Dynamic Response Analysis Of Asphalt Concrete Core Dam On Deep Overburden

Due to the limitation of geological conditions of dam site,more and more asphalt concrete core wall dams will be built in deep overburden and high intensity areas.There are many problems.and challenges in the construction of the dam on the deep overburden,such as the complex and changeable structure and materials,and even the change of the seismic characteristics introduced into the dam body,which has a significant effect on the dynamic response of the dam body.Therefore,based on the actual overlay site platform record,the study on the variation of ground motion characteristics with depth,the sensitivity of overburden characteristic parameters to the dynamic response of overburden and asphalt concrete core wall dam is carried out.Based on the seismic overload method,the ultimate seismic capacity of overburden to foundation-dam system is analyzed.The main contents of this paper are as follows:(1)The variation of peak acceleration magnification factor,spectrum and acceleration response spectrum with depth of the Treasure Island and 36 ground motion acceleration records of La Cienega and Californian arrays were studied.The equivalent linear constitutive model parameters of Shen Zhujiang River are fitted based on the acceleration record of the down formation of the well,and the ground motion field of the overburden site is reconstructed considering the influence of nonlinear and complex terrain of the soil.Calculated results are compared with the measured records and the results conform to the good.(2)A two-dimensional finite element model of the overburden and asphalt core wall dam is established based on the La Cienega matrix and a asphalt concrete core wall dam built on the overburden.The influence degree of the dynamic response of the foundation-dam system is analyzed by the variation of ground dynamic strength,overburden thickness,soil dynamic characteristic parameters(dynamic shear modulus and Poisson’s ratio)and soil structure type.The results show that the acceleration magnification factor at the top of the asphalt core wall does not increase gradually with the increase of the overburden thickness,but there is a critical thickness.The existence of soft fine sand layer limits the seismic response input to the dam body and has obvious energy absorption function.(3)The presence of the weak fine sand layer significantly affects the dynamic response of the asphalt core wall dam.Therefore,based on this parameter,using the residual deformation of the dam top and the maximum tensile stress,the influence on the ultimate seismic capacity of the foundation-dam system.The research shows that the existence of weak fine sand layer reduces the ultimate seismic capacity of asphalt wall dam.