Design method of diversion tunnel structure for ultra-high arch dam

Abstract

The present invention discloses a design method for a diversion tunnel structure in an ultra-high arch dam, relating to the field of water conservancy and hydropower engineering. The method addresses the problem of existing diversion tunnel structures being unable to maintain the diversion tunnel chamber during high flow conditions during the dry season, and determines the layout parameters of the diversion tunnel structure in an ultra-high arch dam. The present invention employs the following technical solution: a design method for a diversion tunnel structure in an ultra-high arch dam, wherein the outlet of the ecological bypass tunnel is connected to the main diversion tunnel tunnel, a diversion tunnel chamber is provided at the inlet of the main diversion tunnel, and a partition pier is also provided at the inlet of the main diversion tunnel to separate the main diversion tunnel into tunnel A and tunnel B. Both tunnels A and B are provided with front and rear diversion gates; a bypass tunnel chamber is provided at the inlet of the ecological bypass tunnel, and a front and rear bypass gates are provided within the bypass tunnel chamber. By determining the values ​​of the layout parameters of the diversion tunnel structure in an ultra-high arch dam, the present invention achieves the multiple functions of the ultra-high arch dam: flood control, discharge control, water storage, and maintenance. The present invention is used for diversion design of ultra-high arch dams.

Description

Technical Field

[0001] The present invention relates to the field of water conservancy and hydropower engineering, and in particular to a design method for a diversion tunnel structure of an ultra-high arch dam. Background Art

[0002] Ultra-high arch dams are located in high mountain canyons, with steep slopes on both sides of the riverbed. Construction diversion uses a tunnel diversion scheme, excavating diversion tunnels in the mountain. The construction diversion system for ultra-high arch dams often needs to have the following functions simultaneously: First, construction diversion during flood season: Ultra-high arch dam construction generally involves many years of flood and dry seasons, requiring river water to be diverted downstream through bank diversion tunnels for construction diversion to meet the conditions for dry-land construction of ultra-high arch dams; Second, ecological water supply: Due to environmental protection requirements, the downstream river channel is not allowed to be interrupted, and the downstream flow must meet the requirements for ecological water supply flow; Third, water storage and discharge control: Due to the special structure of ultra-high arch dams and the fact that they are often built in high mountain canyons, the water level rise rate needs to be controlled during the water storage period to ensure the safety of the dam structure and reservoir bank slopes.

[0003] The safety of the diversion tunnel chamber (including the gate slot) of a super-high arch dam is crucial for its closure and sealing. Sedimentary rivers or water from upstream channels, carrying solid impurities, continuously scour the diversion tunnel of a super-high arch dam, potentially causing scour damage to the chamber. For example, projects such as Dagangshan, Changheba, and Yebatan have all experienced varying degrees of scour damage, impacting power generation efficiency at the most minor level and causing significant losses to the project at the most serious. Therefore, to ensure smooth closure and sealing of the diversion tunnel, super-high arch dam diversion tunnels should also include maintenance capabilities for the chamber.

[0004] In order to meet the requirements for diversion tunnel maintenance, most ultra-high arch dams in the past adopted a double diversion tunnel arrangement to achieve alternating maintenance of the diversion tunnels, such as the Dagangshan, Changheba, Yebatan and other projects.

[0005] Patent application publication number CN 105735215 A discloses a diversion tunnel structure capable of conducting tunnel lock chamber maintenance. The diversion tunnel structure comprises a diversion tunnel body and a maintenance water tunnel. The upstream section of the diversion tunnel body is the tunnel being maintained, which is equipped with a lock chamber structure. The inlet of the maintenance water tunnel is connected to the upstream river channel, and the outlet of the maintenance water tunnel is connected to the diversion tunnel body at a location downstream of the lock chamber structure. The tunnel section of the maintenance water tunnel is equipped with a maintenance lock chamber and a gate. This patent provides a maintenance water tunnel next to the diversion tunnel body. The diversion tunnel lock chamber can be maintained during the maintenance water tunnel's water supply period. Before the diversion tunnel is closed when maintenance conditions are no longer available, the diversion tunnel inlet lock chamber structure and gate slot embedded parts can be inspected. Simultaneously, after the diversion tunnel being maintained is closed, the maintenance water tunnel releases river ecological flow downstream to ensure downstream ecological stability.

[0006] However, in recent years, most power stations have been built downstream of existing controlled cascade power stations upstream. Due to the influence of the power generation flow of the power stations, the flow during the dry season is significantly higher than the natural flow, resulting in high flow during the dry season. This has brought new difficulties to the construction and diversion of ultra-high arch dams, resulting in the following deficiencies in the diversion tunnel structure disclosed in the above patent:

[0007] First, the existing diversion tunnel structure is mainly designed for the underground vertical shaft lock chamber of the diversion tunnel, and is difficult to be applied to the ground shore tower lock chamber at the diversion tunnel inlet.

[0008] Second, the water level rise height of the ultra-high arch dam is very high, and the slopes inside the reservoir and the dam body itself have special requirements for the speed of water level rise. The existing diversion tunnel structure uses flat gates, which cannot dynamically control the water level of the upstream reservoir area.

