Deeply buried underground powerhouse system based on TBM method and integrated construction method thereof

Abstract

The application discloses a deep-buried underground powerhouse system based on a TBM method and an integrated construction method thereof. The underground powerhouse system comprises a main powerhouse for arranging a water turbine generator set, a main transformer tunnel for arranging a main transformer and switch equipment, a tail water diffusion section for connecting a tail water pipe in the main powerhouse and a downstream tail water tunnel, a drainage gallery arranged along the periphery of the main powerhouse and the main transformer tunnel, a middle pilot tunnel located on the central axis of the main powerhouse and the main transformer tunnel, prestressed anchor cables for locking surrounding rocks and inhibiting deformation and rock burst, and a construction slag guide well for allowing slag to drop to the tail water section under the self weight. The construction method comprises the following steps: S1, pre-supporting construction; S2, pre-monitoring arrangement and data acquisition; S3, pre-supporting construction; and S4, three-dimensional parallel construction. According to the application, part of the ground stress is released in advance through the TBM pre-excavation, and the geological hidden danger is checked, pre-monitoring is carried out in advance relying on the drainage gallery, original surrounding rock information and rock burst precursor signals are acquired, and early warning and active prevention and control of geological disasters are realized.

Description

Technical Field

[0001] This invention belongs to the field of underground powerhouse construction technology, specifically relating to a deep-buried underground powerhouse system based on the TBM method and its integrated construction method, which is particularly suitable for the construction of deep-buried underground powerhouses for water conservancy and hydropower projects with a burial depth of not less than 400m, high ground stress, and long structural surfaces. Background Technology

[0002] As my country's major infrastructure construction moves towards deeper, higher-stress, and more complex geological conditions, the number of deep-buried underground powerhouse projects has increased dramatically. These projects are typically characterized by depths exceeding 400 meters, high-stress environments (maximum horizontal stress reaching 30-40 MPa), and the development of large structural surfaces. They are highly susceptible to sudden geological disasters such as rock bursts, surrounding rock instability, and large deformations, seriously threatening construction safety and project schedules.

[0003] Currently, the mainstream construction methods are still mainly based on drill-and-blast method, sequential layered excavation, and layered support, which have the following key drawbacks: (1) Disconnection between excavation, support and monitoring: The main cavern lacks systematic pretreatment before excavation, and it is impossible to release ground stress or identify potential geological hazards in advance; the auxiliary cavern (such as drainage corridor) has low construction efficiency and it is difficult to quickly form ventilation, drainage and operation channels.

[0004] (2) Monitoring lags behind disaster occurrence: Traditional monitoring is mostly deployed after excavation is completed, which makes it impossible to obtain the original surrounding rock state parameters, difficult to capture rock burst precursor signals, weak early warning capability, and relatively passive prevention and control measures.

[0005] (3) Slow support response: The support process is generally delayed after the excavation and forming, especially in high ground stress areas where the surrounding rock deformation rate is fast, which can easily lead to the failure of the initial support or even collapse.

[0006] (4) Simple construction organization: The sequential construction mode is adopted, the working face is concentrated, the resource utilization rate is low, the overall construction cycle is long, and it is difficult to meet the requirements of large-scale hub projects for the construction period.

[0007] (5) Insufficient integration of technology: Although TBM is currently used to construct drainage corridors, it only focuses on structural design and excavation itself. It does not combine drainage corridors with central tunnels, nor does it build a three-in-one proactive prevention and control mechanism of "pre-excavation - pre-monitoring - pre-support". It does not utilize pre-excavated tunnels to enter the various working faces of the plant in advance to achieve parallel construction, nor does it solve the problem of geological disaster prevention and control caused by high ground stress and long structural faces in deep underground plants. It cannot give full play to the advantages of TBM construction method and cannot meet the needs of efficient, safe and green construction of deep underground plants. Summary of the Invention

[0008] The purpose of this invention is to address the technical problems described in the background section by providing a deep-buried underground powerhouse system based on the TBM method and its integrated construction method.

