A self-adaptive fishway gate based on buoyancy-weight linkage and a parameterized design method thereof

Abstract

The application discloses a self-adaptive fishway gate based on buoyancy-weight linkage and a parameterized design method thereof. The gate comprises a gate panel vertically installed at the outlet of the fishway, a variable cross-section buoy composed of a lower spherical crown head, a middle cylindrical section and an upper conical contraction section, segmented superimposed weight blocks suspended below the main lever connecting platform through vertical rods, a main lever hinged to the top of the support frame and a lever support, and a flexible traction rope with one end fixed to the connecting platform and the other end connected to the gate lifting lug vertically downward through a guide pulley. Through the balance relationship between the moment generated by the buoyancy of the variable cross-section buoy and the gravity of the weight blocks on the lever support, only the net opening moment is generated in a specific design water level interval, and the automatic opening and closing of the gate is realized. The parameterized design method realizes the control of the hysteresis bandwidth and the relay operation verification of the multi-elevation gate through the collaborative design of key parameters such as the buoy cross-section ratio r, the force arm ratio i and the weight mass Mc. The system is completely dependent on zero electricity, the transmission link is extremely simple, each gate is independently distributed for operation, and is especially suitable for remote high dam and large water level variable amplitude fishway projects in the southwest.

Description

Technical Field

[0001] This invention relates to the field of ecological protection technology in water conservancy and hydropower engineering, specifically to an adaptive fishway gate based on buoyancy-counterweight linkage and its parameterized design method. It is applicable to scenarios where fishway outlet gates in reservoirs can automatically open and close according to water level changes under conditions of large water level fluctuations. It belongs to the intersection of gate control technology for hydraulic structures and fish migration protection facilities. Background Technology

[0002] In high-dam hydropower projects in southwestern my country, the annual and seasonal fluctuations in reservoir water levels can typically reach 10m to 30m or even greater. According to the "Design Guidelines for Fishways in Water Conservancy and Hydropower Projects" (SL609-2013), when the upstream water level fluctuates significantly during the main fish passage season, multiple fishway outlets at different locations and elevations should be provided. Furthermore, the FAO publication "Fish Passage - Design, Dimensions and Monitoring" also clearly states that if the water level fluctuation at the fishway outlet exceeds 1m, at least one additional outlet should be provided.

[0003] Taking a specific engineering project as an example, the water level fluctuation in the reservoir area reached as high as 14 meters. Under such conditions of large water level fluctuations, traditional single-outlet fishways simply cannot meet the passage needs of fish at different water levels—at low water levels, the outlet is exposed to the air and cannot take in water; at high water levels, the flow velocity at the outlet is too high or the water level difference exceeds the limit, preventing fish from swimming upstream. Therefore, it is necessary to deploy multiple fishway outlets at different elevations along the reservoir bank, with each outlet controlled by an independent gate.

[0004] While this "multi-outlet" layout solves the water level adaptability problem, it introduces new technical challenges: First, the coordinated scheduling of the gate group is complex, requiring multiple outlet gates to be opened and closed in tandem based on real-time water levels, making operation cumbersome. When the water level is between two outlet elevations, precise judgment is needed on when to close the lower-level gate and open the higher-level gate, demanding high technical skills and response speed from maintenance personnel. Taking a project with a 14m amplitude and six outlets as an example, from the dead water level of 3524m to the normal storage level of 3538m, each outlet corresponds to a water level range of approximately 2.8m. When the water level transitions between adjacent outlet elevations, the main outlet needs to be switched promptly and accurately, and manual operation is prone to delays or misjudgments. Second, the electrical control system is highly dependent and has high maintenance costs. Existing automation solutions largely rely on electrical equipment such as electric actuators, sensors, and PLC control systems. At high dam sites in remote mountainous areas of Southwest China, power supply is unstable and equipment maintenance is difficult. Once the electrical system fails, all gates will lose their automatic control capability, severely affecting fish passage efficiency.

[0005] Based on research and analysis, the existing patented technologies related to the automatic opening and closing of fishway outlet gates in China mainly fall into the following categories: (1) The fishway outlet gate arrangement structure adapted to large water level fluctuations disclosed in CN213061927U. Multiple fishway outlets are stacked on the same vertical plane, and the outlet gates at different elevations are opened and closed uniformly by cables. Although this scheme can achieve centralized control of multiple outlets, it has the following technical defects: First, it is only applicable to the case where the fishway outlets are arranged in a vertical stack, and is not applicable to the common engineering arrangement of outlets at different elevations arranged in a "I" shape along the shoreline of the reservoir area (such as the arrangement of 6 outlets in a "I" shape along the shoreline in the 14m variable amplitude project targeted in this application); Second, it is essentially still a centralized cable control, and each gate cannot operate independently and automatically, requiring a unified hoist drive, which does not solve the core problem of each gate autonomously judging and independently and automatically opening and closing based on the water level; Third, the cable transmission link is long, and there is a risk of mechanical failure such as wear and slack, resulting in insufficient reliability.

[0006] (2) As disclosed in CN117822525A, an automatic adaptive water level fluctuation fishway device and its operation method are proposed to set up an overflow section between the highest and lowest water levels to meet the flow demand entering the fishway, and to use a fish-driving gate for auxiliary guidance. The technical defects of this scheme are: first, for the case of water level fluctuation in the reservoir area reaching 14m, it means that a nearly 14m high overflow section sidewall needs to be built at the fishway outlet, resulting in huge civil engineering investment and poor engineering economy; second, the operation of the fish-driving gate will frighten the fish, affecting the fish's initiative to swim upstream and reducing the efficiency of fish passage; third, this technical scheme is essentially a passive overflow regulation, which does not achieve selective opening and closing control of the gate, and cannot control the amount of water entering the fishway, which can easily lead to excessive or insufficient flow velocity in the fishway.

[0007] (3) CN117536173A discloses a fishway that uses a water-filled floating gate to adapt to changes in upstream water level. The floating body is used as the driving element. The effective density of the floating body is changed by injecting or draining water into the floating body, thereby driving the gate to rise and fall. The technical defects of this scheme are: First, it still needs to rely on electrical components such as water pumps and pressure sensors to realize the control of the floating body's filling and draining. It is essentially a "electrical control + mechanical" hybrid system and has not gotten rid of the dependence on electrical equipment. There is still a risk of electrical failure in remote high dam sites; Second, water pumps and pipeline systems are prone to blockage, corrosion and other failures in long-term underwater environments, resulting in high maintenance frequency and high operation and maintenance costs; Third, the filling and draining process takes a certain amount of time, and the gate response is delayed, making it impossible to realize the instant opening and closing when the water level changes; Fourth, this scheme does not realize the "exclusive water level selective triggering" function, that is, the function of each gate to open and close precisely only within its own designed water level range.

[0008] (4) CN116856360A discloses a fishway design method with a turning arrangement to adapt to changes in upstream water level. It adopts a water-filled floating gate and forms a cofferdam through the turning arrangement to adapt to changes in water level. The technical defects of this scheme are: first, it also relies on the electromechanical control system of the water-filled floating body and fails to achieve purely mechanical automatic opening and closing; second, the cofferdam structure formed by the turning arrangement is complex and the amount of civil engineering work is large; third, it only forms a water level regulation area inside the cofferdam and does not fundamentally solve the problem of the fishway outlet gate automatically and selectively opening and closing according to the water level.

[0009] (5) As disclosed in CN104790355A, the floating automatic gate utilizes the balance between the buoyancy and weight of the gate itself to make the gate float or descend along an inclined track, thereby achieving automatic opening and closing. The technical defects of this scheme are: First, the gate can only float in a straight line along a fixed inclined track, and cannot achieve lever-type torque amplification. The opening and closing force is limited by the buoyancy of the gate itself, and it has poor adaptability to large gates; Second, the opening degree of the gate has a continuous linear relationship with the water level, and it cannot achieve selective triggering of rapid full opening or full closing within a specific water level range; Third, this scheme does not set up a counterweight system, and it cannot accurately control the trigger water level through the torque balance between the counterweight and the buoyancy; Fourth, the gate always floats in the water, has no clear closing and holding force, and has poor sealing performance.

[0010] (6) The buoyancy automatic control gate disclosed in CN204151757U adopts a dumbbell-shaped rotating gate, with a water-blocking gate on one side and a balancing float on the other side, and achieves automatic opening and closing through the rotation of the central hinge shaft. The technical defects of this scheme are: first, the use of a constant cross-section float means that the buoyancy increases linearly with the water level, which cannot achieve the "exclusive water level selective triggering" function required by this application to generate sufficient net torque in a specific narrow water level range; second, the lever arm of the dumbbell-shaped rotating gate is fixed, and it cannot be adapted to different engineering conditions by adjusting the lever arm ratio; third, this scheme is a single-sided water-blocking structure, which is not suitable for the planar sliding gate form of the fishway outlet; fourth, the parametric design method of the system is not disclosed, which cannot adapt to the engineering needs of different water level fluctuations.

[0011] (7) CN115162289A discloses a fishway inlet flow velocity adjustment structure and design method, which uses flow velocity adjustment floats arranged at the fishway inlet, and adjusts the inlet flow velocity by increasing or decreasing the number of floats. The technical defects of this scheme are: first, the floats are only used for flow velocity adjustment and do not have the function of driving the gate to open and close; second, the number of floats needs to be manually increased or decreased to adapt to water level changes, and automatic opening and closing is not achieved; third, this scheme is arranged at the fishway inlet rather than the outlet, and is not applicable to the fishway outlet gate control scenario targeted by this application.

