Flood drainage tunnel and flood self-adaptive adjustment design method thereof

Abstract

The invention provides a flood drainage tunnel and a flood self-adaptive adjustment design method thereof. The flood drainage tunnel is used for flood control and drainage in a karst trough and valley area. The flood drainage tunnel comprises a tunnel body, breast wall type gate holes and vent holes. The flood self-adaptive adjustment design method comprises the following steps: determining a designed submerging water level of a flood drainage area under a designed flood standard, calculating a designed discharge flow of a flood drainage tunnel, and initially planning relevant parameters of the flood drainage tunnel; and the calculation is repeated until the relevant parameters of the flood drainage tunnel meet the flood control requirements under the designed flood standard of the flood bearing area. The structure is simple, the cost is low, manual dispatching intervention is avoided, the response time is short, free flow exists in the tunnel, the hydraulic condition is good, and in a small-scale flood event, rapid flood drainage is achieved through the self-flow open drainage function of the flood drainage tunnel; under the condition of large-scale flood, a combined peak regulation mechanism is formed by combining the natural reservoir capacity of the depression and a tunnel breast wall type gate hole leakage control system, fluctuation of flood magnitude is flexibly coped with, and flood control safety of upstream and downstream areas is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flood control and drainage engineering design of hydraulic engineering, and particularly relates to a flood drainage tunnel and a flood self-adaptive regulation design method thereof. BACKGROUND

[0002] Karst valley areas are prone to flood disasters and ecological fragile areas, which bring many challenges to local human production and life. Therefore, flood control and drainage facilities need to be equipped in related areas. As an important infrastructure for flood control and drainage in karst valley areas, newly-built flood drainage tunnels can effectively alleviate the risk of flood disasters in the basin through inter-basin flood regulation, but may cause the problem of transferring flood control pressure from the flood drainage area to the flood receiving area, forming safety contradictions between different flood control units. In order to achieve the dynamic balance of flood control demand between basins, the engineering design needs to consider the coordination between the flood drainage area and the flood receiving area, build a flood regulation system based on multi-objective optimization, and realize the matching of flood diversion level and flood carrying capacity through precise engineering measures. However, the current field is facing the following problems: first, remote mountainous areas generally have complex geological structure and hydrological conditions, it is difficult to accurately regulate the flood with steep rise and fall, the operation and maintenance force is insufficient, and it is difficult to match local financial funds during the operation period; second, under the constraint of limited budget, the contradiction between engineering structure safety and operation economy needs to be solved simultaneously.

[0003] Due to the characteristics of short confluence time, small river channel storage capacity, turbulent flow, rapid rainstorm flood, and steep rise and fall of river water in mountainous areas. In order to reduce the impact on the third-party flood control safety of towns, embankments, power stations and other along the downstream river, and to consider the safety of the flood drainage area and the flood receiving area, the discharge flow of the flood drainage area needs to be controlled, and the flood of the flood drainage area needs to be regulated and peak cut before being discharged into the downstream river. There are two methods to control the discharge: one is to control the discharge through the gate opening at the tunnel entrance, and the tunnel behind the gate chamber is a non-pressure tunnel. When the tunnel entrance is controlled by the gate, strong dispatching force is needed, different dispatching schemes are used for different flood levels, and the gate and the opening and closing system need to be maintained regularly to ensure timely response and reliable operation of the project. The operation cost of this scheme is high, and the quality of the dispatching personnel is high. If the dispatching is not timely or there is a dispatching error, the flood level of the flood drainage area or the flood receiving capacity of the flood receiving area is too large, which may cause serious social problems in the flood drainage area and the flood receiving area. The acceptance of this scheme in economically underdeveloped areas and remote mountainous areas is not high. The second is to set a pressure short pipe at the tunnel entrance to control the maximum discharge flow by reducing the flow area of the short pipe, and then connect a non-pressure tunnel. Both of these two schemes can control the discharge of flood and reduce the flood control pressure of the downstream. When the tunnel entrance is controlled by the pressure short pipe (pressure tunnel), the pressure short pipe will produce unstable flow state of clear full flow alternation when encountering common flood or the water depth in front of the tunnel is lower than the control water depth of the pressure flow, which will have adverse effects on the stress state and discharge capacity of the tunnel structure, and even cause the destruction of the structure, so the safety of the project cannot be guaranteed.

[0004] In order to solve the above problems, the Chinese invention application with the application number CN202310205628.4 discloses a water conservancy gate opening and closing height automatic control device and a use method. The method realizes dynamic adjustment of the gate height through water level detection and mechanical linkage. However, the method relies on multiple mechanical components such as gears, and has short boards in reliability and environmental adaptability. Moreover, the method relies on motor drive, and has problems such as high energy consumption and low efficiency. The Chinese invention application with the application number CN202410967985.9 discloses an automatic opening and closing water discharge device and method. The method uses mechanical principles to realize automatic opening and closing by relying on water pressure and the self-weight of the gate. The gate opening and closing function under different water level control conditions is met without external power equipment. The arrangement is relatively simple, and the construction and cost are relatively low. However, the rotating sleeve and sliding guide groove in the device for driving the water retaining valve to rotate around the shaft are prone to wear during operation, affecting the operation efficiency. The Chinese invention patent with the application number CN202322256422.2 discloses an automatic flood storage body. The invention uses mechanical principles to design an automatic start-stop flood storage facility that does not rely on electric power and other automatic equipment. The flood impact force can be segmented and eliminated by the cascade arrangement of the automatic flood storage body. However, the durability of the mechanical components such as the rotating shaft under the impact of floodwater is prone to problems. Moreover, the coordination process of the upper and lower levels of the cascade arrangement is complex and difficult to implement. SUMMARY

[0005] In order to overcome the shortcomings of the above-mentioned technologies, the purpose of the present application is to provide a flood discharge tunnel and a flood self-adaptive adjustment design method, which solves the problems of weak operation and dispatching force, high operation cost, and difficult to guarantee structural safety in remote mountainous areas, and has the advantages of low energy consumption, high efficiency, and simple implementation.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows: A flood discharge tunnel for flood control and drainage in karst valley areas; one end of the tunnel is arranged at the entrance of the discharge area in the valley region, and the other end is connected to the downstream flood receiving area to discharge the flood in the valley region to the river in the flood receiving area. The special feature is that the tunnel body includes a gate hole fixedly connected to the entrance of the tunnel body; the gate hole is a breast wall type gate hole; the gate hole includes a gate hole body, which is a plate structure; a hole is arranged in the middle of the gate hole body, so that water can enter the inside of the tunnel body through the hole, and then be discharged to the river in the flood receiving area; a vent cylinder is fixedly connected to the top of the gate hole body; a vent hole is arranged through the vent cylinder in the height direction, and the vent hole extends downward from the top of the vent cylinder to communicate with the hole.

[0007] As a preferred solution, the two sides of the tunnel body are provided with stone backfill areas filled with stone residues generated after the tunnel is excavated.

[0008] As a preferred solution, the top and upper part of the two sides of the tunnel body are provided with slope support areas, and slope support measures are taken to protect the tunnel body.

