材料模型参数对自由场地震响应的影响

Effects of material model parameters on seismic free ground response

水平自由场地震响应分析是岩土地震工程近几十年的研究热点之一。利用完全耦合有限元程序SUMDES 2006和临界状态砂土本构模型,分析了15m深的饱和砂土自由场在地震作用下的响应,包括加速度的传播、孔隙水压力的发展、侧向变形以及地面沉降。通过增大和减小10%参数值,分析了材料本构模型中12个参数值的变化对土层地震响应的影响。分析结果表明,在这些参数中,临界状态应力比M和e-pξ平面中临界状态线在e轴上的截距eΓ的影响比较显著,因而利用室内试验数据率定模型参数时,需保证其有足够的精度。分析结果也说明,用于自由场地震响应分析时,临界状态砂土本构模型仍然有进一步简化以减少参数个数的空间。

Analysis of response of level ground subjected to earthquake is one of the most active research areas in geotechnical earthquake engineering. In this paper,seismic response including propagation of acceleration,development of pore pressure,lateral displacement and settlement,of a level ground consisting of 15 m saturated sand is analyzed,by using the finite element procedure SUMDES 2006,incorporating a critical state constitutive model for sand. Effects of model parameters on seismic ground response are studied by adjusting the values of parameter by ± 10 %. The analytical results show that,among these parameters,the critical state stress ratio M and eΓ,the intercept of the critical state line on the e axis in the e -pξ plane,impose stronger effect. Therefore,the accuracy of the two parameters should be secured when the parameters are calibrated against the experimental data. The results also imply that the number of parameter in the model may be reduced when it is applied to the analysis of seismic response of level ground.