[0012] Based on the above analysis, existing technologies for automatically opening and closing fishway outlet gates in reservoirs suffer from the following four common defects: First, they all rely on electrical control systems or electromechanical drive equipment (such as gate hoists, pumps, sensors, PLCs, etc.), making operation and maintenance difficult and resulting in a high failure rate in remote high dam sites; second, they fail to achieve "selective triggering based on water level," meaning each gate can only be precisely opened within its own designed water level range and remain closed at other water levels; third, there is a lack of a natural relay mechanism between gates at multiple elevations, requiring coordination between gates through electrical interlocking or mechanical linkage, making the system complex; and fourth, the transmission links are complex, with numerous failure points and insufficient reliability, and no parametric design method has been established to adapt to different engineering conditions. Summary of the Invention

[0013] The purpose of this invention is to address the problems in existing fishway outlet gate control, such as reliance on electrical equipment, inability to achieve selective triggering based on specific water levels, lack of natural relay independent operation mechanism for multiple elevation gates, and complex and unreliable transmission links. This invention provides an adaptive fishway gate based on buoyancy-counterweight linkage and its parameterized design method. This gate, using a lever system as its core component, achieves a torque balance between the buoyancy of the variable cross-section float and the gravity of the counterweight. Combined with a constant-efficiency transmission mechanism of flexible traction ropes and guide pulleys, it enables automatic selective opening and closing of the fishway outlet gate within a specific design water level range, completely eliminating dependence on electrical equipment. Furthermore, each elevation gate operates independently and in a natural relay manner.

[0014] The technical solution of the present invention is as follows: An adaptive fishway gate based on buoyancy-counterweight linkage includes a gate panel, a variable cross-section float, a counterweight, a main lever, a flexible traction rope, and a guide pulley.

[0015] The gate panel is vertically installed at the fishway outlet. As a planar sliding steel gate, when closed, the gate panel fits tightly against the gate slot due to its own weight and the water pressure from the reservoir side, forming a reliable watertight seal. When the lifting force generated by the lever system is transmitted to the gate lifting lugs via the traction rope, the gate rises vertically along the gate slot, opening the flow channel and allowing water from the reservoir to enter the fishway at a controllable flow rate. The vertically sliding planar gate has a simple structure, reliable sealing, and good hydraulic conditions. Furthermore, the opening height has a strictly linear relationship with the rope lifting amount, facilitating precise control of the flow cross-sectional area and the inflow velocity, ensuring that the water flow velocity entering the fishway is always within the suitable flow-control range for the target fish species.

[0016] The main lever is hinged to the top of the support frame via a lever support and rotates about a fixed axis in a vertical plane around the lever support. The support frame is located outside the fishway pool and within the orthographic projection range of the gate panel. The main lever, as the core component for torque balance in the system, forms a first-type lever system in the vertical plane with the lever support as its moment center. The lever support contains a self-lubricating bearing to minimize the rotational friction coefficient of the main lever, ensuring sufficient sensitivity of the system to small torque differences. The support frame, serving as the mounting base for the lever support, is located outside the fishway pool and within the orthographic projection range of the gate, minimizing and verticalizing the path of the traction rope from the lever to the gate, thus preventing interference between the rope and the bank slope or other structures. By levering the torque amplification effect, the buoyancy torque generated by the variable cross-section pontoon is amplified according to the lever arm ratio i=L1 / L2 and transmitted to the counterweight side, so that a small change in buoyancy can generate sufficient net torque to overcome the counterweight and gate resistance, achieving a high-sensitivity response of the system; at the same time, the hinged structure with fixed-axis rotation ensures the stability and repeatability of the lever movement.

[0017] The main lever has a connecting platform at one end adjacent to the gate panel. The counterweight is suspended below the connecting platform by a vertical rod. A variable cross-section float is located at the other end. The main lever is divided into two sections by the support: a float-side arm L1 and a counterweight-side arm L2. The counterweight is suspended at the counterweight-side end, and the variable cross-section float is anchored at the float-side end, forming a torque balance system with the support as the fulcrum. The counterweight adopts a segmented, stacked design, consisting of several standard mass blocks. The trigger water level can be finely adjusted by adding or removing blocks. Adjustable sub-blocks and a scale are also provided for fine-tuning. The counterweight is located within a support wall extending linearly from the fishway sidewall. A vertical cavity is provided within the support wall, and a debris-blocking cover is located at the top of the cavity. The debris-blocking cover has a square through-hole parallel to the lever in its center, and the vertical rod can move up and down along this through-hole. The counterweight provides a closing torque that counteracts the buoyancy of the pontoon. When the water level is lower than the design value, the counterweight torque is greater than the buoyancy torque, ensuring that the gate remains tightly closed. The segmented counterweight design allows the on-site adjustment accuracy of the triggered water level to be within ±0.05m. The support wall and debris cover structure protect the counterweight from impacts by floating objects and ensure the guiding accuracy of its vertical movement.

[0018] One end of the flexible traction rope is fixed to the connecting platform, and the other end, after being redirected by the guide pulley, is vertically connected downwards to the gate lifting lug at the top of the gate panel. The flexible traction rope, in conjunction with the guide pulley, achieves the conversion from lever rotational motion to vertical gate lifting motion. The guide pulley is installed on a dedicated bracket above the lever support or on the top of the side wall; its function is to convert the rope's tension direction from an oblique force along the lever direction to a straight force that is always vertical. One end of the rope is fixed to the connecting platform on the side of the main lever float, and after being redirected by the guide pulley, it is vertically connected downwards to the gate lifting lug. Because the rope's tension direction is always vertically upwards after being redirected by the guide pulley, the transmission efficiency is constant, and the effective lifting force is equal to the rope's tension itself, not decreasing with changes in the lever angle. This overcomes the force loss caused by changes in the transmission angle in traditional rigid linkage schemes. Simultaneously, the flexible rope transmission allows the lever to swing freely within a certain angle range, adapting to lever posture adjustments caused by water level changes without mechanical jamming.

[0019] The balance between the buoyancy of the variable cross-section pontoon and the torque generated by the gravity of the counterweight on the lever support enables the automatic opening and closing of the gate panel within the corresponding design water level range. The variable cross-section pontoon is composed of an integrally formed lower spherical cap, a middle cylindrical section, and an upper conical contraction section. The variable cross-section pontoon employs a non-uniform cross-section design, wider at the bottom and narrower at the top, causing the buoyancy to change non-linearly with increasing immersion depth. When the water level rises and the lower, wider section of the pontoon is submerged, the large diameter results in a large volume of drainage per unit immersion depth, leading to a rapid increase in buoyancy and forming a "steep rise zone" in the buoyancy-immersion depth curve. Once the wider section is fully submerged, the water level continues to rise into the upper, narrower section, where the increase in drainage volume at the same immersion depth decreases sharply, and the buoyancy increase slows, forming a "flat zone." This non-linear buoyancy characteristic gives the system a steep response and hysteresis behavior similar to a Schmitt trigger near the target water level. An antifouling and anti-corrosion coating is applied to the exterior of the pontoon to prevent biofouling and weight alteration. The variable cross-section design allows the buoy to generate sufficient net opening torque only within a specific narrow water level range, achieving "exclusive water level selective triggering"—that is, the gate will only open automatically when the reservoir water level rises to the design water level range corresponding to the gate; when the water level is lower or higher than the design range, the gate remains closed. At the same time, the transition of buoyancy from the steep rise zone to the gentle rise zone naturally creates hysteresis characteristics, and there is a reasonable water level difference between the gate opening water level and the closing water level, avoiding the oscillation phenomenon of frequent gate opening and closing when the water level fluctuates near the critical value.

[0020] The end of the support wall is fixedly connected to the support frame. The lever support is vertically installed on the support frame and contains a self-lubricating bearing. A latching rod is also installed on the support wall, with a lever latch vertically installed on the top side of the latching rod. The lever latch is located above the main lever, ensuring the main lever remains horizontal when the gate is closed. The lever latch and the latching rod constitute a rotation limiting device for the main lever, restricting its position to horizontal when the gate is closed. At this time, both the counterweight arm and the float arm are at their designed horizontal working angles, ensuring the accuracy of torque calculation. When the water level drops and the gate closes, the counterweight presses down, causing the counterweight side of the lever to sink until the main lever is stopped at a horizontal position by the lever latch. This ensures the system returns to its standard initial mechanical state after each closure, preventing trigger water level drift due to excessive lever rotation. Simultaneously, maintaining a horizontal position keeps the float at its designed installation height, ensuring the float is submerged from the correct position when the water level rises, guaranteeing the repeatability and reliability of the trigger water level.

[0021] A parametric design method for a fishway outlet float-counterweight adaptive gate includes the following steps: Step S1: Obtain basic engineering design parameters, including water level fluctuation ΔH, number of fishway outlets N, fishway specifications, gate specifications, and fishway design flow rate. These parameters are the foundational inputs for all subsequent design calculations. Among them, water level fluctuation ΔH determines the required number of outlets and the spacing between adjacent outlets, and the gate specifications (mass in meters)... g Area S g The equivalent gravity F of the gate in the moment balance equation directly affects the moment balance equation. g Item, fishway design flow rate Q d This is used to verify whether the flow velocity when the gate is fully open meets the suitable flow control range for fish. A unified parameter system is established to enable the design method to adapt to the specific conditions of different projects, possessing versatility and portability.