[0009] As a preferred solution, the gate hole is an integrated reinforced concrete structure formed by pouring concrete combined with steel bars.

[0010] As a preferred solution, the height of the gate hole body is not less than the height of the tunnel body at the entrance.

[0011] As a preferred solution, the height of the orifice away from the tunnel body side of the gate hole body is lower than that close to the tunnel body side, and the bottom elevation of the gate hole is consistent. This structural design can ensure the smoothness of the water inflow and outflow of the gate hole, reducing the impact of water flow.

[0012] As a preferred solution, a trash rack is arranged in front of the side of the gate hole away from the tunnel body.

[0013] Further, the trash rack is a steel structure.

[0014] A flood self-adaptive adjustment design method of the above flood drainage tunnel, which is characterized by comprising the following steps: 1) Collecting basic data of the flood drainage area and the flood bearing area; 2) Based on the basic data of the flood drainage area, determining the design flood level range of the flood drainage area under the design flood standard; 3) Based on the design flood level range, determining the design flood level of the flood drainage area and calculating the design discharge of the flood drainage tunnel and the preliminary parameters of the flood drainage tunnel through flood regulation calculation, trial calculation, investment comparison, etc.; 4) Based on the basic data of the flood bearing area, determining whether the current parameters of the flood drainage tunnel meet the flood control requirements under the design flood standard of the flood bearing area. If yes, the design parameters of the flood drainage tunnel are determined to use the current calculated parameters of the flood drainage tunnel. If not, the design discharge of the flood drainage tunnel is reduced, the parameters of the flood drainage tunnel are adjusted, and whether the current parameters of the flood drainage tunnel meet the flood control requirements under the design flood standard of the flood bearing area is determined again; 5) Repeating step 4) to repeatedly perform flood regulation calculation until the parameters of the flood drainage tunnel meet the flood control requirements under the design flood standard of the flood bearing area, and then determining the design parameters of the flood drainage tunnel; 6) Designing the flood drainage tunnel based on the design parameters of the flood drainage tunnel for self-adaptive adjustment of flood.

[0015] The adaptive regulation of flood refers to that in small-scale flood events, the rapid flood discharge is realized through the self-flowing discharge function of the flood discharge tunnel; and in large-scale flood conditions, the joint peak regulation mechanism is formed by combining the natural storage capacity of the depression and the tunnel breast wall type gate control discharge system, so as to flexibly cope with the fluctuation of flood level and ensure the flood control safety of the upstream and downstream areas.

[0016] As a preferred solution, in step 1), the basic data of the flood discharge area includes the tank storage capacity curve, the boundary condition data, and the basic data of the flood bearing area includes the boundary condition data; the boundary condition data of the flood discharge area includes the hydrology, topography, living facilities, built flood discharge facilities, and relevant data of the existing natural flood discharge facilities; the boundary condition data of the flood bearing area includes the hydrology, built embankments, and relevant data of the simple flood control measures that can be used when encountering floods.

[0017] Further, in the basic data of the flood discharge area, the hydrology related data includes the natural flood process under the design flood standard; the topography related data includes the elevation of the karst cave and the falling hole and the discharge flow thereof; the living facilities related data includes the elevation of the roads, houses and farmland; the built flood discharge facilities related data includes the elevation of the flood discharge channel and the discharge flow thereof; the existing natural flood discharge facility related data includes the flow capacity of the falling hole, and the flow capacity is the discharge flow of the existing natural flood discharge facility. In the basic data of the flood bearing area, the hydrology related data includes the discharge river and its direction in the flood bearing area and the natural flood process under the design flood standard; the related data of the built embankment includes the safety heightening value of the embankment engineering, the calculation value of the embankment top superhigh, the actual superhigh of the embankment top, and the highest allowable flood level; the simple flood control measures include setting curb or wave wall, etc.

[0018] As a preferred solution, in step 2), the determination method of the design submergence water level range includes the following steps: Based on the basic data of the flood discharge area, the submergence elevation a1 that does not affect the farmland planting and ensures the traffic conditions of the rural roads and the submergence elevation a2 that does not affect the safety of the houses are determined; Based on the tank storage capacity curve, a plurality of submergence elevation trial values are determined in the submergence elevation range a1~(a2+Δa), and the regulation and storage capacity corresponding to each submergence elevation trial value under the design flood standard of the flood discharge area is calculated to determine the minimum submergence elevation a3 with regulation and storage capacity; wherein, Δa is the excess calculation allowance; The submergence elevation range a3~a2+Δa is selected as the design submergence water level range.

[0019] Further, the submergence elevation a1 is lower than or equal to the elevation of most of the farmland and rural roads; the submergence elevation a2 is lower than or equal to the elevation of the bottom of most of the houses; the most refers to that the area of the farmland and rural roads or the area of the houses accounts for 90% or more of the total area.

[0020] Furthermore, the method for determining whether the inundation elevation has storage capacity includes: determining the total flood volume of the natural flood process under the design flood standard of the flood discharge area; when the storage capacity at the inundation elevation is not less than 5% of the total flood volume, the inundation elevation is determined to have storage capacity.

[0021] As a preferred embodiment, step 3) includes: Within the proposed range of the design inundation level, multiple trial values ​​of the design inundation level are proposed. Determine the natural flood process under the design flood standard of the flood discharge area. Based on the flow capacity of the existing flood discharge facilities, calculate the maximum discharge flow of the flood discharge tunnel and the calculated values ​​of relevant parameters of the flood discharge tunnel corresponding to the calculated values ​​of each design inundation water level under the design flood standard of the flood discharge area. Calculate the inundation loss and comprehensive project investment cost corresponding to the calculated design inundation water level under the design flood standard of the flood discharge area; The design inundation water level that minimizes the overall cost of inundation loss and project investment is selected as the design inundation water level of the flood discharge area, the corresponding maximum discharge flow of the flood discharge tunnel is selected as the design discharge flow of the flood discharge tunnel, and the relevant parameters of the flood discharge tunnel are selected as the relevant parameters of the flood discharge tunnel.

[0022] As a preferred embodiment, in step 3), the relevant parameters of the flood discharge tunnel include the gate size, tunnel discharge capacity, gate ventilation hole size, and tunnel size.

[0023] As a preferred option, in step 4), the flood control requirement under the design flood standard of the flood-bearing area is that the flood-bearing area can withstand the flood and the discharge flow of the flood discharge tunnel without taking any measures or by adding simple measures under the design flood standard of the flood-bearing area.

[0024] As a preferred embodiment, step 4) includes the following steps: Determine the maximum peak flow Q of the natural flood process under the design flood standard in the flood-bearing area. max ; Based on the preliminary parameters of the flood discharge tunnel, the maximum peak flow Q of the flood-bearing area after superimposing the discharge flow from the flood discharge tunnel of the flood discharge area at different time periods is calculated when both the flood-bearing area and the flood discharge area encounter a natural flood process under the design flood standard of the flood-bearing area. max ', and determine the water level of the river section receiving the flood discharge in the flood-receiving area at this time; Determine whether the water level of the flood-bearing area of the flood-bearing river section exceeds the existing dike engineering allowable maximum flood level; if not, determine that the flood drainage tunnel design parameter adopts the current calculation used flood drainage tunnel parameter; if yes, determine whether the simple flood control measure can meet the design flood control standard, if the simple flood control measure can meet the design flood control standard, determine that the flood drainage tunnel design parameter adopts the current calculation used flood drainage tunnel parameter, if the simple flood control measure still cannot meet the design flood control standard, adjust the related parameters of the flood drainage tunnel.

