Ecological stilling pool

Abstract

The utility model relates to the technical field of hydraulic facilities, and discloses an ecological stilling pool which is characterized in that a left side wall or a right side wall or an original riverbed structure is arranged along a riverway, and a pool entering drop sill, a compound trapezoidal section stilling sill and a short weir tail sill are sequentially arranged between the left side wall and the right side wall or the original riverbed structure from upstream to downstream; a first-stage stilling pool is arranged between the pool entering drop sill and the compound trapezoidal section stilling sill, a second-stage stilling pool is arranged between the compound trapezoidal section stilling sill and the short weir tail sill, and bottom plates of the first-stage stilling pool and the second-stage stilling pool are natural riverbeds. According to the stilling pool, the three-stage structural bank is adopted, the two-stage stilling pool with the natural riverbed as the bottom is formed, the problems that damage of a stilling pool apron endangers safety and energy dissipation is insufficient are solved, the uncertainty evolution of a downstream river channel is improved and adapted, the engineering amount is small, construction is easy and economical, and the energy dissipation effect of a riverbed covering layer is fully utilized; and the problem of ecological migration of fishes caused by undercutting of the river channel can be solved by combining the arrangement of the existing fishway or fish guide channel.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of hydraulic facilities, especially relates to an ecological stilling basin. BACKGROUND

[0002] The southwest region of China is rich in water energy resources, with the rapid development of water conservancy projects and the improvement of dam building technology in China, more and more high dam hubs have been built and put into operation. However, the deep overburden layer is generally developed in the rivers of the region, and the engineering properties of the stratum are poor. During the operation of the power station, the overburden layer of the downstream riverbed is subjected to flushing by clear water all year round, and the riverbed incision is significant.

[0003] The evolution of the main riverbed of the downstream river channel of the power station due to long-term sand mining and riverbed scouring, combined with the scouring of floodwater during the flood season and the interception of sediment supply by the gate dam, has caused great changes in the boundary conditions and flow pattern of the river channel. This leads to an increase in the water level difference between the upstream and downstream of the flood discharge and sand flushing gate, the water flow cannot be smoothly connected, and a drop is formed at the end of the sea flat, which cannot form a submerged hydraulic jump energy dissipation flow pattern, and the energy dissipation is not sufficient. The operating conditions are worse than the original design conditions, which may further cause serious scouring damage and even threaten the safety of the main structures. Due to the large foundation permeability coefficient at the dam site, the problem of permeation damage is more prominent. This includes uneven settlement of the dam body foundation after the operation of the power station, which causes some gates to be unable to open normally; and the overburden layer foundation below it is subjected to washing and even partial hollowing. Under such circumstances, with the passage of time, not only will the scouring of the downstream riverbed be intensified, but also the safety operation of the upstream related structures and even the dam may be threatened.

[0004] Under the influence of natural evolution and strong human activities (hydropower, river hub construction and river sand mining, etc.), the mountainous river channels of the Minjiang River (Daduhe River, Qingyi River), Fujiang River and Tuojiang River in the upper reaches of the Yangtze River suddenly and sharply eroded, and the flood washed away bridges and river weirs (gates), threatening the safety of hydropower hubs, river weirs (gates) and railway and highway bridges.

[0005] Through consulting and summarizing relevant literature, combined with the actual situation of the sea flat of the stilling basin in the project, the adopted regulation engineering scheme is summarized as a conventional stilling basin scheme. The conventional stilling basin scheme, i.e. the artificially constructed stilling basin, corresponds to a series of engineering measures for energy dissipation, such as the addition of a downstream stilling basin (growth), the increase of energy dissipation works (energy dissipation sill, energy dissipation pier) or the heightening of the tail sill of the stilling basin.

[0006] Prior art one

[0007] On the basis of the original stilling basin energy dissipation, one or more stages of stilling basin are added to the damaged sea flat section to increase the energy dissipation effect and the structural safety protection effect on the upstream structure. The problem of drop at the end of the sea flat can be temporarily solved, and the energy of the discharged water flow in the added stage of stilling basin is killed, which plays a certain role in energy dissipation and anti-scouring.

