Arch dam flood discharge and energy dissipation structure

Abstract

The utility model discloses an arch dam flood discharge energy dissipation structure which comprises a dam body, an overflow surface hole and a flood discharge middle hole are formed in the dam body, a plunge pool and an auxiliary dam are arranged on the downstream of the dam, the overflow surface hole comprises side walls and a bottom plate arranged between the two side walls, and the tail end of the bottom plate is located on the inner sides of the tail ends of the side walls. A first energy dissipater located in the overflow surface hole is arranged at the tail end of an outlet of the overflow surface hole, and a second energy dissipater is arranged at the tail end of an outlet of the flood discharge middle hole. A lifting area is arranged on the upstream side of the plunge pool, and the horizontal length of the lifting area does not exceed the falling point position of the overflow surface hole nappe; the height of the lifting area does not exceed half of the height of the auxiliary dam, and a deep water area is formed between the lifting area and the auxiliary dam. According to the special-shaped plunge pool, the problem that the hydrodynamic pressure intensity of impact of the plunge pool bottom plate is too large due to the fact that water enters the surface middle hole nappes in a concentrated mode is solved, a more complete resistance body can be reserved on the downstream side of the dam body, the stability of the dam body is enhanced, and meanwhile engineering investment is reduced.

Description

Technical Field

[0001] The utility model relates to an energy dissipation structure for arch dam flood discharge, belonging to the technical field of energy dissipation and scour prevention in hydropower projects. Background Art

[0002] An arch dam is a common dam building form in water conservancy and hydropower projects, usually built in high mountains and canyons. The main technical difficulties in its flood discharge layout are: huge flood discharge flow of the dam body, high water head, narrow river valley, and poor geological conditions. To reduce the impact of flood discharge atomization on the two side mountains, the non-collision water entry method of surface and deep hole water tongues has gradually become the preferred choice for flood discharge energy dissipation of high arch dam projects.

[0003] However, non-collision water entry means that most of the energy dissipation can only rely on the shear of the water tongue and the water body in the plunge pool. To ensure the safety of the plunge pool bottom slab under the impact of strong water flow, the plunge pool needs to have sufficient excavation depth.

[0004] As Figure 1 shown Figure 1 is a typical layout form of the plunge pool behind a high arch dam, including the dam body 1, on which an overflow surface hole 2 and a flood discharge middle hole 3 are arranged. A plunge pool 7 and a secondary dam 10 are successively arranged downstream of the dam body 1, and the flood discharge center line coincides with the plunge pool center line; the excavation depth is relatively large near the dam heel position on the upstream side of the plunge pool, which affects the integrity of the resistance body, increases the excavation workload of the plunge pool, and there is an obvious still water area on the upstream side of the plunge pool, and most of the water body does not participate in the shear energy dissipation of the incoming water flow during the flood discharge operation. Content of the Utility Model

[0005] The utility model aims at the above technical problems, and provides an energy dissipation structure for arch dam flood discharge, which can retain as many resistance bodies at the dam shoulder and dam heel positions as possible under the premise of ensuring the flood discharge capacity and the safety of the plunge pool bottom slab, and enhance the stability of the dam body.

[0006] To achieve the above purpose, the technical scheme adopted by the utility model is:

[0007] An energy dissipation structure for arch dam flood discharge, including a dam body, on which an overflow surface hole and a flood discharge middle hole are arranged. A plunge pool and a secondary dam are successively arranged downstream of the dam body, and the flood discharge center line coincides with the plunge pool center line. The plunge pool includes a raised area, and the downstream side of the raised area is provided with a plunge pool bottom slab with a height less than that of the raised area; one side of the raised area is connected to the dam body, and the other side of the raised area extends along the upstream to downstream direction; the extension length of the raised area from upstream to downstream does not exceed the position of the near landing point of the water tongue of the overflow surface hole in the plunge pool; the height of the raised area is less than the height of the secondary dam; a deep water area is formed between the downstream side of the raised area and the secondary dam.