[0025] Further, the adjustment method of the related parameters of the flood drainage tunnel comprises: based on the current calculation orifice width plus the change amount of the orifice width, that is, the adjusted orifice width is obtained; the change amount of the orifice width is calculated according to the design flow variation of the tunnel, and the calculation formula is as follows: When H1 / H0>0.65, the change amount of the orifice width is calculated according to the following formula:

[0026] In the formula, ΔB is the change amount of the orifice width, m; ΔQ is the design flow variation of the tunnel, m 3 / s; H0 is the total water head above the gate hole bottom plate elevation, m; H1 is the orifice height, m; k is the flow coefficient; and g is the gravity acceleration, m / s 2 ; When H1 / H0≤0.65, the change amount of the orifice width is calculated according to the following formula:

[0027] In the formula, ΔB is the change amount of the orifice width, m; ΔQ is the design flow variation of the tunnel, m 3 / s; H1 is the orifice height, m; H0 is the total water head above the gate hole bottom plate elevation, m; and μ is the free outflow flow coefficient of the gate hole, for a round smooth orifice, μ=0.90.

[0028] Compared with the prior art, the beneficial effects of the present application are: The flood drainage tunnel and the flood self-adaptive adjustment design method provided by the present application have the advantages that: the tunnel inlet gate adopts a breast wall type gate hole, the gate hole structure is simple and the cost is low, the gate does not need to be set, manual scheduling intervention is avoided, the response time is greatly reduced, the inlet is connected with a non-pressure tunnel, the flow in the tunnel is free flow, the overfall flow does not produce the alternating phenomenon of overfall flow and full flow, the hydraulic condition is good, the self-adaptive adjustment of different magnitude floods can be realized, the technical bottleneck that the flood in the karst area rises and falls steeply and is difficult to accurately schedule is broken through, and the stability and operation reliability of the flood drainage system are significantly improved.

[0029] In order to avoid the occurrence of turbulent flow state and ensure the safety of the inlet, the inlet type is selected to be a breast wall type rectangular gate hole. The size of the breast wall type gate hole is determined according to different flood scales and the requirements of the downstream discharge area by hydraulic formula trial calculation, and in order to avoid the entry of pollutants into the tunnel and affect the discharge, a steel trash screen is arranged in front of the breast wall type gate hole.

[0030] The flood self-adaptive adjustment design method of the application optimizes the size of the gate hole by adjusting the discharge flow of the flood drainage area and adjusting the width of the gate hole, coordinates the flood drainage area and the flood bearing area, realizes the self-adaptive adjustment of the flood, and has the advantages of simple optimization process.

[0031] The application realizes a multi-target flood management model through the breast wall type gate hole, aiming to realize the accurate matching of the flood drainage area and the flood bearing area in the demand of flood control. The application innovatively uses the natural storage of the karst valley for peak regulation, effectively balances the flood control demand of the peak period and the valley period through the time redistribution of the flood. Through analysis and trial calculation, the flood control demand of the flood drainage area and the flood bearing area is balanced, the discharge flow of the tunnel is determined, and the ungate breast wall type gate hole and the air vent are arranged at the inlet of the tunnel, combined with the natural storage of the valley and the tunnel control and discharge system, to form a joint peak regulation mechanism, flexibly cope with the fluctuation of different flood scales, and ensure the flood control safety of the upstream and downstream areas. The innovation of the model lies in accurately regulating the flood, unattended, improving the management efficiency, saving the operation and maintenance cost, realizing the self-adaptive adjustment of different flood scales, breaking through the technical bottleneck of accurately scheduling the flood in the karst area, and significantly improving the stability and operation reliability of the flood drainage system. The effectiveness of the method for different scale floods has been verified in multiple projects, and has broad application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only some embodiments of the application, and for those skilled in the art, without creative labor, other drawings can also be obtained from the structure shown in the drawings.

[0033] Fig. 1 It is a three-dimensional drawing of the breast wall type gate hole at the inlet of the tunnel. Fig. 2 It is a longitudinal section view of the breast wall type gate hole at the inlet of the tunnel. Fig. 3 It is a transverse section view of the breast wall type gate hole at the inlet of the tunnel. Fig. 4 It is a flowchart of the design method. Fig. 5 It is a schematic diagram of the multi-target flood management model. Fig. 6Model and actual engineering view of the inlet of a gateless controlled-release tunnel; In the diagram: 1. Tunnel body; 2. Gate opening; 201. Gate body; 202. Opening; 203. Ventilation cylinder; 2031. Ventilation hole; 3. Trash rack; H1. Opening height; B1. Opening width; H2. Height at the entrance of the tunnel body.

[0034] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1 like Figs. 1-3 As shown, this invention provides a flood drainage tunnel for flood control and drainage in karst valley areas. One end of the tunnel's entrance is located in the valley area of ​​the flood drainage zone, and the other end's exit connects to the downstream flood-receiving river, used to discharge floodwater from the valley area at the entrance to the downstream flood-receiving river. The flood drainage tunnel includes a tunnel body 1, which is embedded in the mountain rock. Stone backfill areas are set on both sides of the tunnel body, filled with stone debris generated after tunnel excavation. Slope protection areas are set on both sides and the upper part of the tunnel body, and slope protection measures are taken to protect the tunnel body.

[0037] A gate 2 is fixedly connected to the entrance of the flood discharge tunnel. Gate 2 is a breast wall type gate used to regulate the discharge flow of the flood discharge tunnel. Gate 2 is an integral reinforced concrete structure, cast with concrete and steel reinforcement. Gate 2 includes a gate body 201, which is a square plate structure located at the entrance of the flood discharge tunnel. The entrance of gate body 201 connects to the flood discharge area's valley region, and the exit connects to and is fixedly connected to the tunnel body 1. The height of gate body 201 is not lower than the height of the entrance of tunnel body 1. An orifice 202 is provided in the middle of gate body 201, allowing water to enter the interior of tunnel body 1 through orifice 202, and then discharge into the receiving river of the flood discharge area. The orifice 202 is a smooth orifice. Its dimensions begin from a first predetermined size on the side away from the tunnel body 1, gradually decreasing in height and width. After decreasing to a second predetermined size (orifice height H1 × orifice width B1), it maintains the second predetermined size and extends for a predetermined length, gradually increasing in height until it matches the height H2 at the entrance of the tunnel body 1. This ensures that the width of the orifice 202 on the side away from the tunnel body 1 is greater than that on the side near the tunnel body 1, while its height is lower, and the bottom elevation of the orifice 202 is consistent. The second predetermined size (orifice height H1 × orifice width B1) is the design parameter for a breast-wall type gate orifice in conventional technology. A square vent 203 is installed at the top of the gate body 201. A ventilation hole 2031 is provided through the ventilation cylinder 203 along the height direction; the ventilation hole 2031 is a square through hole that extends from the top of the ventilation cylinder 203 downward to connect with the orifice 202, so that the breast wall gate 2 is connected to the air through the ventilation hole 2031. It is used to connect the orifice 202 with the outside air when the water flows into the orifice 202, and to replenish the air into the tunnel during flood discharge, so as to avoid the formation of negative pressure at the orifice, avoid violent fluctuations in the gas-liquid two-phase flow, and reduce the water hammer effect.

