Arrangement structure and excavation method of underground powerhouse drainage gallery and gravity drainage tunnel

Abstract

This invention provides a drainage corridor and gravity-flow drainage tunnel layout structure for an underground powerhouse, including a gravity-flow drainage tunnel, an underground powerhouse drainage corridor, and a water diversion tunnel drainage corridor. The underground powerhouse drainage corridor has a first excavation section constructed using a TBM (Tunnel Boring Machine) arranged in a ring around the underground powerhouse. Within the first excavation section, there are three spirally ascending corridor sections. The top spiral corridor section connects to the water diversion tunnel drainage corridor via TBM excavation. An intermediate annular corridor section, excavated by the TBM, is located above the top spiral corridor section. The bottom spiral corridor section connects to the gravity-flow drainage tunnel. By employing a TBM spiral excavation method for the underground powerhouse drainage corridor and gravity-flow drainage tunnel, the TBM equipment can be assembled at an assembly site outside the gravity-flow drainage tunnel. This allows for bottom-up excavation of the first excavation section based on the excavation of the gravity-flow drainage tunnel, making the overall excavation or drill-and-blast construction more convenient.

Description

Technical Field

[0001] This invention relates to the technical field of underground power plant drainage corridors and gravity drainage tunnels, specifically to the layout structure and excavation method of underground power plant drainage corridors and gravity drainage tunnels. Background Technology

[0002] Drainage corridors are required around the underground powerhouse caverns of a hydropower station to intercept and divert seepage water from the surrounding rock, preventing it from entering the caverns and damaging the structure and equipment. Traditional drainage corridors are arranged in multi-layered parallel rings, independent of each other. The independent arrangement of each layer of drainage corridors makes it difficult to complete them simultaneously, inevitably resulting in a delayed completion time for the entire drainage corridor. Consequently, it cannot play its role in lowering the water level in the underground caverns before the excavation of the hydropower station's underground powerhouse system is completed. Furthermore, excavation can only be carried out using the drill-and-blast method, which has low mechanization, high labor input, high safety risks, long construction period, and poor working environment, causing occupational health hazards to on-site construction and management personnel and easily leading to safety accidents. Summary of the Invention

[0003] The primary objective of this invention is to provide a layout structure for bottom-up spiral excavation using a TBM (Tunnel Boring Machine). To this end, the invention employs the following technical solution:

[0004] The underground powerhouse drainage corridor and gravity drainage tunnel layout structure includes a gravity drainage tunnel, an underground powerhouse drainage corridor, and a water diversion tunnel drainage corridor. The underground powerhouse drainage corridor has a first excavation section constructed by TBM arranged in a ring around the underground powerhouse. The first excavation section has a three-layer spiral corridor section. The top spiral corridor section is connected to the water diversion tunnel drainage corridor through TBM excavation. An intermediate annular corridor section is set on the top spiral corridor section and excavated by TBM. The bottom spiral corridor section is connected to the gravity drainage tunnel. The gravity drainage tunnel forms the starting point of TBM excavation.

[0005] Furthermore: The self-draining tunnel is used to set up an assembly area outside the underground factory cavern complex.

[0006] Furthermore: a second tunnel section is provided at the inner end of the assembly site, the end of the second tunnel section is connected to the underground factory drainage corridor, and a tunnel opening starting section is also provided between the second tunnel section and the assembly site.

[0007] Furthermore, the flatness of the assembly site is less than 1cm, and the ground elevation of the assembly site is lower than the bottom elevation of the starting tunnel section at the tunnel entrance.

[0008] Furthermore, an in-tunnel maintenance section is set up along the tunneling path of the spiral corridor section.

[0009] Furthermore: the maintenance tunnel section includes a bottom maintenance tunnel section, an intermediate maintenance tunnel section and a top maintenance tunnel section. The bottom maintenance tunnel section is located at the intersection of the construction adit and the TBM excavation direction of the spiral corridor section. The intermediate maintenance tunnel section is located between the access tunnel near the plant and the main transformer intake tunnel. The top maintenance tunnel section is located between the main transformer exhaust tunnel and the ventilation and safety tunnel near the plant.

