CN-117005369-B - Medium-low earth-rock dam overtopping protection drainage structure and design method thereof

Abstract

The invention discloses a top-flood protection drainage structure of a medium-low earth-rock dam and a design method thereof, wherein the top-flood protection drainage structure of the medium-low earth-rock dam comprises a top-flood drainage structure, a downstream slope surface drainage structure and a dam foot drainage energy dissipation structure which are sequentially arranged from top to bottom along the cross section of the dam, the top-flood drainage structure is used for converging partial top-flood water flow, the downstream slope surface drainage structure is used for receiving top-flood water flow converged by the top-flood drainage structure and further guiding, collecting and dissipating energy of water flow which flows onto a downstream slope surface, and the dam foot drainage energy dissipation structure is used for dissipating energy of incoming flow of the downstream slope surface drainage structure and discharging the energy. The invention comprehensively considers the centralized guiding, discharging and energy dissipation of the flood peak flushing water flow, and has better flood peak protection effect.

Inventors

• CAI QIAN
• ZHANG DAWEI
• SHENG JINBAO
• WANG ZHAOSHENG
• LI ZHUO
• YANG MIAOFAN
• LONG ZHIFEI
• LI DANDAN
• ZHOU KEFA
• SUN WEIWEI

Assignees

• 水利部交通运输部国家能源局南京水利科学研究院
• 河海大学

Dates

Publication Date

20260508

Application Date

20230817

Claims (6)

