CN-116695630-B - Stepped drainage groove arrangement method for accelerating blocking and improving drainage efficiency of barrier lake

CN116695630BCN 116695630 BCN116695630 BCN 116695630BCN-116695630-B

Abstract

The invention discloses a stepped drainage groove arrangement method for accelerating collapse of barrier lake and improving drainage efficiency. The method comprises the following steps of firstly excavating drainage grooves at beaks of the damming body or relatively low natural parts, determining the cross section and longitudinal section structural form of the drainage grooves by taking the goal of relatively small excavation engineering amount, highest overcurrent efficiency and combination of the structural composition of the damming body substances as the goal, and secondly, longitudinally halving the drainage grooves, vertically excavating the drainage grooves at equal intervals on the downstream side of the midpoint of the drainage grooves, and forming vertical steps with gradually increased vertical heights until the vertical steps are connected to a dam slope at the downstream of the damming body. The invention has the advantages of effectively shortening the water storage time of the barrier lake, reducing the water storage volume of the barrier lake, safely and rapidly draining the water stored in the barrier lake, and reducing the maximum water level of the barrier lake and the burst flood peak, thereby reducing the flooding loss of the reservoir area and the downstream burst damage to a greater extent.

Inventors

ZHOU ZHAO
YANG QIGUI
CAI YAOJUN
LU JIANHUA
LIU JIALONG

Assignees

长江勘测规划设计研究有限责任公司

Dates

Publication Date: 20260508
Application Date: 20230614

Claims (4)

1. A stepped drainage groove arrangement method for accelerating breaking of barrier lake and improving drainage efficiency is characterized by comprising the following steps, Digging a drainage groove on a bealock of a damming body or a relatively low concave natural part, and determining the structural form of the cross section and the vertical section of the drainage groove by combining the structural composition of a damming body substance; When the water storage capacity of the barrier lake reaches 0.1 hundred million m 3 and the barrier body is mainly composed of a material structure composed of stone blocks or boulders, D 50 is more than or equal to 200mm, the cross section of the drainage groove adopts deep and narrow shape, namely the transverse width of the bottom of the drainage groove is kept at 3-5 m, and the transverse slope ratio of the two sides of the drainage groove is 1:0.8-1:1.2; When the water storage capacity of the barrier lake reaches 0.1 hundred million m 3 and the barrier body is mainly composed of a material structure composed of broken stone, gravel or soil, D 50 is smaller than or equal to 200mm, the drainage groove of the barrier lake adopts a wide-slow cross section, namely the transverse width of the bottom of the drainage groove is kept to be 5-8 m, and the transverse slope ratio of the two sides of the drainage groove is 1:1.2-1:2.0; the drainage groove longitudinally maintains the longitudinal slope of the original natural river; And secondly, longitudinally halving the drainage grooves, vertically excavating the drainage grooves at equal intervals on the downstream side of the midpoint of the drainage grooves, and forming vertical steps with gradually increased vertical heights until the vertical steps are connected to the downstream dam slope of the damming body.
2. The method for arranging the stepped drainage grooves for accelerating the breaking and improving the drainage efficiency of the barrier lake according to claim 1 is characterized in that in the second step, the maximum height of the vertical steps is less than or equal to 5m, the heights of the adjacent vertical steps are equal to or different from 1m, and the longitudinal spacing is 20-50 m.
3. The method for arranging the stepped drainage groove for accelerating the breaking and improving the drainage efficiency of the barrier lake according to claim 1, wherein when the water storage capacity of the barrier lake reaches 0.1 hundred million m 3 and the material structure composition D 50 of the barrier body is more than or equal to 200mm, vertical steps with the height gradually increased from 20 m to 30m are vertically excavated at intervals from the downstream area of the midpoint of the drainage groove, and the maximum height of the vertical steps is less than or equal to 5m.
4. The method for arranging the stepped drainage groove for accelerating the breaking and improving the drainage efficiency of the barrier lake according to claim 1, wherein when the water storage capacity of the barrier lake reaches 0.1 hundred million m 3 and the material structure composition D 50 of the barrier body is less than or equal to 200mm, vertical steps with the height gradually increased from 30m to 50m are vertically excavated at intervals from a downstream area of the midpoint of the drainage groove, and the maximum height of the vertical steps is less than or equal to 5m.