[0009] The technical solution of the present invention: This invention provides a deep-buried underground powerhouse system based on the TBM method, including a main powerhouse for arranging hydro-generator units, a main transformer tunnel for arranging main transformers and switchgear, a tailrace diffusion section connecting the tailrace pipe between the main generator rooms and the downstream tailrace tunnel, drainage corridors arranged around the main powerhouse and the main transformer tunnel, a central guide tunnel located on the central axis between the main powerhouse and the main transformer tunnel, prestressed anchor cables for locking the surrounding rock and suppressing deformation and rockburst, and a construction chute guide shaft for lowering slag material to the tailrace section by its own weight.

[0010] Specifically, the drainage corridor is a three-layer drainage corridor.

[0011] Furthermore, the three-layer drainage corridor is a circular cross-section channel arranged in layers according to elevation around the main plant and main transformer tunnel, namely the first layer drainage corridor at the top, the second layer drainage corridor in the middle, and the third layer drainage corridor at the bottom.

[0012] This invention also provides an integrated construction method for a deep-buried underground powerhouse system based on the TBM method, comprising the following steps: S1: Pre-support construction: Before the main plant and main transformer tunnel are excavated, the drainage gallery and the central tunnel are constructed first using the TBM method to achieve the connection between the drainage gallery and the central tunnel. S2: Pre-monitoring setup and data acquisition: After step S1 is completed, monitoring instruments are pre-installed in the drainage corridor to establish a real-time monitoring system, so as to realize the real-time acquisition and monitoring of the original surrounding rock information and rockburst information of the main plant and main transformer tunnel. S3: Pre-support construction: Based on the surrounding rock information and rockburst risk level obtained from pre-monitoring, and combined with the stress distribution of the long structural surface, pre-support is carried out in layers by entering the main plant and main transformer tunnel excavation faces in advance through drainage corridors and central guide tunnels. S4: Three-dimensional parallel construction: Based on the tunneling sequence of the drainage gallery, the three-dimensional parallel construction is carried out according to the tunneling sequence of the TBM from bottom to top, forming a three-dimensional multi-area and multi-elevation three-dimensional parallel construction working face for the main plant and the main transformer tunnel, and pre-anchor cable support is carried out at the elevation of the main plant and the main transformer tunnel.

[0013] Furthermore, in step S1, the TBM method is carried out in a bottom-up sequence.

[0014] Furthermore, in step S1, the diameter, length, and longitudinal slope of the drainage corridor are determined according to drainage needs and TBM operating requirements.

[0015] Furthermore, in step S2, the monitoring instruments include a surrounding rock displacement gauge, a stress gauge, and a piezometer.

[0016] Furthermore, in step S3, the layered pre-support construction is carried out at one or more elevation layers in the tailrace section, turbine layer, busbar layer, and top arch layer of the main powerhouse and main transformer tunnel.

[0017] Preferably, when carrying out pre-support construction, the shotcrete and anchor support is first completed at the corresponding elevation layer. After the shotcrete and anchor support reaches the preset strength, anchor cables are then laid for reinforcement support.

[0018] Specifically, the anchor cable includes one or more of the following: high-strength anchor cable, through-hole anchor cable, and suspension anchor cable.

[0019] Preferably, during the excavation of the tailrace section at the elevation level, a construction chute guide shaft is drilled, which connects the upper excavation layer with the tailrace diffusion section.

[0020] Furthermore, in step S1, after the central pilot tunnel is completed, a pre-set period for stress release is allowed before subsequent excavation and support construction are carried out.

[0021] Furthermore, in step S4, the three-dimensional parallel construction working faces are arranged in three-dimensional layers, and each working face carries out construction operations independently; the excavation and support operations of the main cavern follow the principle of excavation and support at the same time.

[0022] Furthermore, the main plant and the main transformer tunnel are underground plants with a burial depth of not less than 400m, and the underground plants are located in a high ground stress environment and have long structural surface geological structures.