[0038] A trash rack 3 is installed in front of the side of the breast wall gate 2 away from the flood discharge tunnel to prevent dirt from entering the tunnel and affecting the discharge; the trash rack 3 is a steel structure.

[0039] Example 2 like Fig. 4 As shown, the present invention provides a flood adaptive regulation design method for a flood discharge tunnel, comprising the following steps: 1) Collect basic data on flood discharge areas and flood receiving areas.

[0040] Basic data for the flood discharge area includes reservoir capacity curves and boundary condition data. The reservoir capacity curves represent the relationship between water storage capacity and elevation in the flood valley. Basic data for the flood-receiving area includes boundary condition data.

[0041] The boundary condition data of the flood drainage area includes hydrology, topography, living facilities, built flood drainage facilities, and related data of the current natural flood drainage facilities. The hydrology data includes the natural flood process under the design flood standard of the flood drainage area, such as the flood peak flow and total flood volume of the flood drainage area under the 10-year flood, and the data of the relevant river section of the river serving as the flood drainage channel, such as the elevation distribution and discharge of the river. The topography data includes the data of karst caves and drawdown holes, such as the lowest point elevation and discharge. The living facilities data includes the elevations of farmland, roads, and houses in the flood drainage area. The built flood drainage facility data includes the elevations and discharges of the flood drainage channels. The current natural flood drainage facilities include drawdown holes, karst caves, and their flow capacities, which are the discharges of the flood drainage facilities.

[0042] The boundary condition data of the flood receiving area includes hydrology, built embankments, and simple flood control measures that can be used when encountering floods. The hydrology data includes the natural flood process under the design flood standard of the flood drainage area, such as the flood peak flow, total flood volume, and flood level of each river section under the 20-year flood, and the discharge and direction of the river receiving the flood. The built embankment data includes the safe heightening value of the embankment engineering, the calculated value of the embankment top superhigh, the actual superhigh of the embankment top, and the highest flood level allowed by the embankment. The simple flood control measures that can be used include setting kerbs and wave walls.

[0043] The natural flood process line of the flood drainage area and the flow capacity of the current flood drainage facilities can be obtained using engineering hydrology algorithms and historical flood investigation data.

[0044] 2) Based on the basic data of the flood drainage area, the natural flood process line of the design flood standard of the flood drainage area is determined, and the design submerged water level range under the design flood standard of the flood drainage area is determined. The design submerged water level is the highest water level that can be submerged in the flood drainage area determined when designing the flood drainage tunnel.

[0045] The design principle of the design flood level and the storage capacity of the flood drainage area is to protect the safety of residents and most of the houses in the flood drainage area. In actual operation, the design submerged water level range can be determined by the following methods: 2.1) Based on the basic data of the flood drainage area, the submerged elevation a1 that does not affect the normal life of local residents and the planting of farmland, and the submerged elevation a2 that ensures the safety of local residents and houses are determined under the condition that the rural roads have traffic conditions; among them, the elevations of 90% or more of the farmland and roads are greater than or equal to the submerged elevation a1; the bottom elevations of 90% or more of the houses are greater than or equal to the submerged elevation a2; 2.2) Based on the reservoir capacity curve, a plurality of trial values of the submerged elevation in the range of a1~(a2+Δa) are determined, and the storage capacity corresponding to each trial value of the submerged elevation under the design flood standard of the flood drainage area is calculated to determine the minimum submerged elevation a3 with storage capacity. Specifically, it can be calculated in sequence from a1 with an interval of 0.2, 0.5 m or 1 m until a2+Δa is calculated, and the calculation interval is determined according to the actual engineering precision requirement. In the calculation process, a certain height Δa can be appropriately increased on the basis of a2 without affecting the safety of houses and people's property as much as possible. The increase of 0.5 m~1 m has little effect on the safety of houses and people's property, and whether to increase and how much to increase can be determined according to the specific situation of the flood drainage area. The determination method of whether it has storage capacity is: the total amount of flood under the natural flood process of the design flood standard is determined, and when the storage capacity under the submerged elevation is ≥5% of the total amount of flood, it is determined that the submerged elevation has storage capacity.

[0046] The selected submerged elevation range a3~a2+Δa is the design submerged water level determination range.

[0047] 3) Based on the above design submerged water level determination range, the design submerged water level of the flood drainage area is determined through flood regulation calculation, trial calculation, investment comparison, etc., and the design discharge of the flood drainage tunnel and the preliminary parameters of the flood drainage tunnel are calculated; 3.1) A plurality of design submerged water level trial values are determined in the above design submerged water level determination range; 3.2) The natural flood process under the design flood standard of the flood drainage area is determined, and based on the flow capacity of the existing flood drainage facilities, the discharge of the flood drainage tunnel in all calculation periods corresponding to each design submerged water level trial value when encountering the natural flood process under the design flood standard of the flood drainage area is calculated, and then the maximum discharge of the tunnel is determined; wherein the existing flood drainage facilities include the built flood drainage facilities and the existing natural flood drainage facilities.

[0048] 3.3) Based on the above maximum discharge, the parameters of the flood drainage tunnel are determined; the parameters of the flood drainage tunnel include the size of the gate hole (orifice height H1 x orifice width B1), the discharge capacity of the tunnel, the size and elevation of the gate hole vent, and the size of the tunnel; The determination of this part of the parameters of the flood drainage tunnel belongs to the prior art, and will not be described here.

[0049] 3.4) Based on the above parameters of the flood drainage tunnel and the design submerged water level trial value, the comprehensive cost of submerged loss and engineering investment under each design submerged water level trial value under the design flood standard is calculated; 3.5) Select the design inundation water level that minimizes the overall cost of inundation loss and project investment as the design inundation water level of the flood discharge area, the maximum discharge flow of the corresponding flood discharge tunnel as the design discharge flow of the flood discharge tunnel, and the corresponding trial values ​​of the relevant parameters of the flood discharge tunnel as the relevant parameters of the flood discharge tunnel.

[0050] 4) Based on the basic data of the flood-bearing area, determine whether the relevant parameters of the current flood discharge tunnel can meet the flood control requirements under the design flood standard of the flood-bearing area. If yes, determine that the design parameters of the flood discharge tunnel are the parameters currently used in the calculation. If not, reduce the design discharge flow of the flood discharge tunnel, adjust the relevant parameters of the flood discharge tunnel, and determine again whether the relevant parameters of the current flood discharge tunnel meet the flood control requirements under the design flood standard of the flood-bearing area.