[0009] Third, the existing diversion tunnel structure can only meet the low flow rate in the dry season (flow rate less than 700m 3 / s) for the diversion tunnel lock chamber maintenance, for the dry season with large flow (flow greater than 700m 3 / s), the existing diversion tunnel structure suffers from two deficiencies: First, the diversion tunnel structure relies on an inlet cofferdam to retain water during the maintenance period, which is only suitable when the water level is below the diversion tunnel roof. However, when the flow rate increases during the dry season, the riverbed water level rises significantly during the maintenance period and exceeds the diversion tunnel roof. Due to the limited height of the inlet cofferdam, the cofferdam retaining method can no longer meet the water retention requirements during the diversion tunnel lock chamber repair period, resulting in the existing diversion tunnel structure being unable to meet the requirements for repairing the diversion tunnel lock chamber. Second, during the dry season, the flow rate is high. According to the existing diversion tunnel structure maintenance method, the maintenance water diversion tunnel is the only water discharge channel. When the dry season flow rate increases, the cross-section of the maintenance water diversion tunnel needs to be significantly increased, which in turn increases the scale of the lock chamber, gates, and other projects. This increases investment, poor economic efficiency, and increases the difficulty of construction. Furthermore, due to the structural safety requirements of the lock chamber and gates, the cross-section of the maintenance water diversion tunnel must be controlled within a certain range and cannot be increased arbitrarily.

[0010] Therefore, it is necessary to study a multifunctional diversion tunnel structure for ultra-high arch dams that is more economical and can realize flood diversion, ecological water supply, water storage and discharge control, as well as maintenance of the diversion tunnel chamber under high flow in the dry season, and to determine the layout parameters of the diversion tunnel structure for ultra-high arch dams. Summary of the Invention

[0011] The present invention provides a design method for a diversion tunnel structure of an ultra-high arch dam, which solves the problem that the existing diversion tunnel structure cannot perform maintenance on the diversion tunnel gate chamber under high flow conditions during the dry season, and determines the layout parameters of the diversion tunnel structure of the ultra-high arch dam.

[0012] The technical solution adopted by the present invention is: a design method for a diversion tunnel structure of an ultra-high arch dam, comprising the following steps:

[0013] S1. Based on the topographic and geological conditions, determine the layout of the main diversion tunnel and the ecological bypass tunnel. The inlet of the main diversion tunnel is connected to the upstream river channel, and a diversion tunnel lock chamber is set at the inlet of the main diversion tunnel. A middle partition pier is also set at the inlet of the main diversion tunnel, which separates the main diversion tunnel into tunnel A and tunnel B. In tunnel A, a front diversion gate and a rear diversion gate are set in sequence along the direction of water flow. In tunnel B, a front diversion gate and a rear diversion gate are set in sequence along the direction of water flow. The inlet of the ecological bypass tunnel is connected to the upstream river channel, and a bypass tunnel lock chamber is set at the inlet of the ecological bypass tunnel. The outlet of the ecological bypass tunnel is connected to the main diversion tunnel, and the connection position is located downstream of the diversion tunnel lock chamber.

[0014] In order to improve the structural strength of the main tunnel of the diversion tunnel and facilitate construction, further: in step S1, the main tunnel of the diversion tunnel is a city gate tunnel type.

[0015] In order to improve the structural strength of the ecological bypass tunnel and facilitate construction, further: in step S1, the ecological bypass tunnel is a city gate tunnel type.

[0016] S2. Clarify the main design parameters of the diversion tunnel structure of the ultra-high arch dam

[0017] The main design parameters of the diversion tunnel structure of the super-high arch dam include: the inlet elevation H of the main diversion tunnel Z ; Width of the main diversion tunnel B Z , hole height A Z ; Elevation of the upper edge of the diversion tunnel chamber inlet H Y ; Elevation Z of diversion tunnel chamber D ; The entrance elevation of the ecological bypass tunnel H S ; Width B of the ecological bypass tunnel S Hedong High A S ; Height Z of bypass tunnel chamber S ; Maximum height H of reverse water retaining cofferdam W .

[0018] S3. Determine the inlet elevation H of the main diversion tunnel Z and the outlet elevation H of the main diversion tunnel C

[0019] The entrance elevation H of the main diversion tunnel Z The range is: N Z -2m<H Z <N Z +3m, determine the outlet elevation H of the main diversion tunnel C , where: N Z It is the riverbed elevation at the entrance of the main diversion tunnel.

[0020] S4. Determine the width B of the main diversion tunnel Z , hole height AZ , and the elevation H of the upper edge of the diversion tunnel chamber inlet Y

[0021] According to the regulations and the requirements of the super-high arch dam for flood control, combined with the construction progress, the flood control standards for the initial construction period and the mid-construction period, as well as the corresponding design flow rates, are determined; the gate closing standards, water storage standards, and plugging standards, as well as the corresponding design flow rates, are determined. Then, the width B of the main diversion tunnel is determined through calculation and analysis. Z , hole height A Z , and the elevation H of the upper edge of the diversion tunnel chamber inlet Y , and the discharge curve of the main tunnel of the diversion tunnel is given.

[0022] S5. Initial elevation of the entrance of the proposed ecological bypass tunnel H S and hole width B S , hole height A S

[0023] First, require H S >H Z Then, according to the hub layout and topographic and geological conditions, the connection position of the ecological bypass tunnel and the main diversion tunnel is determined. The intersection angle between the ecological bypass tunnel and the main diversion tunnel is not less than 30°. The width of the ecological bypass tunnel is initially planned to be B. S Hedong High A S , and obtain the discharge curve of the ecological bypass tunnel.

[0024] In order to ensure that the ecological bypass tunnel has sufficient discharge flow and facilitate construction, specifically: in step S4, the tunnel width B S >2.5m.

[0025] S6. Elevation H of the entrance to the ecological bypass tunnel S and hole width B S , hole height A S Conduct a review.

[0026] S6-1. Review of the relay capacity of the ecological bypass tunnel during the water storage period

[0027] The main diversion tunnel is closed to store water and relay it to the ecological bypass tunnel. Check whether the discharge capacity of the ecological bypass tunnel meets the relay needs. If it does, continue. Otherwise, reduce H S , or increase B S and A S , until satisfied;

[0028] The A and B holes of the main diversion tunnel are closed one by one in relay mode. When only one hole is discharging, the corresponding reservoir water level under the design flow of the closed gate is calculated. Then, it is determined whether the discharge flow of the ecological bypass tunnel meets the requirement of being greater than the ecological flow under this reservoir water level. If so, continue. Otherwise, reduce H. S , or increase B Sand A S , until the requirement that the discharge flow during the water storage period is greater than the ecological flow is met.