[0023] The beneficial effects of this invention are: (1) This invention transforms the traditional passive chain of “excavation → support → monitoring” into an active prevention and control system of “pre-excavation, pre-monitoring and pre-support” through the integrated process of “pre-excavation-pre-monitoring-pre-support”. By pre-excavating with TBM to release some ground stress in advance and investigate geological hazards, and by carrying out pre-monitoring in advance based on drainage corridors, it is possible to accurately obtain original surrounding rock information and rockburst precursor signals, so as to realize early warning and active prevention and control of geological disasters. At the same time, pre-support is carried out in advance to constrain the deformation of surrounding rock and improve the stability of surrounding rock. It can effectively avoid geological disasters such as rockburst and collapse caused by long structural surfaces and high ground stress in deep underground powerhouses, greatly improve construction safety, ensure the safety of construction personnel and equipment, and solve the pain point of passive prevention and control of geological disasters in traditional construction.

[0024] (2) This invention uses a drainage gallery and a central guide tunnel to form a three-dimensional construction channel network, breaking the limitation of a single construction surface, realizing parallel operation in multiple areas, and improving construction efficiency. The three-layer drainage gallery and central guide tunnel formed by the TBM method form a three-dimensional parallel construction working surface for the subsequent layered excavation of the main cavern, realizing synchronous construction in multiple areas, changing the traditional sequential construction mode, further improving construction efficiency, and shortening the overall construction period by 15% to 30%; in addition, the pre-excavation, pre-support, and pre-monitoring procedures are smoothly connected with the subsequent main construction, reducing the waiting time of procedures and further improving the continuity of construction.

[0025] (3) Improve project quality and reduce project costs: The TBM method has high construction precision and causes little disturbance to the surrounding rock, which can reduce the deformation of the surrounding rock and improve the quality of tunnel formation; pre-support can be carried out in advance to avoid rework and repair after the surrounding rock collapses, thus reducing the cost of rework; pre-monitoring data provides support for the optimization of support schemes and the adjustment of construction parameters, which can reasonably control the amount of support materials used, avoid waste, and reduce economic losses caused by geological disasters. At the same time, the drainage gallery integrates dual functions, not only undertaking the drainage function, but also serving as a construction channel for pre-excavation, pre-monitoring and pre-support, reducing additional excavation, saving about 10% to 15% of investment, and realizing intensive use of resources.

[0026] (4) Strong applicability and high promotion value: This invention is applicable to the construction of various deep-buried underground powerhouses (especially underground powerhouses with long structural surfaces, high ground stress and other geological disaster risks), and can flexibly adapt to the engineering needs of different cross-sectional sizes and different geological conditions; combined with the advantages of TBM construction method, it realizes the integrated construction of pre-excavation, pre-support and pre-monitoring, with mature technology and simple operation, no need to add complicated equipment, and is more practical than the existing technology, and can be widely promoted and applied to the construction of underground powerhouses in the fields of water conservancy and hydropower, transportation, energy and other fields. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the present invention.

[0028] Attached reference numerals: 1 – long structural surface; 21 – main powerhouse; 22 – main transformer tunnel; 23 – tailrace diffusion section; 31 – first-level drainage gallery; 32 – second-level drainage gallery; 33 – third-level drainage gallery; 4 – intermediate guide tunnel; 5 – anchor cable; 6 – construction slag chute. Detailed Implementation

[0029] refer to Figure 1This invention provides a deep-buried underground powerhouse system based on the TBM method, including a main powerhouse 21 for arranging hydro-generator units, a main transformer tunnel 22 for arranging main transformers and switchgear, a tailrace diffusion section 23 connecting the tailrace pipe of the main generator room to the downstream tailrace tunnel, drainage corridors arranged around the main powerhouse 21 and the main transformer tunnel 22, a central guide tunnel 4 located on the central axis of the main powerhouse 21 and the main transformer tunnel 22, prestressed anchor cables 5 for locking the surrounding rock and suppressing deformation and rock bursts, and a construction chute guide shaft 6 for lowering slag material to the tailrace section by its own weight.

[0030] In this application, the central guide tunnel 4 can release the ground stress of the deeply buried underground cavern in advance.

[0031] Specifically, the drainage corridor is a three-layer drainage corridor.