1. 1. The utility model provides a well low earth-rock dam overtopping protection drainage structures which characterized in that includes: the dam top drainage structure is used for converging partial flood peak water flow; the downstream slope surface drainage structure is used for receiving the top water flow converged by the dam top drainage structure and further guiding, collecting and dissipating energy of the water flow which overflows onto the downstream slope surface; the dam foot drainage energy dissipation structure is used for dissipating energy of incoming flow of the downstream slope surface drainage structure and discharging the incoming flow; The dam top drainage structure comprises a wave wall (3) arranged on the upstream side of the dam top, drainage grooves (4) which are arranged in a fan-shaped symmetrical manner are formed in the top of the wave wall (3), a diversion wall (5) which is provided with a horn-shaped inlet is arranged in front of the drainage grooves (4), a dam top longitudinal drainage ditch (6) is arranged on the upstream side and the downstream side of the dam top in a through-length manner respectively, a dam top transverse drainage ditch (7) is arranged behind the drainage grooves (4) and below a dam top road (2), the dam top transverse drainage ditches (7) are communicated with the two dam top longitudinal drainage ditches (6), an energy dissipation apron board (11) is arranged at the bottom of the dam top transverse drainage ditches (7), the energy dissipation apron board (11) is of a lining stainless steel structure, and quincuncial pile umbrella-shaped comb teeth are arranged on the surface of the energy dissipation apron board; The downstream slope surface drainage structure comprises a downstream slope transverse drainage ditch (8) connected with a dam top transverse drainage ditch (7), a scale-shaped locking piece slope protection (9) with drainage and energy dissipation functions is arranged on the downstream slope surface of the dam, the scale-shaped locking piece slope protection (9) is formed by dry construction of scale-shaped locking pieces, the scale-shaped locking pieces are composed of an I-shaped self-locking base and a diversion ridge, the diversion ridge is in a round-head pier shape, the included angle between the diversion ridge and the plane horizontal axis of the I-shaped self-locking base is 20-30 degrees, when the slope is flushed by a small flow overturned, the scale-shaped locking piece slope protection (9) can guide the running out number of slope surface water to the downstream slope transverse drainage ditch, water is quickly drained, and when the slope is flushed by a large flow, the scale-shaped locking piece slope protection (9) can serve as a force dissipation ridge to carry out underflow energy dissipation at the same time of guiding water flow, and the overflow brushing of the overturned water flow on the dam foot is reduced; the dam foot drainage energy dissipation structure comprises a stone throwing anti-flushing groove (10) which is arranged on the downstream slope foot of the dam in a through length mode, and the stone throwing anti-flushing groove (10) also serves as a longitudinal drainage ditch.
2. 2. The medium-low earth-rock dam flood-roof protection drainage structure according to claim 1, wherein the main grooving direction of the drainage groove (4) points to the intersection point of the cross section of the middle main grooving and the downstream side of the dam roof, the maximum half-center angle of the main grooving direction is smaller than 15 degrees, the groove depth is 0.3-0.5 m, the total grooving clear width of the single drainage groove (4) is 2.0-4.0 m, and the longitudinal spacing of the drainage groove (4) is 10-30 m; the thickness of the guide wall (5) is 0.2-0.3 m, the top elevation is aligned with the wave wall (3), the wall bottom is connected with the base of the wave wall (3), and the upstream extends out of the wall surface of the wave wall (3) by 1.0-1.2 m.
3. 3. The flood-roof protection drainage structure of the medium-low earth-rock dam according to claim 1 is characterized in that a longitudinal drainage ditch (6) of the dam roof adopts a U-shaped or rectangular section, the width is 0.3-0.5 m, the depth is the same as that of a transverse drainage ditch (7) of the dam roof, and the bottom slope is concentrated to the transverse drainage ditch (7) of the dam roof; The dam crest transverse drainage ditches (7) are in one-to-one correspondence with the drainage ditches (4), double U-shaped or trapezoid cross sections are adopted, the total width of the surface of each cross section is 3.0-4.5 m, the slope ratio of the trapezoid cross sections is 1:0.8-1:1.25, the bottom slope is downstream, and the gradient is 0.01-0.02.
4. 4. The structure of claim 1, wherein the overflow flow is estimated according to a weir flow formula, and the continuous equation, the energy equation, the momentum equation and the weir flow formula are solved step by a combination to approximately obtain the slope water flow distribution, the flow conductivity and the energy dissipation coefficient, assuming that the overflow flow passes through the slope flow guide ridge, and is decomposed into the flow along the flow guide ridge and the overflow flow crossing the flow guide ridge: ; ; ; And To the point of In the process, the Is the flow of the flood peak; for the horizontal row label of fish scale type locking piece, the meter A row; Is the first Drainage ditch flow at the drainage lock block slope protection diversion ridge; The flow is guided by a guiding ridge; Is the overflow flow of the diversion ridge; is the water depth in front of the diversion ridge; is the slope overcurrent width; Is the flow rate coefficient; gravitational acceleration; Calculating the total water head difference of the top of the guide ridge of the last row from the front of the guide ridge; Is the angle of the side slope; is water density; A overflow velocity vector for the guide ridge; a diversion flow velocity vector is used as a diversion ridge; the reaction force vector of the whole locking block to the water flow; is a diversion ridge height; is a slope flow guide coefficient; Is the slope energy dissipation coefficient; Calculating the total water head of the slope for the dam foundation; slope water flow distribution is by Step by step, the slope drainage coefficient and the energy dissipation coefficient are respectively calculated by And And (5) calculating.
5. 5. The medium-low earth-rock dam flood-roof protection drainage structure according to claim 1, wherein the bottom of the dam roof drainage structure and the bottom of the downstream slope surface drainage structure are respectively paved with a wash-proof broken stone cushion layer (12).
6. 6. A method for designing a medium-low earth-rock dam overtopping protection drainage structure as claimed in claim 1, which is characterized by comprising the following steps: S1, determining a design over-standard flood process; S2, according to the flow of the flood peak and the length of the axis of the dam of the ultra-standard flood, the grooving depth of the initial drainage groove (4) and the total grooving clear width of the single-hole drainage groove (4) are drawn, the longitudinal distance of the drainage groove (4) is determined, and the drainage capacity of the single-hole drainage groove (4) is calculated; S3, reservoir drainage and flood regulation calculation is carried out under the condition of super-standard flood, if the drainage capacity of the drainage groove (4) meets the condition that the water level of the reservoir does not exceed the top elevation of the wave wall (3) in the flood drainage process, the next step is carried out, otherwise, the step S2 is returned to adjust the grooving depth and the total clear width of the drainage groove (4), and the total clear width of the grooving is preferentially increased; S4, determining the arrangement of the diversion walls (5) and the surface width of the dam top transverse drainage ditch (7) according to the slotting width of the single-hole diversion trenches (4), wherein the surface width of the dam top transverse drainage ditch (7) is more than or equal to the total width of the single-hole diversion trenches (4); s5, determining the cross section size of the transverse drainage ditch (7) at the top of the dam according to the maximum drainage flow of the drainage groove (4) by flood regulation algorithm so as to meet the drainage requirement of the drainage groove (4); s6, correspondingly determining the width of a dam crest longitudinal drainage ditch (6) according to the surface width of the dam crest transverse drainage ditch (7), wherein the depth of the dam crest longitudinal drainage ditch (6) is identical to that of the dam crest transverse drainage ditch (7); s7: the downstream slope transverse drainage ditch (8) is connected with the dam crest transverse drainage ditch (7) and is arranged conventionally, and the section size is the same as that of the dam crest transverse drainage ditch (7); And S8, determining the depth of a dam foundation riprap anti-punching groove (10) according to energy dissipation anti-punching calculation, and determining the particle size of the block stone.