[0010] Furthermore: an in-tunnel starting section is set at the end of the spiral corridor section where the main transformer air intake tunnel intersects with the TBM tunneling direction.

[0011] Furthermore: a drill-and-blast tunnel section is provided on the drainage corridor of the underground plant. The drill-and-blast tunnel section includes a first connecting tunnel section at the bottom and a second connecting tunnel section at the top. The first connecting tunnel section is located between the main and auxiliary plant buildings and the bottom spiral corridor section. The second connecting tunnel section is located between the top spiral corridor section and the drainage corridor of the water diversion tunnel. The second connecting tunnel section crosses the drainage corridor of the water diversion tunnel and directly connects to the other end of the top spiral corridor section.

[0012] Furthermore: the water diversion tunnel drainage gallery includes a third excavation section and an intermediate branch tunnel. The third excavation section protrudes from the outer ring of the spiral gallery section, and both ends of the third excavation section intersect with the top spiral gallery section. The third excavation section is constructed using a TBM. The intermediate branch tunnel is located between the third excavation section and the second connecting section, and it is constructed using the drill-and-blast method.

[0013] The second objective of this invention is to provide a convenient excavation method. To this end, the invention adopts the following technical solution:

[0014] The excavation method for the layout structure of underground powerhouse drainage corridors and gravity drainage tunnels includes the following steps:

[0015] The TBM equipment is assembled at the assembly site outside the gravity drainage tunnel, and after assembly, it is advanced into the starting section inside the tunnel.

[0016] Subsequently, the TBM was excavated upwards on a gentle slope to the second section of the gravity drainage tunnel, reaching the underground powerhouse drainage corridor at its end. Then, it was excavated clockwise in a spiral pattern to excavate the three-layer spiral corridor surrounding the underground powerhouse. When the TBM reached the intersection with the construction adit, it was pushed into the bottom maintenance section without a pilot tunnel. The TBM's muck removal and power supply systems needed to be transferred to this section. Afterwards, without a pilot tunnel, the spiral corridor section continued to be excavated clockwise in a spiral pattern. When it reached the section near the powerhouse at the access tunnel, it was pushed into the middle maintenance section without a pilot tunnel. The TBM's muck removal and power supply systems needed to be transferred to this section. It was then pushed into the starting section within the tunnel. Continuing the clockwise spiral ascent of the spiral gallery section, when the tunneling reaches the intersection with the outer ring of the drainage gallery of the water diversion tunnel, the TBM tunneling section of the outer ring of the drainage gallery of the water diversion tunnel is tunneled clockwise. Then, the tunneling of the underground powerhouse drainage gallery continues to the top-level maintenance tunnel section at the end of the tunneling line. The TBM muck removal and power supply system need to be transferred to this tunnel section. This top-level maintenance tunnel section also serves as the TBM equipment dismantling tunnel section. Subsequently, without a guide tunnel, the top-level middle ring gallery section is tunneled clockwise. After the tunneling is completed, it is pushed to the top-level maintenance tunnel section for TBM equipment dismantling. The equipment is then transported out of the tunnel and removed from the site through the main transformer exhaust tunnel and the ventilation and safety tunnel.

[0017] After all the tunnel sections of the TBM tunneling were excavated, the first connecting tunnel section, the second connecting tunnel section, and the intermediate branch tunnel were excavated and connected by drilling and blasting.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This invention employs a TBM spiral excavation method for underground powerhouse drainage corridors and gravity-flow drainage tunnels. The TBM equipment can be assembled at an assembly site outside the gravity-flow drainage tunnels, allowing for bottom-up excavation of the first tunnel section based on the excavated drainage tunnels. This simplifies the overall excavation or drill-and-blast construction. Furthermore, the excavation of underground powerhouse drainage corridors and gravity-flow drainage tunnels offers advantages such as mechanized and intelligent construction, reduced safety risks in underground engineering, and improved project quality and inherent safety. Attached Figure Description

[0020] Figure 1 This is an overall layout diagram of the drainage corridor and gravity drainage tunnel on the third floor of the underground plant of the present invention.

