Anti-sliding Stability Analysis Of Wukengli Tailings Dam Under Heavy Rainfall

The Wukengli tailings pond is valley-type tailings pond,which is built on the geographical advantage of natural valleys and surrounded by mountains on three sides.During the storm and flood season,due to heavy rainfall,rainwater pooling often occurs and the water level in the reservoir area rises and falls rapidly,which is likely to cause the dam body to become unstable and collapse.Therefore,it is of great engineering significance to explore the anti-sliding stable evolvement rule of Wukengli tailings dam in the whole process of rainfall under heavy rainfall.In this paper,based on the Wukengli tailings pond in Shaoyang,Hunan,combined with local climatic and hydrological data,the confluence calculation of the corresponding recurrence period rainfall is carried out to obtain the rainfall-water level evolvement rule of the whole rainfall process.By using the finite element software to calculate and analyze the seepage field and anti-sliding stability of the dam body during the whole rainfall process,it revealed the evolvement rule of the seepage field and anti-sliding stability of the tailings dam during the whole rainfall process,put forward corresponding solutions to the problems at each stage.The main contents and conclusions of this paper are as follows:(1)Particle size test of tailings dam and prediction of soil-water characteristic curve.Particle size tests were conducted on the two silt materials,tail silt and tail silt in Wukengli tailings pond,and their respective soil-water characteristic curves were predicted using fractal methods for later seepage calculation.(2)Analysis of the variation rule of rainfall-water level in the whole process of rainfall.According to the hydrological data in the reservoir area,the design rainstorm in the corresponding recurrence period was obtained using the rainstorm calculation method.Through the calculation of confluence,the rainfall-water level evolvement rule of the whole process of rainfall was obtained and divided into the following five stages:initial rainfall-water level unchanged(stage 1),continuous rainfall-water level rise(stage 2),stop rain-continuous water level rise(stage 3),water level fall(stage 4),steady water level(stage 5).(3)Analysis on the evolvement rule of the seepage field of Wukengli tailings dam in the whole process of rainfall.The Seep/W module in GeoStudio was used to calculate the seepage of the five stages of the rain-water level evolvement of the Wukengli tailings dam during the whole rainfall process.1)The phenomenon of the degree of uplift or descent rises to the highest position at 17h.2)With the change of rainfall-water level fluctuation,the length of the dry shoal also shortens and then recovers.The code requires a minimum dry beach length of 70m.3)During the whole process of rainfall,the matrix suction value of different dam sections of the dam is greatly affected by rainfall.The suction value gradually decreases from shallow to deep,and the surface layer changes rapidly and the amplitude is large.The deep layer suction value is less affected by rainfall.(4)Analysis of the stability evolvement rule of Wukengli tailings dam during the whole process of rainfall.Based on the seepage analysis,based on the limit equilibrium method,the Slope/W module in GeoStudio was used to calculate the anti-sliding stability calculation for the five stages of the rainfall-water level evolvement of the Wukengli tailings dam during the entire rainfall process,taking into account the influence of the matrix suction.The results show that:1)During the 15-hour design storm,the safety factor of the tailings dam decreases continuously,and the safety factor of the dam body meets the requirements of the specification.2)The safety factor value of the dam body is still decreasing within 2 hours after the rain stops,the safety factor at 17h drops to the minimum value of 1.197,and the minimum safety factor of 1.20 is not met.3)As the water level of the reservoir drops,the minimum safety factor of the dam body also gradually increases,and the safety factor at 28h returns to the original water level is 1.247,not restore the safety value to the initial state.The reservoir water is stable after returning to the initial water level.4)The minimum safety factor for 96h is 1.309,which is close to the initial value,and the dam body returns to a safe state.