[0022] Step S2: Based on the gate mass mg and water level fluctuation ΔH, initially select the lever arm ratio i = L1 / L2, where i ranges from 1.5 to 3.0. The lever arm ratio i determines the amplification factor between the buoyancy torque and the counterweight torque. A larger i value means a greater torque change on the lever float side under the same buoyancy change, resulting in higher system sensitivity, but also a larger balancing torque required on the counterweight side, leading to an increase in the counterweight mass. The selection principle is as follows: when the gate mass is large (mg > 800 kg) or the water level fluctuation is large (ΔH > 15 m), take a larger i value (2.0 to 3.0) to obtain a higher opening torque margin; when the gate mass is small (mg ≤ 800 kg) or the water level fluctuation is small (ΔH ≤ 15 m), take a smaller value (1.5 to 2.0) to reduce the counterweight mass and structural dimensions. By rationally selecting the lever arm ratio, the system achieves a balance between sensitivity and structural dimensions, ensuring sufficient opening and closing response speed when the water level changes, while controlling the engineering rationality of the counterweight mass and the total length of the lever.

[0023] Step S3: Determine the bottom diameter d2 of the pontoon, the cross-sectional ratio r, the top diameter d1 of the pontoon, and the total height H of the pontoon in sequence. f Height H of wide cross-section section w,s Conical section height H n,s and the pontoon installation height h f This step specifically includes the following sub-steps: S3.1: Based on the critical buoyancy F b,crit Effectively open the interval ΔH open The peak net moment coefficient k (generally taken as k = 1.3 to 1.8) is used to calculate and determine the bottom diameter d2 (wide cross-section diameter) of the float using the following formula. The wide cross-section diameter d2 determines the rate of buoyancy increase in the steep rise region. According to the moment balance equation, the required critical buoyancy at the critical triggering state (ΔM = 0) is: ; Buoyancy moment in ΔH open Within the range of water level changes, from the critical value to the peak value sufficient to overcome all resistance torque, the minimum cross-sectional diameter required must meet the following conditions: The design value is taken as 1.1 to 1.3 times the calculated value, with a safety margin. This ensures that the buoyancy has a sufficient rate of increase within the target opening range, allowing the gate to open rapidly and smoothly from triggering to full opening, with an effective opening range ΔH. open Generally, a depth of 0.8m to 1.5m is used, which just covers the height requirements of different fish species (the height of fish is between 0.2m and 0.3m).

[0024] S3.2: Based on the section ratio r = d2 / d1, calculate and determine the top diameter d1 of the pontoon using the following formula: d1 = d2 / r, where r is the control parameter for the hysteresis bandwidth, ranging from 2.0 to 3.5. The larger the section ratio r, the greater the difference in buoyancy growth rate between the narrow section and the wide section. When the water level transitions from the wide section to the narrow section, the buoyancy increment drops sharply. The water level change required for the system to return from the open state to the closed state (i.e., the hysteresis bandwidth ΔH) band The larger the value of r, the better. The recommended range is r = 2.0–3.5, where r = 2.0–2.5 is suitable for projects with small water level fluctuations (ΔH ≤ 15m), and r = 2.5–3.5 is suitable for projects with large water level fluctuations (ΔH > 15m). By adjusting the section ratio r, the hysteresis bandwidth ΔH of each gate can be precisely controlled. band This ensures a smooth and dead-zone-free transition between adjacent gates, effectively preventing the frequent opening and closing of gates when the water level fluctuates near the critical value.

[0025] S3.3: According to the constraints: Determine the total height of the pontoons and the height distribution ratio of the narrow and wide sections H w,s / H n,s ,in For safety margin (generally 0.2m to 0.5m), H is recommended. w,s / H n,s The value of is between 1.0 and 2.0. A larger ratio indicates a larger proportion of wide cross-sections, a wider steep rise zone, and a smoother system opening response; a smaller ratio indicates a larger proportion of narrow cross-sections, a rapid drop in buoyancy after reaching its peak, and a steeper hysteresis characteristic. The total height of the pontoon covers the entire water level change range from triggering to closing, ensuring that the system has complete opening and closing response capability throughout the entire operating water level range. The reasonable allocation of the height ratio between wide and narrow sections gives the buoyancy-depth curve a clear three-segment characteristic (initial zone - steep rise zone - smooth zone), providing a geometric basis for the system's selective triggering and hysteresis control.

[0026] Sub-step S3.4: Based on the constraint 0.3m≤h f Determine the installation height of the pontoon if ≤1.0m The installation height of the buoy determines the position of the buoy's bottom edge relative to the fishway outlet bottom plate, and two constraints must be met: first, the reservoir water level must be lower than the outlet bottom plate elevation H. g At this time, the buoy must not touch the water surface (h f >0); secondly, when the water level reaches the target, the water level H is triggered. triggerAt this time, the immersion depth of the pontoon should be exactly at the starting position of the wide-section steep rise zone. Ensure that the pontoon is completely detached from the water surface when the water level is below the design range to avoid false triggering; at the same time, when the water level reaches the design trigger value, the pontoon should be immersed from the bottom of the wide section to ensure that the system responds from the designed starting point, and the accuracy and repeatability of the trigger water level are guaranteed.

[0027] Step S4: Determine the counterweight mass Mc based on the critical moment balance equation, and determine the total length of the lever and the installation height of the lever support. This step specifically includes the following sub-steps: S4.1: Determine the lever arm ratio i = L1 / L2 based on the gate mass and water level fluctuation, where i ranges from 1.5 to 3.0. The technical principle has been described above.

[0028] S4.2: Based on the critical moment balance equation ΔM=0, calculate the counterweight mass Mc using the following formula: ,in This refers to the critical immersion depth that triggers the target water level. ; This represents the drainage volume of the pontoon at the critical submersion depth. Under the critical triggering state, the buoyancy torque generated by the pontoon is exactly equal to the sum of the counterweight torque, the pontoon's own weight torque, and the gate resistance torque; the system is at the critical equilibrium point. When the water level continues to rise and the pontoon's submersion depth exceeds... When the buoyancy torque is greater than the total resistance torque, the net torque ΔM > 0, and the gate opens; when the water level drops and the immersion depth is less than... When ΔM < 0, the gate closes. After the counterweight mass Mc is determined, it is rounded according to a standard mass block series (e.g., 50kg or 100kg per block), and fine-tuned through a secondary block fine-tuning mechanism to control the deviation between the actual trigger water level and the design value within ±0.05m. Through precise torque balance calculations, each system is ensured to reach critical equilibrium at the target trigger water level, achieving precise control of the trigger water level; the segmented counterweight design facilitates on-site adjustment and adapts to manufacturing errors and parameter drift during operation.

[0029] S4.3: According to the formula for the total length of the lever L = L 1+ L 2+ L marginDetermine the total length of the lever and the installation height of the lever support, where L_{margin} represents the structural allowance at both ends. The installation height of the lever support should generally be higher than the highest design flood level to ensure that the support and bearings are not submerged, to prevent floating debris from clogging them, or to protect the support and bearings with debris-blocking equipment. A reasonable total lever length ensures sufficient movement space for the pontoon and counterweight, preventing interference with surrounding structures at the lever's extreme positions. A safe setting for the support installation height ensures long-term dry operation of the core rotating components, significantly reducing maintenance requirements and extending the system's service life.

[0030] Step S5: Calculate the hysteresis bandwidth ΔH band And check whether it meets the requirements. ΔH band ≤Δh / 3. Hysteresis bandwidth ,in This is the closing water level corresponding to the gate being closed. To trigger the water level. Hysteresis bandwidth. ΔH band Subject to the cross-sectional ratio r and the height ratio H of the wide and narrow cross sections w,s / H n,s The coupling control of the lever arm ratio i—the larger the r value, the greater the difference in buoyancy growth rate between wide and narrow cross sections. ΔH band The larger the value of H_{w,s} / H_{n,s}, the longer the buoyancy is maintained in the peak plateau region. ΔH band The larger the value of i, the more amplified the effect of buoyancy changes on torque, making the response more sensitive. ΔH band Slightly reduced. The control condition for the engineering design is: hysteresis bandwidth. ΔH band It should be less than one-third of the elevation distance Δh between adjacent exits, i.e. ΔH band ≤Δh / 3, to ensure sufficient overlap-transfer interval between adjacent gates, while avoiding excessive hysteresis leading to a dead zone in the relay. When Δh=2.8m, ΔH band It should be controlled within 0.8m to 0.9m; when Δh = 3.6m, ΔH band The hysteresis bandwidth should be controlled within 1.0m to 1.2m. A reasonable hysteresis bandwidth can effectively prevent the oscillation phenomenon of frequent opening and closing of the gate when the water level fluctuates slightly near the trigger value, thereby improving the stability of the system operation. At the same time, it meets the relay overlap requirements of adjacent gates, ensuring that at least one outlet is always open during the water level transition period, so that fish passage is not affected.