[0051] Based on the basic data of the flood-bearing area, analyze the impact of the superimposed discharge flow from the flood discharge tunnel on the flood-bearing area. If the flood-bearing area can withstand the discharge flow without taking measures or by adding simple measures, then determine the size of the breast wall gate, the size and elevation of the ventilation hole, and the tunnel size of the flood discharge tunnel inlet. If the flood-bearing area cannot withstand the discharge flow without taking measures and cannot withstand the discharge flow even by adding simple measures, then reduce the design discharge flow of the flood discharge tunnel determined in step 3), and re-determine whether the relevant parameters of the current flood discharge tunnel meet the flood control requirements under the design flood standard of the flood-bearing area. The specific steps are as follows: 4.1) Determine the maximum peak discharge Q of the natural flood process under the design flood standard in the flood-bearing area. max ; 4.2) Based on the design discharge flow of the flood discharge tunnel and the discharge capacity of the breast wall gate, calculate the maximum peak flow Q of the flood-bearing area after superimposing the discharge flow of the flood discharge tunnel in the flood discharge area at different time periods when both the flood-bearing area and the flood discharge area encounter a natural flood process under the design flood standard of the flood-bearing area. max The process involves determining the water level of the receiving and discharge river sections within the flood-receiving area at that time. Time-segment superposition refers to the fact that the natural flood process curve under the design flood standard of the flood-receiving area is a curve showing the relationship between time and flood flow, and the discharge flow process of the flood discharge tunnel under the design flood standard of the flood-receiving area is also a curve showing the relationship between time and discharge flow. The sum of the flood flow and discharge flow of the two at the same time period is time-segment superposition, and the maximum flow after superposition is less than or equal to the sum of the maximum flows of the two. 4.3) Determine whether the water level of the flood-bearing section of the flood-bearing area exceeds the allowable maximum flood level of the existing embankment project; if not, determine that the flood drainage tunnel design parameters use the current calculation of the flood drainage tunnel parameters; if so, determine the height of the allowable maximum flood level, and determine whether the simple flood control measures can meet the design flood control standard, if it can meet the design flood control standard, determine that the flood drainage tunnel design parameters use the current calculation of the flood drainage tunnel parameters, if it cannot meet the design flood control standard, reduce the design discharge of the flood drainage tunnel, adjust the orifice width of the breast wall type gate hole, and determine again whether the current flood drainage tunnel parameters meet the flood control requirements under the design flood standard of the flood-bearing area; the flood drainage area adopts non-engineering measures such as personnel transfer to avoid transferring additional flood control pressure to the flood-bearing area.

[0052] The adjustment method of the flood drainage tunnel related parameters includes: based on the current calculation of the orifice width plus the change of the orifice width, the adjusted orifice width is obtained. Specifically, the change of the orifice width is calculated according to the change of the design flow of the tunnel, and the calculation formula is as follows: The discharge capacity of the tunnel increases with the rise of the water level in front of the tunnel, and the calculation formula and the dividing point of the orifice width are as follows: When H1 / H0>0.65, the water flow into the hole is a wide-top weir flow, and the change of the orifice width is calculated as follows:

[0053] In the formula: ΔB is the change of the orifice width, m; ΔQ is the change of the design flow, m 3 / s; H0 is the total head above the gate hole bottom plate elevation, m; H1 is the orifice height, m; k is the flow coefficient; ε is the side contraction coefficient of the pier; g is the acceleration of gravity, m / s 2 .

[0054] When H1 / H0≤0.65, the water flow changes from weir flow to gate hole outflow, and the change of the orifice width is calculated as follows:

[0055] In the formula: ΔB is the change of the orifice width, m; ΔQ is the change of the design flow, m 3 / s; H1 is the orifice height, m; H0 is the total head above the gate hole bottom plate elevation, m; μ is the free outflow flow coefficient of the gate hole, for a smooth orifice, μ=0.90.

[0056] 5) Repeat step 4.3) to perform repeated flood regulation calculation until the flood control requirements under the design flood standard of the flood-bearing area are met, and then determine the flood drainage tunnel design parameters.

[0057] 6) Design the flood drainage tunnel based on the flood drainage tunnel design parameters for adaptive regulation of flood.

[0058] The adaptive regulation of flood refers to that in a small-scale flood event, the rapid flood discharge is realized through the free flow discharge function of the flood discharge tunnel; and in a large-scale flood situation, the joint peak regulation mechanism is formed by combining the natural storage capacity of the depression and the tunnel breast wall gate control discharge system, so that the fluctuation of the flood level is flexibly responded, and the flood control safety of the upstream and downstream areas is ensured.

[0059] The gate hole structure of the present application is simple, low in cost, does not need to set a gate, avoids manual scheduling intervention, greatly reduces the response time, the flow in the tunnel is free flow, the flow does not produce the phenomenon of clear full flow alternation, the hydraulic condition is good, the adaptive regulation of different level floods can be realized, the technical bottleneck that the flood in karst area rises steeply and falls steeply and is difficult to accurately schedule is broken through, and the stability and operation reliability of the flood discharge system are significantly improved.

[0060] The advantages of the present application are further illustrated by applying the method of the present application to the flood discharge of the A area karst valley. The structure in Example 1 is used as a flood discharge tunnel in the karst valley area, which is used for flood control and drainage in the A area.

[0061] The A area of the flood discharge area is a karst valley area, and the topographic feature is that the basin is surrounded by mountains on four sides. In order to increase the discharge capacity in the A area, a new flood discharge tunnel is needed to divide the flood in the A area. According to the geographical location and the nearby river system of the A area karst valley, the flood enters the C branch stream in the downstream D town and flows into the B main stream. The A area flood discharge project must also consider the flood control safety of the downstream D town while solving its own drainage problem. That is, in the present example: Flood discharge area: A area; Flood receiving area: D town, and the flood receiving area discharges the B main stream.

[0062] The entrance of the newly built flood discharge tunnel connects the karst valley area of the A area, and the outlet connects the B main stream through the C branch stream.

[0063] 1) Collect the basic data of the flood discharge area and the flood receiving area.

[0064] ① Flood discharge area: storage capacity curve, boundary condition data.

[0065] The boundary condition data includes: Hydrology: the design flood standard of the A area of the flood discharge area is 10-year flood, the total amount of flood under the design flood standard is 6.72 million m 3 , and the flood peak flow is 195 m 3 / s; the natural flood process under the 20-year flood standard.

[0066] Topography: the lowest point of the existing fall hole in the flood discharge area is 809.57 m.

[0067] Living facilities: In the karst valley area of ​​Area A, all rural farmland is located above 817m elevation, all roads are located above 818m elevation, and 90% of the town and scattered residential houses are located above 822m elevation.

[0068] Existing flood drainage facilities: The bottom elevation of the existing flood drainage channels is 810~822m, and the top elevation is 813~824m.

[0069] Existing natural drainage facilities: drawdown tunnels, including karst caves in this area, with a maximum discharge capacity of 40 m³ / h. 3 / s.