[0008] The water jet of the overflow surface outlet is divided into the near - impact point water jet and the far - impact point water jet according to its position in the plunge pool. When the shape of the surface outlet is determined, the thickness of the water flow discharging from the open bottom is small, and the near - impact point of the surface outlet water jet is basically fixed, while the far - impact point varies with the operating water level.

[0009] Therefore, a raised area is set on the upstream side of the plunge pool, so that the main water inlet point of the surface outlet water jet is located in the deeper area of the water cushion, and both the near and far impact points of the water jet are located in the deeper area of the plunge pool depth. By setting the raised area, while maintaining the original excavation depth, the water depth at the main water inlet point of the water jet is increased, a more complete resistance body can be reserved on the downstream side of the dam body, the excavation depth is reduced, and the dam body stability is enhanced while reducing the project investment.

[0010] According to the embodiments of the present invention, the present invention can be further optimized. The following are the technical solutions formed after optimization:

[0011] In order to prevent the discharged water flow from directly impacting the upstream side bottom plate of the plunge pool at the beginning of the surface outlet opening, further, the height of the raised area does not exceed half of the height of the secondary dam.

[0012] Further, a first energy dissipator located inside the overflow surface outlet is provided at the outlet end of the overflow surface outlet, and a second energy dissipator is provided at the outlet end of the flood discharge middle hole.

[0013] Further, both the overflow surface outlet and the flood discharge middle hole include side walls and a bottom plate arranged between the two side walls, and the end of the bottom plate is located inside the end of the side wall.

[0014] Further, both the first energy dissipator and the second energy dissipator are contraction - type energy dissipators. The contraction - type energy dissipator forms a contraction section by the contraction of the two - side walls towards the middle, forcing the water flow to deform, enhancing turbulence and air entrainment, and forming a water flow pattern with vertical and longitudinal diffusion. The characteristic of the contraction - type energy dissipator to contract the water flow causes the outlet sections of the surface outlet and the middle hole on the dam to gradually narrow simultaneously to form a narrow slit. Thus, the discharged water flow diffuses and stretches in the vertical and longitudinal directions of the river channel in space, interpenetrates with each other in the air and enters the water in different areas of the plunge pool, seeking a new flood discharge and energy dissipation form that not only makes full use of the longitudinal space of the river channel, enables the water jets discharged from the surface and middle holes to have no or less collision, thus avoiding the atomization problem caused by the collision of water flows in the air, greatly reducing the intensity of the flood discharge atomization of the entire project, but also ensuring that the impact dynamic pressure of the water flow on the bottom plate of the energy dissipation pool of the plunge pool is relatively small, which is suitable for the engineering characteristics of narrow river valleys.

[0015] The first energy dissipator and the second energy dissipator adopt a contraction type energy dissipator, and the ends of the bottom plates of the overflow surface holes and the flood discharge middle holes are located inside the tail ends of the side walls, so that the water tongues flowing out from the surface holes are longitudinally separated, the water tongue landing points present a spindle shape, the main flow of the water is located in the front part of the water tongue, and the bottom plate of the plunge pool is impacted. The concentration degree of the main flow of the water tongue of the surface hole is adjusted by the extension length of the outlet bottom plate inside the tail end of the side wall.

[0016] Furthermore, the crest elevations of the overflow surface holes are on the same horizontal plane, and the flood discharge middle holes have a flat bottom outflow, and the bottom plate elevations are the same.

[0017] For the integrity of the bedrock on both sides, on the premise of not affecting the water entry of the water tongue of the surface hole, furthermore, side walls are arranged on at least one side of the elevated area, and the side walls extend towards the center line direction of the plunge pool on one side facing the left bank or the right bank.

[0018] Furthermore, a plunge pool bottom plate with a height less than that of the elevated area is arranged on the downstream side of the elevated area, and an inclined connecting section is arranged between the elevated area and the plunge pool bottom plate.

[0019] Furthermore, there are concrete slope protections on both banks of the plunge pool.