[0032] Furthermore, the three-layer drainage corridor is a circular cross-section channel arranged in layers according to elevation around the main plant 21 and the main transformer tunnel 22, namely the first-layer drainage corridor 31 at the top, the second-layer drainage corridor 32 in the middle, and the third-layer drainage corridor 33 at the bottom.

[0033] This invention also provides an integrated construction method for a deep-buried underground powerhouse system based on the TBM method, comprising the following steps: S1: Pre-support construction: Before the main plant 21 and main transformer tunnel 22 are excavated, the drainage gallery and the central guide tunnel 4 are constructed first using the TBM method to achieve the connection between the drainage gallery and the central guide tunnel 4, and a ground stress release period of not less than 2 months is reserved. Specifically, before the excavation of the main underground powerhouse 21 and the main transformer tunnel 22, the TBM method is used to construct a multi-layered drainage corridor surrounding the underground powerhouse and a central guide tunnel 4 that runs through the main underground tunnel. The multi-layered drainage corridor is laid out in layers along the elevation of the underground powerhouse, and the central guide tunnel 4 is located in the central area of ​​the main underground powerhouse 21 and the main transformer tunnel 22.

[0034] Furthermore, the TBM method employs a bottom-up construction sequence.

[0035] Furthermore, the diameter, length, and longitudinal slope of the drainage corridor are determined based on drainage needs and TBM operating requirements.

[0036] This invention combines multiple functions, including construction access, ventilation access, monitoring reference access, and groundwater diversion. Compared with traditional drainage corridors that only serve a drainage function, it achieves intensive use of resources and reduces additional excavation work.

[0037] Furthermore, after the completion of the central pilot tunnel 4, a pre-set period for stress release will be reserved before subsequent excavation and support construction can proceed.

[0038] Specifically, after the completion of the central tunnel 4, a pre-set stress release period is reserved before subsequent excavation and support construction is carried out; preferably, the stress release period is not less than 2 months, so as to reduce the risk of geological disasters induced by stress during subsequent construction by naturally releasing some of the stress.

[0039] Furthermore, the main plant 21 and the main transformer tunnel 22 are underground plants with a burial depth of not less than 400m, and the underground plants are located in a high ground stress environment and have a long structural surface 1 geological structure.

[0040] Specifically, this step is carried out as follows: Before excavating the main underground chamber, the TBM method is used to construct the first-level drainage gallery 31 at the top, the second-level drainage gallery 32 in the middle, the third-level drainage gallery 33 at the bottom, and the central guide tunnel 4, thereby achieving the connection between the first-level drainage gallery 31, the second-level drainage gallery 32, the third-level drainage gallery 33, and the central guide tunnel 4. The drainage gallery serves as a construction passage, ventilation passage, and monitoring reference passage. Its cross-section is circular, and its diameter, length, and longitudinal slope are determined according to drainage needs and TBM operating requirements. The TBM is used for construction from bottom to top.

[0041] The monitoring instruments include one or more of the following: surrounding rock displacement monitoring equipment, stress monitoring equipment, seepage monitoring equipment, and microseismic monitoring equipment, which can be flexibly selected according to engineering geological conditions and monitoring needs; the geological disaster precursor signals include rockburst precursor microseismic signals, and early warning of rockburst disasters can be achieved through real-time capture and analysis of microseismic signals; the physical and mechanical parameters of the original surrounding rock include at least surrounding rock displacement and stress distribution parameters, providing accurate data support for subsequent support scheme design and construction parameter adjustment. S2: Pre-monitoring setup and data acquisition: After step S1 is completed, monitoring instruments are pre-installed in the drainage corridor to establish a real-time monitoring system, so as to realize the real-time acquisition and monitoring of the original surrounding rock information and rockburst information of the main plant 21 and the main transformer tunnel 22. Specifically, after the drainage corridor and the central tunnel 4 are formed, monitoring instruments are deployed in the surrounding rock of the underground powerhouse through the drainage corridor to establish a real-time monitoring system, and to collect the physical and mechanical parameters of the original surrounding rock of the underground powerhouse, groundwater seepage data and geological disaster precursor signals.