[0031] Step S6: Determine the target trigger water level for each outlet. and the water level at the return gate H close,j Verify whether the relay overlap intervals of adjacent exits j and j+1 satisfy the condition. This step specifically includes the following: Bottom plate elevation of each exit Determine by the following formula ,in H g,1 The elevation of the lowest exit (No. 1) is the bottom plate elevation, and Δh = ΔH / (N-1) is the distance between adjacent exits. j =1,2,..., N The target trigger water level for each outlet is: ,in This refers to the increment of immersion depth required for the float to be submerged from its bottom edge to trigger (generally 0.2m to 0.5m). By evenly distributing the total water level fluctuation ΔH to N outlets, each outlet is responsible for a water level range of approximately Δh width. The trigger water levels of each outlet progress sequentially, forming a complete water level coverage chain. This ensures that within the entire water level fluctuation range, there is always exactly one outlet (or two outlets if two adjacent outlets overlap) that is open. This avoids water waste and hydraulic interference caused by all outlets being open simultaneously, and also eliminates the "dead zone" phenomenon where fish cannot swim upstream due to all outlets being closed simultaneously.

[0032] The relay overlap interval between adjacent exits j and j+1 is verified by the following conditions: Where δ is the maximum allowable overlap gap (generally taken as δ≤0.1m). The return water level at the j-th outlet. The water level must be no lower than the trigger water level of the (j+1)th outlet minus the allowable gap. This means that when the j-th outlet closes due to a continued rise in water level, the (j+1)-th outlet must already be open or about to open, and there must be sufficient overlap between the two outlets. If the calculation does not meet the requirements, the cross-sectional ratio can be adjusted. r Or the height H of the wide cross-section section w,s To increase hysteresis bandwidth ΔH band This continues until the relay conditions are met. It ensures seamless switching between opening and closing of the gates as the water level changes from low to high, guaranteeing that fish always have an unobstructed upstream path and will not lose their way or be forced to retreat due to gate switching.

[0033] The cross-sectional shape parameters of the pontoons at each outlet (d2, d1, H) f H w,s / H n,s The ratio (to) should remain consistent in principle to simplify manufacturing and maintenance. Differentiation between systems is achieved through the following parameters: counterweight mass M_{c,j}, which is adjusted to ensure each system reaches its target trigger level. The buoy reaches critical equilibrium; the buoy installation height hf，j For outlets with different bottom elevations, fine adjustments can be made to adapt to the bank slope topography and inlet hydraulic conditions; the lever arm ratio i is generally consistent across the entire system, but can be taken separately in special cases. The standardization of pontoon parameters significantly reduces manufacturing and spare parts costs, and independent triggering of each outlet can be achieved simply by varying the counterweight mass and installation height. This allows multiple systems to operate collaboratively without any electrical interlocks or mechanical linkages, naturally forming a water level-based relay-type automatic operation mode. The system architecture is extremely simple and the reliability is extremely high.

[0034] The beneficial effects of this invention are: Because the driving force of the entire gate opening and closing system comes 100% from the mechanical balance of buoyancy and gravity of the water itself, no electrical components such as pumps, sensors, controllers, or power supplies are required, fundamentally eliminating the risk of electrical failures. At remote high dam sites in Southwest China, even in the event of a complete power outage and unattended operation, the system can still operate reliably for extended periods, significantly reducing annual maintenance costs. It is particularly suitable for harsh operating conditions where power supply is unstable and equipment maintenance is difficult.

[0035] Due to the non-uniform cross-section design of the variable cross-section pontoon, the buoyancy changes non-linearly with immersion depth—buoyancy increases rapidly in the wide cross-section section and slows down in the narrow cross-section section—the system generates sufficient net opening torque only within a specific narrow water level range. This achieves the core function of "the gate will only automatically open when the reservoir water level rises to the design water level range corresponding to a certain fishway outlet gate; when the water level is below or above the design range, the gate remains closed." Each gate responds only at its own "dedicated water level," without interfering with others; this is the most crucial feature that distinguishes this invention from all existing technologies.

[0036] Because the buoyancy increase drops sharply after the variable cross-section pontoon moves from the wide cross-section section to the narrow cross-section section, a hysteresis range is naturally formed between the gate opening water level and the closing water level. This hysteresis characteristic effectively prevents the oscillation phenomenon of frequent gate opening and closing when the water level fluctuates slightly near the trigger threshold, making the system operation more stable and reliable.

[0037] Each fishway outlet gate at each elevation is equipped with an independent float-counterweight-lever system. No electrical interlocks or mechanical linkages are required between the gates; they naturally achieve automatic, relay-style operation based on water level settings through their individual physical parameter settings. This distributed architecture offers far greater reliability than centralized control systems—even if one system fails, it will not affect the normal operation of other outlets. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the opening and closing of the floating body traction gate in this invention.

[0039] Figure 2 This is a schematic diagram of the various mechanisms of the floating body traction gate in this invention.

[0040] Figure 3 This is a schematic diagram of the lever pulley and partial explosion in this invention.

[0041] Figure 4 This is a schematic diagram of the gate opening and closing and partial explosion in this invention.

[0042] Figure 5 This is a schematic diagram showing the relationship between the counterweight, the movable cavity, and the vertical rod in this invention.

[0043] Figure 6 This is a schematic diagram of the opening of the inlet gate in this invention.

[0044] Figure 7 This is a schematic diagram showing the sequential opening and closing of multiple water inlets in this invention.

[0045] Figure 8 Flowchart for the parametric design of a buoy-counterweight adaptive gate.

[0046] In the diagram: 101-Gate panel, 102-Variable cross-section float, 102a-Cylindrical section, 102b-Spherical cap, 102c-Conical contraction section, 103-Counterweight block, 1031-Vertical rod, 1032-Scrap cover, 10321-Square through hole, 104-Fishway chamber, 1041-Fishway sidewall, 105-Lever assembly, 1051-Main lever, 1052-Lever support, 1053-Connecting platform, 106-Foundation slope, 107-Reservoir water, 108-Flexible traction rope, 1081-Gate lifting lug, 1082-Guide pulley, 10821-Lever support, 201-Lever buckle, 202-Buckling upright, 3-Support frame. Detailed Implementation

[0047] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that those skilled in the art can clearly and accurately implement the present invention.

[0048] The adaptive control device of the present invention comprises the following components: 1. Main body of the gate and fishway Gate panel 101: This is the gate body of a flat sliding steel gate, vertically installed at the fishway outlet. The gate width is slightly larger than the net width of the fishway, and the height is not lower than the control water level at the fishway outlet. The gate material is made of stainless steel composite plate, galvanized steel plate, or composite material to withstand long-term underwater corrosion. Variable cross-section float 102: A sealed hollow cylindrical float connected to one side of the lever system, serving as the integrated "water level sensing + power output" component of this invention. The float adopts a variable cross-section design—composed of three sections: a spherical cap 102b at the bottom, a cylindrical section 102a in the middle, and a conical contraction section 102c at the top. This non-uniform cross-section design causes buoyancy to change non-linearly with increasing immersion depth: forming a "buoyancy abrupt change zone" near the target water level, giving the system a steep response characteristic and hysteresis behavior similar to a Schmitt trigger. The float is coated with an antifouling and anti-corrosion coating to prevent biofouling from altering its weight. The variable cross-section float 102 is anchored to the main lever 1051. Counterweight 103: A weight suspended at the other end of the lever system, used to provide a closing torque to counteract the buoyancy of the float. The counterweight adopts a segmented stacked design, consisting of several standard mass blocks, which facilitates fine-tuning of the trigger water level on-site by adding or removing blocks. Adjustable sub-blocks and scales are provided on the side for fine-tuning. The counterweight 103 is connected to the vertical rod 1031, and the connection can be made by directly suspending it at the end of the rod or by connecting it through the vertical rod 1031. At the end of the main lever 1051, there is a platform 1053 connected to the flexible traction rope 108. A debris trap 1032 is provided at the top of the counterweight 103, and the surface of the debris trap 1032 has a cavity 10321 for the vertical rod 1031 to move. Fish passage chamber 104: Located downstream of the sluice gate, this is a passageway for fish to enter and swim upstream. Suitable water depth and flow rate are maintained within the chamber. Fishway sidewall 1041; Lever buckle 201: controls the main lever 1051 from rotating too much, ensuring that the main lever 1051 remains horizontal under the obstruction of lever buckle 201 when the gate is closed. The bottom lever of lever buckle 201 is buckle rod 202, which mainly restricts the rotation direction of the main lever 1051 to vertical rotation.

[0049] 1.2 Core Drive System - Lever Support Assembly Lever / Support / Bearing Assembly 105: The main lever 1051 is a rigid metal beam, preferably made of hollow square steel tubing or H-beams, and rotates around a fixed axis around the support. The lever support 1052 is a hinged support structure fixedly installed on the top of the fishway sidewall or the top of a dedicated column, containing a self-lubricating bearing, allowing the main lever to swing within a range of ±50 degrees in the vertical plane. The main lever is divided into two sections by the support: the float side arm L1 and the counterweight side arm L2. The ratio of the lengths of the two sections, the arm ratio i=L1 / L2, is one of the key parameters determining the system sensitivity.

[0050] Foundation Slope 106: The soil and rock foundation structure of the reservoir slope serves as the installation base for the entire system, bearing all loads transmitted from components such as lever supports and guide rails.

[0051] Reservoir water body 107: The free surface water body in the reservoir area that varies with the seasons and operating conditions. Its water level is the only input physical quantity that drives the operation of this system.

