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

世界上大多数人口稠密的地区都集中在山谷中，也就是说，集中在由不同层的无粘性和粘性土壤组成的沉积物上，包括非塑性和塑性泥沙。沉积沉积物中地面运动的放大现象，以及所有类型土壤的承载力损失，以及由于地震震动而饱和的沙质或粉质土壤的液化，只是部分了解。为了充分理解上述现象，必须了解所有土体材料（砾石、砂土、粉土、粘土）在不规则地震荷载作用下的工程特性。本研究项目包括对饱和粉质土对不规则地震荷载的响应进行实验室调查和分析建模。采用循环直接单剪装置和循环三轴装置在实验室模拟地震波传播所对应的加载条件。研究了循环加载过程中土体刚度的退化、循环孔隙压力的变化以及不规则循环应力-应变行为的规律。对粉质土壤所得到的结果正在与砂质和粘土的相应的现有结果进行比较。这一比较为开发适用于所有三种类型土壤的刚度降低和孔隙水压力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.