[0021] Figure 2 This is an overall layout diagram of the drainage corridor on the second floor of the underground plant of the present invention;

[0022] Figure 3 This is an overall layout diagram of the drainage corridor on the first floor of the underground powerhouse and the drainage corridor of the water diversion tunnel of the present invention.

[0023] Figure 4 This is a schematic diagram of a typical cross-sectional structure of the assembly hole section of the present invention;

[0024] Figure 5 This is a schematic diagram of a typical cross-sectional structure of the initial tunnel section of the present invention;

[0025] Figure 6 This is a schematic diagram of the cross-sectional structure of the tunnel section of the present invention.

[0026] The markings in the attached diagram are as follows: 1-Self-flowing drainage tunnel; 11-Assembly site; 12-Starting tunnel section at the entrance; 13-Second tunnel section; 2-Underground powerhouse drainage gallery; 21-First tunnel section; 211-Spiral gallery section; 212-Intermediate annular gallery section; 22-Starting tunnel section inside the tunnel; 23-Maintenance tunnel section inside the tunnel; 241-First connecting tunnel section; 242-Second connecting tunnel section; 3-Water diversion tunnel drainage gallery; 31-Third tunnel section; 32-Intermediate branch tunnel. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0028] like Figures 1-6 As shown, the underground powerhouse drainage corridor and gravity drainage tunnel layout structure includes gravity drainage tunnel 1, underground powerhouse drainage corridor 2, and water diversion tunnel drainage corridor 3. The underground powerhouse drainage corridor 2 is arranged in a ring around the underground powerhouse, with a first excavation section 21 constructed by TBM. The first excavation section 21 includes a three-layer spiral corridor section 211 and a middle annular corridor section 212 located at the top. The spiral corridor section 211 includes straight sections and turning sections. The top spiral corridor section 211 is connected to the water diversion tunnel drainage corridor 3 through TBM excavation. The top spiral corridor section 211 is connected to the middle annular corridor section 212 through TBM. The bottom spiral corridor section 211 is connected to the gravity drainage tunnel 1. The gravity drainage tunnel 1 forms the starting point for TBM excavation.

[0029] In this embodiment, the cross-section of the first excavation section 21 is circular with a diameter of 3.53m and a turning radius of not less than 30m.

[0030] like Figure 1 As shown, specifically, an assembly site 11 is set up outside the underground plant cavern complex of the gravity drainage tunnel 1. A second excavation tunnel section 13 is set up at the inner end of the assembly site 11. The end of the second excavation tunnel section 13 is connected to the underground plant drainage corridor 2. An opening starting tunnel section 12 is also set up between the second excavation tunnel section 13 and the assembly site 11.

[0031] In this embodiment, the assembly site 11 outside the tunnel is hardened with concrete. Areas with weak foundations must be compacted to prevent subsidence. Assembly site 11 uses C30 concrete, with a laying length not less than 50 meters, a width not less than 10 meters, a thickness of 30 cm, and a flatness controlled within 1 cm. The ground elevation of assembly site 11 is 0.15 meters lower than the bottom elevation of the starting tunnel section 12 at the tunnel entrance, facilitating the installation of the stepping frame.

[0032] The starting section 12 of the tunnel is circular and will be excavated using the drill and blast method. Its length should be determined based on the geological conditions and should not be less than 7m. The reinforcement and lining thickness should be determined based on the geological conditions and the support pressure. The net dimension is 3.7m in diameter.