[0070] ② Flood-bearing area: Boundary condition data Hydrology: The main stream B is the river that receives floodwaters in the flood-receiving area. The design flood standard is a 20-year flood, and the peak flow under the design flood standard is 823 m³ / h. 3 / s; Existing dikes: The safety height increase value of the B main stream dike project is 0.3m, the calculated value of the dike crest freeboard is 0.78m, the actual dike crest freeboard is 0.80m, the safety margin is 0.02m, and the allowable maximum flood level is 347.60m; Simple flood control measures: Install curb stones or wave walls.

[0071] ③ Drainage tunnel: Proposed to be shaped like a city gate.

[0072] 2) Based on basic data, select the proposed range of the flood discharge area's design inundation water level and explore the reservoir's storage capacity. To avoid disrupting the normal lives of local residents and agricultural production, and to ensure that rural roads are passable, the flood inundation elevation within the flood discharge area must not exceed 818m, i.e., inundation elevation a1=818m; to avoid affecting the personal safety and housing safety of local residents, the flood inundation elevation within the area must not exceed 822m, i.e., inundation elevation a2=822m.

[0073] Based on the reservoir capacity curve for area A, multiple trial values ​​for inundation elevations are proposed within the range of a1 to (a2 + Δa). The corresponding storage capacity for each trial value under the design flood standard of the flood discharge area is then calculated, determining the minimum inundation elevation a3 with storage capacity. Here, Δa represents the excess calculation margin. Δa = 1m, indicating that increasing the inundation elevation by 1m has minimal impact on personal safety.

[0074] The reservoir with a flooding elevation of 817m has a storage capacity of only 28,400 cubic meters. 3 The reservoir capacity at an inundation elevation of a1=818m is only 55,400 m³. 3 It has almost no water storage capacity; the water storage capacity below the flooding elevation a2=822m is 962,600 m³. 3 The reservoir capacity below 821m is 544,700 m³.3 , 823m below the regulation storage capacity of 164.4 million m 3 , all have certain regulation capacity, the minimum submerged elevation a3 = 820m with regulation capacity, the regulation storage capacity below the submerged elevation a3 is 33.6 million m 3 . Then the design submerged water level is determined to be 820-823m.

[0075] 3) Based on the design submerged water level determination range, the design submerged water level of the flood drainage area is calculated through flood regulation calculation, trial calculation, investment comparison, etc., and the design discharge of the flood drainage tunnel and the preliminary parameters of the flood drainage tunnel are calculated.

[0076] Through flood regulation calculation and trial calculation, the design discharge of the flood drainage tunnel is preliminarily determined: the peak flow Q h of the 10-year natural flood process in the area is 195m 3 / s, and the total flood volume is 672 million m 3 , of which the maximum discharge Q x of the karst cave and the flood drainage channel is 44m 3 / s. After fully considering the flood drainage capacity of the karst cave, if the remaining flood volume is discharged by the flood drainage tunnel, the maximum discharge Q s of the flood drainage tunnel is 151m 3 / s. Since there is no regulation storage capacity below the elevation of 818m, the upstream flood is discharged by the karst cave and the flood drainage tunnel, at this time the regulation storage capacity is not fully utilized, and the discharge of the tunnel can still be reduced. The submerged elevations of 820m, 821m, 822m and 823m are selected as the trial values of the design submerged water level, the maximum discharge of the flood drainage tunnel in all calculation periods is calculated under the 10-year flood process in the flood drainage area A, the trial values of the related parameters of the flood drainage tunnel are determined based on the maximum discharge, and the comprehensive cost of the submerged loss and the engineering investment is calculated.

[0077] The results are shown in Table 1. Although the elevation below the submerged elevation of 821m has no submerged loss, the lower the submerged elevation, the maximum investment of the tunnel engineering, which is not economical. The submerged elevation of 823.00m has a larger impact on houses and population, which is contrary to the principle of protecting the objects determined by the construction of the project. The submerged loss + building engineering investment of the scheme with the submerged elevation of 822.00m as the flood level control submerged elevation is optimal, and the influence range is smaller. Therefore, 822m is adopted as the flood level control elevation of the trough valley area, i.e. the design submerged water level, and the maximum discharge of the flood drainage tunnel corresponding to the design submerged water level is adopted as the design discharge of the flood drainage tunnel, i.e. 101m 3 / s.

[0078] Table 1: Influence analysis table corresponding to different design submerged water level trial values

[0079] In the table, P = 10% refers to the design flood standard of 10-year flood.

[0080] Preliminary flood discharge tunnel entrance parapet gate size and discharge capacity Under the condition of 10-year flood standard, the maximum discharge of the tunnel is 101.0 m 3 / s, the size of the parapet gate of the preliminary flood discharge tunnel entrance is 4m x 4.0m (net width x net height), that is, the orifice width B1 = 4m, the orifice height H1 = 4m. The cross-sectional size of the proposed flood discharge tunnel is 4m x 5.0m (net width x net height), the parapet gate is provided with a rectangular air vent with a clear size of 0.8m x 0.8m, the longitudinal slope of the tunnel is designed and the discharge capacity of the tunnel is calculated. With the parameters of the flood discharge tunnel, the maximum discharge under the condition of 20-year flood standard is 109.1 m 3 / s.

[0081] 4) Through the hydrology, topography, and built embankment data of the flood-bearing area, analyze the influence of the superimposed flood discharge tunnel discharge on the flood-bearing area Analyze the flood impact of the superimposed tunnel discharge on the flood-bearing area, and study the feasibility of taking simple measures to eliminate the impact. The downstream D town has completed the flood control revetment project of the town according to the requirements of small and medium river regulation, and the flood control standard of the flood control revetment project is 20 years. The peak flow of B main stream is 823 m 3 / s, of which C tributary is 490 m 3 / s.

[0082] To make the A area housing reach the 10-year flood control standard, the 10-year design flood level of the flood discharge area must be controlled not higher than 822.00m. With the parameters of the flood discharge tunnel, the maximum discharge of the flood discharge tunnel under the condition of 20-year flood standard is 109.1 m 3 / s.

[0083] After the A area flood discharge tunnel discharge under the condition of 20-year flood standard is superimposed with the D town flood in different time periods, the corresponding 20-year maximum peak flow of D town increases from 823 m 3 / s to 854 m 3 / s, and the maximum peak flow of D town B main stream increases by 31 m 3 / s.

[0084] According to the collected basic information, after the implementation of the flood drainage tunnel project in A area, when encountering 20-year flood, the flood level of B main stream river section in D town is raised by 0.11~0.15m compared with before the implementation. The flood control revetment of B main stream in D town is a dike project that allows overtopping, the safety heightening value is 0.3m, the calculated dike top superhigh value is 0.78m, the actual dike top superhigh is 0.80m, the safety margin is 0.02m, and the allowed maximum flood level is 347.60m. Considering the safety margin of 0.02m of the dike top elevation, the water level rise of the river section after the implementation of the project is only 0.09~0.13m higher than the allowed maximum flood level. This problem can be solved by setting kerb on the original dike top of D town on the river side. This scheme has simple engineering measures, small cost, and is easy to be accepted by the flood bearing area.