Description

Medium-low earth-rock dam overtopping protection drainage structure and design method thereof Technical Field The invention relates to a soil-rock dam overtopping protection structure, in particular to a medium-low soil-rock dam overtopping protection drainage structure and a design method thereof. Background The flood control standard of the medium-low earth-rock dam in China is generally low, and the flood control standard of the small (1) reservoir design is only 10-50 years. Climate change has been exacerbated in recent years, with over-standard flood events occurring frequently. Because the earth and rockfill dam has weak anti-scouring capability, the earth and rockfill dam is extremely easy to damage and even break when being subjected to over-standard flood overtopping scouring. The existing earth-rock dam flood-roof protection structure mainly adopts a fully-covered rigid or flexible facing, the anti-seepage and anti-scouring capabilities of the dam surface are mainly considered to be increased, the main structural forms comprise concrete slab slope protection, concrete blocks, gabions and the like, the structural function is single, after the earth-rock dam facing is subjected to the flushing and penetrating actions of diffuse-roof high-speed water flow, the facing and the dam slope bottom material below the facing are often corroded and damaged, and the integral protection effect is further affected. Disclosure of Invention The invention aims to provide a top-overturned protective drainage structure of a medium-low earth-rock dam, which has better protective effect, and is suitable for the medium-low earth-rock dam with the dam height not exceeding 30m, and a design method of the top-overturned protective drainage structure of the medium-low earth-rock dam. The technical scheme is that the medium-low earth-rock dam overtopping protection drainage structure comprises: the dam top drainage structure is used for converging partial flood peak water flow; the downstream slope surface drainage structure is used for receiving the top water flow converged by the dam top drainage structure and further guiding, collecting and dissipating energy of the water flow which overflows onto the downstream slope surface; and the dam foot drainage energy dissipation structure is used for dissipating energy of the inflow of the downstream slope surface drainage structure and discharging the inflow. Compared with the traditional dam crest protective structure, the drainage function is increased, so that the dam crest can provide partial water passing capacity, and a drainage, drainage and energy dissipation structure system can be formed by matching with a subsequent drainage structure. The dam top drainage and drainage structure is utilized to properly collect and drain the dam top-flooding water flow to the downstream slope surface drainage and drainage structure, so that about 40% of the top-flooding water flow can be reduced to directly wash the dam top and the dam slope, and the dam top-flooding damage can be prevented or the dam top-flooding damage process can be slowed down. The downstream slope surface drainage structure can collect and rapidly drain the flood peak water flow as an emergency channel when the flood peak water flow is used, the slope surface drainage capacity is enhanced by guiding the water flow, and meanwhile, the slope surface energy dissipation function is increased, so that direct flushing of the flood peak water flow to a dam slope and a dam foot is reduced, and the rainfall slope surface drainage function can be achieved in daily operation. The earth-rock dam foot is not provided with anti-flushing measures generally, but the anti-flushing measures of the dam foot are key links in the process of overtopping protection, so that the erosion damage to the dam foot can be effectively prevented under the action of high water head and high flow, and the damage is further prevented from developing to the dam body, and therefore, the dam foot drainage energy dissipation structure is necessary for overtopping protection. The invention comprehensively considers the concentrated guiding, discharging and energy dissipation of the overtopping flushing water flow, can guide the overtopping water flow to automatically and rapidly drain water when overtemperature flood or other sudden events cause overtopping, and dissipates energy in the drainage process, can achieve better overtopping protection effect of the earth and rockfill dam, and achieves the purposes of 'diffuse without collapsing' or 'diffuse with slow collapsing' of the earth and rockfill dam. The overtopping protection drainage structure can be used as a conventional drainage structure of a dam. The dam top drainage structure comprises a dam top, wherein the dam top drainage structure comprises a wave wall arranged on the upstream side of the dam top, drainage grooves which are arranged in a fan-shaped symmetrical mode are formed in the top o