[0008] The defects of the prior art one are as follows:

[0009] Because the problem of the downstream river channel incising and the main flow of the downstream river channel being biased to one side bank is not solved, when the flood frequency is high and the flood peak flow is large, the newly added first-stage stilling basin has a great risk of further damage. Although the stilling basin operates independently, the energy dissipation is not sufficient, the problem of the original building facilities being scoured due to the sharp incision of the downstream river channel is not fundamentally solved, the direct investment of the technology project is relatively large, the deep foundation pit excavation may cause piping seepage damage and bring safety risks, the strong pumping of the downstream water during the construction period may increase seepage and lower the dam area phreatic line, and the overall safety and stability of the dam body may be threatened. Meanwhile, the scheme has large temporary engineering quantity and large construction difficulty, the seepage control of the construction foundation pit is not easy to control, the water pumping capacity is large, and the quality of underwater concrete pouring is difficult to guarantee. The large-area construction of the entire river section where the conventional stilling basin is located has a great impact on the river bed and ecology, under the condition of the ecological flow of the downstream fish migration period of the water conservancy project hub, the flow velocity in the stilling basin is very small, and the conventional stilling basin forms a blocking effect in the fish upstream channel, which brings great difficulty to the layout or reconstruction of the fishway. Content of the utility model

[0010] The technical problems to be solved by the utility model are as follows:

[0011] 1. The prior art has the problem of insufficient energy dissipation;

[0012] 2. The existing stilling basin construction has the problem of water pumping, and the water pumping further intensifies the scouring and suspension of the lower part of the overtopping stilling basin, seriously threatens the stability and safety of the overtopping stilling basin and even the dam, and may even lead to dam breach; the construction period is long and cannot guarantee completion in one dry period;

[0013] 3. The existing stilling basin cuts off the fish migration channel of the original downstream river channel, the water level difference between the upstream and downstream of the end of the stilling basin is increased, a long detour to the suitable fishway inlet position downstream of the stilling basin needs to be added for the extension of the fishway, the technical improvement difficulty of the fishway is greatly increased, and the investment is also greatly increased;

[0014] 4. The existing technology temporarily solves the problems of reinforcement and danger removal of damaged buildings and energy dissipation, but when the downstream river channel further incises and evolves, the existing conventional stilling basin will be further damaged and the safety of the hub building will be threatened.

[0015] The purpose of the utility model is to provide an ecological stilling basin, which only needs to be constructed in a small range of three structure steps (pool drop, compound trapezoidal cross-section stilling step and low weir tail step), the original river bed ecology is maximally protected, and the safe, economic, fast and environmentally-friendly practical improvement scheme completely solves or alleviates the above technical problems.

[0016] The utility model provides the following technical scheme:

[0017] An ecological type stilling basin is arranged in a natural riverbed downstream of a hydraulic structure, and left and right side walls or a former riverbed structure are arranged along a river channel, and an inlet drop, a compound trapezoidal cross-section stilling block and a low weir tail sill are sequentially arranged from upstream to downstream between the left and right side walls or the former riverbed structure, a first stilling basin is formed between the inlet drop and the compound trapezoidal cross-section stilling block, a second stilling basin is formed between the compound trapezoidal cross-section stilling block and the low weir tail sill, and the bottom plates of the first and second stilling basins are all natural riverbeds.

[0018] According to some embodiments, a flow guide platform for preventing scouring is connected in a downstream direction of the drop under the inlet drop.

[0019] According to some embodiments, the compound trapezoidal cross-section stilling block is a compound trapezoidal cross-section structure simulating a riverbed, and the middle part is a lower platform or a former river channel cross-section, which gradually increases towards both sides.

[0020] According to some embodiments, the low weir tail sill is a horizontal weir body, the width of which is smaller than that of the compound trapezoidal cross-section stilling block, and the height of the low weir tail sill is equal to or close to the middle part of the compound trapezoidal cross-section stilling block.

[0021] According to some embodiments, the low weir tail sill is surrounded by natural riverbeds on both sides and upstream and downstream.

[0022] According to some embodiments, the length of the first stilling basin along the river is greater than the length of the second stilling basin along the river.

[0023] According to some embodiments, the left and right side walls are newly built, former riverbed bank slopes or former structure surfaces.

[0024] Compared with the prior art, the utility model has the following beneficial effects:

[0025] 1. The utility model solves the problem of insufficient energy dissipation in the prior art. The compound trapezoidal cross-section stilling block used in the middle part of the stilling basin formed by the inlet drop and the low weir tail sill in the natural riverbed makes the stilling basin form two-stage natural riverbeds as the bottom, solves the problems of damage and insufficient energy dissipation of the upstream stilling basin, improves and adapts to the uncertainty evolution of the downstream river channel, reduces the engineering quantity, is simple and economical to construct, fully utilizes the energy dissipation effect of the riverbed covering layer, and realizes relatively effective flood discharge and energy dissipation with the simplest engineering measures under the condition of changing the actual conditions of the river channel in a small range.

[0026] 2. The ecological stilling basin construction of the utility model technical scheme does not involve pumping problem, does not affect the existing safety condition of the stilling basin sea flat and project hub; the construction period is short, and the completion can be ensured in a dry period. The engineering quantity and engineering investment are obviously reduced after calculation.