Description

Stepped drainage groove arrangement method for accelerating blocking and improving drainage efficiency of barrier lake Technical Field The invention relates to a stepped drainage groove arrangement method for accelerating collapse of barrier lake and improving drainage efficiency. Background The barrier lake is used as a great natural disaster in the high mountain gorge valley area, and mainly forms a barrier body as a natural lake formed by landslide and collapse of a mountain or blockage of a natural river by mud-rock flow due to dynamic geological effects such as heavy rainfall, earthquake and the like, and a solid accumulation body such as the landslide or the collapse and the like falls into the river. The natural river is blocked by the damming body, the normal drainage of the natural river is blocked, and the drainage of the upstream and downstream of the damming body is extremely unbalanced, so that the continuous rising of the water level of the dam area of the damming lake is extremely easy to cause the overtopping and breaking of the damming body, an abnormal breaking flood peak is formed, and the life and property safety of coastal people is seriously endangered. Aiming at dangerous situations of high-risk barrier lakes, the engineering measures which are most widely applied at present and have the best effect are a drainage groove danger removing technology, namely, a trapezoid section drainage groove is longitudinally excavated at the top of the barrier body, the water passing height of the barrier body is reduced, the water storage volume of the barrier lake is reduced, the barrier body is eroded by utilizing the gradual flushing of the barrier body of the barrier lake by natural gravity and induced by potential utilization of flood, and the gradual flood discharge of the flood storage water of the barrier lake is promoted, so that the inundation loss of the barrier lake reservoir area and the damage of downstream flood are effectively reduced. The dam breaking process of the barrier lake is complex, the top breaking flow of the diversion trench is smaller and is far lower than the storage flow of the barrier lake in the initial stage of the dam breaking of the barrier lake, the water level of the barrier lake is continuously increased, the water storage capacity of the barrier lake is continuously increased, the reservoir area is extremely easy to submerge and lose, the flow velocity of the top water is gradually increased and continuously and longitudinally cuts down to erode the slope of the dam at the downstream of the barrier body in the source tracing erosion stage of the barrier lake, the concave-convex multi-stage tracing back to the steep bank is formed until the multi-stage steep banks are converged to form a larger drop steep bank, and the breaking flow of the barrier lake is rapidly increased and even is far higher than the storage flow of the barrier lake in the rapid breaking stage of the barrier lake, the water level of the barrier lake is continuously decreased, and the breaking flood peak is extremely easy to cause the damage of the downstream river segment along the journey. Aiming at the typical burst development process of the current high-risk barrier lake, the engineering world generally lacks effective engineering measures to regulate the burst development process of the barrier lake, once the conventional trapezoid cross section diversion trench is overturned, the normal trapezoid cross section diversion trench can only freely overflow by the overturned water flow, namely, the overturned water flow slowly and stole to rise along the diversion trench longitudinally and stole to the downstream dam slope of the barrier body, so that the barrier body is caused to trace to a steep bank, when the barrier body gradually collapses, the process takes longer time, has low drainage efficiency, even occupies 70-80% of the whole burst development process of the barrier lake, the water level of the barrier lake continuously rises at the stage (the warehousing flow is far higher than the overturned flow), the water storage volume continuously increases, the water storage time is long, and therefore, a large burst flood peak is extremely easy to form when the barrier body bursts. The current engineering field mainly adopts front-slow back steep slope-changing drainage grooves and vertical abrupt bank type drainage grooves, and aims to accelerate early drainage of the drainage grooves and shorten the water storage time of the barrier lake, for example, the longitudinal slope of the Tang Gushan barrier lake drainage grooves is 0.006, the longitudinal slope of 0+326-0+444m is 0.24 and the longitudinal slope of 0+444-0+550 m is 0.16 within the range of 0+00-0+326m. The vertical abrupt bank type drainage groove is similar to the variable slope drainage groove, and although the vertical abrupt bank type drainage groove can locally lift the flow velocity of the flood peak, the vertical abrup