[0042] Furthermore, in step S2, the monitoring instruments include a surrounding rock displacement gauge, a stress gauge, and a piezometer.

[0043] Specifically, the operation of this step is as follows: After the drainage gallery is connected to the central tunnel 4, monitoring and microseismic instruments are pre-installed in the drainage gallery to achieve real-time acquisition and monitoring of the original surrounding rock information and rockburst information of the main powerhouse 21 and the main transformer tunnel 22. Surrounding rock displacement gauges and stress gauges are used to monitor the original surrounding rock displacement and stress distribution parameters, while piezometers are used to monitor groundwater seepage.

[0044] The monitoring instruments include one or more of the following: rock displacement gauges, stress gauges, and piezometers, which can be flexibly selected according to engineering geological conditions and monitoring needs; the geological disaster precursor signals include rockburst precursor microseismic signals, and by capturing and analyzing the microseismic signals in real time, early warning of rockburst disasters can be achieved; the physical and mechanical parameters of the original surrounding rock include at least the surrounding rock displacement and stress distribution parameters, providing accurate data support for subsequent support scheme design and construction parameter adjustment.

[0045] S3: Pre-support construction: Based on the surrounding rock information and rockburst risk level obtained from pre-monitoring, and combined with the stress distribution of the long structural surface 1, pre-support is carried out in layers by entering the excavation working faces of the main plant 21 and the main transformer tunnel 22 through the drainage gallery and the central guide tunnel 4. Furthermore, in step S3, the layered pre-support construction is carried out at one or more elevation layers in the tailrace section, turbine layer, busbar layer, and top arch layer of the main powerhouse 21 and the main transformer tunnel 22.

[0046] Preferably, when carrying out pre-support construction, the shotcrete and anchor support is first completed at the corresponding elevation layer. After the shotcrete and anchor support reaches the preset strength, anchor cables are then laid for reinforcement support.

[0047] Specifically, the anchor cable includes one or more of the following: high-strength anchor cable, through-hole anchor cable, and suspension anchor cable.

[0048] Preferably, during the excavation of the tailrace section at the elevation level, a construction chute guide shaft 6 is drilled, which connects the upper excavation level with the tailrace diffusion section 23.

[0049] Specifically, the specific steps for this operation are as follows: Based on the surrounding rock information and rockburst risk level obtained from pre-monitoring, and combined with the high ground stress distribution of the long structural surface 1, layered pre-support construction is carried out by pre-entering each excavation face of the underground powerhouse through a three-layer drainage gallery and a central guide tunnel 4. Specifically, this includes: 1) First, once the TBM reaches the excavation elevation of the third-level drainage gallery 33, construction personnel can access the tailrace diffusion section 23 working face via the third-level drainage gallery 33. This allows for large-scale excavation from top to bottom and the first phase of support engineering. When excavation reaches the middle of the tailrace diffusion section 23, a riser drill should be used to drill upwards to obtain the construction chute guide shaft 6. The main powerhouse 2A guide shaft should be drilled to the turbine floor elevation, and the main transformer tunnel 21 guide shaft should be drilled to the busbar floor elevation. Each tailrace diffusion section 23 should include two construction chute guide shafts 6. The completion of this section will provide a channel for transporting construction waste for subsequent excavation operations.

[0050] 2) Secondly, once the TBM reaches the excavation elevation of the second-level drainage corridor 32 upstream, construction personnel can access the turbine floor of the main powerhouse 21 via the second-level drainage corridor 32. The excavation height of this layer is 4-6m. The excavated material enters the tailrace diffusion section 23 directly through the slag chute 6 and flows to the ground. The support works should immediately follow the excavation work. At this elevation, the first-stage shotcrete and anchor support should be carried out first to ensure a tight bond between the shotcrete and anchor support and the surrounding rock, initially restraining the deformation of the surrounding rock. After the first-stage shotcrete and anchor support is completed and reaches the design strength, the second-stage anchor cable support should be carried out, with high-strength anchor cables installed on the upstream sidewall to suppress the deformation of the surrounding rock and the risk of rockburst caused by high ground stress.

