Response of soils under generalised loading and drainage conditions

土壤的行为通常是在完全排水或完全不排水的条件下，沿着特定的加载路径进行评估。然而，在现实中，变形依赖于存在于现场的三维应力状态，并且必然涉及孔隙体积和孔隙压力的同时变化。排水和不排水的近似在某些情况下工作得很好，但在评估土壤的震后反应时可能不能产生令人满意的结果。在实际的现场问题中，适当的表征应该考虑到孔隙体积和压力同时变化的事实。所提出的实验研究将提供一个深入了解土体在孔隙体积和压力同时变化时的剪切变形特征。液化的触发除了考虑不排水载荷外，还考虑孔隙水的迁移。新的加拿大国家建筑规范（NBCC2005）中的地震规定更加严格，设计师将不得不处理更高级别的地震震动。通常用于评估循环阻力的经验方法是基于比NBCC2005规定的更低震动水平的数据。研究三维应力状态对土体循环阻力和循环后变形特性的影响将有助于这方面的研究。研究结果将使我们能够评估当前的设计方法，并提出改进的循环阻力评估技术。更好地了解液化土的流变学是自信地预测地震诱发位移的关键。如果确定目前的做法是保守的，则有巨大的经济效益潜力。拟议的研究将提高我们对土壤力学行为的理解，并提高数值模型和当前设计方法的可靠性。它将带来更自信的设计和更经济的解决方案。

Behaviour of soils is typically assessed under either fully drained or fully undrained conditions, and along specific loading paths. However, in reality the deformation is dependent on the three dimensional stress state that exists in the field, and would invariably involve simultaneous changes in both pore volume and pore pressure.The drained, and undrained approximations work well under certain situations, but may not yield satisfactory results when evaluating the post-earthquake response of soils. A proper characterization should consider the fact that both pore volume and pressure change simultaneously in actual field problems. The proposed experimental research will provide an insight into the shear-deformation characteristics of soils when subjected to simultaneous changes in pore volume and pressure. Triggering of liquefaction will be considered not only due to undrained loading, but also due to pore water migration.Seismic provisions in the new National Building Code of Canada (NBCC2005) are stricter, and designers will have to deal with higher levels of earthquake shaking. The empirical approach typically used to evaluate cyclic resistance is based on data at lower shaking levels than those specified by NBCC2005. Proposed research will contribute to this aspect by studying the effect of three dimensional stress state on the cyclic resistance of soils, and on the post-cyclic deformation characteristics. Outcome of the research will allow us to evaluate currentdesign methodologies, and propose improved cyclic resistance assessment techniques. Better understanding of the rheology of the liquefied soils is key to confidently predict earthquake induced displacements.There is significant potential for economic benefits if current practice is determined to be conservative.  Proposed research will improve our understanding of the mechanical behaviour of soils, and enhance the reliability of numerical models, and current design methodologies. It will lead to more confident designs, and economic solutions.