT-36 automatic leveling hydraulic control console, and an operating panel and suspended auxiliary panel were used. The slipform device was assembled, debugged, and tested for load at the wellhead. After passing the acceptance test, it was lowered to the starting position at the bottom of the shaft. During construction, the three processes of rebar tying, concrete pouring, and formwork slipforming were carried out in parallel and continuously, with the concrete being poured continuously from the bottom of the shaft towards the wellhead in one go. The concrete was centrally supplied by the mixing plant and transported to the wellhead using 8m³ tank trucks, then placed into the formwork through a Φ200 chute and hose. The concrete is poured symmetrically in 30cm layers, compacted using a Φ50 immersion vibrator, and vibration is stopped during formwork slipforming. The slipforming speed and single-slipforming height are adjusted according to the site temperature and initial concrete setting. Normal slipforming intervals are 1-2 hours, with a single slipforming height of 30cm, and the daily slipforming height controlled at approximately 3m. During slipforming, the center position of the formwork is monitored in real-time using four plumb lines, and the levelness of the formwork is controlled using a level and jack synchronizer. The formwork is checked every 30cm slipforming, and deviations are adjusted promptly, keeping the deviation within 5mm. Immediately after demolding, the surface is finished with the original slurry, and continuous watering is carried out simultaneously through the ring-shaped water sprinkler on the auxiliary plate. If slipforming needs to be stopped during construction, it is raised 1-2 strokes every 30 minutes until the concrete no longer adheres to the formwork. Before resuming work, the construction joints are roughened and washed according to regulations. After the lining concrete reaches 100% of its design strength, a 50t crane is used at the wellhead to dismantle the slipform device from top to bottom.

[0045] This step employs slipform technology to achieve parallel and continuous operation of three processes, with continuous casting in one go. This solves the problems of numerous construction joints, poor structural integrity, and low construction efficiency associated with traditional segmented formwork lining, significantly improving the quality and efficiency of lining construction. At the same time, the automatically leveling hydraulic slipform system ensures the forming accuracy of the lining structure, avoids dimensional deviations caused by manual formwork, and the continuously cast structure also enhances the long-term waterproofing and load-bearing capacity of the well body.

[0046] S7: Using the established receiving shaft, the TBM is dismantled in a split manner. The TBM cutterhead is hoisted from the shaft and transported out, while the remaining components are transported and dismantled by trailers inside the tunnel. During the TBM split dismantling, only the cutterhead and the main unit core components are hoisted out through the shaft. The remaining components are separated from the main unit and transported to the pre-designated maintenance chamber for dismantling and transport out by trailers inside the tunnel.

[0047] After the shaft lining structure passed inspection, the TBM dismantling operation was carried out using the completed receiving shaft. First, the TBM main unit was moved to the corresponding position at the center 12 of the shaft through the stepping tunnel 41 and the bottom plate guide groove. After locking the TBM main unit, the dismantling operation was carried out. A 50t truck crane at the shaft opening, with special lifting tools, was used to smoothly lift the core components such as the TBM cutterhead, main bearing, and main beam from the shaft to the ground. After inspection, the components were transported to the equipment storage area by flatbed truck. The TBM's rear auxiliary trolley, connecting bridge, hydraulic system, electrical system, and auxiliary components were separated from the main unit and transported to the pre-set maintenance chamber near the 5-1# branch tunnel by a 100t tractor inside the tunnel. The components were dismantled in the maintenance chamber and then transported to the storage area outside the tunnel through the branch tunnel. The entire dismantling process was directed by a dedicated person. A warning zone was set up for the hoisting operation. Non-operating personnel were strictly prohibited from entering. The speed of the vehicle was controlled to not exceed 5km / h throughout the tunnel transportation process, and a dedicated person was assigned to monitor the entire process.

[0048] This step adopts a TBM split-type dismantling process, where only the cutterhead and core components are hoisted through the vertical shaft, while the remaining parts are transported and dismantled through the existing tunnel. This significantly reduces the design cross-section of the vertical shaft, solving the problems of functional redundancy, large workload, and high construction costs caused by the traditional method of designing the vertical shaft for hoisting the entire machine. It also significantly reduces construction costs and safety risks. At the same time, it enables parallel operations of vertical shaft hoisting and in-tunnel dismantling, greatly shortening the total TBM dismantling period and improving the efficiency of process connection.

[0049] S8: After dismantling the machine, the shaft is backfilled and sealed in layers, and the construction site is reclaimed and restored; the shaft backfilling adopts a graded backfilling structure with the lower cavity slag layered filling, the middle concrete partition, and the top top top top top soil covering.