[0029] S6-2. Review of the drainage and return water height during the repair period

[0030] Simulate the repair of Hole A. The water retaining structure during the repair period is the front diversion gate in Hole A and the reverse water retaining cofferdam in Hole A. The flow passage during the repair period is the ecological bypass hole and Hole B. The maximum height H of the reverse water retaining cofferdam is proposed. W Then, the hydraulic numerical simulation technology of the hydropower project discharge structure or the diversion model test of the water conservancy and hydropower project construction is used to obtain the backwater height h of the diversion tunnel gate chamber during the repair period. f , and finally determine whether h is satisfied f <H W If the requirements are met, continue, otherwise reduce H S , or increase B S and A S , until h f <H W .

[0031] Simulate the repair of hole B. The water retaining structure during the repair period is the front diversion gate in hole B and the reverse water retaining cofferdam in hole B. The flow channel during the repair period is the ecological bypass hole and hole A. The maximum height of the reverse water retaining cofferdam H is proposed. W Then, the hydraulic numerical simulation technology of the hydropower project discharge structure or the diversion model test of the water conservancy and hydropower project construction is used to obtain the backwater height h of the diversion tunnel gate chamber during the repair period. f , and finally determine whether h is satisfied f <H W If the requirements are met, continue, otherwise reduce H S , or increase B S and A S , until h f <H W .

[0032] The reverse water retaining cofferdams in hole A and hole B are temporary water retaining structures. Specifically: in step S6-2, the reverse water retaining cofferdam is a woven bag cofferdam, and H W <7m.

[0033] S6-3. Review of the highest water level in front of the dam during the repair period

[0034] Simulate the repair of Hole A. The water retaining structure during the repair period is the front diversion gate in Hole A and the reverse water retaining cofferdam in Hole A. The flow passage during the repair period is the ecological bypass hole and Hole B. According to the design flow of once in 5 years, the highest water level in front of the dam is rechecked. b The elevation H of the upper edge of the diversion tunnel chamber inlet Y Whether h is satisfied b <HY If the requirements are met, continue, otherwise reduce H S , or increase B S and A S , until h b <H Y .

[0035] S7. Calculate the elevation Z of the diversion tunnel chamber D And design the front diversion gate and the rear diversion gate

[0036] According to the design flow corresponding to the initial flood control standard, calculate the initial flood control maximum water level, and add the initial flood control maximum water level plus the safety super height as the elevation Z of the diversion tunnel gate chamber. D Then design the front and rear diversion gates in tunnel A, and the front and rear diversion gates in tunnel B. For example, the safety overheight is 0.5 to 1.5 meters.

[0037] The front guide gates in hole A and hole B are both used for maintenance and water retention. Specifically: in step S7, the front guide gates in hole A and hole B are both flat gates.

[0038] The rear diversion gates in both hole A and hole B are used for closing and blocking. Specifically, in step S7, the rear diversion gates in both hole A and hole B are flat gates.

[0039] Furthermore, in step S7, when designing the front diversion gate, the highest water level in front of the dam is calculated according to the conditions of the ecological bypass hole plus the discharge of hole A or hole B during the repair period, and is used as the highest water level of the front diversion gate.

[0040] Furthermore, in step S7, when designing the rear diversion gate, the design maximum water level is calculated based on the design flow rate of 20-year return period during the plugging period, and is used as the maximum water level of the rear diversion gate.

[0041] S8. Calculate the height Z of the bypass tunnel chamber S , and the front bypass gate and the rear bypass gate are designed in sequence along the water flow direction in the bypass tunnel chamber.

[0042] The front bypass gate is used to control the water level rise speed and the water level range during water storage. Specifically, in step S8, the front bypass gate is a radial gate. The rear bypass gate is used for closing the gate and blocking the reverse flow. Specifically, in step S8, the rear bypass gate is a flat gate.

[0043] S8-1. Calculate the height of the bypass chamber: Calculate the maximum water level h for mid-term flood control based on the design flow corresponding to the mid-term flood control standard. z , and calculate the water level h when the flood discharge hole of the super-high arch dam meets the ecological flow during the water storage period j , then take h zand h j The larger value of the bypass tunnel chamber is added with the safety superheight as the height of the bypass tunnel chamber. For example, the safety superheight is 0.5 to 1.5 meters.

[0044] S8-2. Calculate the mid-term flood control maximum water level h according to the design flow corresponding to the mid-term flood control standard. z , and calculate the water level h when the flood discharge hole of the super-high arch dam meets the ecological flow during the water storage period j , take the larger value of the two as the highest water retaining level of the front bypass gate; take the water level from the entrance elevation of the ecological bypass tunnel to the time when the deep discharge hole of the super-high arch dam meets the ecological flow as the discharge control water level variation range of the front bypass gate, and then design the front bypass gate according to the highest water retaining level and discharge control water level variation range of the front bypass gate.

[0045] S8-3. Calculate the maximum water level h for mid-term flood control based on the design flow corresponding to the mid-term flood control standard. z , use it as the reverse water retaining height of the rear bypass gate, and then design the rear bypass gate accordingly.

[0046] For ease of operation, further steps are as follows: In steps S8-1, S8-2 and S8-3, a flood control algorithm is used to calculate the mid-term flood control maximum water level h z .

[0047] Considering that the time for closing the gate is about half an hour, further: in steps S8-1 and S8-2, the water level half an hour after the water storage period is relayed to the deep hole of the super high arch dam body is used as h j .