[0033] The second tunnel section 13 is circular with a diameter of 3.53m. It is excavated by gently sloping upwards, and its end is connected to the underground plant drainage corridor 2.

[0034] like Figure 1-4 As shown, specifically, an internal maintenance tunnel section 23 is set up along the tunneling path of the spiral corridor section 211. In this embodiment, the cross-section of the internal maintenance tunnel section is in the shape of a city gate, and it is excavated using the drill and blast method. The cross-sectional dimensions are 8.7×9.7m, and the length is not less than 45m.

[0035] The maintenance tunnel section 23 includes a bottom maintenance tunnel section 231, an intermediate maintenance tunnel section 232, and a top maintenance tunnel section 233. The bottom maintenance tunnel section 231 is located at the intersection of the construction adit and the spiral corridor section 211TBM excavation direction. The intermediate maintenance tunnel section 232 is located between the access tunnel near the plant and the main transformer intake tunnel. The top maintenance tunnel section 233 is located between the main transformer exhaust tunnel and the ventilation and safety tunnel near the plant.

[0036] The starting tunnel section 22 is located at the end of the spiral corridor section 211 where the main ventilation tunnel intersects with the TBM excavation direction. In this embodiment, the starting tunnel section 22 has a circular cross-section, is excavated using the drill-and-blast method, has a diameter of 3.9m, a spray layer thickness of 0.1m, and a length of not less than 7m.

[0037] like Figure 1 and 3 As shown, specifically, a drill-and-blast tunnel section is constructed on the underground powerhouse drainage corridor 2. This section includes a first connecting tunnel section 241 at the bottom and a second connecting tunnel section 242 at the top. The first connecting tunnel section 241 is located between the main and auxiliary powerhouses and the bottom spiral corridor section 211. The second connecting tunnel section 242 is located between the top spiral corridor section 211 and the water diversion tunnel drainage corridor 3. The second connecting tunnel section 242 crosses the water diversion tunnel drainage corridor 3 and directly connects to the other end of the top spiral corridor section 211. In this embodiment, the drill-and-blast tunnel section excavated using the drill-and-blast method has a cross-sectional dimension of 3×3m.

[0038] like Figure 3 As shown, specifically, the water diversion tunnel drainage gallery 3 includes a third excavation section 31 and an intermediate branch tunnel 32. The third excavation section 31 protrudes from the outer ring of the spiral gallery section 211, and both ends of the third excavation section 31 intersect with the top spiral gallery section 211. The third excavation section 31 is constructed using a TBM. The intermediate branch tunnel 32 is located between the third excavation section 31 and the second connecting section 242, and it is constructed using the drill and blast method.

[0039] In this embodiment, the third excavation section 31 has a circular cross-section with a diameter of 3.53m and a turning radius of not less than 30m. The intermediate branch tunnel 32 has a gate-shaped cross-section with dimensions of 3×3m.

[0040] Please see Figures 1-6 The excavation of the underground powerhouse drainage corridor and gravity drainage tunnel structure includes the following steps:

[0041] The TBM equipment is assembled at the assembly site 11 outside the self-draining tunnel 1, and after assembly, it is advanced into the starting tunnel section 12 inside the tunnel.

