阅读说明：本技术 一种改善水电站尾水隧洞明满流影响的逆坡堰结构 (Improve power station tailrace tunnel open-full flow influence's adverse slope weir structure ) 是由 陈益民 杨飞 孙洪亮 侯博 戴熙武 纪昌知 于 2019-10-28 设计创作，主要内容包括：本发明提供了一种改善水电站尾水隧洞明满流影响的逆坡堰结构,尾水隧洞由导流洞改建,在尾水隧洞出口设置逆坡堰结构,逆坡堰结构上游迎水面采用逆坡流线形式,逆坡堰顶高程高于隧洞出口底板；逆坡堰下游河床高程不高于逆坡堰堰顶高程。本发明可以避免尾水隧洞明满流对隧洞衬砌结构的危害及对输水系统运行稳定性的影响,并且工程量小。(The invention provides an adverse slope weir structure for improving the influence of open-full flow of a hydropower station tail water tunnel, wherein the tail water tunnel is reconstructed by a diversion tunnel, an adverse slope weir structure is arranged at the outlet of the tail water tunnel, the upstream surface of the adverse slope weir structure adopts an adverse slope streamline form, and the elevation of the adverse slope weir top is higher than the bottom plate of the tunnel outlet; the elevation of the riverbed at the downstream of the adverse slope weir is not higher than the elevation of the weir top of the adverse slope weir. The invention can avoid the damage of the open-full flow of the tailrace tunnel to the tunnel lining structure and the influence to the operation stability of the water delivery system, and has small engineering quantity.)

1. The utility model provides an improve adverse slope weir structure of power station tailrace tunnel open-full flow state influence, the tailrace tunnel is rebuild by the diversion tunnel, its characterized in that: an adverse slope weir structure (7) is arranged at the tail water tunnel outlet, the upstream surface of the adverse slope weir structure (7) adopts an adverse slope streamline form, and the elevation of the adverse slope weir top is higher than the tunnel outlet bottom plate (8); the elevation of the riverbed (9) at the downstream of the adverse slope weir is not higher than the elevation of the weir top of the adverse slope weir (7).

2. The adverse slope weir structure for improving the influence of the open-full flow state of the tailwater tunnel of the hydropower station according to claim 1, wherein: the adverse slope weir (7) is arranged at the open canal section of the tail water tunnel outlet.

3. The adverse slope weir structure for improving the influence of the open-full flow state of the tailwater tunnel of the hydropower station according to claim 1, wherein: the elevation of the top of the adverse slope weir (7) is not more than one third of the height of the tail water tunnel.

Technical Field

The invention relates to a reverse slope weir structure for improving the influence of the open-full flow state of a tailwater tunnel of a hydropower station. Is suitable for the field of water conservancy and hydropower engineering.

Background

The large underground powerhouse type hydropower station saves the engineering investment, reduces the excavation rate of underground rock masses, and effectively maintains the integrity and the stability of the rock masses. The diversion tunnel is often reconstructed into a power station tail water tunnel by adopting a form of arrangement of the tail water tunnel and the diversion tunnel, such as a river luodie, a beach, a Wudongde, a rock threshold and other hydroelectric projects. Due to the engineering task requirements borne by the diversion tunnel, the elevation of the bottom plate is generally high, the height of the tail water level of the power station is influenced by flood discharge of a reservoir and power generation flow, the water level amplitude is large, and when the tail water level is low, the phenomenon of alternation of open flow and full flow in the tail water tunnel is inevitable in the transition process of the hydropower station.

The flow state of the water flow phenomenon of the alternation of the open flow and the full flow is complex, the hole is sometimes pressurized and sometimes not pressurized, and the air bag is intercepted and moves along with the water flow, and the pressure pulsation phenomenon is accompanied. The large transient pressure easily causes the structural damage of the tunnel, and simultaneously can influence the stability of the operation of the power station. In order to ensure safe and stable operation of the power generation and water delivery system building and the unit, improvement measures of the open-full flow phenomenon need to be researched and adopted. The conventional improvement method mainly comprises the steps of arranging vent holes, shortening the length of a tail water tunnel reconstructed by a diversion tunnel and arranging a tail water surge chamber to separate the tail water tunnel. The arrangement of the vent holes can effectively improve the negative pressure problem caused by the full flow, thereby reducing the influence of pulsating pressure on the building structure, but the influence range is limited, and more vent holes need to be arranged. The length of the tailrace tunnel reconstructed by the diversion tunnel is inconsistent with the purpose of reconstructing the tailrace tunnel by the diversion tunnel initially, the arrangement of the tail adjusting partition can reduce the influence of the open and full flow phenomenon on the stability of the unit, but the manufacturing cost is high, and the pressure regulating chamber cannot be arranged under the condition that the tailrace tunnel is not very long.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: aiming at the problems, the adverse slope weir structure for improving the influence of the open and full flow of the tailwater tunnel of the hydropower station is designed to avoid the damage of the open and full flow of the tailwater tunnel to the lining structure of the tunnel and the influence on the operation stability of a water delivery system, and the engineering quantity is small.

The technical scheme adopted by the invention is as follows: the utility model provides an improve adverse slope weir structure of power station tailrace tunnel open-full flow state influence, the tailrace tunnel is rebuild by the diversion tunnel, its characterized in that: an adverse slope weir structure is arranged at the exit of the tailwater tunnel, the upstream surface of the adverse slope weir structure adopts an adverse slope streamline form, and the elevation of the adverse slope weir top is higher than the bottom plate of the tunnel exit; the elevation of the riverbed at the downstream of the adverse slope weir is not higher than the elevation of the weir top of the adverse slope weir.

