Dynamic Reliability Analainties Of Tailing Dam Under Random Earthquake Ground Motions And Parameter Uncertainty

Tailings Dam is a special industrial bulilding,most of the ore is piled up in the tailings dam after being mined.At present,there are tens of thousands of tailings dams in China,and the number is increasing every year.The construction of these tailings dams is limited by technical conditions,and most of them are constructed by the upstream method,including no-main tailings dam,“three-side reservoir”,overhead reservoir,etc.Tailings Dam is an important source of danger,the failure and leakage of tailings dam is directly related to the downstream people's lives and property safety and the surrounding ecological environment.The factors that induce the failure of tailings dam are very complex,including the uncertainty and spatial variability of the parameters,seepage failure and earthquake liquefaction caused by the accumulation of tailings and damming materials for decades.Although the stability analysis method of tailings dam has been greatly developed at present,the objective existence of the spatial variability of tailing material parameters brings some difficulties to the stability analysis of tailing dam slope,and the commonly used deterministic analysis method cannot reflect the influence of spatial variability.In addition,the dynamic reliability evaluation of tailings dam under earthquake action has also become an important subject in the tailings dam project in the face of the frequency of earthquakes and the randomness of earthquake motions in China.Aiming at the above problems,this paper has carried out related research work.the main work and conclusions are as follows:(1)Based on the literature investigation of tailings dam stability analysis methods at home and abroad,the current research status of tailings dam spatial variability and random seismic stability evaluation methods is reviewed,and the shortcomings of current tailings material parameter spatial variability characterization and dynamic stability analysis methods under seismic action are summarized.(2)To effectively evaluate the stability of the tailing dam,a non-intrusive stochastic finite element method developed considering spatial variation of tailing parameters for reliability analysis of tailings dam is developed in the framework of the random field theory and limit equilibrium analysis.The Karhunen-Loève expansion method is used to discrete the random fields of the tailing material parameters.The series expansion method using the Hermite polynomial chaos expansion fitting random tailings dam safety coefficient and the implicit function relation between the input parameters,the tailings dam seepage and stability analysis as a black box direct call,implements the tailings dam deterministic analysis and reliability analysis of the coupling.Compared with the direct Latin hypercube sampling method,the proposed method can satisfy the calculation accuracy and reduce the calculation amount by 80%,which provides an effective path for solving the stability reliability problem of tailings dam considering the spatial variability of multiple material parameters(3)To properly evaluate the dynamic stability of tailings dams,this paper aims to propose a non-intrusive analysis method for the reliability analysis of tailings dam considering the random earthquake ground motions as well as the uncertainties of tailing material parameters.The random ground motion process of the reaction site and seismic characteristics is simulated,and the random motion program is written.According to the designated site information,2000 ground motions are synthesized artificially,and Newmark permanent displacement analysis is used to calculate the dynamic permanent displacement of tailings dam.This method can effectively avoid the subjective shortcoming caused by only selecting one or several historical seismic data curves for analysis in the past engineering practice,and the calculation results which are consistent with the actual engineering can be obtained(4)Through sensitivity analysis,the effects of magnitude epicentral distance and allowable deformation of the dam on the permanent displacement and failure probability of the acceleration of the tailings dam are discussed.The effects of earthquakes with different magnitudes and epicentral distance on tailings dam are significantly different.Under the same earthquake magnitude,the failure probability of tailings dam decreases with the increase of epicentral distance,and the allowable deformation of the dam has a significant effect on the failure probability of tailings dam,especially when the epicentral distance is small or the earthquake magnitude is large.Therefore,it is necessary to reasonably determine the allowable deformation of the dam body according to the engineering practice.