[0085] Determination of tunnel discharge and balance and precise matching of flood control requirements of discharge area and bearing area: From the above analysis, the influence of A area flood diversion tunnel on D town is small, and simple engineering measures can be taken to eliminate the influence, which meets the governance goal of A area reaching 10-year flood control standard, saves investment, and maximizes the protection of A area population and housing, without affecting the flood control capacity of D town, which is reasonable. This project adopts this scheme.

[0086] Considering the flood regulation calculation after the water drainage tunnel in A area is discharged, the flood level of A area is 821.99m at 10-year flood frequency, and the design discharge of the flood drainage tunnel is finally determined as 101.0m 3 / s.

[0087] 5) Since the design size of the above flood drainage tunnel meets the flood control requirements under the design flood standard of the flood bearing area, step 4) need not be repeated.

[0088] 6) Based on the design parameters of the flood drainage tunnel, the flood drainage tunnel is designed for adaptive regulation of flood.

[0089] Among them, the adaptive regulation is: in small-scale flood events, the self-flowing free discharge function of the flood drainage tunnel is used to realize rapid flood discharge; in large-scale flood conditions, combined with the natural storage capacity of the valley and the automatic control discharge system of the tunnel inlet breast wall type gate, a joint peak regulation mechanism is formed to flexibly respond to the fluctuation of flood level and ensure the flood control safety of the upstream and downstream areas.

[0090] The newly built flood drainage tunnel project can quickly discharge flood into the adjacent basin, which can solve the problem of flood control and drainage in karst valley areas. The storage capacity of the valley terrain and the natural cave flow capacity, the flood bearing capacity of the flood bearing area should be fully considered to reasonably determine the design discharge of the tunnel, so as to avoid directly using the flood flow under the flood control standard as the design flow of the flood drainage tunnel, which may lead to the oversize of the tunnel and further increase the flood control pressure of the flood bearing area.

[0091] As in the specific case described above, the flood control standard of the upstream flood drainage area is 10 years, the downstream flood receiving area is 20 years, and the flood receiving margin is small, so how to effectively control the flood is a challenge to the design. The present application provides a kind of flood drainage tunnel flood self-adaptive regulation design method, which overcomes the weakness of weak operation and scheduling force, high operation cost, and easy to appear clear full flow alternation in tunnel inlet in remote mountainous area, and proposes a kind of multi-objective flood management model, which aims at realizing the accurate matching of flood drainage area and flood receiving area in flood control demand. The innovation of the model lies in its accurate flood control strategy: in small-scale flood events, the self-flow discharge function of the flood drainage tunnel is used to realize rapid flood drainage; in large-scale flood conditions, the natural storage capacity of the groove valley / sink and the automatic control discharge system of the tunnel inlet breast wall gate are combined to form a joint peak regulation mechanism, which can flexibly respond to the fluctuation of flood level and ensure the flood control safety of the upstream and downstream areas. Based on this model, an efficient flood joint regulation system is built, which significantly improves the adaptability and response speed of flood management. The tunnel inlet breast wall gate technology introduced in the design method uses gateless control discharge technology, which optimizes the discharge process by using the dynamics of natural water flow, avoids manual intervention, greatly reduces the response time, and thus enhances the stability and reliability of the flood drainage system.

[0092] The principle of not affecting the safety of most local residents' houses is used to determine the highest submerged water level elevation of the flood drainage area under the design flood standard. The natural storage capacity of the groove valley is used to store flood water, and the tunnel and existing flood drainage facilities (such as flood drainage channels, natural caves, etc.) are used for joint flood discharge to reasonably determine the tunnel design discharge flow.

[0093] In summary, the structure design in the present application is scientific and reasonable, and the flood discharge flow is smooth. By setting a breast wall gate structure at the entrance of the flood drainage tunnel and a vent tube on the top of the gate body, and the vent hole penetrates to the orifice, the air resistance effect and pressure fluctuation in the water inlet process are effectively reduced, ensuring the smooth flow of water in the flood drainage process, avoiding water flow impacting the breast wall gate and tunnel structure, and prolonging the service life of the facility.

[0094] The present application improves the operation safety and reliability of the flood drainage facility. The breast wall gate is a whole reinforced concrete structure with high strength and good rigidity. The smooth orifice can reduce local head loss, prevent water flow turbulence and local scouring, and improve the stability of the structure.

[0095] The present application makes full use of tunnel construction resources and is green and environmentally friendly. Stone backfilling areas are set on both sides of the tunnel body, and the stone generated during the tunnel excavation process is used for backfilling treatment, reducing the amount of discarded stone, realizing the resource utilization of construction waste, and reducing the construction cost and environmental impact.

[0096] The application enhances overall engineering stability and adaptability to complex terrain; the slope support area is arranged, and corresponding support measures are taken, so that the complex and unstable slope conditions in karst areas can be effectively responded, and the collaborative stability of the engineering structure and the geological environment is enhanced.

[0097] The application considers the flood control capacity and flood bearing capacity of the upstream and downstream areas; the flood control capacity of the flood bearing area is considered in the design process, the water level calculation of the river, the safety margin of the dike and the simple flood control measures are combined, so that the tunnel flood discharge does not cause risk transfer in the downstream, and the linkage regulation and control and the collaborative flood control system of the upstream and downstream are realized.

[0098] The application optimizes the comprehensive benefits of engineering investment and submerged loss; by analyzing the storage capacity and loss-investment relationship under different submerged elevations, the submerged water level with the lowest comprehensive cost is selected, so that the scheme has good economy while ensuring the flood control efficiency, and the overall performance-price ratio of the project is improved.

[0099] The calculation method of the application is clear and has strong engineering applicability; the clear gate width adjustment formula and hydraulic calculation logic are adopted, so that the guidance is strong, the practical application and computer program implementation are convenient, and the method can be widely used in flood storage and discharge engineering in complex terrains such as karst areas and mountain valleys.

[0100] The other parts not described belong to the prior art.

[0101] The above description is only the preferred embodiment of the application, and does not limit the patent range of the application, and any equivalent structural transformation made under the inventive concept of the application, or direct / indirect application in other related technical fields is included in the patent protection range of the application.

Claims

1. A flood discharge tunnel for flood control; one end of the tunnel is arranged at a valley area of a flood discharge area, the other end of the tunnel is connected to a downstream flood receiving area to discharge a river, for discharging the flood of the flood discharge area at the entrance to the flood receiving area of the river, characterized in that: The flood discharge tunnel comprises a tunnel body, and a sluice hole fixedly connected with the tunnel body at an entrance; the sluice hole is a breast wall type sluice hole; the sluice hole comprises a sluice hole body which is a plate-shaped structure; an orifice is arranged in the middle of the sluice hole body; a vent cylinder is fixedly connected to the top of the sluice hole body; and a vent hole is arranged through the vent cylinder along the height direction.

2. The flood-relief tunnel of claim 1, wherein: The height of the sluice hole body is not less than the height of the tunnel body at the entrance.

