Static And Dynamic Analysis Of Asphalt Concrete Core Dam Based On Non-Invasive RFDM

The northwest of China is rich in water resources,but the natural environment is harsh,and it is located in the seismic zone,so the geological conditions are complex and the seismic intensity is high.The earth-rock dam with asphalt concrete core wall has become one of the most superior dam types in western China because of its simple construction,strong adaptability to deformation,good anti-seepage performance and little influence by climate.In this paper,the random field theory and finite difference analysis method are combined,and Flac3 D software is used to calculate and analyze an earth-rock dam with asphalt concrete core wall in western China,aiming at studying the behavior characteristics of the dam under the condition of considering the spatial variability of soil.The main research contents and conclusions of this paper are as follows:(1)The present situation of random field theory and its application in earth-rock dam are summarized,and the hydraulic splitting of core wall is preliminarily discussed.On the basis of literature review,stochastic finite difference method(RFDM)is proposed and implemented in Flac3 D by using fish program.(2)A stochastic finite difference mathematical model was established to study the stress and deformation characteristics of the dam body and the hydraulic fracturing condition of the core wall under static conditions by using two methods of deterministic analysis and stochastic finite difference analysis,considering the spatial variability of soil.The results show that the random finite difference simulation results of the maximum settlement,the maximum horizontal displacement upstream,the maximum horizontal displacement downstream and the maximum principal stress and the maximum principal stress of the earth-rock dam with asphalt concrete core wall are normal distribution.If the uncertainty of soil is ignored and the deterministic method is adopted,the probability of underestimating the five response values is considerable.In addition,the hydraulic fracturing of the core wall does not occur under the three criteria of small principal stress,medium principal stress and combined stress of(3σ2-σ1).It is found that the influence of soil spatial difference on the hydraulic fracturing of the core wall under static condition is very small and can be properly ignored in general.(3)The influence of soil spatial variability on the dynamic response and hydraulic splitting of asphalt concrete core dam is studied by using the unified static and dynamic constitutive model.The results show that the peak acceleration,maximum settlement and maximum horizontal displacement of the dam body are discretized,and all the responses except the maximum settlement of the dam body follow normal distribution.After earthquake,the displacement dispersion degree of the dam crest and the slope far from the core wall is the largest,which requires special attention in the seismic design of asphalt concrete core wall dam.The core wall is stable in the stochastic finite difference simulation,but the dispersion degree of small principal stress at some monitoring points is very high.Especially for the dam with small principal stress as the evaluation criterion,the spatial variability of soil material cannot be ignored in the hydraulic fracturing analysis.(4)the safety assessment of earth-rockfill dam is numerical model,based on the slope safety factor and failure probability of slope two indicators to study the spatial variability of soil influence on the dam slope stability,the results show that the slope failure probability of spatial variability of soil are the most sensitive,especially when the variation coefficient of 0.25 after spatial variation effect on it is very significant,Therefore,when evaluating the stability of soil slope with large variability,it is necessary to select the variation coefficient corresponding to the actual situation of soil to avoid the distortion of evaluation results caused by the selection error of variation coefficient.Among them,the variation of cohesion C has a greater impact on the stability of earth-rock dam than the friction Angle.The influence of soil spatial variability on slope stability under dynamic conditions is more prominent,so it is suggested to use comprehensive evaluation method to evaluate dam slope stability,instead of using a single index.