[0051] 3) Then, the TBM reaches the excavation elevation of the second-level drainage gallery 32 downstream. Construction personnel can then access the main transformer tunnel 22 at the busbar level via the second-level drainage gallery 32. The excavation height of this level is 4-6m. The excavated material enters the tailrace diffusion section 23 directly through the slag chute 6 and flows to the ground. After the main transformer tunnel 21 is excavated down to the turbine level, through-cable anchors should be installed to the upstream wall of the main powerhouse. This serves to pre-reinforce and lock the two main tunnels (main powerhouse 21 and main transformer tunnel 22), suppressing the risk of surrounding rock deformation and rockburst caused by high ground stress.

[0052] 4) Then, the TBM passes through the first-level drainage corridor 31 to reach the elevation of the intermediate tunnel 4 of the main powerhouse 21 and the main transformer tunnel 22. After the stress release of the intermediate tunnel 4 is completed (≥2 months), the construction personnel enter the intermediate tunnel 4 and excavate it to the elevation of the top arch of the main powerhouse 21 and the main transformer tunnel 22. The top arch is then suspended with anchor cables to cope with the risk of surrounding rock deformation and rock burst caused by high ground stress.

[0053] 5) Finally, after the TBM tunneling is completed, the main powerhouse 21 and the main transformer tunnel 22 are excavated step by step and layer by layer from the elevation of the central pilot tunnel, with support provided during excavation.

[0054] S4: Three-dimensional parallel construction: Based on the tunneling sequence of the drainage gallery, the three-dimensional parallel construction is carried out according to the tunneling sequence of the TBM from bottom to top, forming a three-dimensional multi-area and multi-elevation three-dimensional parallel construction working face for the main plant 21 and the main transformer tunnel 22, and pre-anchor cable support is carried out at the elevation of the main plant 21 and the main transformer tunnel 22.

[0055] Furthermore, the three-dimensional parallel construction working faces are arranged in three-dimensional layers, and each working face carries out construction operations independently; the excavation and support operations of the main cavern follow the principle of excavation and support at the same time.

[0056] The specific operations for this step are as follows: The three-dimensional parallel construction sequence unfolds according to the bottom-up tunneling sequence of the TBM, relying on the tunneling sequence of the three-layer drainage gallery to form a three-dimensional, multi-area, multi-elevation parallel construction working face for the underground powerhouse, and pre-anchor cable support is carried out at key elevations of the main powerhouse (arch top, waist, and bottom). This achieves a "three-dimensional, layered, synchronous advancement" construction organization method.

[0057] During the three-dimensional parallel construction process, the construction area is rationally divided, the elevation is divided in three dimensions, the construction procedure is optimized, and the three-dimensional parallel construction is carried out simultaneously to avoid mutual interference between different work faces. At the same time, the drainage gallery is used to divert groundwater, lower the groundwater level, reduce the impact of groundwater on construction, and further improve the stability of the surrounding rock. Compared with the traditional drainage gallery which only undertakes the drainage function, it achieves the dual function of drainage and construction assistance.

[0058] The following implementation examples illustrate the solution of this invention: In this embodiment, a deep-buried underground powerhouse project has a maximum burial depth of 620m, complex geological conditions, multiple long structural planes, high ground stress (maximum horizontal ground stress 17.8MPa, vertical ground stress 32.3MPa), and a surrounding rock strength-stress ratio of less than 4, indicating a high risk of rockburst. The surrounding rock is mainly phyllite, with poor integrity and low strength. The construction method described in this invention is adopted, and the specific steps are as follows: A1. Construction Preparation: Collect detailed geological survey data for the underground powerhouse, clarify the distribution location and orientation of the long structural surface 1, the magnitude and direction of the ground stress, and determine the layout of the main powerhouse 21, main transformer tunnel 22, tailrace diffusion section 23, first-level drainage corridor 31, second-level drainage corridor 32, third-level drainage corridor 33, and central guide tunnel 4. The first-level drainage corridor 31, second-level drainage corridor 32, and third-level drainage corridor 33 are arranged in layers according to elevation around the perimeter of the underground powerhouse, with a spacing of 30~40mm between adjacent layers. The cross-section is circular with a diameter of 3.53m, and the length is determined according to the perimeter of the underground powerhouse. The longitudinal slope is set at 0.5% according to the drainage requirements. The central guide tunnel 4 is located in the middle of the main cavern, with a circular cross-section and a diameter of 3.53m, and runs through the entire cross-section of the main cavern.