[0050] After the TBM dismantling operation is completed and all equipment inside the tunnel is removed, the backfilling and site reclamation work will commence. Backfilling will begin after the concrete lining at the main tunnel intersection reaches 90% of its design strength. The shaft will employ a tiered backfilling structure: lower layered backfilling with tunnel slag, a middle concrete partition, and top top top covering with topsoil. Within 8 meters of the shaft opening, layered backfilling with tunnel slag will be used, with each layer no more than 50cm thick. Compaction will be achieved using a small vibratory roller, with a compaction degree of no less than 93%. Backfill material will be transported to the backfilling work surface using a crane with a slag bucket; it must not be dumped directly from the shaft opening. When backfilling reaches 3.3m from the original ground level, 1.2m of silty soil will be used for backfilling and compacted, with a compaction degree of no less than 94%. Simultaneously construct a 60cm thick C30 reinforced concrete partition. Before the partition construction, remove the corresponding height of the well wall lining 53, treat the construction joint between the partition and the surrounding rock, and install a waterstop. After the partition concrete reaches 90% of its design strength, backfill and compact the excavated soil at the top 0.7m of the partition. Cover the surface with topsoil at least 0.5m thick, with a compaction degree of at least 85%. Before the site reclamation operation, remove all hardened ground, temporary fences, production buildings, and other temporary facilities in the construction site. Transport construction waste to the designated disposal site by dump truck. After the site is leveled, reclaim the land using the original soil and topsoil to restore the original farmland properties of the site and complete the surface drainage facilities.

[0051] This step employs a tiered backfilling structure for shaft sealing, which solves the problems of uneven ground settlement and subsequent structural instability that are easily caused by one-time backfilling in traditional construction methods, ensuring the long-term stability of the ground after backfilling. At the same time, site reclamation is completed simultaneously, realizing a closed-loop disposal of the temporary project throughout its entire life cycle. This solves the problems of non-standard disposal and non-compliance with environmental protection standards in the later stages of temporary projects using traditional construction methods, and meets the requirements of soil and water conservation and ecological environmental protection for the project.

[0052] Although some preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0053] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application is also intended to include such modifications and variations.

Claims

1. A method for constructing a TBM receiving shaft, characterized in that, Includes the following steps: S1. Based on the TBM dismantling space requirements, determine the location of the receiving shaft, and complete the construction site layout, topsoil treatment, and supporting system installation. S2. The slag chute is constructed using a reverse drilling rig. First, a pilot hole is drilled from top to bottom and connected to the main tunnel. Then, the hole is enlarged from bottom to top to form the slag chute. S3. Construction shaft lock and lock ring structure; S4. The shaft body is excavated in layers. The overburden layer is excavated mechanically, and the rock section is excavated by mechanical crushing or static blasting without vibration. The excavated slag is discharged into the main tunnel through the slag chute and transported out. Initial support is carried out in a timely manner after each cycle of excavation. S5. Construct the structure of the intersection between the vertical shaft and the main tunnel, as well as the step tunnel, and complete the reinforcement support of the intersection; S6. After the shaft excavation is completed, the shaft lining is constructed from bottom to top using the slipform process; S7. Utilize the existing receiving shaft to dismantle the TBM in a modular manner, hoisting the TBM cutterhead out of the shaft and transporting it outside, while the remaining components are transported and dismantled by trailers inside the tunnel; S8. After dismantling the machine, the shaft will be backfilled and sealed in layers, and the construction site will be reclaimed and restored.

2. The TBM receiving shaft construction method according to claim 1, characterized in that, In S2, the slag chute is located inside the vertical shaft. The pilot hole is aligned with the axis of the main tunnel throughout the drilling process. After the pilot hole is connected to the main tunnel, the reaming drill bit is replaced inside the main tunnel to ream the hole from bottom to top.

3. The TBM receiving shaft construction method according to claim 1, characterized in that, In S4, the rock section adopts a vibration-free excavation process with hydraulic breakers for main excavation and static blasting for auxiliary excavation. The excavated slag is discharged into the main tunnel in real time through a chute, realizing simultaneous excavation and slag removal.

4. The TBM receiving shaft construction method according to claim 1, characterized in that, In S5, when the excavation reaches near the top of the main tunnel, the height of the slag pile in the chute is controlled to be connected to the top of the tunnel. The original arch frame at the intersection is dismantled in sections, and anchor bolts are added to the arch tops upstream and downstream of the intersection for reinforcement.

5. The TBM receiving shaft construction method according to claim 1, characterized in that, In S5, after the construction of the tunnel is completed, the tunnel floor slab concrete is poured, and a TBM stepping guide groove is reserved in the floor slab.

6. The TBM receiving shaft construction method according to claim 1, characterized in that, In S6, during the slipform lining construction process, the three processes of steel bar binding, concrete pouring, and formwork slip-lifting are carried out in parallel and continuously, and the formwork is continuously poured from the bottom of the shaft to the shaft opening in one go.

7. The TBM receiving shaft construction method according to claim 1, characterized in that, In S7, when the TBM is dismantled in a split manner, only the cutter head and the main core components are hoisted and transported out through the vertical shaft. The remaining components are separated from the main unit and transported to the pre-designated maintenance chamber for dismantling and transportation by trailers inside the tunnel.

8. The TBM receiving shaft construction method according to claim 1, characterized in that, In S8, the backfilling of the vertical shaft adopts a graded backfilling structure with the lower part filled with slag in layers, the middle part set with concrete partitions, and the top covered with topsoil.

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