[0027] 3. The conventional stilling basin cuts off the fish migration channel of the original downstream river channel.

[0028] The stilling sill of the technical scheme is a trapezoidal compound section, the bottom is smoothly connected with the original riverbed bottom, the middle bottom of the structure of the trapezoidal section is extended to the left and right sides and gradually raised to simulate the natural riverbed section, even in the case of releasing ecological flow in the dry period, the natural migration channel can be created for fish, the main flow can be guided to the middle of the riverbed to reduce the scouring kinetic energy of the two banks, and the buildings on the two banks are protected. The ecological flow released in the dry period also meets the requirements of fish migration.

[0029] 4. When the downstream river channel further develops sharp incision evolution, the conventional stilling basin will be further damaged and the safety of the hub building will be endangered.

[0030] The technical scheme adopts the "ecological stilling basin combined with downstream stepped fixed-bed weir", solves the reinforcement and danger removal of damaged buildings and the energy dissipation problem, improves the sharp evolution of the downstream river channel through the stepped fixed-bed weir, and finds through years of operation that the uncertainty of the downstream river channel evolution can be adapted, and a long-term solution to the safety, economy and applicable scheme of the damaged project is provided. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The structure schematic view of the ecological stilling basin provided by the utility model embodiment is shown.

[0032] In the drawing:

[0033] The pool drop 1, the left side wall 2, the right side wall 3, the first stage stilling basin 4, the second stage stilling basin 5, the low weir tail sill 6, the compound trapezoidal section stilling sill 7. DETAILED DESCRIPTION

[0034] The utility model is described in detail in combination with the embodiments and the drawings, but it should be understood that the embodiments and the drawings are only used for exemplarily describing the utility model, and cannot constitute any limitation on the protection scope of the utility model. All reasonable changes and combinations included in the utility model purpose range of the utility model fall into the protection scope of the utility model.

[0035] In the description of the utility model, it needs to be explained that, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "front", "back" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, and thus cannot be understood as limiting the utility model; the terms "first", "second" and "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance, and in addition, unless otherwise explicitly specified and limited, the terms "setting", "mounting", "connection", "connection" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or electrically connected; it can be directly connected, or indirectly connected through an intermediate medium, or it can be connected inside two elements. For ordinary skilled persons in the art, the specific meanings of the above terms in the utility model can be understood according to the specific circumstances.

[0036] The utility model will be further described below with reference to the drawings.

[0037] Embodiment 1

[0038] As Figure 1 , the ecological type stilling basin provided by the embodiment comprises three parts between the left side wall 2 and the right side wall 3, from the upstream to the downstream river channel direction, the three parts comprise a pool-in drop 1, a compound trapezoidal cross-section stilling sill 7 and a low weir tail sill 6, the pool-in drop 1 and the compound trapezoidal cross-section stilling sill 7 are connected to form a first-stage stilling basin 4, and the compound trapezoidal cross-section stilling sill 7 and the low weir tail sill 6 are connected to form a second-stage stilling basin 5; the first-stage and second-stage stilling basins are both natural river bed cover layers; the left side wall 2 and the right side wall 3 are respectively built on the left and right sides of the river bed, and can also be the original river bed bank slope or the original structure surface without the requirement of anti-scour.

[0039] The pool-in drop 1 is connected to a flow guide platform in the downstream direction, the flow guide platform has a certain guiding effect on the water flow direction of the pool-in drop for preventing scouring of the pool-in drop and the upstream; the compound cross-section structure stilling sill 7 has a trapezoidal compound cross-section structure in the horizontal direction; the low weir tail sill 6 is a conventional horizontal weir body arranged at the bottom of the river bed; the bottom plates of the first-stage and second-stage stilling basins are natural river beds, not artificially created.

[0040] The pool-in drop 1 is connected to a flow guide platform below, which is made of reinforced concrete. The main function is to prevent further scouring damage to the upstream structure, and sufficient embedding depth can play a safety protection role for the upstream flood discharge and energy dissipation facilities and even the entire dam hub; and the water flow is guided into the stilling basin to form a bottom flow energy dissipation flow state.

[0041] The complex trapezoidal cross-section bucket 7 is a trapezoidal complex cross-section structure imitating riverbed, with a deep groove in the middle and gradually increasing to both sides, and is made of reinforced concrete. The main function is to provide energy dissipation water cushion in the pool, which can adapt to various flow rates to achieve full energy dissipation effect, and play a regulating role. At the same time, the middle bottom of the trapezoidal complex cross-section guides the main flow of the river to the middle of the riverbed, reducing the erosion of both banks (especially the right bank), and the middle lower part smoothly connects with the natural riverbed, maintaining the continuity of fish migration channels during dry season.