[0059] A2. TBM Pre-excavation Construction: Before the excavation of the underground powerhouse 21, main transformer tunnel 22 and tailwater diffusion section 23, TBM is used to construct the first drainage gallery 31, the second drainage gallery 32, the third drainage gallery 33 and the central guide tunnel 4.

[0060] A3. Pre-monitoring setup and data acquisition: After the first-level drainage corridor 31, the second-level drainage corridor 32 and the third-level drainage corridor 33 are connected to the central guide tunnel 4, monitoring instruments are installed through the side walls and top of the drainage corridors; after the instruments are installed, they are debugged and calibrated to ensure that the instruments work normally, and a monitoring data acquisition system is established to collect monitoring data in real time.

[0061] A4. Pre-support construction: Based on the pre-monitoring report and geological conditions, the first-level drainage gallery 31, the second-level drainage gallery 32, the third-level drainage gallery 33 and the central guide tunnel 4 are used to pre-enter each excavation working face, and the layered pre-support construction is carried out according to the construction organization plan given in step S3 of this invention.

[0062] A5. Three-dimensional parallel construction and dynamic monitoring and adjustment: After the pre-support construction is completed, three three-dimensional parallel construction working faces are formed based on the first-level drainage gallery 31, the second-level drainage gallery 32, the third-level drainage gallery 33 and the central guide tunnel 4, the turbine elevation of the main powerhouse 21, the tailrace diffusion section 23 and the main powerhouse unit section, and the subsequent excavation and support construction of the main cavern are carried out simultaneously. During the construction process, monitoring data is continuously collected through pre-deployed monitoring instruments to monitor the deformation of the surrounding rock, changes in ground stress and rock burst signals in real time.

[0063] In this embodiment, the key engineering parameters are shown in Table 1. Table 1 Key Engineering Parameters of Embodiments of the Invention

[0064] Table 2 shows a comparison of the construction effects of this invention with the traditional drill-and-blast method. Table 2 Comparison of construction effects between the present invention and the traditional drill-and-blast method

[0065] Compared with the traditional drill-and-blast method, the construction period is shortened by 22% when the construction method described in this invention is used. No geological disasters such as rock bursts and collapses occur, and the construction safety is significantly improved. The rework rate is reduced by 85%, the amount of support material used is reduced by 18%, and the project cost is significantly reduced. The underground powerhouse cavern has good forming quality, and the deformation of the surrounding rock is controlled within the design allowable range, meeting the requirements of the project.

Claims

1. A deep-buried underground powerhouse system based on the TBM method, characterized in that: It includes the main powerhouse (21) for arranging the hydro-generator units, the main transformer tunnel (22) for arranging the main transformer and switchgear, the tailwater diffusion section (23) connecting the tailwater pipe between the main generator room and the downstream tailwater tunnel, the drainage corridor arranged around the main powerhouse (21) and the main transformer tunnel (22), the central guide tunnel (4) located on the central axis between the main powerhouse (21) and the main transformer tunnel (22), the prestressed anchor cable (5) for locking the surrounding rock and suppressing deformation and rock bursts, and the construction slag chute (6) for the slag material to be lowered to the tailwater section by its own weight.

2. The deep underground powerhouse system based on the TBM method according to claim 1, characterized in that: The drainage corridor is a three-layer drainage corridor.

3. The deep underground powerhouse system based on the TBM method according to claim 2, characterized in that: The three-layer drainage corridor is a circular cross-section channel set up according to elevation around the main plant (21) and the main transformer tunnel (22), namely the first-layer drainage corridor (31) at the top, the second-layer drainage corridor (32) in the middle and the third-layer drainage corridor (33) at the bottom.

