A flood discharge energy dissipation structure for alleviating the impact of water flow impact vibration on high dam chamber

Abstract

The present invention discloses a flood discharge and energy dissipation structure for mitigating the impact of water flow impact vibration in a high dam chamber, comprising a first-level energy dissipation pool, a second-level energy dissipation pool and a tail sill which are sequentially arranged downstream of a sluice chamber, a flat-bottomed nose sill is adopted for the outlet nose sill at the end of the sluice chamber, a vertical drop sill is arranged at the head of the first-level energy dissipation pool, a continuous energy dissipation sill with a water-facing surface upright is arranged at the tail of the first-level energy dissipation pool, and the continuous energy dissipation sill is located 1 to 2 meters upstream of the critical point position of the submerged water jump in the first-level energy dissipation pool when the downstream low water level is in operation control condition. The present invention controls and guides the downstream water flow by adjusting the shape of the outlet structure, firstly controls the formation of a far-drive water jump away from the sluice chamber when the downstream low water level is in operation, and then forms a critical or slightly submerged water jump for energy dissipation, which not only meets the requirements of structural safety and normal use function, but also has good economic efficiency, and has good demonstration and reference significance for the design of other similar projects.

Description

Technical Field

[0001] The invention relates to a flood discharge and energy dissipation structure, in particular to a flood discharge and energy dissipation structure for alleviating the impact of water flow impact vibration on a high dam chamber. Background Art

[0002] The flood discharge and energy dissipation of sluice projects generally adopt the bottom flow energy dissipation method, relying on the formation of water jump to eliminate water energy. The gate scheduling and operation mode of multi-hole and high dam projects with large single-width flow, low Froude number, large upstream and downstream water level fluctuations are complex, and the water level boundary conditions during operation are also relatively complex. In the conventional bottom flow energy dissipation design, in order to minimize the length of the energy dissipation pool to save engineering volume, part of the energy dissipation area is often located in the inner area of ​​the gate chamber. When the gate is partially opened, single-hole or few-hole operation, the energy in this range is relatively concentrated. In addition, the energy dissipation rate of the bottom flow energy dissipator is low, and the flow rate in the pool is high, which makes the water flow turbulence in the energy dissipation area of ​​the gate chamber more intense. In particular, when the pulsating pressure caused by water flow turbulence acts on hydraulic structures such as high dams and multi-hole gates with large gate pier heights and relatively thin gate pier structures, it often induces water flow impact vibrations in the structure, resulting in a large deformation amplitude in the upper part of the structure, affecting the safe operation of the structure. When the downstream tailwater is low, it is more difficult to form a stable water jump in the bottom flow stilling pool. The energy dissipation rate is low and cannot meet the energy dissipation requirements. It also aggravates the impact of water flow impact vibration on the gate chamber. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a flood discharge and energy dissipation structure which has a simple structure, good economy, low requirements on construction technology and is relatively convenient to construct and can mitigate the impact of water flow impact vibration in the gate chamber of a high gate dam.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a flood discharge and energy dissipation structure for mitigating the impact of water flow impact vibration in a high dam chamber, comprising a first-level energy dissipation pool, a second-level energy dissipation pool and a tail sill arranged in sequence downstream of the sluice chamber, a flat-bottomed nose sill is adopted for the outlet nose sill at the end of the sluice chamber, a vertical drop sill is arranged at the head of the first-level energy dissipation pool, and a continuous energy dissipation sill with an upright water-facing surface is arranged at the tail of the first-level energy dissipation pool. The continuous energy dissipation sill is located 1 to 2 m upstream of the critical point position of the submerged water jump occurring in the first-level energy dissipation pool when the downstream low water level operation control condition is in progress.

[0005] The flat bottom nose sill and the vertical drop sill make the downstream a low water level operation control condition, and the downstream water flow jump is located outside the sluice chamber.

[0006] The continuous stilling sill adopts a trapezoidal section upright on the water-facing surface, with a height of 3 to 5 m, and a top elevation 0.5 to 1 m higher than the top elevation of the tail sill of the secondary stilling pool.

