Study On The Dynamic Stability Of A Tailings Dam In Sichuan Under Earthquake Actio

Tailings ponds are a major source of danger with high potential energy,and in the event of a dam failure,it will cause huge environmental pollution and loss of people and property.As a mining powerhouse,most tailings ponds in China are located in seismic zones or areas of high seismic activity,increasing the risk of dam failures due to earthquakes.With the improvement of the beneficiation process in recent years,more and more fine-grained tailings have been discharged into the reservoir,which reduces the dam’s seepage discharge capacity and is not conducive to the improvement of the dam’s dynamic stability.Therefore,this paper investigates the influence of tailings dynamics and other influencing factors on the dynamic stability of the dam through a combination of indoor geotechnical tests,theoretical analysis,and numerical simulations,using a tailings pond in Sichuan as the engineering background.The main findings are as follows:(1)The physical and mechanical properties of tailings materials with different fines contents were investigated by geotechnical tests on tailings particles.The results of the study showed that: The permeability coefficient of tailings with different fines content shows a decreasing trend with the increase of fines content,and the decreasing trend of the permeability coefficient of tailings is more obvious when the fines content exceeds 60%.The plasticity index of tailings generally tends to increase with the increase of fines content.(2)The macroscopic mechanism of the deposition characteristics of tailings with different fines content was investigated using tailings sedimentation column tests and combined with electron microscopy scanning,XRD and XRF tests.The deposition pattern of tailings in the sediment column test generally shows certain stratification characteristics,and the stratification effect is correlated with the tailings grade.With the increase of fine particle content,the tailing particle morphology transitions from granular to flaky,adsorption is enhanced,and the tailing particle settling mode changes from single particle settling to flocculent settling.(3)The dynamic tests of stratified tailings with two fines contents were carried out using a dynamic triaxial apparatus to investigate the dynamic strength variation and pore pressure growth pattern of stratified tailings with different fines contents.The study found that: When the dynamic strain value reaches a certain fixed value,the dynamic modulus of elasticity of the layered tailings decreases rapidly until it tends to zero.Power function relationship curve between dynamic shear stress ratio and damage vibrations of layered tailings.The growth law of dynamic pore pressure is generally an "S"-shaped inverse sine function,and the initial growth slope of pore pressure tends to decrease with the increase of consolidation stress.(4)Numerical simulation software is used to analyze the factors influencing the dynamic stability of the dam.The analysis results show that: A good linear relationship between the minimum safety factor of the hazardous slip surface of the dam and the peak seismic wave acceleration.The increase in the length of the dry beach surface can effectively reduce the depth of the infiltration line,improve the minimum safety factor of the dam’s dangerous slip surface,and enhance the dam’s seismic capacity.The increase in fine-grained tailings can reduce the seismic stability of the dam.The maximum horizontal displacement of the dam body occurs at the top of the dam and spreads outward in a fan-shaped distribution centered on it.