[0048] The beneficial effects of the design method of the diversion tunnel structure of the ultra-high arch dam of the present invention are:

[0049] First, the bypass tunnel chamber of the ecological bypass tunnel is equipped with a front bypass gate and a rear bypass gate. During the main flood season every year, the front bypass gate and the rear bypass gate can be closed to prevent flood damage to the front bypass gate and the rear bypass gate and scouring of the bypass tunnel chamber, thereby ensuring the stability of the front bypass gate and the rear bypass gate, and at the same time ensuring the safety of the bypass tunnel chamber. Therefore, the structure fully meets the requirements for the construction of the diversion tunnel main tunnel during the flood season.

[0050] Second, the front bypass gate is an arc-shaped gate, and the flow of the ecological bypass tunnel is adjustable and controllable, which can realize dynamic control of the reservoir water level and meet the requirements of ecological water supply and water storage and discharge control.

[0051] Third, during the dry season, under certain flow conditions and with the front bypass gate closed for protection, the gate slots of the gate chamber and flat gate can be inspected; during the dry season, the front bypass gate can also be inspected and tested under certain flow conditions.

[0052] Fourth, a front diversion gate is set in the diversion tunnel lock chamber to block water upstream during the repair period, which increases the upstream blocking water level and meets the requirements for dry land repair of the diversion tunnel lock chamber under high flow during the dry season.

[0053] Fifth, the diversion tunnel lock chamber is located at the entrance of the main diversion tunnel, and the bypass tunnel lock chamber is located at the entrance of the ecological bypass tunnel. Both the diversion tunnel lock chamber and the bypass tunnel lock chamber are ground-level tower lock chambers, rather than vertical shaft lock chambers, which saves project investment. The central partition pier is located at the entrance of the main diversion tunnel and divides the main diversion tunnel into A and B. When A is under maintenance, B and the ecological bypass tunnel can be used for flow. When B is under maintenance, A and the ecological bypass tunnel can be used for flow. This allows the diversion tunnel lock chamber to be repaired during high flow conditions during the dry season.

[0054] Sixth, this invention provides design methods for the main diversion tunnel inlet elevation, outlet elevation, and tunnel diameter; the ecological bypass tunnel inlet elevation and tunnel diameter; the bypass tunnel chamber height, front bypass gate, and rear bypass gate; and the diversion tunnel chamber inlet top elevation, as well as the front and rear diversion gates. This entire design process is easy to implement and offers clear calculations. It enables precise selection of structural parameters for the diversion tunnel structure of ultra-high arch dams, fulfilling their multiple functions of flood control, water discharge control, water storage, and maintenance, and has great potential for widespread adoption.

[0055] In summary, the diversion tunnel structure of the ultra-high arch dam is simple in layout and easy to construct. It also has the functions of flood diversion, ecological water supply, water storage and discharge control, as well as the maintenance of the diversion tunnel chamber under high flow conditions during the dry season, achieving the purpose of multiple uses of one tunnel and meeting the multiple needs of the ultra-high arch dam. The diversion tunnel structure of the ultra-high arch dam, while having the corresponding functions, reduces the number of other functional tunnels or structures required for the ultra-high arch dam, greatly reduces the amount of engineering work, and saves engineering investment. For example, the Yagen Secondary Hydropower Station adopts the ultra-high arch dam diversion tunnel structure of the present invention, which can save one diversion tunnel compared to the traditional double-tunnel arrangement scheme, with huge economic benefits and obvious safety and construction period benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a schematic diagram of the planar layout of the diversion tunnel structure of the ultra-high arch dam in the present invention.

[0057] Figure 2 It is a schematic diagram of the plane layout when simulating the repair of hole A in the present invention.

[0058] Figure 3 It is a schematic diagram of the plane layout when simulating the repair of hole B in the present invention.

[0059] Figure 4 yes Figure 1 Schematic diagram of the structure of the middle bypass tunnel chamber in the vertical section along the water flow direction.

[0060] Figure 5 yes Figure 2 and Figure 3 Schematic diagram of the structure of the vertical section of hole A or hole B in the middle diversion tunnel lock chamber with a reverse water retaining cofferdam along the water flow direction.

[0061] Figure numerals: diversion tunnel main tunnel 1, ecological bypass tunnel 2, diversion tunnel lock chamber 3, middle partition pier 4, front diversion gate 5, rear diversion gate 6, bypass tunnel lock chamber 7, front bypass gate 8, rear bypass gate 9, reverse water retaining cofferdam 10. DETAILED DESCRIPTION

[0062] The present invention will be further described below with reference to the accompanying drawings.

[0063] The design method of the diversion tunnel structure of an ultra-high arch dam of the present invention is used for designing the diversion tunnel structure of an ultra-high arch dam, and includes the following steps.

[0064] S1. Determine the layout of the diversion tunnel 1 and the ecological bypass tunnel 2 based on the topographic and geological conditions.

[0065] like Figure 1 As shown, the entrance of the diversion tunnel main tunnel 1 is connected to the upstream river channel. A diversion tunnel lock chamber 3 is located at the entrance of the diversion tunnel main tunnel 1. The diversion tunnel lock chamber 3 is a ground-based bank tower lock chamber. A vertical partition pier 4 is also installed at the entrance of the diversion tunnel main tunnel 1. The partition pier 4 is arranged vertically and divides the diversion tunnel main tunnel 1 into tunnel A and tunnel B. A front diversion gate 5 and a rear diversion gate 6 are arranged in sequence along the direction of water flow in tunnel A. A front diversion gate 5 and a rear diversion gate 6 are arranged in sequence along the direction of water flow in tunnel B.