[0007] The single width flow rate of the downstream water flow in the flood discharge and energy dissipation structure is 150-200m 3 / s, the Froude number in the pool is 1-2, the flow velocity is 14-20m / s, the lock chamber height is 30-50m, and the cross-river thickness of the lock chamber structure is 3-6m.

[0008] The beneficial effects of the present invention are as follows: it breaks the design concept of adopting conventional bottom flow energy dissipation outlet section to immediately form a submerged water jump for energy dissipation in the energy dissipation design of general sluice projects, and controls and guides the downstream water flow by adjusting the nose sill and the drop sill shape of the gate chamber outlet. First, it controls the formation of a long-drive water jump away from the gate chamber when the downstream low water level runs, and then forms a critical or slightly submerged water jump for energy dissipation. It not only meets the requirements of structural safety and normal use function, but also has good economy, and has good demonstration and reference significance for the design of other similar projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 The present invention is a schematic cross-sectional view of a flood discharge and energy dissipation structure for alleviating the impact of water flow impact vibration on a high dam chamber.

[0010] In the figure:

[0011] 1 – sluice chamber;

[0012] 2——First-level stilling pool;

[0013] 3——Flat nose;

[0014] 4 – vertical fall;

[0015] 5——Continuous energy dissipation sill;

[0016] 6——Secondary stilling pool;

[0017] 7——Tail sill. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0019] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0020] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "mounted / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] like Figure 1 As shown, the flood discharge and energy dissipation structure for mitigating the impact of water flow impact vibration in a high dam chamber of the present invention comprises a first-level energy dissipation pool 2, a second-level energy dissipation pool 6 and a tail sill 7 which are sequentially arranged downstream of a sluice chamber 1. The nose sill at the end outlet of the sluice chamber 1 adopts a flat nose sill 3, a vertical drop sill 4 is arranged at the head of the first-level energy dissipation pool 2, and a continuous energy dissipation pool 5 with a water-facing surface upright is arranged at the tail of the first-level energy dissipation pool 2. The continuous energy dissipation pool 5 is located 1 to 2 m upstream of the critical point position where a submerged hydraulic jump occurs in the first-level energy dissipation pool 2 when the downstream low water level operation control condition is in progress.

[0022] The flat nose sill 3 and the vertical drop sill 4 make the downstream a low water level operation control condition, and the downstream water flow jump is located outside the sluice chamber 1.

[0023] The continuous stilling sill 5 has a trapezoidal cross section with a water-facing surface upright, a height of 3 to 5 m, and a top elevation 0.5 to 1 m higher than the top elevation of the tail sill 7 of the secondary stilling pool.

[0024] The single width flow rate of the downstream water flow in the flood discharge and energy dissipation structure is 150-200m 3 / s, the Froude number in the pool is 1-2, the flow velocity is 14-20m / s, the lock chamber height is 30-50m, and the cross-river thickness of the lock chamber structure is 3-6m.

[0025] The outlet nose sill at the end of the lock chamber adopts a flat nose sill, and the drop sill at the head of the pool is a vertical drop sill. The combination of the two makes the downstream low-water-level control condition form a far-driven water jump, so that the head of the downstream water flow jump is located on the downstream side outside the lock chamber; a continuous stilling sill is set in the energy dissipation pool downstream of the lock chamber to form a primary stilling pool and a secondary stilling pool. The layout position of the continuous stilling sill should make the water flow in the primary stilling pool have a critical or slightly submerged water jump; by setting a flat nose sill at the end of the lock chamber and a vertical drop sill at the head of the stilling pool, the control condition of the downstream low-water-level operation forms a far-driven water jump, the water jump is moved downstream, pushed out of the lock chamber, and energy is dissipated behind the lock chamber, so as to reduce the strong turbulence of the water flow in the lock chamber and slow down the impact of the water flow on the tall and thin gate pier structure. By setting a continuous stilling sill upright on the water-facing surface at the front section of the stilling pool, a critical or slightly submerged water jump is formed in the primary stilling pool to facilitate energy dissipation. In order to control the secondary drop of water caused by excessive height of the stilling sill or unreasonable shape setting, and avoid excessive increase of energy in secondary energy dissipation protection, the height of the stilling sill and the shape of the water-facing surface are controlled. The residual energy after the first energy dissipation is further dissipated by the secondary stilling pool behind the stilling sill to achieve the energy dissipation target.