[0020] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0021] 1) The arch dam flood discharge and energy dissipation structure of the present utility model makes full use of the water cushions at different depths in the plunge pool for shear energy dissipation, avoiding the problem of excessive impact dynamic water pressure on the bottom plate of the plunge pool caused by the concentrated water entry of the surface and middle holes. A more complete resistance body can be reserved on the downstream side of the dam body, enhancing the dam body stability while reducing the project investment.

[0022] 3) For the arch dam flood discharge and energy dissipation structure of the present utility model, both the near and far landing points of the water tongue are located in the area with a deeper water cushion. While increasing the shear area with the water body in the plunge pool, a larger space is provided for the water entry of the surface hole water tongue in the transverse direction, realizing collision-free flow in the air; the horizontal length of the upstream side bottom plate lifting area of the special-shaped plunge pool is controlled by the position of the main flow landing point of the surface hole water tongue, so that the main flow water entry point of the surface hole water tongue is located in the area with a deeper water cushion. Description of the Drawings

[0023] Figure 1 is the typical layout form of the plunge pool behind the high arch dam in the prior art;

[0024] Figure 2 is the schematic diagram of the water entry shape of the surface and middle hole water tongues of the present utility model;

[0025] Figure 3 is Figure 2 the A-A cross-sectional view in

[0026] Figure 4 Yes Figure 2 Central sectional view of the center of the overflow surface outlet;

[0027] Figure 5 Yes Figure 2 Central sectional view of the center of the flood discharge middle hole;

[0028] Figure 6 Isometric structural schematic diagram of the plunge pool of the present utility model;

[0029] Figure 7 Isometric structural schematic diagram of the combined state of the dam body and the plunge pool of the present utility model.

[0030] In the figure

[0031] 1 - Dam body; 2 - Overflow surface outlet; 3 - Flood discharge middle hole; 4 - Side wall; 5 - Bottom slab; 6 - Concrete slope protection; 7 - Plunge pool; 71 - Elevated area; 711 - Side wall; 72 - Plunge pool bottom slab; 8 - Drop point of the surface outlet water tongue; 9 - Drop point of the middle hole water tongue; 10 - Second dam; 11 - First energy dissipator; 12 - Second energy dissipator. Detailed implementation manners

[0032] The present utility model will be described in detail below with reference to the drawings and in conjunction with embodiments. It should be noted that, without conflict, the embodiments in the present utility model and the features in the embodiments can be combined with each other. For the convenience of description, words such as "upper", "lower", "left", and "right" hereinafter only represent the same directions as the upper, lower, left, and right directions of the drawings themselves, and do not limit the structure.

[0033] As Figures 2 - 7 shown, the arch dam flood discharge and energy dissipation structure of this embodiment includes a dam body 1, an overflow surface outlet 2 and a flood discharge middle hole 3 are arranged on the dam body 1, a plunge pool 7 and a second dam 10 are sequentially arranged downstream of the dam body 1, the flood discharge center line coincides with the center line of the plunge pool 7, and there are concrete slope protections 6 on both sides of the plunge pool 7.

[0034] An elevated area 71 is arranged on the upstream side of the plunge pool 7, one side of the elevated area 71 is connected to the dam body 1, and the other side of the elevated area 71 extends towards the downstream side of the plunge pool 7; the extension length of the elevated area 71 from upstream to downstream does not exceed the position of the water tongue of the overflow surface outlet 2 at the near drop point in the plunge pool 7; the height of the elevated area 71 does not exceed half of the height of the second dam 10, and a deep water area is formed between the elevated area 71 and the second dam 10. The flood discharge center line coincides with the plunge pool center line and is parallel to the arch dam center line.

[0035] A plunge pool bottom slab 72 with a height less than that of the elevated area 71 is arranged on the downstream side of the elevated area 71, and an inclined connection section 73 is arranged between the elevated area 71 and the plunge pool bottom slab 72.