[0066] The entrance of the ecological bypass tunnel 2 is connected to the upstream river channel. A bypass tunnel lock chamber 7 is set at the entrance of the ecological bypass tunnel 2. The bypass tunnel lock chamber 7 is a ground bank tower lock chamber. The outlet of the ecological bypass tunnel 2 is connected to the diversion tunnel main tunnel 1, and the connection position is located downstream of the diversion tunnel lock chamber 3. The diversion tunnel lock chamber 3 is set at the entrance of the diversion tunnel main tunnel 1. The diversion tunnel lock chamber 3 is a ground bank tower lock chamber. The bypass tunnel lock chamber 7 is provided with a front bypass gate 8 and a rear bypass gate 9 in sequence along the direction of water flow. Figure 4 The outlet of the ecological bypass tunnel 2 is connected to the main tunnel 1 of the diversion tunnel, and the connection position is located downstream of the diversion tunnel lock chamber 3.

[0067] In order to improve the structural strength of the diversion tunnel main tunnel 1 and facilitate construction, the diversion tunnel main tunnel 1 is a city gate tunnel type. In order to improve the structural strength of the ecological bypass tunnel 2 and facilitate construction, the ecological bypass tunnel 2 is a city gate tunnel type.

[0068] S2. Clarify the main design parameters of the diversion tunnel structure of the ultra-high arch dam

[0069] According to the structural design characteristics of the diversion tunnel of the super-high arch dam, the main design parameters of the diversion tunnel structure of the super-high arch dam include: the inlet elevation H of the main diversion tunnel 1 Z ; Width B of the main diversion tunnel 1 Z , hole height A Z ; Elevation H of the upper edge of the diversion tunnel chamber 3 inlet Y ; Elevation Z of diversion tunnel chamber 3 D ; The entrance elevation of ecological bypass tunnel 2 is H S ; Width B of ecological bypass tunnel 2 S Hedong High A S ; Height Z of bypass tunnel chamber 7 S ; The maximum height H of the reverse water retaining cofferdam 10 W .

[0070] S3. Determine the inlet elevation H of the main diversion tunnel Z and the outlet elevation H of the main diversion tunnel C

[0071] Combined with the topographic and geological conditions, the entrance elevation H of the main diversion tunnel 1 is Z The range is: N Z -2m<H Z <N Z +3m, determine the outlet elevation H of the main diversion tunnel 1 C The range is: N C -5m<H C <N C +4m. Of which: N Z is the riverbed elevation at the entrance of the main diversion tunnel 1, N C It is the riverbed elevation at the exit of the main diversion tunnel 1.

[0072] S4. Determine the width B of the diversion tunnel main tunnel 1 Z , hole height A Z , and the elevation H of the upper edge of the diversion tunnel chamber 3 inlet Y

[0073] According to the regulations and the requirements of the super-high arch dam for flood control, combined with the construction progress, the flood control standards for the initial construction period and the mid-construction period, as well as the corresponding design flow rates, are determined; the gate closing standard, water storage standard, plugging standard, and the corresponding design flow rates are determined. Then, the width B of the diversion tunnel main tunnel 1 is determined through calculation and analysis. Z , hole height A Z , determine the elevation H of the upper edge of the diversion tunnel gate chamber 3 inlet Y , and give the discharge curve of the diversion tunnel main tunnel 1. Z 、A Z When calculating the discharge curve of the main diversion tunnel 1, the construction progress of the ultra-high arch dam, flood control requirements and diversion layout can be combined.

[0074] S5, the initial elevation of the entrance of the ecological bypass tunnel 2 is H S and hole width B S , hole height A S

[0075] First, require H S >H Z Then, according to the hub layout and topographic and geological conditions, the connection position of the ecological bypass tunnel 2 and the diversion tunnel main tunnel 1 is determined. The intersection angle between the ecological bypass tunnel 2 and the diversion tunnel main tunnel 1 is not less than 30°. The initial width of the ecological bypass tunnel 2 is B S Hedong High A S , and the discharge curve of the ecological bypass tunnel 2 is obtained. In order to ensure that the ecological bypass tunnel 2 has sufficient discharge flow and is convenient for construction, the tunnel width B S The value requirements are generally: hole width B S >2.5m.

[0076] S6, entrance elevation H of ecological bypass tunnel 2 S and hole width B S , hole height A S The review includes the following three steps.

[0077] S6-1. Review of the relay capacity of the ecological bypass tunnel 2 during the water storage period

[0078] The diversion tunnel main tunnel 1 is closed to store water and relay to the ecological bypass tunnel 2. Check whether the discharge capacity of the ecological bypass tunnel 2 meets the relay needs. If it does, continue. Otherwise, reduce H S , or increase B S and A S , until satisfied.

[0079] The gates of either hole A or hole B of the diversion tunnel main tunnel 1 are closed in sequence, and after the gate is closed until only the other hole is discharged, the corresponding reservoir water level under the gate-down design flow is calculated. That is, the gate of hole A is closed and the gate is relayed to only hole B for discharge, and then the reservoir water level is calculated. Then the gate of hole B is closed and the gate is relayed to only hole A for discharge, and the reservoir water level is calculated again. Then, it is determined whether the discharge flow of the ecological bypass hole 2 meets the requirement of being greater than the ecological flow under this reservoir water level. If so, continue, otherwise reduce H. S , or increase B S and A S , until the requirement that the discharge flow during the water storage period is greater than the ecological flow is met.

[0080] S6-2. Review of the drainage and return water height during the repair period

[0081] Simulate the repair of hole A. The water retaining structure during the repair period is the front diversion gate 5 in hole A and the reverse water retaining cofferdam 10 in hole A. Figure 2As shown in the figure, the flow channels during the restoration period are the ecological bypass hole 2 and hole B, and the maximum height H of the reverse water retaining cofferdam 10 is proposed. W Then, the hydraulic numerical simulation technology of the hydropower project discharge structure or the water diversion model test of the water conservancy and hydropower project construction is used to obtain the backwater height h of the diversion tunnel gate chamber 3 during the repair period. f , and finally determine whether h is satisfied f <H W If the requirements are met, continue, otherwise reduce H S , or increase B S and A S , until h f <H W .