4. An integrated construction method for a deep-buried underground powerhouse system based on the TBM method as described in any one of claims 1-3, characterized in that: Includes the following steps: S1: Pre-support construction: Before the main building (21) and the main transformer tunnel (22) are excavated, the drainage gallery and the central guide tunnel (4) are constructed from bottom to top using the TBM method to achieve the connection between the drainage gallery and the central guide tunnel (4). S2: Pre-monitoring setup and data acquisition: After step S1 is completed, monitoring instruments are pre-installed in the drainage corridor to establish a real-time monitoring system, so as to realize the real-time acquisition and monitoring of the original surrounding rock information and rockburst information of the main plant (21) and the main transformer tunnel (22); S3: Pre-support construction: Based on the surrounding rock information and rockburst risk level obtained from pre-monitoring, and combined with the stress distribution of the long structural surface (1), pre-support is carried out in layers by entering the main plant (21) and the main transformer tunnel (22) excavation working faces in advance through the drainage corridor and the central guide tunnel (4). S4: Three-dimensional parallel construction: Based on the tunneling sequence of the drainage corridor, the three-dimensional parallel construction is carried out according to the tunneling sequence of the TBM from bottom to top, forming a three-dimensional multi-area and multi-elevation three-dimensional parallel construction working face of the main plant (21) and the main transformer tunnel (22), and pre-anchor cable support is carried out at the elevation of the main plant (21) and the main transformer tunnel (22).

5. The integrated construction method for a deep-buried underground powerhouse system based on the TBM method according to claim 4, characterized in that: In step S1, the TBM method is carried out in a bottom-up sequence.

6. The integrated construction method for a deep-buried underground powerhouse system based on the TBM method according to claim 4, characterized in that: In step S1, the diameter, length, and longitudinal slope of the drainage gallery are determined according to drainage needs and TBM operating requirements.

7. The integrated construction method for a deep-buried underground powerhouse system based on the TBM method according to claim 4, characterized in that: In step S2, the monitoring instruments include a surrounding rock displacement gauge, a stress gauge, and a piezometer.

8. The integrated construction method for a deep-buried underground powerhouse system based on the TBM method according to claim 4, characterized in that: In step S3, the layered pre-support construction is carried out at one or more elevation layers in the tailrace section, turbine layer, busbar layer and top arch layer of the main powerhouse (21) and main transformer tunnel (22).

9. The integrated construction method for a deep-buried underground powerhouse system based on the TBM method according to claim 8, characterized in that: When carrying out pre-support construction, first complete the shotcrete and anchor support at the corresponding elevation layer. After the shotcrete and anchor support reaches the preset strength, then lay anchor cables for reinforcement support.

10. The integrated construction method for a deep-buried underground powerhouse system based on the TBM method according to claim 9, characterized in that: The anchor cable includes one or more of the following: high-strength anchor cable, through anchor cable, and suspension anchor cable.

11. The integrated construction method for a deep-buried underground powerhouse system based on the TBM method according to claim 8, characterized in that: During the excavation of the tailwater section elevation layer, a construction chute guide shaft (6) is drilled, which connects the upper excavation layer with the tailwater diffusion section (23).

12. The integrated construction method for a deep-buried underground powerhouse system based on the TBM method according to claim 4, characterized in that: In step S1, after the construction of the central tunnel (4) is completed, a pre-set period for the release of ground stress is reserved before subsequent excavation and support construction is carried out.

13. The integrated construction method for a deep-buried underground powerhouse system based on the TBM method according to claim 4, characterized in that: In step S4, the three-dimensional parallel construction working faces are arranged in three-dimensional layers, and each working face carries out construction operations independently; the excavation and support operations of the main cavern follow the principle of excavation and support at the same time.

14. The integrated construction method for a deep-buried underground powerhouse system based on the TBM method according to claim 4, characterized in that: The main plant (21) and the main transformer tunnel (22) are underground plants with a burial depth of not less than 400m, and the underground plants are in a high ground stress environment and have a long structural surface (1) geological structure.

Images