[0042] The low weir tail bucket 6 is a conventional horizontal weir body arranged at the bottom of the riverbed, with a width smaller than the complex trapezoidal cross-section bucket 7, and a height close to or equal to the lowest point of the complex trapezoidal cross-section bucket 7, and is made of reinforced concrete. The erosion base level of the downstream river section acts as a fulcrum, which plays a role in raising the upstream water level and intercepting upstream sediment, and the water level and riverbed incision process along the way will change compared with the natural incision river, which can repair and improve the sharp evolution of the downstream riverbed to a certain extent.

[0043] The bottom plate of the primary and secondary energy dissipation pool is the natural riverbed, and the length of the primary energy dissipation pool 4 is greater than that of the secondary energy dissipation pool 5, and the low weir tail bucket 6 is also a natural riverbed. The main function is to utilize the energy dissipation effect of the riverbed cover layer; the natural riverbed and the trapezoidal complex cross-section smoothly connect, ensuring the fish migration channel during the discharge of ecological flow. The use of natural riverbed instead of artificial construction can greatly reduce the engineering quantity, and the construction is simple and economical.

[0044] The present embodiment forms a large multi-stage energy dissipation pool through the pool drop 1, the complex trapezoidal cross-section bucket 7 and the low weir tail bucket 6, and the original natural riverbed. The complex trapezoidal cross-section bucket 7 plays a role of connecting the upper and lower stages, and the reasonable optimization of its cross-sectional shape and the water storage of the low weir tail bucket 6 make the ecological energy dissipation pool form upper and lower stage water jump energy dissipation effects, which can adapt to automatic adjustment of ecological flow to large flood to reasonably and safely distribute energy dissipation of the upper and lower stages, and fully utilize the energy dissipation effect of the original riverbed cover layer, while maximizing the protection of the natural properties of the riverbed to provide a natural ecological channel for fish migration; if the riverbed has a further tendency to incise in the later period, a number of conventional dam bodies or embankments (simple construction) can be arranged at appropriate positions downstream according to the site conditions to further strengthen the safety protection.

[0045] In water conservancy and hydropower engineering, when the power station outlet is far away from the main hub, the present ecological energy dissipation pool can successfully combine with the existing fishway and fish guide channel layout, so that the problem of fish ecological migration caused by river incision is perfectly solved, and the engineering quantity is small and the investment is saved.

[0046] The above embodiments are only preferred embodiments of the present application, and the protection scope of the present application is not limited to the above embodiments. Any technical scheme falling within the concept of the present application belongs to the protection scope of the present application. It should be pointed out that, for ordinary skilled in the art, improvements and refinements without departing from the principles of the present application, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. An ecological stilling basin provided in a natural riverbed downstream of a hydraulic structure, characterized in that: The left and right side walls are arranged along the river channel or the original riverbed structure, and the pool-in drop, the compound trapezoidal cross-section stilling basin and the low weir tail sill are sequentially arranged from the upstream to the downstream between the left and right side walls, the pool-in drop and the compound trapezoidal cross-section stilling basin are a first-stage stilling basin, the compound trapezoidal cross-section stilling basin and the low weir tail sill are a second-stage stilling basin, and the bottom plates of the first-stage and second-stage stilling basins are the natural riverbeds.

2. The ecological stilling basin according to claim 1, characterized in that: The pool-in drop is connected with a flow guide platform in the downstream direction to prevent scouring.

3. The ecological stilling basin according to claim 2, characterized in that: The compound trapezoidal cross-section stilling basin is a compound trapezoidal cross-section structure in imitation of the riverbed, and the middle part is a lower platform or an original river channel cross-section which gradually increases in height towards both sides.

4. The ecological stilling basin according to claim 3, characterized in that: The low weir tail sill is a horizontal weir body, and the width of the low weir tail sill is smaller than that of the compound trapezoidal cross-section stilling basin, and the height of the low weir tail sill is equal to or close to the middle part of the compound trapezoidal cross-section stilling basin.

5. The ecological stilling basin according to claim 4, characterized in that: The low weir tail sill is surrounded by the natural riverbeds in the upstream and downstream directions and on both sides.

6. The ecological stilling basin according to claim 1, characterized in that: The length of the first-stage stilling basin along the river is greater than the length of the second-stage stilling basin along the river.

7. The ecological stilling basin according to any one of claims 1 to 6, characterized in that: The left and right side walls are newly built, the original riverbed bank slopes or the original structure surfaces of the buildings.

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