[0042] Subsequently, the second excavation section 13 within the gravity drainage tunnel 1 is excavated upwards on a gentle slope until it reaches the underground powerhouse drainage corridor 2 at its end. Then, the TBM is excavated clockwise in a spiral pattern, forming a three-layer spiral corridor section 211 surrounding the underground powerhouse. When the TBM reaches the intersection with the construction adit, it is pushed without air to the bottom maintenance section 231 where the construction adit and the TBM's excavation direction intersect. The TBM's muck removal and power supply systems need to be transferred to this section. Then, without a pilot tunnel, the spiral corridor section 211 continues to be excavated clockwise in a spiral pattern. When the TBM reaches the section near the powerhouse entrance access tunnel, it is pushed without air to the intermediate maintenance section 232 between the section near the powerhouse entrance access tunnel and the main transformer intake tunnel. The TBM's muck removal and power supply systems need to be transferred to this section. Then, it is pushed without air to the starting section 22 within the tunnel where the main transformer intake tunnel and the TBM's excavation direction intersect. The excavation continues clockwise in a spiral pattern. When the spiral corridor section 211 reaches the intersection with the outer ring of the drainage corridor 3 of the water diversion tunnel, it advances clockwise into the outer ring TBM tunneling section 31 of the drainage corridor. Then, it continues to advance from the underground powerhouse drainage corridor 211 to the top-level maintenance section 233 between the main transformer exhaust tunnel and the ventilation and safety tunnel near the powerhouse at the end of the tunneling line. The TBM muck removal and power supply system need to be transferred to this section. This top-level maintenance section 233 also serves as the TBM equipment dismantling section. Then, without a guide tunnel, it starts to advance clockwise into the top-level middle ring corridor section 212. After the tunneling is completed, it is pushed to the top-level maintenance section 233 for TBM equipment dismantling. The equipment is then transported out of the tunnel and removed from the site through the main transformer exhaust tunnel and the ventilation and safety tunnel. The overall route of the spiral corridor section 211 is a spiral continuous ascent, with the slope of the straight section controlled within 5% and the slope of the turning section controlled within 3%.

[0043] After all the tunnel sections excavated by the TBM are completed, the remaining sections that cannot be excavated by TBM are excavated by drill and blast method. The first connecting tunnel section 241 between the main and auxiliary powerhouse and the bottom spiral gallery section 211, the second connecting tunnel section 242 between the top spiral gallery section 211 and the drainage gallery 3 of the water diversion tunnel, and the intermediate branch tunnel 32 between the third tunnel section 31 and the second connecting tunnel section 242 are drilled and blasted.

[0044] The above embodiments are merely preferred technical solutions of the present invention. Those skilled in the art should understand that modifications or substitutions to the technical solutions or parameters in the embodiments can be made without departing from the principles and essence of the present invention, and all such modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. An excavation method for the layout structure of underground powerhouse drainage corridors and gravity drainage tunnels, characterized in that: The underground plant drainage corridor and gravity drainage tunnel layout structure includes a gravity drainage tunnel (1), an underground plant drainage corridor (2), and a water diversion tunnel drainage corridor (3). The underground plant drainage corridor (2) has a first tunnel section (21) constructed by TBM arranged in a ring around the underground plant. The first tunnel section (21) has a three-layer spiral corridor section (211) that rises in a spiral. The top spiral corridor section (211) is connected to the water diversion tunnel drainage corridor (3) by TBM excavation. The top spiral corridor section (211) is equipped with an intermediate ring corridor section (212) that is excavated by TBM. The bottom spiral corridor section (211) is connected to the gravity drainage tunnel (1). The gravity drainage tunnel (1) forms the starting point of TBM excavation. The excavation method includes the following steps: The TBM equipment is assembled at the assembly site (11) outside the self-draining tunnel (1), and after assembly, it is advanced to the starting tunnel section (12) at the tunnel entrance. Subsequently, the TBM is excavated upwards on a gentle slope to the second excavation section (13) within the gravity drainage tunnel (1) and then to the underground plant drainage corridor (2) at the end. Following this, the TBM is excavated clockwise in a spiral pattern to the three-layer spiral corridor section (211) arranged in a ring around the underground plant. When the TBM reaches the intersection with the construction adit, it is pushed to the bottom maintenance tunnel section (231). The TBM's slag removal and power supply system need to be transferred to this section. Then, without a pilot tunnel, the TBM continues to excavate the spiral corridor section (211) clockwise in a spiral pattern. When the TBM reaches the section near the plant access tunnel, it is pushed to the middle maintenance tunnel section (232). The TBM's slag removal and power supply system need to be transferred to this section. Then, it is pushed to the starting tunnel section (22) inside the tunnel and continues to excavate clockwise in a spiral pattern. The spiral tunnel section (211) is excavated clockwise. When it reaches the intersection with the outer ring of the drainage tunnel (3) of the water diversion tunnel, the outer ring TBM tunnel section (31) of the drainage tunnel of the water diversion tunnel is excavated clockwise. Then, it continues to excavate the underground powerhouse drainage tunnel (211) to the top maintenance tunnel section (233) at the end of the tunneling line. The TBM slag removal and power supply system need to be transferred to this tunnel section. The top maintenance tunnel section (233) also serves as the TBM equipment dismantling tunnel section. Then, the top middle ring tunnel section (212) is excavated clockwise without a guide tunnel. After the excavation is completed, it is pushed to the top maintenance tunnel section (233) for TBM equipment dismantling. The equipment is transported out of the tunnel and removed from the site through the main transformer exhaust tunnel and ventilation and safety tunnel. After all the tunnel sections of the TBM tunneling were excavated, the first connecting tunnel section (241), the second connecting tunnel section (242), and the intermediate branch tunnel (32) were excavated by drilling and blasting.