[0026] The following is a detailed description with reference to specific embodiments:

[0027] In a large hydropower station project, the main hub building consists of a concrete dam and a riverbed powerhouse. From left to right, they are arranged in sequence: installation room, powerhouse main engine room, left guide wall connecting dam section, left 5-hole sand flushing flood gate, right guide wall connecting dam section, right 7-hole sand flushing flood gate, right bank non-overflow dam section, etc. The flood gate pier is 5m wide, the net width of a single hole is 14m, the maximum height of the gate pier at the end of the gate chamber is 37.5m, and the designed peak flow rate for a century is 27,500m 3 / s, the millennium verified peak flow is 32600m 3 / s. The principle of opening the gates of the water discharge structure is to open the left five-hole sand flushing flood discharge gate first, and then open the right seven-hole sand flushing flood discharge gate. Therefore, the left five-hole sand flushing flood discharge gate is used more frequently and is the focus of downstream protection. When the left 5-hole sand flushing flood discharge gate is partially opened, single-hole or few-hole operation, the single-width flow is large, the energy is concentrated, the flow velocity is high, the water flow in the gate chamber is strongly turbulent, and the first-order fundamental frequency of the gate pier under the wet mode is about 2.0Hz, which is close to the fundamental frequency of the transverse oscillation vibration mode of the gate structure, and the coupled vibration of the structure is prone to occur; at the same time, under this operating condition, due to the large fluctuation of the upstream and downstream water levels, the single-width flow rate entering the energy dissipation pool varies greatly, and the Froude number is low. When conventional bottom flow energy dissipation is adopted, the energy dissipation pool has poor adaptability and it is difficult to form a stable water jump flow state. The water flow state is poor, the energy dissipation rate is low, and the water flows out of the tail sill of the energy dissipation pool in the form of a torrent. The flow velocity out of the energy dissipation pool is 6-11m / s, which is greater than the bedrock anti-scouring flow velocity. There is a relatively serious scouring problem in the range of about 80m behind the tail sill.

[0028] The design of the downstream energy dissipation and anti-scouring structure must not only meet the requirements of downstream energy dissipation and anti-scouring, but also try to slow down the impact of the downstream water flow on the gate pier's slap vibration. In order to reduce the strong turbulence of the water flow in the gate chamber and slow down the impact of the water flow on the tall and thin gate pier structure, it is necessary to control and guide the downstream water flow, send it out of the gate chamber as smoothly as possible, and at the same time migrate the water jump downstream and push it out of the gate chamber. Therefore, a structural type of a combination of a flat nose sill + a vertical drop sill is proposed, the purpose of which is to ensure that the control condition of the downstream low water level operation is to form a far-driven water jump: a flat nose sill is set at the end of the gate chamber to ensure the smooth discharge of the water flow; a vertical drop sill is set at the head of the energy dissipation pool to form a far-driven water jump, and the jump head is pushed out of the gate chamber section. After adopting the above structural setting, although the impact of the gate chamber water flow slap vibration is slowed down, the energy is pushed to the downstream energy dissipation pool. In order to solve the problem of water flow energy dissipation after the gate is discharged, while at the same time improving the energy dissipation rate as much as possible, slowing down the surface fluctuation of the water flow, reducing the length of the energy dissipation pool, and reducing the amount of protective engineering, a continuous energy dissipation sill with a vertical water surface is set up at the front of the energy dissipation pool to raise the water level and form a first-level energy dissipation pool. The layout position of the energy dissipation sill should make the water flow in the first-level energy dissipation pool have a critical or slightly submerged water jump. In order to dissipate the energy of the downstream water flow as quickly as possible, the height of the energy dissipation sill is increased to increase the volume of the energy dissipation water body. However, in order to avoid the secondary drop of the water flow caused by the excessive height of the energy dissipation sill, which causes the energy of the secondary energy dissipation protection of the secondary energy dissipation pool to increase too much, the height of the energy dissipation sill needs to be controlled. At the same time, the hydraulic model test verifies that the water surface of the top of the sill after the vertical surface of the continuous energy dissipation sill is slightly lower than that of the slope surface, which is also conducive to reducing the secondary drop of the water flow behind the energy dissipation sill. The residual energy after the first energy dissipation is further dissipated by the secondary energy dissipation pool behind the energy dissipation sill to achieve the energy dissipation target. Taking into account the connection between the outlet water flow of the tail sill of the secondary stilling pool and the downstream water level, the coordination of the height of the stilling sill of the first-level stilling pool and the tail sill of the secondary stilling pool, and the energy required to dissipate energy in the secondary stilling pool is lower than that of the first-level stilling pool, the elevation of the stilling sill and the tail sill top should not differ much, and the elevation of the tail sill top of the secondary stilling pool should be slightly lower than that of the stilling sill of the first-level stilling pool by 0.5 to 1m.