[0082] Simulate the repair of hole B. The water retaining structure during the repair period is the front diversion gate 5 in hole B and the reverse water retaining cofferdam 10 in hole B. Figure 3 As shown in the figure, the flow channels during the restoration period are the ecological bypass hole 2 and hole A, and the maximum height H of the reverse water retaining cofferdam 10 is proposed. W Then, the hydraulic numerical simulation technology of the hydropower project discharge structure or the water diversion model test of the water conservancy and hydropower project construction is used to obtain the backwater height h of the diversion tunnel gate chamber 3 during the repair period. f , and finally determine whether h is satisfied f <H W If the requirements are met, continue, otherwise reduce H S , or increase B S and A S , until h f <H W .

[0083] See also Figure 2 、 Figure 3 and Figure 5 The reverse water retaining cofferdam 10 in hole A and the reverse water retaining cofferdam 10 in hole B are both temporary water retaining structures. The front diversion gate 5 and the reverse water retaining cofferdam 10 in the same hole can solve the dry land construction problem of repair under the condition of large flow in the dry season. For example, the reverse water retaining cofferdam 10 is a woven bag cofferdam, which requires H W <7m is appropriate.

[0084] S6-3. Review of the highest water level in front of the dam during the repair period

[0085] Simulate the repair of Hole A. The water retaining structures during the repair period are the front diversion gate 5 in Hole A and the reverse water retaining cofferdam 10 in Hole A. The flow channels during the repair period are the ecological bypass hole 2 and Hole B. Based on the design flow of once in 5 years, the highest water level in front of the dam is rechecked. b The elevation H of the upper edge of the diversion tunnel chamber 3 inlet Y Whether h is satisfied b <H YIf the requirements are met, continue, otherwise reduce H S , or increase B S and A S , until h b <H Y .

[0086] S7. Calculate the elevation Z of diversion tunnel chamber 3 D And design the front diversion gate 5 and the rear diversion gate 6

[0087] According to the design flow corresponding to the initial flood control standard, calculate the initial flood control maximum water level, and add the initial flood control maximum water level to the safety super height as the elevation Z of the diversion tunnel gate chamber 3. D Then design the front diversion gate 5 and the rear diversion gate 6 in hole A, and the front diversion gate 5 and the rear diversion gate 6 in hole B. Generally, the safety overheight is 0.5 to 1.5 meters.

[0088] The front diversion gates 5 in both A and B tunnels are used for maintenance and water retention, while the rear diversion gates 6 in both A and B tunnels are used for closing and blocking. Therefore, both the front diversion gates 5 and 6 are flat plate gates. The length of the diversion tunnel chamber 3 must meet the requirements for arranging two flat plate gates.

[0089] When designing the front diversion gate 5, the maximum water level in front of the dam was calculated based on the conditions of using the ecological bypass tunnel 2 plus the discharge from tunnels A or B during the restoration period, and this was used as the maximum water level for the front diversion gate 5. When designing the rear diversion gate 6, the design maximum water level was calculated based on the design flow of a 20-year return period during the plugging period, and this was used as the maximum water level for the rear diversion gate 6.

[0090] S8. Calculate the height of the bypass tunnel chamber 7, and sequentially provide a front bypass gate 8 and a rear bypass gate 9 in the bypass tunnel chamber 7 along the direction of water flow.

[0091] The front bypass gate 8 is used to control the water level rise rate and the water level range during water storage, and is also used to regulate the downstream ecological flow. Therefore, the front bypass gate 8 is a curved gate. The rear bypass gate 9 is used for closing the gate and blocking the reverse flow. Therefore, the rear bypass gate 9 is a flat gate.

[0092] S8-1. Calculate the height of the bypass chamber 7: Calculate the maximum water level h for mid-term flood control based on the design flow corresponding to the mid-term flood control standard. z For example, the flood control algorithm is used to calculate the maximum water level h for mid-term flood control. z , and calculate the water level h when the flood discharge hole of the super-high arch dam meets the ecological flow during the water storage period j , then take h z and h jThe larger value of , plus the safety super height as the height of the bypass tunnel chamber 7. For example, the safety super height is 0.5 to 1.5 m. j Considering that the closing time of the gate is about half an hour, the water level half an hour after the water storage period is relayed to the deep hole of the super high arch dam can be taken as h j .

[0093] S6-2. Calculate the mid-term flood control maximum water level h according to the design flow corresponding to the mid-term flood control standard. z For example, the flood control algorithm is used to calculate the maximum water level h for mid-term flood control. z , and calculate the water level h when the flood discharge hole of the super-high arch dam meets the ecological flow during the water storage period j , take the larger value of the two as the highest water level of the front bypass gate 8; take the water level from the entrance elevation of the ecological bypass tunnel 2 to the time when the deep discharge hole of the super-high arch dam meets the ecological flow as the control and discharge level range of the front bypass gate 8, and then design the front bypass gate 8 according to the highest water level and control and discharge level range of the front bypass gate 8 in combination with the requirements of the specification. j Considering that the closing time of the gate is about half an hour, the water level half an hour after the water storage period is relayed to the deep hole of the super high arch dam can be taken as h j .

[0094] S6-3. Calculate the mid-term flood control maximum water level h according to the design flow corresponding to the mid-term flood control standard. z For example, the flood control algorithm is used to calculate the maximum water level h for mid-term flood control. z , use it as the water retaining height of the rear bypass gate 9, and then combine it with the specification requirements to design the rear bypass gate 9 according to the water retaining height of the rear bypass gate 9.

