Research Initiation: Response of Saturated Silty Soils to Irregular Seismic Loads

世界上大多数人口聚居区集中在山谷中，即由不同层的无粘性和粘性土壤组成的沉积沉积物，包括非塑性和塑性粉土。沉积沉积物中的地面运动放大现象、各类土的承载能力丧失以及饱和砂土或粉质土因地震震动而液化的现象，目前还只有部分了解。为了充分了解上述现象，必须了解不规则地震荷载作用下所有土体材料(砾石、砂、粉土、粘土)的工程性质。本研究项目包括饱和粉质土对不规则地震荷载响应的实验室调查和分析模型。在实验室中，将使用循环直接、简单剪切和循环三轴装置来模拟与地震波传播相对应的加载条件。土体在循环荷载作用下的刚度退化、循环孔压的相关变化以及不规则循环应力-应变行为的规律正在被研究。对粉质土壤得到的结果与相应的关于砂土和粘土的结果进行了比较。这种比较为建立对三种类型的土都适用的刚度降低和孔压发展的数学模型提供了基础。

Most of the populated regions of the world are concentrated in valleys, that is, on sedimentary deposits composed of different layers of cohesionless and cohesive soils, including nonplastic and plastic silts. The phenomenon of the amplification of ground motion in sedimentary deposits, as well as the loss of bearing capacity in all types of soils, and the liquefaction of saturated sandy or silty soils due to earthquake shaking, are only partially understood. The engineering properties if all soil materials (gravel, sand, silt, clay) under irregular seismic loads must be known in order to fully understand the above phenomena. This research project involves a laboratory investigation and analytical modelling of the response of saturated silty soils to irregular seismic loads. Loading conditions corresponding to the propagation of seismic waves will be simulated in the laboratory using cyclic direct simple shear and cyclic triaxial devices. Degradation of soil stiffness during cyclic loading, the associated variation of cyclic pore pressure, and the rules governing irregular cyclic stress-strain behavior are being investigated. The results obtained for silty soils are being compared to the corresponding available results on sands and clays. This comparison provides a basis for the development of mathematical models for the reduction in stiffness and the development of pore water pressure, valid for all three types of soils.