3. The flood-relief tunnel of claim 1, wherein: A trash rack is arranged in front of the side of the sluice hole away from the tunnel body.

4. The flood self-adapting regulation design method of the flood discharge tunnel according to any one of claims 1-3, characterized in that: The method comprises the following steps: 1) collecting basic data of a flood discharge area and a flood receiving area; 2) determining a design flood level range of the flood discharge area under a design flood standard based on the basic data of the flood discharge area; 3) determining a design flood level of the flood discharge area and calculating a design discharge flow of the flood discharge tunnel and preliminary parameters of the flood discharge tunnel by flood regulation calculation, trial calculation and investment comparison based on the design flood level range; 4) determining whether the current parameters of the flood discharge tunnel meet the flood control requirements under the design flood standard of the flood receiving area based on the basic data of the flood receiving area; if yes, determining that the design parameters of the flood discharge tunnel adopt the current parameters of the flood discharge tunnel; if no, reducing the design discharge flow of the flood discharge tunnel, adjusting the parameters of the flood discharge tunnel, and again determining whether the current parameters of the flood discharge tunnel meet the flood control requirements under the design flood standard of the flood receiving area; 5) repeating step 4) to repeatedly perform flood regulation calculation until the parameters of the flood discharge tunnel meet the flood control requirements under the design flood standard of the flood receiving area, and then determining the design parameters of the flood discharge tunnel; 6) designing the flood discharge tunnel based on the design parameters of the flood discharge tunnel for adaptive regulation of flood.

5. The flood-adaptive design method of claim 4, wherein: In step 1), the basic data of the flood discharge area comprises reservoir capacity curve, boundary condition data, and the basic data of the flood receiving area comprises boundary condition data; the boundary condition data of the flood discharge area comprises hydrology, terrain, living facilities, built flood discharge facilities and relevant data of existing natural flood discharge facilities; and the boundary condition data of the flood receiving area comprises hydrology, built embankments and relevant data of simple flood control measures available during flood.

6. The flood-adaptive design method of claim 5, wherein: In the basic data of the flood discharge area, the hydrology-related data comprises natural flood process under the design flood standard; the terrain-related data comprises elevations of karst caves and drop holes and their discharge flows; the living facility-related data comprises elevations of roads, houses and farmlands; the built flood discharge facility-related data comprises elevations of flood discharge channels and their discharge flows; and the relevant data of the existing natural flood discharge facilities comprises discharge flow of drop holes. In the basic data of the flood receiving area, the hydrology-related data comprises rivers in the flood receiving area and their directions and natural flood process under the design flood standard; the relevant data of the built embankments comprises safety heightening value of embankment engineering, embankment top calculation value, actual embankment top superhigh, and highest allowable flood level; and the simple flood control measures comprise setting curb stones or wave walls.

7. The flood-adaptive design method of claim 4, wherein: In step 2), the determination method of the design flood level range comprises the following steps: Based on the basic data of the flood discharge area, determining a flood submerged elevation a1 which does not affect farmland planting and ensures that rural roads have traffic conditions, and a flood submerged elevation a2 which does not affect the safety of houses; Based on the reservoir capacity curve, a plurality of trial values of the submerged elevation in the submerged elevation range a1~(a2+Δa) are determined, and the regulation and storage capacity corresponding to each trial value of the submerged elevation under the design flood standard of the flood drainage area is calculated to determine the minimum submerged elevation a3 with regulation and storage capacity; wherein Δa is an excess calculation allowance; The submerged elevation range a3~(a2+Δa) is selected as the design submerged water level determination range.

8. The flood-adaptive design method of claim 4, wherein: Step 3) comprises: A plurality of design submerged water level trial values are determined in the design submerged water level determination range; Based on the flow capacity of the existing flood drainage facility, the maximum discharge of the flood drainage tunnel and the flood drainage tunnel related parameter trial value corresponding to each design submerged water level trial value under the design flood standard of the flood drainage area are calculated; The submerged loss and the comprehensive cost of engineering investment corresponding to the design submerged water level trial value under the design flood standard of the flood drainage area are calculated; The design submerged water level trial value that makes the submerged loss and the comprehensive cost of engineering investment the lowest is selected as the design submerged water level of the flood drainage area, and the corresponding maximum discharge of the flood drainage tunnel is selected as the design discharge of the flood drainage tunnel, and the flood drainage tunnel related parameter trial value is selected as the flood drainage tunnel related parameter.

9. The flood-adaptive design method of claim 4, wherein: In step 3), the flood drainage tunnel related parameters include gate size, tunnel discharge capacity, gate vent size, and tunnel size.

10. The flood-adaptive design method according to any one of claims 4-9, wherein: In step 4), the flood control requirement under the design flood standard of the flood receiving area is that the flood receiving area can withstand the flood of the flood receiving area and the discharge of the flood drainage tunnel under the design flood standard of the flood receiving area without taking measures or by increasing simple measures.

11. The flood-adaptive design method of claim 10, wherein: Step 4) comprises the following steps: Determining the maximum flood peak flow Q of a natural flood process under a design flood standard of a flood-bearing area max ; Based on the preliminary parameters of the flood drainage tunnel, the maximum flood peak flow Q of the flood-bearing area when the flood-bearing area and the flood drainage area encounter the design flood standard of the flood-bearing area is calculated, and the water level of the flood-bearing area at this time is determined. max ' Determine whether the water level of the flood receiving area exceeds the maximum flood level allowed by the existing dike engineering; if not, determine that the flood drainage tunnel design parameters use the current calculated flood drainage tunnel parameters; if so, determine whether simple flood control measures can meet the design flood control standard, if the simple flood control measures can meet the design flood control standard, determine that the flood drainage tunnel design parameters use the current calculated flood drainage tunnel parameters, if the simple flood control measures still cannot meet the design flood control standard, adjust the flood drainage tunnel related parameters.

12. The flood-adaptive design method of claim 11, wherein: The adjustment method of the flood drainage tunnel related parameters comprises: based on the current calculation orifice width plus the change of the orifice width, the adjusted orifice width is obtained; the change of the orifice width is calculated according to the design flow variation of the tunnel, and the calculation formula is as follows: When H1 / H0>0.65, the change of the orifice width is calculated as follows: ， Where: ΔB is the change of the orifice width, m; ΔQ is the change of the design flow of the tunnel, m 3 / s; H0 is the total head above the elevation of the gate bottom, m; H1 is the height of the orifice, m; k is the flow coefficient; ε is the side contraction coefficient of the gate pier; g is the acceleration of gravity, m / s 2 ; When H1 / H0≤0.65, the change of the orifice width is calculated as follows: When H1 / H0≤0.65, the change of the orifice width is calculated as follows: ， where: ΔB is the change of the orifice width, m; ΔQ is the change of the design flow of the tunnel, m3 / s; H1 is the height of the orifice, m; H0 is the total head above the elevation of the bottom plate of the orifice, m; and μ is the free outflow flow coefficient of the orifice. 3 / s; H1 is the height of the orifice, m; H0 is the total head above the elevation of the bottom plate of the orifice, m; and μ is the free outflow flow coefficient of the orifice.

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