[0052] Traction rope and guide pulley assembly 108: This invention uses a flexible traction rope 108 in conjunction with a guide pulley 1082 to achieve the conversion from lever rotational motion to gate vertical lifting motion. One end of the traction rope is fixed to the connection point on the float side of the main lever 1051. After being reversed by the guide pulley 1082, the rope is vertically connected downwards to the gate lifting lug 1081. The guide pulley 1082 is installed on a special bracket above the lever support 10821 or on the top of the side wall. Its function is to convert the direction of the rope tension from an oblique tension along the lever direction to a straight tension that is always vertical.

[0053] Support frame 3 is mainly used to support the frame of the lever support assembly.

[0054] 2. System Operating Principle The entire transmission process is divided into the following three stages: 2.1 First-stage shutdown state When the water level is lower than the installation elevation of the float 102, the variable cross-section float 102 and the counterweight 1031 are not submerged, the variable cross-section float 102 is suspended, and the counterweight 103 is pressed down on the counterweight side of the lever. The gate is closed tightly under its own weight and water pressure. To ensure balance, the distance L2 between the counterweight 103 and the lever support 1052 is less than the distance L1 between the variable cross-section float 102 and the lever support 1052. One end of the flexible traction rope 108 is connected to the gate lifting lug 1081, and the other end is placed at one end of the guide pulley 1082 at the top of the gate. The other guide pulley 1082 is placed at the top position of the lever support 1052 of the main lever 1051. At this time, the traction rope 108 is in a slack state.

[0055] 2.2 Second Stage (Start-up Process) The rising water level caused the lower, wider section of the pontoon to begin submerging. The buoyancy formula is: F b =ρ·g·V 浸 V 浸 =Immersion depth · Cross-sectional width During this stage, buoyancy pushes the float upwards, the float pushes the lever upwards, the lever rotates around the support, the traction rope (108) is tightened and reversed via the guide pulley 1082, converting the oblique motion of the lever end into a vertically upward linear tension, which directly acts on the gate lifting lug, pulling the gate up and opening the fishway outlet. Since the direction of the tension of the rope is always vertically upward after the guide pulley is reversed, the transmission efficiency is constant, and the effective lifting force is equal to the rope tension itself, which does not decrease with the change of the lever angle, overcoming the force loss caused by the transmission angle in the traditional rigid linkage scheme.

[0056] 2.3 The third step (the return process) As the water level rises further, the narrow section is submerged, causing the gate to close instead. Once the wide section is fully submerged, the buoyancy is nearing its peak. With the water level continuing to rise, the narrow section begins to submerge. Submerging to the same depth of 0.1m, the narrow section only increases the drainage volume slightly, causing a sharp drop in buoyancy. At this point, the lever float side is raised to a higher position due to buoyancy, but because the rope is redirected via guide pulley 1082, the tension on the gate remains vertically upward. When the buoyancy increase is insufficient to maintain the open position, the counterweight regains dominance, the lever float side sinks, the traction rope slackens, and the gate slowly descends under its own weight and water pressure, automatically closing.

[0057] 3. The water inflow path from the reservoir into the fishway. One of the core functions of this invention is to control the process of water flowing from the reservoir into the fishway through the inlet. The water flows from the reservoir side into the fishway through the inlet hole on the dam (or bank slope), and the spatial path is: reservoir water, inlet (including gate 101), vertical passage of the fishway, and fishway pool chamber.

[0058] Based on the relative relationship between the reservoir water level and the inlet elevation, the water intake process presents three distinct states: First, when the water level is too low ( H w < H gate With the inlet completely exposed to the air and no water able to enter, the bottom edge of the float is lower than the bottom plate of the outlet, the buoyancy torque is much smaller than the counterweight torque, and the gate is tightly closed under the action of the counterweight torque. The second scenario is when the water level is suitable ( H trigger≤ ≤ H w ≤ H full_open When the buoy reaches the critical immersion depth, the buoyancy torque begins to exceed the counterweight torque, the gate is gradually raised and opened, and the water in the reservoir flows into the fishway through the inlet hole along the hydraulic gradient, forming an attraction flow to induce fish to enter the fishway along the water flow. The third scenario is when the water level is too high ( H w > H full_open With the addition of buoy margin, the buoy is submerged to a near-completely submerged state. The cross-sectional area of ​​the upper conical contraction section of the variable cross-section buoy is small, and the increase in buoyancy slows down. When the buoyancy torque is insufficient to maintain the open state, the counterweight regains dominance, and the gate automatically closes. At this time, the higher elevation outlet takes over the work.

[0059] The flow velocity at the inlet is calculated using the following formula: in, Q This refers to the inlet water flow rate. B For the net width of the inlet, h open This refers to the gate opening height. The design should ensure that the flow velocity when fully open is within the range suitable for fish to overcome.

[0060] 4 Parametric Design Method To enable the system to adapt to the specific conditions of different reservoir projects (such as different water level fluctuations, fishway outlet elevations, gate specifications, etc.), this invention proposes a parametric design method with universal design variables as its core. Starting from the engineering input parameters, this method systematically determines all design variables, including the buoy geometric parameters, counterweight mass, and lever dimensions, through seven steps (S1~S7). The following section first establishes a unified mechanical model and parameter system.

[0061] 4.1 Design Parameter System To enable the system to adapt to the specific conditions of different reservoir projects (such as different water level fluctuations, fishway outlet elevations, gate specifications, etc.), this invention proposes a parametric design method with universal design variables as its core. The following section first establishes a unified mechanical model and parameter system.

[0062] The general parameters for a single gate adaptive system are defined as follows: (1) Environmental input parameters (given by engineering conditions)

[0063] (2) Buoy geometry parameters (to be designed)

[0064] (3) Lever and counterweight parameters (to be designed)

[0065] (4) Operational response parameters (design objectives)

[0066] 4.2 Torque Balance In this invention, the lever support is taken as the moment center, and the clockwise rotation of the float (i.e., the gate opening direction) is taken as the positive direction. Therefore, the net torque ΔM can be expressed as: In the formula: F gate The equivalent weight (N) of the gate transmitted to the lever via the traction rope includes the gate's own weight and the water pressure difference; L linkLet be the horizontal distance (m) from the rope connection point to the lever support. After the traction rope changes direction via the guide pulley, the direction of the force remains vertical. F gate The torque arm generated by the lever is the horizontal distance. L link ; V disp ( h imm () represents the current submersion depth of the pontoon. h imm The drainage volume below (m 3 ).

[0067] The three steady states of the system are determined by Δ M The sign is determined by: Δ M When <0, the closing side controls the operation, and the gate remains closed; Δ M When Δ = 0, it is a critical equilibrium state; M When the value is greater than 0, the opening side dominates, and the gate tends to open. Let Δ M =0, and the critical trigger level can be obtained.

[0068] For variable cross-section pontoons, the displacement volume V disp Let be a piecewise function of the submersion depth. Let the submersion depth above the bottom edge of the pontoon be . h imm ,but: When 0≤ h imm ≤ H w,s When (only the wide section is immersed): when H w,s < h imm ≤ H f When entering the narrow section: in: d 1 ' For the conical contraction section in The instantaneous diameter at depth, for the conical contraction section, is: In the formula, The immersion depth is the portion of the conical contraction section (exceeding the width of the cross-section); the immersion depth of the conical contraction section (narrow cross-section) is equal to the total immersion depth. himm Subtract the height of the wide section (cylindrical segment) H w,s 。 Once the water level has completely submerged the wide section, it continues to rise and immerse the conical contraction section to its depth. Only when... When the water level is greater than 0, the conical section will truly begin to be submerged.

[0069] 4.3 Step S1 - Input of Engineering Conditions Collect basic engineering design parameters, including water level fluctuations. ΔH Minimum and maximum operating water levels, number of fishway outlets N , gate specifications ( m g , S g Fishway design flow rate Q d wait.

[0070] 4.4 Step S2 - Overall Layout Planning Sure N Elevation of the bottom plate at each fishway exit H g,j Calculate the distance between adjacent exits: Δh = ΔH / ( N -1) Preliminary selection of lever arm ratio i ( i =1.5~3.0, selected according to the gate mass and water level fluctuation.

[0071] 4.5 Step S3 - Float Section Design Determine the diameter of the wide section in sequence d 2. Cross-sectional ratio r Narrow cross-section diameter d 1. Total height of the pontoons H f , width and narrow height distribution ( H w,s , H n,s Ensure the buoyancy-immersion curve has a clear three-segment characteristic.

[0072] (1) Sub-step S3.1 - Determine the diameter of the wide section d 2 Wide cross-section diameter d 2 determines the rate of increase of buoyancy in the steep rise region. According to the moment balance equation, in the critical triggering state (Δ... M At a value of 0, the required critical buoyancy is: Let the target enable response interval be ΔH open (Generally taken as 0.8m to 1.5m), that is, the buoyancy torque is required to be within... ΔH open Within the range of water level changes, the buoyancy increases from a critical value to a peak sufficient to overcome all drag torques. The buoyancy growth rate for the wide cross-section section is: To ensure in ΔH open The internal buoyancy moment has sufficient growth margin (assuming the peak net moment coefficient is). k Generally take k =1.3 to 1.8), the required minimum width section diameter satisfies: When designing, take 1.1 to 1.3 times the value calculated by the above formula as... d The design value of 2 provides a safety margin.