[0095] The technical solution of the present invention was used to test the diversion tunnel structure of the Yagen Secondary Hydropower Station on the Yalong River in Southwest China. The project is located downstream of the Lianghekou Hydropower Station that has been built upstream. The flood flow during the flood season is 5340m3 / 20 years. 3 / s, the cross-section of the diversion tunnel is 15m×18m. Affected by the power generation of the power station, the flow rate in the dry season is significantly higher than the natural flow rate. The design flow rate during the dry season repair period reaches 1660m 3 / s. Patent application publication number CN 105735215 A discloses a diversion tunnel structure that allows for maintenance of the tunnel chamber section. If the maintenance method provided in this patent is adopted, the cross-section of the ecological bypass tunnel would need to be designed to 15m x 18m. The front curved gate structure exceeds existing specifications, significantly increasing the difficulty of designing the rear flat gate structure. The upstream retaining cofferdam would need to be built to a height of 20m. Due to the narrow river channel, insufficient space for the cofferdam would make it impossible to repair the diversion tunnel chamber during the high flow periods of this project. Furthermore, a comparison of the feasible solution of this invention with the traditional dual-tunnel solution (two 11.0m x 12.6m tunnels) under these conditions would save approximately 85 million yuan in investment, demonstrating significant economic benefits.

Claims

1. The design method of the diversion tunnel structure of the ultra-high arch dam is characterized by: The steps include: S1. Based on the topographic and geological conditions, the layout of the diversion tunnel main tunnel (1) and the ecological bypass tunnel (2) is determined. The inlet of the diversion tunnel main tunnel (1) is connected to the upstream river channel. A diversion tunnel lock chamber (3) is set at the inlet of the diversion tunnel main tunnel (1). A middle partition pier (4) is also set at the inlet of the diversion tunnel main tunnel (1). The middle partition pier (4) separates the diversion tunnel main tunnel (1) into A tunnel and B tunnel. A front diversion gate (5) and a rear diversion gate (6) are set in sequence in the direction of water flow in the A tunnel. A front diversion gate (5) and a rear diversion gate (6) are set in sequence in the direction of water flow in the B tunnel. The inlet of the ecological bypass tunnel (2) is connected to the upstream river channel. A bypass tunnel lock chamber (7) is set at the inlet of the ecological bypass tunnel (2). The outlet of the ecological bypass tunnel (2) is connected to the diversion tunnel main tunnel (1), and the connection position is located downstream of the diversion tunnel lock chamber (3). S2. Clarify the main design parameters of the diversion tunnel structure of the ultra-high arch dam The main design parameters of the diversion tunnel structure of the super-high arch dam include: the inlet elevation H of the diversion tunnel main tunnel (1) Z ; Width B of the main diversion tunnel (1) Z , hole height A Z ; Elevation H of the upper edge of the diversion tunnel chamber (3) inlet Y ; Elevation Z of diversion tunnel chamber (3) D ; The entrance elevation H of the ecological bypass tunnel (2) S ; Width B of the ecological bypass tunnel (2) S Hedong High A S ; Height Z of bypass tunnel chamber (7) S ; Maximum height H of reverse water retaining cofferdam (10) W ; S3. Determine the inlet elevation H of the diversion tunnel main tunnel (1) Z and the outlet elevation H of the main diversion tunnel (1) C The entrance elevation H of the main diversion tunnel (1) Z The range is: N Z -2m<H Z <N Z +3m, determine the outlet elevation H of the main diversion tunnel (1) C , where: N Z The riverbed elevation at the entrance of the main diversion tunnel (1); S4. Determine the width B of the main diversion tunnel (1) Z , hole height A Z , and the elevation H of the upper edge of the diversion tunnel lock chamber (3) Y According to the regulations and the requirements of the super-high arch dam for flood control, combined with the construction progress, the flood control standards for the initial construction period and the mid-construction period, as well as the corresponding design flow rates, are determined; the gate closing standard, water storage standard, plugging standard, and the corresponding design flow rates are determined; then, the width B of the diversion tunnel (1) is determined through calculation and analysis. Z , hole height A Z , determine the elevation H of the upper edge of the diversion tunnel chamber (3) inlet Y , and give the discharge curve of the main tunnel of the diversion tunnel (1); S5. Initial elevation H of the entrance of the proposed ecological bypass tunnel (2) S and hole width B S , hole height A S First, require H S >H Z Then, according to the hub layout and topographic and geological conditions, the connection position of the ecological bypass tunnel (2) and the diversion tunnel main tunnel (1) is determined. The intersection angle between the ecological bypass tunnel (2) and the diversion tunnel main tunnel (1) is not less than 30°. The initial width B of the ecological bypass tunnel (2) is S Hedong High A S , the discharge curve of the ecological bypass hole (2) is obtained; S6. Elevation H of the entrance to the ecological bypass tunnel (2) S and hole width B S , hole height A S Conduct a review S6-1. Review of the relay capacity of the ecological bypass tunnel (2) during the water storage period The diversion tunnel (1) is closed to store water and relay to the ecological bypass tunnel (2). Check whether the discharge capacity of the ecological bypass tunnel (2) meets the relay requirements. If it does, continue. Otherwise, reduce H S , or increase B S and A S , until satisfied; The A and B holes of the diversion tunnel main tunnel (1) are closed one by one to relay the flow. After the relay reaches the point where only the other hole is discharging, the corresponding reservoir water level under the design flow of the closed gate is calculated. Then, it is determined whether the discharge flow of the ecological bypass tunnel (2) meets the requirement of being greater than the ecological flow under this reservoir water level. If so, continue; otherwise, reduce H. S , or increase B S and A S , until the requirement that the discharge flow during the water storage period is greater than the ecological flow is met; S6-2. Review of the drainage and return water height during the repair period Simulate the repair of hole A. The water retaining structure during the repair period is the front diversion gate (5) in hole A and the reverse water retaining cofferdam (10) in hole A. The flow passage during the repair period is the ecological bypass hole (2) and hole B. The maximum height H of the reverse water retaining cofferdam (10) is proposed. W Then, the hydraulic numerical simulation technology of the hydropower project discharge structure or the diversion model test of the water conservancy and hydropower project construction is used to obtain the backwater height h of the diversion tunnel chamber (3) during the repair period. f , and finally determine whether h is satisfied f <H W If the requirements are met, continue, otherwise reduce H S , or increase B S and A S , until h f <H W ; Simulate the repair of B hole. The water retaining structure during the repair period is the front diversion gate (5) in B hole and the reverse water retaining cofferdam (10) in B hole. The flow channel during the repair period is the ecological bypass hole (2) and A hole. The maximum height H of the reverse water retaining cofferdam (10) is proposed. W Then, the hydraulic numerical simulation technology of the hydropower project discharge structure or the diversion model test of the water conservancy and hydropower project construction is used to obtain the backwater height h of the diversion tunnel chamber (3) during the repair period. f , and finally determine whether h is satisfied f <H W If the requirements are met, continue, otherwise reduce H S , or increase B S and A S , until h f <H W ; S6-3. Review of the highest water level in front of the dam during the repair period Simulate the repair of Hole A. The water retaining structure during the repair period is the front diversion gate (5) in Hole A and the reverse water retaining cofferdam (10) in Hole A. The flow passage during the repair period is the ecological bypass hole (2) and Hole B. According to the design flow of once in 5 years, the highest water level in front of the dam is verified. b The elevation H of the upper edge of the inlet of the diversion tunnel chamber (3) Y Whether h is satisfied b <H Y If the requirements are met, continue, otherwise reduce H S , or increase B S and A S , until h b <H Y ; S7. Calculate the elevation Z of the diversion tunnel chamber (3) D And design the front diversion gate (5) and the rear diversion gate (6) According to the design flow corresponding to the initial flood control standard, calculate the initial flood control maximum water level, and add the initial flood control maximum water level to the safety super height as the elevation Z of the diversion tunnel gate chamber (3). D ; Redesign the front diversion gate (5) and the rear diversion gate (6) in hole A, as well as the front diversion gate (5) and the rear diversion gate (6) in hole B; S8. Calculate the height Z of the bypass tunnel chamber (7) S , and designing a front bypass gate (8) and a rear bypass gate (9) in sequence along the water flow direction in the bypass tunnel chamber (7); S8-1. Calculate the height of the bypass chamber (7): Calculate the maximum water level h for mid-term flood control based on the design flow corresponding to the mid-term flood control standard. z , and calculate the water level h when the flood discharge hole of the super-high arch dam meets the ecological flow during the water storage period j , then take h z and h j The larger value of , plus the safety super height is used as the height of the bypass tunnel chamber (7); S8-2. Calculate the mid-term flood control maximum water level h according to the design flow corresponding to the mid-term flood control standard. z , and calculate the water level h when the flood discharge hole of the super-high arch dam meets the ecological flow during the water storage period j , take the larger value of the two as the highest water retaining level of the front bypass gate (8); take the water level from the inlet elevation of the ecological bypass tunnel (2) to the time when the deep discharge hole of the super-high arch dam meets the ecological flow as the controlled discharge water level variation range of the front bypass gate (8), and then design the front bypass gate (8) according to the highest water retaining level and the controlled discharge water level variation range of the front bypass gate (8); S8-3. Calculate the maximum water level h for mid-term flood control based on the design flow corresponding to the mid-term flood control standard. z , which is used as the reverse water retaining height of the rear bypass gate (9), and the rear bypass gate (9) is designed accordingly.