[0036] As Figure 4 , Figure 5 , Figure 7 shown, the overflow surface outlets 2 and the flood discharge middle outlets 3 are staggeredly arranged in the width direction of the dam body 1, so that the surface water jet and the middle water jet will not cross; a first energy dissipator 11 located inside the overflow surface outlet 2 is arranged at the outlet end of the overflow surface outlet 2, a second energy dissipator 12 is arranged at the outlet end of the flood discharge middle outlet 3, the crest elevations of the overflow surface outlets 2 are on the same horizontal plane, the flood discharge middle outlets 3 are bottom-outflow, and the bottom slab elevations are the same; both the overflow surface outlets 2 and the flood discharge middle outlets 3 include side walls 4 and a bottom slab 5 arranged between the two side walls 4, the end of the bottom slab 5 is located inside the tail end of the side wall 4, and both the first energy dissipator 11 and the second energy dissipator 12 are contracted energy dissipators.

[0037] In the arch dam flood discharge and energy dissipation structure of this embodiment, flood discharge surface outlets 2 and flood discharge middle outlets 3 are arranged at different elevations of the dam body, and a special-shaped plunge pool 7 is arranged on the downstream side of the arch dam. Among them, both the flood discharge surface outlets 2 and the flood discharge middle outlets 3 adopt contracted energy dissipators, and the outlet bottom slabs are made permeable.

[0038] Among them, after the outlet of the flood discharge surface outlet 2 adopts a contracted energy dissipator and the bottom slab is completely permeable, the surface water jet of the outlet is longitudinally pulled apart, the landing point of the water jet presents a spindle shape, the main flow of the water flow is located in the front part of the water jet, impacting the bottom slab of the plunge pool, and the concentration degree of the main flow of the surface water jet of the outlet is adjusted by the permeable length of the outlet bottom slab. The flood discharge middle outlet 3 adopts a flat-bottom layout and a narrow slot outflow form with both sides contracted, so that the water flow discharged from the middle outlet is stretched and diffused in the longitudinal direction of the river channel, and the near and far landing points of the water jet are both located in the area with a deeper water cushion, while increasing the shear area with the water body in the plunge pool and providing a larger space for the surface water jet to enter the water in the transverse direction, realizing collision-free flow in the air.

[0039] As Figure 2 , Figure 7 shown, in order to ensure the integrity of the bedrock on both sides, side walls 711 are arranged on at least one side of the raised area 71, and the side walls 711 extend towards the center line direction of the plunge pool 7 on the side facing the left bank or the right bank. If necessary, side walls 711 can be arranged on both the left bank and the right bank, provided that it does not affect the entry of the surface water jet into the water.

[0040] Since the horizontal length of the raised area 71 does not exceed the landing position of the water tongue of the overflow surface hole 2 in the plunge pool 7, the landing points 8 of the surface hole water tongue and the landing point 9 of the middle hole water tongue are both in the deep water area of the plunge pool 7. While increasing the shear area with the water body in the plunge pool, it provides a larger space for the surface hole water tongue to enter the water in the transverse direction, realizing collision-free flow in the air. The horizontal length of the upstream side bottom plate lift area 71 of the special-shaped plunge pool 7 is controlled by the position of the main landing point of the water tongue of the flood discharge surface hole 2, so that the main water entry point of the surface hole water tongue is located in the deeper water area of the plunge pool. The height of the upstream side bottom plate lift area 71 of the plunge pool 7 is controlled within half of the dam height of the second dam 10 to prevent the downstream water flow from directly impacting the upstream side bottom plate of the plunge pool 7 at the beginning of the opening of the surface hole. The side wall of the upstream side bottom plate lift area 71 of the plunge pool is completely controlled by the anti-sliding bodies on both banks of the arch dam and approaches the center line of the plunge pool 7.

