本构模型特性对深厚场地非线性地震反应的影响

采用基于Davidenkov和Matasovic骨架曲线构造的不规则加卸荷应力—应变滞回圈,数值模拟了2个剖面的苏州第四纪深厚场地二维非线性地震反应。结果表明:(1)采用Matasovic模型计算的地表峰值加速度稍大于采用Davidenkov模型计算的地表峰值加速度,但前者计算的地表地震动持续时间稍小于后者计算的。随着基岩输入地震动强度的增大,两者给出的地表峰值加速度差异呈现逐渐增大的趋势,并与土体的横向不均匀特性有关;(2)两者给出的地表谱加速度谱形基本相似,其差异随基岩输入地震动强度的增大而增大;远场地震动作用下地表谱加速度的卓越周期也随输入地震动强度的增大而增大;(3)两者给出的峰值加速度随土层深度和横向的空间变化特征基本一致,远场地震动作用下的地表峰值加速度明显大于近场地震动作用下的地表峰值加速度。

Effect of Constitutive Model Characteristics on Nonlinear Seismic Response of Deep Site

Based on the Davidenkov and Matasovic skeleton curves with the irregular and unloading stress-strain hysteresis loops, two-dimensional nonlinear seismic response of two soil profiles in Suzhou quaternary sedimentary soils is studied using numerical simulation. The results show that: (1) the surface peak ground acceleration (PGA) obtained by the Matasovic model is slightly higher than that obtained by the Davidenkov model. However, ground motion durations calculated by the Matasovic model is slightly less than those obtained by the Davidenkov model. The relative difference values of surface PGA calculated by two models increases with increasing PGA of bedrock motion, which is related to the horizontal inhomogeneity of in-situ soils. (2) The shape of surface ground acceleration response spectrum is similar, and the difference of surface spectrum ground acceleration increases with increasing PGA of bedrock motion. The predominant period of surface ground acceleration response spectrum under far-field seismic motion increases with increasing PGA of bedrock motion. (3) The peak acceleration obtained by two constitutive models is fairly consistent with respect to the soil depth and lateral spatial variation, and the surface PGA under far-field seismic motions is significantly larger than that under the near-field seismic motions.