互层土的动参数试验研究及其地震反应分析

通过对两个工程场地的淤泥质粉质粘土、粉土、粘土、粉细砂及粉土与(粉质)粘土、粘土与粉砂互层土的自振柱试验结果进行分析,给出了部分土的G/Gmax-γ和λ-γ曲线,与Seed和Idriss建议的砂土和粘性土的G/Gmax-γ和λ-γ曲线变化范围进行了对比;同时分析了这两个场地的地震反应,结果表明:在强震时互层土对地震波有很强的滤波作用,且互层土的最大剪应变远大于一般土,在水平地震作用下很容易接近或达到破坏状态。初步分析结果表明:互层土具有软土的动力特性,这主要是由互层土的特殊物理构造造成的,即在互层土中存在很密的水平薄弱面。

A study on dynamic parameters and seismic response of interbedded soil

By using resonant column apparatus, the dynamic parameters of interbedded soil and other soils in two sites are tested; the curves of dynamic shear modulus ratio G/Gmax and damping ratio versus dynamic shear strain amplitude of the soils in two sites are given. Compared with the variation range of G/Gmax vs. and D vs. curves of other soils, it is obviously that the G/Gmax vs. and D vs. curves of mucky silty clay and fine sand interbedded strata are more close to those of soft clay. By calculating the seismic response of the two sites, the results show that the interbedded soil weakens the peak acceleration greatly and its maximal shear strain amplitude is very big which is near to be failure under horizontal earthquake. The dynamic characteristic of interbedded soil is similar to that of soft soil; and this property is caused by its special conformation, i.e. the feeble horizontal joint planes are overgrown.