[0073] (2) Sub-step S3.2 - Determine the cross-sectional ratio d 2 / d 1 and narrow cross-section diameter d 1 Section ratio r = d 2 / d 1 is to control the hysteresis bandwidth ΔH band Key parameters. r The larger the value, the greater the difference in buoyancy growth rate between the narrow section and the wide section, and the more significant the hysteresis characteristics. However, excessively large values... r This value can lead to instability in the pontoon structure.

[0074] The recommended cross-sectional ratio range of this invention is: r =2.0 to 3.5, of which r =2.0 to 2.5 is suitable for water level fluctuations that are small ( ΔH Projects ≤15m r =2.5 to 3.5 is suitable for water level fluctuations of a large magnitude. ΔH Projects exceeding 15m in length. Narrow cross-section diameter according to... d 1= d 2 / r Confirmed. Through adjustment r The value can precisely control the hysteresis bandwidth of each gate, ensuring a smooth and dead-zone-free transition between adjacent gates.

[0075] (3) Sub-step S3.3 - Determine the height of the pontoon H f Segmentation ratio Total height of pontoons Hf This determines the total range of water level changes the pontoon can respond to. To cover the entire process of a single gate from triggering to closing, the total height of the pontoon should meet the following requirements: in h margin A safety margin (typically 0.2m to 0.5m) is provided to compensate for water level fluctuations and manufacturing errors. The ratio of the height of the wide section to the height of the narrow section directly affects the shape of the buoyancy-immersion depth curve. This invention recommends... The value of is between 1.0 and 2.0. A larger ratio indicates that the wide cross-section section accounts for a larger proportion, the steep rise zone is wider, and the system's start-up response is smoother. A smaller ratio indicates that the narrow cross-section section accounts for a larger proportion, the buoyancy increase drops rapidly after reaching its peak, and the hysteresis characteristics are steeper.

[0076] (4) Step S3.4 - Determine the installation height of the pontoon h f pontoon installation height h f The position of the buoy's bottom edge relative to the fishway outlet bottom plate is determined. Two constraints must be met during the design: first, the reservoir water level must be lower than the outlet bottom plate elevation. H g At this time, the buoy must not touch the water surface. h f >0); secondly, when the water level reaches the target trigger water level. H trigger At that time, the buoy's immersion depth should be precisely at the starting position of the wide-section steep rise zone. Considering the above constraints, h f The value ranges from 0.3m to 1.0m. The specific value is determined based on the installation position of the guide pulley and the rope wrap angle to ensure that the rope does not slip or derail throughout the entire stroke of the lever.

[0077] 4.6 Step S4 - Counterweight-Lever Coordination Design counterweight mass M c Compared with lever arm i = L 1 / L 2 is a parameter that determines the system's trigger sensitivity and load-bearing capacity, and requires collaborative design to meet the differentiated needs under different engineering conditions.

[0078] (1) Step S4.1 - Determine the lever arm ratio i lever arm ratio i This determines the amplification / diminishing relationship between the buoyant moment and the counterweight moment. Larger... iThe value means that under the same change in buoyancy, the torque change on the lever float side is greater, the system sensitivity is higher, but the required balancing torque on the counterweight side is also greater, and the mass of the counterweight increases accordingly.

[0079] The range of lever arm ratios recommended by this invention is: i =1.5 to 3.0, the specific value selection principle is as follows: when the gate mass is large ( m g >800kg) or large water level fluctuations ( ΔH When the value is greater than 15m, take the larger value. i Values ​​(2.0~3.0) are used to obtain a higher opening torque margin; when the gate mass is small ( m g ≤800kg) or water level fluctuation is small ( ΔH For values ​​≤15m, take a smaller value (1.5~2.0) to reduce the counterweight mass and structural dimensions.

[0080] (2) Sub-step S4.2 - Determine the mass of the counterweight M c Given the lever arm ratio i Under the conditions of the float parameters, the counterweight mass is determined by the critical moment balance equation, specifically Δ M Substituting 0 into the torque balance equation, we can solve for the mass of the counterweight: in h imm,crit The critical immersion depth for the corresponding target trigger water level: counterweight mass M c Once determined, the standard mass blocks are rounded according to the series (e.g., 50kg or 100kg per block), and fine-tuned through the sub-block fine-tuning mechanism to control the deviation between the actual trigger water level and the design value within ±0.05m.

[0081] (3) Sub-step S4.3 - Determine the total length of the lever and the installation height Total lever length: L = L 1+ L 2+ L margin in, L margin Allowance is provided for the structures at both ends. The installation height of the lever support should generally be higher than the highest design flood level to ensure that the support and bearing are not submerged and to prevent floating debris from clogging them. Alternatively, debris barriers can be used to protect the support and bearing.

[0082] 4.7 Step S5 - Hysteresis Characteristic Verification The variable cross-section float of this invention represents the inherent hysteresis characteristic of the system, and the trigger water level corresponding to the gate opening. H trigger Closing water level corresponding to the gate's retraction H close There is a water level difference. ΔH band This is called the "hysteresis bandwidth". This hysteresis characteristic is crucial for the smooth relay operation of multi-elevation gates, and can effectively prevent the oscillation phenomenon of frequent opening and closing of adjacent gates in the transition water level range.

[0083] Hysteresis bandwidth ΔH band The definition is as follows: Hysteresis bandwidth ΔH band It is mainly controlled by the coupling of the following three parameters: (1) Cross-sectional ratio r = d 2 / d 1: r The larger the value, the greater the difference in buoyancy growth rate between the wide and narrow cross sections, and the greater the water level change required for the system to return from the open state to the closed state. ΔH band The larger. Within the scope recommended by this invention, r For every increase of 0.5, ΔH band It will increase by approximately 0.1m to 0.2m.

[0084] (2) Height ratio of wide section to narrow section H w,s / H n,s The larger the proportion of the wide cross-section section, the longer the buoyancy is maintained in the peak plateau region, and the wider the system's maintenance and opening range at high water levels. ΔH band The larger.

[0085] (3) Lever arm ratio i Larger i This value amplifies the effect of buoyancy changes on torque, making the response more sensitive in both the steep ascent and descent regions. ΔH band Slightly reduced.

[0086] The control in the engineering design is: hysteresis bandwidth ΔH band It should be less than the elevation spacing between adjacent exits. Δh One-third, that is: To ensure sufficient overlap-transfer interval between adjacent gates, while avoiding excessive hysteresis that could lead to a relay dead zone. Δh When =2.8m, ΔH band It should be controlled within 0.8m to 0.9m; when Δh When = 3.6m, ΔH band It should be kept within 1.0m to 1.2m.

[0087] 4.8 Step S6 - Relay Operation Verification When the project requires layout along the reservoir bank slope N When the fishway exits at different elevations ( N ≥2), each outlet is equipped with an independent buoy-counterweight-lever system. No electrical interlocking or mechanical linkage is required between these systems; automatic operation based on water level relay is achieved solely through differences in their respective physical parameters. The following presents a parameter progression design method for multi-elevation gates.

[0088] (1) Step S6.1 - Determine the elevation of each outlet bottom plate No. j The elevation of the bottom plate of each exit is in H g,1 The lowest exit (No. 1) base elevation, Δh = ΔH / ( N -1) represents the distance between adjacent exits. j =1,2,..., N .

[0089] (2) Step S6.2 - Determine the target trigger water level for each outlet No. j The target trigger level for each exit is: in, Δh init The increment of immersion depth required for the pontoon to be submerged from its bottom edge to trigger (determined by the starting position of the wide cross-section steep rise zone, generally 0.2m to 0.5m).

[0090] (3) Step S6.3 - Parameter Consistency and Differentiation Design For the same project N The system, the cross-sectional shape parameters of the pontoon ( d 2. d 1. H f ,H w,s / H n,s The two sides should remain consistent in principle to simplify manufacturing and maintenance.

[0091] The differences between the various systems are achieved through the following parameters: counterweight mass ( M c,j By adjusting the counterweight mass, each system is brought to its respective target trigger level. H trigger,j The critical equilibrium is reached at ( ); the pontoon installation height ( h f,j For outlets with different bottom elevations, the buoy installation height can be finely adjusted to adapt to the bank slope topography and inlet hydraulic conditions. Lever arm ratio i In principle, the values ​​should be consistent across the entire system, but in special circumstances, values ​​can be taken separately.

[0092] (4) Step S6.4 - Verification of relay overlap interval Two adjacent exits j and j The relay overlap interval of +1 is [ H close,j , H trigger,j+1 ],in H close,j For the first j The return water level at each export port H trigger,j+1 For the first j+1 The trigger level for opening each outlet. To ensure that at least one outlet remains open throughout the relay process, the following calculations are required: in δ The maximum allowable overlap gap (generally taken as...) δ (≤0.1m). If the verification does not meet the requirements, the section ratio can be adjusted. r or the height of the wide cross-section H w,s To increase hysteresis bandwidth ΔH band , until the relay conditions are met.

[0093] 4.9 Step S7 - Detailed Design Drawing After all parameters are determined, detailed drawings of the pontoon structure, lever support, linkage mechanism motion analysis, counterweight installation, guide rail and water-stop sealing structure are produced, and construction drawings are output.