[0041] The flood discharge and energy dissipation structure of the arch dam in this embodiment includes flood discharge surface holes and middle holes arranged at different elevations of the dam body, and a special-shaped plunge pool on the downstream side of the arch dam. The flood discharge center line coincides with the center line of the plunge pool and is parallel to the center line of the arch dam. Among them, both the flood discharge surface holes and the middle holes adopt contracted energy dissipation works, and the bottom plate area is made permeable. Through the reasonable arrangement of the surface holes and the middle holes, while the water tongues flowing out of the dam body enter the water without collision, it adapts to the change of the bottom plate of the plunge pool. After the water tongues are dispersed and enter the water, there is no water flow directly impacting the front bottom plate convex platform of the plunge pool, meeting the requirements of flood discharge and energy dissipation of high arch dams. In this embodiment, on the premise of ensuring the flood discharge capacity and the safety of the bottom plate of the plunge pool, as much anti-sliding body at the dam shoulder and dam heel positions as possible is retained, enhancing the stability of the dam body while reducing the project investment.

[0042] The content clarified in the above embodiments should be understood that these embodiments are only used to illustrate the present invention more clearly, rather than to limit the scope of the present invention. After reading the present invention, various equivalent forms of modification of the present invention by those skilled in the art all fall within the scope defined by the appended claims of this application.

Claims

1. An arch dam flood discharge and energy dissipation structure, comprising a dam body (1), wherein an overflow surface hole (2) and a flood discharge middle hole (3) are arranged on the dam body (1), a water cushion pond (7) and a second dam (10) are arranged in sequence downstream of the dam body (1), and the flood discharge center line coincides with the center line of the water cushion pond (7), characterized in that: The cushion pond (7) comprises an elevated area (71), and a cushion pond bottom plate (72) having a height less than that of the elevated area (71) is arranged on the downstream side of the elevated area (71); one side of the elevated area (71) is connected to the dam body (1), and the other side of the elevated area (71) extends in a direction from upstream to downstream; the extension length of the elevated area (71) from upstream to downstream does not exceed the position of the water tongue of the overflow surface hole (2) near the landing point of the cushion pond (7); the height of the elevated area (71) is less than the height of the second dam (10); and a deep water area is formed between the downstream side of the elevated area (71) and the second dam (10).

2. The arch dam flood discharge and energy dissipation structure according to claim 1, characterized in that: The height of the raised area (71) does not exceed half the height of the second dam (10).

3. The arch dam flood discharge and energy dissipation structure according to claim 1, characterized in that: The outlet end of the overflow surface hole (2) is provided with a first energy dissipator (11) located inside the overflow surface hole (2), and the outlet end of the flood discharge center hole (3) is provided with a second energy dissipator (12).

4. The arch dam flood discharge and energy dissipation structure according to claim 3 is characterized in that: The overflow surface hole (2) and the flood discharge middle hole (3) both comprise a side wall (4) and a bottom plate (5) arranged between the two side walls (4), the end of the bottom plate (5) being located on the inner side of the tail end of the side wall (4); the overflow surface hole (2) and the flood discharge middle hole (3) are arranged alternately along the width direction of the dam body (1).

5. The arch dam flood discharge and energy dissipation structure according to claim 3 is characterized in that: The first energy dissipator (11) and the second energy dissipator (12) are both retractable energy dissipators.

6. The arch dam flood discharge and energy dissipation structure according to claim 1, characterized in that: The weir top elevations of the overflow surface holes (2) are on the same horizontal plane, and the flood discharge middle holes (3) are flat-bottomed outflow holes with the same bottom plate elevations.

7. The arch dam flood discharge and energy dissipation structure according to claim 1, characterized in that: At least one side of the elevated area (71) is provided with a side wall (711), and the side of the side wall (711) facing the left bank or the right bank extends in the direction of the center line of the plunge pool (7).

8. The arch dam flood discharge and energy dissipation structure according to claim 1, characterized in that: A connecting section (73) inclined toward one side of the water cushion pond bottom plate is provided between the raised area (71) and the water cushion pond bottom plate (72).

9. The arch dam flood discharge and energy dissipation structure according to any one of claims 1 to 8, characterized in that: Both banks of the water cushion pond (7) are provided with concrete slope protection (6).

Images