Further: the adverse slope weir should be arranged at the open canal section of the tail water tunnel outlet.

Further: the elevation of the top of the adverse slope weir is not more than one third of the height of the tail water tunnel.

When the tail water level is lower, the open and full flow phenomenon can occur in the tail water tunnel reconstructed by the diversion tunnel,

according to the invention, the adverse slope weir is arranged at the outlet of the open-full-flow tailwater tunnel, and when the tailwater level is lower, the water level in the tailwater tunnel can be raised, so that the open-full-flow phenomenon is prevented from being transmitted to the gentle slope tunnel section at the upstream of the diversion tunnel reconstruction section under the working condition of the transition process, the range of the open-full-flow phenomenon can be effectively reduced, and the influence on the lining structure of the tailwater tunnel and the stability of a machine set is reduced.

According to the invention, the adverse slope weir is arranged at the outlet of the open-full flow tailwater tunnel, when the tail water level is lower, under the normal power generation operation working condition (constant flow), the flow state at the outlet of the tailwater tunnel is water drop, and the water level of a downstream reservoir has no influence on the flow state in the tunnel. In the conventional flat slope outlet scheme, the water level in the tail water tunnel is influenced by the fluctuation of the downstream tail water level, so that the flow state in the tail water tunnel and the stability of a water delivery system are influenced.

The invention sets the adverse slope weir at the exit of the open-full flow tailwater tunnel, which can increase the negative pressure extreme value of the inlet of the tailwater connecting pipe, for example, when the invention is applied to a certain project, the negative pressure extreme value of the inlet of the tailwater pipe is increased by 2.86m, from the original-0.9 m to 1.96m, the improvement effect is very obvious, the extreme value required by the specification is-8.0 m, and the invention can effectively reduce the occurrence of serious accidents such as machine lifting and the like.

The invention is applied to a project, the lowest surge of the tail water surge chamber is 3.94m higher than that of a flat slope outlet scheme, and the specification requires that the lowest surge water level of the tail water surge chamber is at least 2.0m higher than that of the impedance plate. Therefore, the invention can improve the lowest surge condition of the tail water surge chamber, thereby avoiding the possibility of bottom exposure of the tail water surge chamber.

The invention requires that the elevation of the riverbed at the downstream of the adverse slope weir is not higher than the elevation of the weir top, so that the excavation amount behind the weir can be reduced, and a large amount of engineering investment is saved.

Drawings

Fig. 1 is a schematic sectional layout of a water delivery system.

FIG. 2 is a schematic sectional view of a tail water outlet reverse slope weir.

Wherein, 1, underground factory building, 2, tail water surge-chamber, 3, tail water connecting pipe, 4, tail water tunnel gentle slope section, 5, the front combination section (steep slope section) of the open full flow section, 6, the open full flow section (the tail water tunnel reconstructed by the diversion tunnel), 7, export adverse slope weir, 8, tail water tunnel bottom plate, 9, downstream riverbed, 10, the rock mass of reducing excavation behind the adverse slope weir, 11, conventional tail water tunnel export bottom plate (only schematic)

Detailed Description

Referring to the attached drawings, the headwall weir structure for improving the influence of the open-full flow state of the tailwater tunnel of the hydropower station is characterized in that the tailwater tunnel 6 is reconstructed by a diversion tunnel, an overflow weir higher than a tunnel outlet bottom plate 8 is arranged at the tail water tunnel outlet, the overflow weir is a headwall weir 7, an upstream face 70 of the overflow weir adopts a headwall streamline form, and the top elevation of the slope weir is higher than the tunnel outlet bottom plate 8. When the tail water level is lower, the open and full flow phenomenon can occur in the tail water tunnel 6 reconstructed by the diversion tunnel, and the structure of the invention can improve the influence of the open and full flow phenomenon on the water delivery system of the power station.

The tail water tunnel outlet overflow weir adopts a reverse slope form, compared with the overflow weir of water discharge of a conventional reservoir or a sluice and the like, the reverse slope weir 7 has the opposite section structure, and the structure of the reverse slope weir is shown in figure 2. The curve of the surface of the adverse slope weir is designed according to the overflow weir body type of a hydraulic engineering design manual, and streamline is selected as much as possible to reduce head loss. When the tail water level is high, under the working condition of the transition process, forward and reverse water flows can occur on the adverse slope weir, the flow state is complex, and model tests or computational fluid dynamics simulation researches are required to be carried out.

The tailrace tunnel outlet adverse slope weir 7 is arranged at the tailrace tunnel outlet open channel section, so that the influence of overlarge head loss on the flow capacity is avoided. The height of the adverse slope weir is determined according to hydraulic model tests and transient flow numerical calculation results, the higher the elevation of the weir top is, the smaller the influence range of the open-full flow is, but the larger the influence on the generating head is, and generally the height of the adverse slope weir should not exceed one third of the height of the tail water tunnel. The elevation of the riverbed at the downstream of the adverse slope weir is not higher than the elevation of the weir top of the adverse slope weir.

It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art should understand that they can make various changes, additions and substitutions within the scope of the present invention.