[0094] Example 1: 14m water level variation project The dead water level of a certain high dam project in Southwest China is 3524.00m, the normal storage water level is 3538.00m, and the water level fluctuation ΔH = 14m; the number of fishway outlets is N = 6, the distance between adjacent outlets is Δh = 2.8m; the gate mass is m. g =500kg, gate area S g =2.8m 2 Fishway design flow rate Q d =1.5m 3 / s.

[0095] According to the parametric design method of the present invention, the specific design process is as follows: Step S1: Input basic engineering parameters—water level fluctuation ΔH = 14m, number of fishway outlets N = 6, distance between adjacent outlets Δh = 2.8m, gate mass m g =500kg, gate area S g =2.8m 2 Design flow Q d =1.5m 3 / s.

[0096] Step S2: Based on the gate mass mg=500kg (medium mass) and water level fluctuation ΔH=14m (medium fluctuation), the lever arm ratio i=2.0 (taking the middle value) is initially selected, then L1=2.0m, L2=1.0m.

[0097] Step S3: Float Section Design S3.1: Calculate the critical buoyancy F b,crit =15.3kN, taking the peak net torque coefficient k=1.5, the effective opening interval ΔH open =1.0m, the minimum width section diameter d is calculated. 2,min =0.86m, take the design value d2=1.0m (leaving a safety margin of 1.16 times).

[0098] S3.2: Select a section ratio r=2.4 (applicable to projects with ΔH≤15m), then the diameter of the narrow section d1=d2 / r=1.0 / 2.4=0.42m.

[0099] Step S3.3: Take ΔH open =1.0m, estimated ΔH band =0.8m, h margin =0.3m, then the total height H of the pontoon f ≥1.0+0.8+0.3=2.1m, take H f =2.0m (confirmed to meet requirements through subsequent calculations). Take H. w,s / H n,s =1.4 / 0.6≈2.3, then the height H of the wide section is...w,s =1.4m, the height of the narrow section (conical contraction section) H_{n,s}=0.6m.

[0100] Step S3.4: Determine the pontoon installation height h f =0.5m (satisfying 0.3m≤h) f (Constraints ≤1.0m).

[0101] Step S4: Counterweight-Lever Coordination Design Step S4.2: Taking export #3 as an example (H) g,3 =3529.60m), target trigger water level H trigger,3 =3529.60 + 0.50 + 0.30 = 3530.40 m, critical immersion depth h imm,crit =3530.40-3529.60-0.50=0.30m. The pontoon is at h imm,crit Drainage volume V when = 0.30m disp =π / 4×d2 2 ×h imm,crit =π / 4×1.0 2 ×0.30=0.236m 3 The mass of the pontoon itself is m. f ≈85kg (made of steel with a wall thickness of 12mm), L f,cog ≈1.05m. Equivalent gravity F of the gate. g =mg×g+ρ×g×h×Sg≈500×9.81+1000×9.81×2.0×2.8≈4905+54936=59841N, take L link =1.8m. Substituting into the critical moment balance equation: Mc=[1000×9.81×0.236×2.0-85×9.81×1.05-59841×1.8] / (9.81×1.0)≈1200kg. Rounding to 1200kg using standard mass blocks (12 standard blocks of 100kg each), and fine-tuning with auxiliary blocks to control the actual trigger water level deviation within ±0.05m.

[0102] Step S4.3: Total lever length L = L1 + L2 + L margin =2.0 + 1.0 + 0.3 = 3.3m (take L) margin =0.3m is the structural margin). The installation height of the lever support is 0.5m above the highest design flood level of 3538.00m, i.e., 3543.00m.

[0103] Step S5: Hysteresis characteristic verification: Calculations show that ΔH band ≈0.8m. Verification: ΔHband / Δh=0.8 / 2.8=0.286<1 / 3, which meets the condition. This hysteresis bandwidth ensures that when the water level rises from 3530.40m (triggered opening) to about 3531.20m (gate fully open), it continues to rise to about 3531.80m before entering a narrow section where buoyancy growth slows down. When the water level continues to rise to about 3532.20m, the counterweight regains dominance, and the gate automatically closes.

[0104] Step S6: Relay Run Verification: The elevations of the six outlet base plates are: 3524.00m (#1), 3526.80m (#2), 3529.60m (#3), 3532.40m (#4), 3535.20m (#5), and 3538.00m (#6). The trigger water levels for each outlet are 3530.40m, 3533.20m, 3536.00m, 3538.80m, 3541.60m, and 3544.40m respectively (Note: The trigger water level for #6 is higher than the normal storage level; in reality, only #1-#5 participate in the operation within the normal storage level range). Taking adjacent outlets #3 and #4 as examples: H close,3 ≈3532.20m, H_{trigger,4}=3533.20m, verify H close,3 ≥H close,4 -δ (take δ=0.1m): 3532.20≥3533.20-0.1=3533.10 is not directly satisfied, but by fine-tuning the counterweight mass of #3, H can be made... close,3 Raise to 3533.15m, or fine-tune the installation height of #4 to make H close,4 Reducing the elevation to 3532.25m satisfies the relay overlap condition. In engineering practice, through closed-loop feedback adjustments in steps S5-S6, all adjacent outlets are ultimately made to meet the relay condition.

[0105] Step S7: Detailed Design and Drawing Production – Complete detailed drawings of the pontoon structure, lever support, counterweight installation, guide rail and water-stop sealing structure, and output construction drawings.

[0106] Taking export #3 as an example to verify the operation process, combined with the attached Figure 1 ~Attached Figure 7 The explanation is as follows: (1) Initial shutdown state (water level below 3530.40m): such as Figure 1 and Figure 6 As shown, at this time, the reservoir water level is lower than the trigger water level of outlet #3, the bottom edge of the variable cross-section pontoon is above the water surface or only the lower spherical cap is slightly submerged, and the buoyancy generated by the pontoon is extremely small. Buoyancy moment M 浮 =ρ·g·V disp L1 is much smaller than the counterweight torque M 配=Mc·g·L2 and gate resistance torque M 阻 =F g ·L link The sum of these forces gives the net torque ΔM = M. 浮 -M 配 -M 阻 <0. Under the action of the counterweight torque, the counterweight side of the main lever 1051 sinks, the float side rises, the flexible traction rope 108 is in a slack state, and the gate panel 101 is tightly fitted to the gate slot under its own weight and water pressure, remaining completely closed. Figure 4 As shown, at this time, lever buckle 201 is in contact with main lever 1051, restricting the main lever to a horizontal state and ensuring that the system is in the standard initial position.

[0107] (2) Start-up process (water level rises from 3530.40m to approximately 3531.20m): as follows Figure 6 As shown, with the rise of the reservoir water level, the lower spherical cap 102b and the middle cylindrical section 102a of the pontoon are gradually submerged. Because the diameter of the cylindrical section d2 = 1.0m is relatively large, the volume of water discharged per unit submersion depth V... disp =π / 4×d2 2 ×h imm Rapid growth, buoyancy F b =ρ·g·V disp It increases rapidly, approximately linearly, with the water level. Buoyancy moment M 浮 =F b L1 increases accordingly. When the water level reaches the trigger level H trigger,3 At a depth of 3530.40m, the buoyancy torque is exactly equal to the total resistance torque, ΔM=0, and the system is in a critical equilibrium state. If the water level continues to rise above the trigger value, ΔM>0, and the net torque drives the main lever 1051 to rotate clockwise around the lever support 1052 (viewed from the buoy side), causing the buoy side to rise and the counterweight side to rise. The flexible traction rope 108 is tightened and reversed via the guide pulley 1082, converting the oblique motion at the lever end into a vertically upward linear force, acting on the gate lifting lug 1081, causing the gate panel 101 to rise vertically along the gate slot. Figure 2 and Figure 3 As shown, since the rope's tension direction remains vertically upward after being reversed by the guide pulley 1082, the transmission efficiency is constant, and the effective lifting force is equal to the rope's tension itself, not decreasing with changes in the lever angle. When the water level rises to approximately 3531.20m (the top of the wide section is completely submerged), the buoyancy moment reaches its peak, ΔM reaches its maximum value, the gate is fully open, and the opening height is approximately 0.9m, which fully meets the flow space required for fish to swim upstream (the target fish's body height is approximately 0.2-0.3m).

[0108] (3) The process of returning to the gate (the water level continues to rise from 3531.20m): such as Figure 6As shown, after the wide section is fully submerged, the water level continues to rise into the upper conical contraction section 102c. The diameter of the conical contraction section gradually decreases with height (linearly shrinking from d2=1.0m to d1=0.42m). For the same 0.1m submersion depth, the narrow section only increases the drainage volume by ΔV≈0.028m³. 3 The wider cross-section section can increase ΔV≈0.079m. 3 The buoyancy increment drops precipitously to about 35% of the wide cross-section. At this point, the buoy side of the lever has been raised to a higher position, but due to the slowing increase in buoyancy, when the water level rises to about 3532.20m, the buoyancy torque is insufficient to maintain the open state, the counterweight regains dominance, and the net torque ΔM becomes negative. The main lever 1051 rotates counterclockwise, the buoy side sinks, the counterweight side falls, the traction rope 108 loosens, and the gate panel 101 slowly falls under its own weight and water pressure, automatically closing until the lever latch 201 blocks the main lever again to return to the horizontal position.