2. The excavation method according to claim 1, characterized in that: The self-drainage tunnel (1) is set up outside the underground plant cavern group as an assembly site (11).

3. The excavation method according to claim 2, characterized in that: The assembly site (11) is provided with a second tunnel section (13) at the inner end, and the end of the second tunnel section (13) is connected to the underground factory drainage corridor (2). A tunnel opening starting section (12) is also provided between the second tunnel section (13) and the assembly site (11).

4. The excavation method according to claim 3, characterized in that: The flatness of the assembly site (11) is less than 1cm, and the ground elevation of the assembly site (11) is lower than the bottom elevation of the starting tunnel section (12) at the tunnel entrance.

5. The excavation method according to claim 1, characterized in that: The spiral corridor section (211) is equipped with an in-tunnel maintenance section (23) along the tunneling direction path.

6. The excavation method according to claim 5, characterized in that: The maintenance tunnel section (23) includes a bottom maintenance tunnel section (231), an intermediate maintenance tunnel section (232), and a top maintenance tunnel section (233). The bottom maintenance tunnel section (231) is located at the intersection of the construction adit and the spiral corridor section (211) TBM excavation direction. The intermediate maintenance tunnel section (232) is located between the access tunnel near the plant and the main transformer intake tunnel. The top maintenance tunnel section (233) is located between the main transformer exhaust tunnel and the ventilation and safety tunnel near the plant.

7. The excavation method according to claim 6, characterized in that: The starting tunnel section (22) is set at the end of the spiral corridor section (211) where the main variable air intake tunnel intersects with the TBM tunneling direction.

8. The excavation method according to claim 1, characterized in that: The underground plant drainage corridor (2) is provided with a drill-and-blast tunnel section, which includes a first connecting tunnel section (241) at the bottom and a second connecting tunnel section (242) at the top. The first connecting tunnel section (241) is located between the main and auxiliary plant buildings and the bottom spiral corridor section (211). The second connecting tunnel section (242) is located between the top spiral corridor section (211) and the water diversion tunnel drainage corridor (3). The second connecting tunnel section (242) crosses the water diversion tunnel drainage corridor (3) and is directly connected to the other end of the top spiral corridor section (211).

9. The excavation method according to claim 8, characterized in that: The water diversion tunnel drainage gallery (3) includes a third excavation section (31) and an intermediate branch tunnel (32). The third excavation section (31) is protruding from the outer ring of the spiral gallery section (211), and the two ends of the third excavation section (31) intersect with the top spiral gallery section (211). The third excavation section (31) is constructed by TBM. The intermediate branch tunnel (32) is located between the third excavation section (31) and the second connecting section (242), and it is constructed by drill and blast method.

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