[0029] Engineering practice shows that the structure described in the present invention is aimed at high dam projects with large single-width flow, low Froude number, and large upstream and downstream water level fluctuations. By setting a flat-bottomed nose sill, a vertical drop sill, a first-level energy dissipation pool, and an upstream upright continuous energy dissipation sill, followed by a combined structural type of a secondary energy dissipation pool, the downstream water flow must first form a remote-driven water jump with a controlled flow rate, and push the water flow energy out of the downstream side of the gate chamber, thereby avoiding or mitigating the impact of the downstream water flow on the gate chamber water flow vibration, and also allowing the energy of the remote-driven water jump to be controlled. Then, a continuous energy dissipation sill with a controlled sill height is set in the energy dissipation pool to dissipate the energy for the first time, thereby improving the energy dissipation rate and controlling the energy of the secondary energy dissipation protection, thereby shortening the length of the entire energy dissipation pool and reducing the amount of protection engineering. This type of energy dissipation structure breaks the design concept of general sluice project energy dissipation design that adopts the conventional bottom flow energy dissipation outlet section to immediately form a submerged water jump for energy dissipation. By adjusting the shape of the outlet structure, the downstream water flow is controlled and guided to first form a long-drive water jump away from the gate chamber, and then form a critical or slightly submerged water jump for energy dissipation. This meets the requirements of structural safety and normal use functions, and at the same time has good economy. It has a good demonstration and reference significance for the design of other similar projects.

[0030] The embodiments described above are only used to illustrate the technical ideas and features of the present invention, and their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. The patent scope of the present invention cannot be limited only by these embodiments, that is, any equivalent changes or modifications made to the spirit disclosed by the present invention still fall within the patent scope of the present invention.

Claims

1. A flood discharge and energy dissipation structure for alleviating the impact of water flow impact vibration on a high dam chamber, comprising a primary energy dissipation pool (2), a secondary energy dissipation pool (6) and a tail sill (7) sequentially arranged downstream of a sluice chamber (1), characterized in that: The outlet nose sill of the sluice chamber (1) adopts a flat nose sill (3), a vertical drop sill (4) is arranged at the head of the first energy dissipation pool (2), and a continuous energy dissipation sill (5) with a water-facing surface upright is arranged at the tail of the first energy dissipation pool (2). The continuous energy dissipation sill (5) is located 1 to 2 meters upstream of the critical point where a submerged water jump occurs in the first energy dissipation pool (2) when the downstream is in a low water level operation control condition; the flat nose sill (3) and the vertical drop sill (4) make the downstream in a low water level operation control condition, and the head of the downstream water flow jump is located outside the sluice chamber (1); the continuous energy dissipation sill (5) adopts a trapezoidal section with a water-facing surface upright, with a height of 3 to 5 meters, and a top elevation higher than the top elevation of the tail sill (7) of the second energy dissipation pool by 0.5 to 1 meter; the single width flow rate of the downstream water flow in the flood discharge and energy dissipation structure is 150 to 200 meters 3 / s, the Froude number in the pool is 1-2, the flow velocity is 14-20m / s, the lock chamber height is 30-50m, and the cross-river thickness of the lock chamber structure is 3-6m.

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