2. The method for designing a diversion tunnel structure for an ultra-high arch dam according to claim 1, wherein: In step S1, the main diversion tunnel (1) is a city gate tunnel type, and the ecological bypass tunnel (2) is a city gate tunnel type.

3. The design method for the diversion tunnel structure of an ultra-high arch dam according to claim 1 is characterized in that: In step S4, the hole width B S >2.5m; the safety super height in step S7 is 0.5~1.5m, and the safety super height in step S8-1 is 0.5~1.5m.

4. The method for designing a diversion tunnel structure for an ultra-high arch dam according to claim 1, wherein: In step S6-2, the reverse water retaining cofferdam (10) is a woven bag cofferdam, and H W <7m.

5. The method for designing a diversion tunnel structure for an ultra-high arch dam according to claim 1, wherein: In step S7, the front diversion gates (5) in hole A and hole B are both flat gates, and the rear diversion gates (6) in hole A and hole B are both flat gates.

6. The method for designing a diversion tunnel structure for an ultra-high arch dam according to claim 5, characterized in that: In step S7, when designing the front diversion gate (5), the highest water level in front of the dam is calculated according to the conditions of using the ecological bypass hole (2) plus the discharge of hole A or hole B during the repair period, and the highest water level is used as the highest water retaining level of the front diversion gate (5).

7. The method for designing a diversion tunnel structure for an ultra-high arch dam according to claim 5, wherein: In step S7, when designing the rear diversion gate (6), the design maximum water level is calculated based on the design flow rate of a 20-year return period during the plugging period, and the design maximum water level is used as the maximum water level of the rear diversion gate (6).

8. The method for designing a diversion tunnel structure for an ultra-high arch dam according to any one of claims 1 to 7, characterized in that: In step S8, the front bypass gate (8) is a curved gate, and the rear bypass gate (9) is a flat gate.

9. The method for designing a diversion tunnel structure for an ultra-high arch dam according to any one of claims 1 to 7, characterized in that: In steps S8-1, S8-2 and S8-3, the flood control algorithm is used to calculate the maximum water level h for mid-term flood control. z .

10. The method for designing a diversion tunnel structure for an ultra-high arch dam according to any one of claims 1 to 7, characterized in that: In steps S8-1 and S8-2, the water level half an hour after the water storage period is relayed to the deep hole of the super high arch dam is taken as h j .

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