[0109] (4) Multi-elevation relay operation process: such as Figure 7 As shown, as the reservoir water level gradually rises from the dead water level of 3524.00m to the normal storage level of 3538.00m, the six outlet gates open and close sequentially according to their respective trigger water levels, forming a natural relay operation mode. At low water levels (3524.00m~3530.40m), only outlet #1 is open (or all are closed, depending on the specific trigger water level setting for #1); as the water level rises, #2 is triggered to open at approximately 3530.40m, and #1 closes at approximately 3532.20m, with the two overlapping in the 3530.40m~3532.20m range to ensure that fish passage is not affected during the switching period; as the water level continues to rise, #3 is triggered to open at approximately 3533.20m, and #2 closes at approximately 3535.00m, and so on. Figure 7 As clearly shown, the relay overlap area between adjacent exits [ H close,j , H trigger,j+1 This ensures that at least one outlet is always open throughout the entire water level fluctuation range, achieving seamless connection throughout the entire process.

[0110] Example 2: 18m water level variation project (a case study assuming a large variation) The water level fluctuation of a certain project is ΔH = 18m; the number of fishway outlets is N = 6, the distance between adjacent outlets is Δh = 3.6m; the gate mass is m. g =600kg, design flow rate Q d =2.0m 3 / s.

[0111] The parametric design process is as follows: Step S2: Select a lever arm ratio of i=2.5 (for larger water level fluctuations, take a larger value to obtain a higher torque margin), then L1=2.5m, L2=1.0m.

[0112] Step S3: Calculate the critical buoyancy F b,crit =18.6kN, take k=1.6, ΔH open =1.2m, d 2,min =1.02m, take d2=1.2m; select section ratio r=2.8 (take the larger value for larger amplitude), then d1=0.43m; total height H of the pontoon f =2.4m, of which H w,s =1.6m, H n,s =0.8m.

[0113] Step S4: Counterweight mass M_c = 1500kg (15 standard blocks of 100kg each).

[0114] Step S5: Calculate the hysteresis bandwidth ΔH band ≈1.1m. Verification: ΔH band / Δh =1.1 / 3.6=0.306≈1 / 3, which satisfies the condition.

[0115] Step S6: The relay overlap condition has been verified to be satisfied.

[0116] As can be seen from the comparison with Example 1, when the water level fluctuation increases from 14m to 18m, the parametric design method of the present invention increases the cross-sectional ratio r (2.4→2.8), increases the lever arm ratio i (2.0→2.5), and increases the size of the pontoon. d 2. Parameter adjustments (1.0m→1.2m) ensured reliable system operation even under greater amplitude variations. This verified the versatility and adaptability of the parametric design method of this invention—by adjusting the buoy geometry, counterweight mass, and lever dimensions, it can adapt to engineering requirements with different water level variations, gate specifications, and number of outlets, without needing to repeatedly calculate from scratch for each project.

Claims

1. An adaptive fishway gate based on buoyancy-counterweight linkage, characterized in that: It includes a gate panel (101), a variable cross-section float (102), a counterweight (103), a main lever (1051), a flexible traction rope (108), and a guide pulley (1082). The gate panel (101) is vertically installed at the fishway outlet; The main lever (1051) is hinged to the top of the support frame (3) via the lever support (1052) and rotates about the lever support (1052) in a vertical plane. The support frame (3) is located outside the fish passage chamber (104) and within the orthographic projection range of the gate panel (101). The main lever (1051) is provided with a connecting platform (1053) at one end adjacent to the gate panel (101). The counterweight (103) is suspended from the connecting platform (1053) by a vertical rod (1031). A variable cross-section float (102) is provided at the other end. One end of the flexible traction rope (108) is fixed to the connecting platform (1053), and the other end is vertically connected to the gate lifting lug (1081) at the top of the gate panel (101) after being reversed by the guide pulley (1082). The buoyancy of the variable cross-section float (102) and the torque generated by the gravity of the counterweight (103) on the lever support (1052) are balanced, so as to realize the automatic opening and closing of the gate panel (101) in the corresponding design water level range.

2. The adaptive fishway gate based on buoyancy-counterweight linkage according to claim 1, characterized in that, The variable cross-section pontoon (102) is composed of an integrally formed lower spherical cap (102b), a middle cylindrical section (102a), and an upper conical contraction section (102c).

3. The adaptive fishway gate based on buoyancy-counterweight linkage according to claim 1, characterized in that, The counterweight (103) adopts a segmented stacked design, consisting of several standard mass blocks, and is equipped with adjustable sub-blocks and scales; the counterweight (103) is located in the support wall extending straight from the fishway side wall (1041), the support wall has a vertical cavity, the top of the cavity is provided with a dirt-blocking cover (1032), and the dirt-blocking cover (1032) has a square through hole (10321) parallel to the lever in the center.

4. The adaptive fishway gate based on buoyancy-counterweight linkage according to claim 3, characterized in that, The end of the support wall is fixedly connected to the support frame (3), and the lever support (1052) is vertically installed on the support frame (3). The lever support (1052) contains a self-lubricating bearing. The support wall is also equipped with a buckle rod (202). A lever buckle (201) is vertically installed on the top side of the buckle rod (202). The lever buckle (201) is located above the main lever (1051) so that the main lever (1051) remains horizontal when the gate is closed.

5. A parametric design method for a fishway outlet float-counterweight adaptive gate, characterized in that, Includes the following steps: S1: Obtain basic engineering design parameters: water level fluctuation ΔH, number of fishway outlets N, fishway specifications, gate specifications, and fishway design flow rate; S2: Based on the gate mass m gate And the water level variation ΔH and the lever arm ratio i were initially selected; S3: Determine the lower diameter d2 of the pontoon, the cross-sectional ratio r, the upper diameter d1 of the pontoon, and the total height H of the pontoon in sequence. f Height H of wide cross-section section w,s Conical section height H n,s and the pontoon installation height h f ; S4: Determine the counterweight mass Mc based on the critical moment balance equation, and determine the total length of the lever and the installation height of the lever support; S5: Calculate the hysteresis bandwidth ΔH band And verify whether ΔH is satisfied. band ≤Δh / 3; S6: Determine the target trigger water level H for each outlet. trigger,j and the return water level H close,j Verify whether the relay overlap intervals of adjacent exits j and j+1 satisfy H. close,j ≥H trigger,j +1-δ.

6. The parameterized design method for the fishway outlet float-counterweight adaptive gate according to claim 5, characterized in that, Step S3 specifically includes: S3.1: Based on the critical buoyancy F b,crit Effective open interval ΔH open And the peak net moment coefficient k, the bottom diameter d2 of the pontoon is calculated and determined by the following formula: ； S3.2: Based on the section ratio r = d2 / d1, calculate and determine the diameter d1 of the upper bottom of the pontoon using the following formula: d1 = d2 / r, where r is the control parameter for hysteresis bandwidth, with a value ranging from 2.0 to 3.5; S3.3: According to the constraints Determine the total height H of the pontoons f and the height distribution ratio of the narrow and wide sections H w,s / H n,s ; S3.4: According to the constraint 0.3m≤h f Determine the pontoon installation height h ≤1.0m f .

7. The parameterized design method for the fishway outlet float-counterweight adaptive gate according to claim 5, characterized in that, Step S4 specifically includes: S4.1: Determine the lever arm ratio i = L1 / L2 based on the gate mass and water level fluctuation, where i ranges from 1.5 to 3.0; S4.2: Based on the critical moment balance equation ΔM=0, calculate the counterweight mass Mc using the following formula: ， Among them, h imm,crit The critical immersion depth for the corresponding target trigger water level: ； in, This represents the volume of water discharged by the pontoon at the critical immersion depth. S4.3: According to the formula for the total length of the lever L = L 1+ L 2+ L margin Determine the total length of the lever and the installation height of the lever support. in, L margin This represents the structural allowance at both ends.

8. The parameterized design method for the fishway outlet float-counterweight adaptive gate according to claim 5, characterized in that, In step S5, the hysteresis bandwidth ΔH band Calculate using the following formula: ， in, H close This is the closing water level corresponding to the gate being closed. H trigger To trigger the water level.

9. The parameterized design method for the fishway outlet float-counterweight adaptive gate according to claim 8, characterized in that, The ΔH band Subject to the cross-sectional ratio r and the height ratio H of the wide and narrow cross sections w,s / H n,s The coupling control of the lever arm ratio i is achieved by adjusting the above parameters to make ΔH band It meets the requirements for relay operation of adjacent gates.

10. The parameterized design method for the fishway outlet float-counterweight adaptive gate according to claim 5, characterized in that, In step S6, the elevation H of the bottom plate at each exit is... g,j and target trigger water level H trigger,j Determine them respectively using the following formulas: ， in, H g,1 This is the lowest elevation of the outlet floor. Δh = ΔH / ( N -1) represents the distance between adjacent exits; ， j =1,2,..., N, Δh init The increment of immersion depth required for the buoy to be submerged from its bottom edge to trigger; Does the relay overlap between adjacent exits j and j+1 satisfy the pass condition? Verification was performed, where δ is the maximum allowable overlap gap; the cross-sectional shape parameters of the pontoons at each outlet remained consistent, and the counterweight mass M at each outlet was adjusted differentially. c,j and the installation height h of the pontoon f,j This causes each outlet to trigger at different target water levels H. trigger,j The system reaches a critical equilibrium and achieves automatic operation based on a relay system according to water level.

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