Fundamental research on the dynamic behaviour of soils and the seismic stability of earth structures.

这项研究涉及两个相关的主题：(A)土的动力特性的基本方面和(B)土结构的地震稳定性。题目A：尽管进行了广泛的研究，但每个专题都有一些方面存在相当大的不确定性，有必要进行进一步的研究，以增进我们的理解，从而改进评价程序，从而推动实践的发展。 天然土壤和水力沉积的填充物(例如尾矿)通常以较细和较粗的材料(粉砂和沙子)分层为特征。仪器地震台试验将被用来表征这类沉积物的动态响应，并为其在工程实践中的评价提供建议。由于对围压对液化影响的研究相互矛盾，将通过循环三轴试验来评估围压对正常和超固结水力淤积土的影响。这项研究可能导致修正的修正系数，以评估在这类土壤的液化。 题目B：由于实践和规范的进步，数值分析越来越多地被用来评价土结构的地震稳定性。这些分析的实用性受到用于模拟材料行为的本构模型的限制。将开发和实施一个包含动态行为关键方面的本构模型。该模型将基于广泛使用的实验室和现场测试程序的相关性，并将考虑双曲线应力-应变关系、细粒含量、初始静剪和固结程度以及液化后强度损失的影响。 将数值方法和解析方法进行比较，以验证拟静力法和Newmark位移法在考虑强度损失和液化的材料组成的土结构中的应用。将制定动态数值分析的基本准则。

This research addresses two related topics; (A) the fundamental aspects of the dynamic behaviour of soil and (B) the seismic stability of earth structures. Topic A : Despite extensive research, there are aspects of each of these topics where there exist considerable uncertainty and further research is necessary to increase our understanding with the objective of improving evaluation procedures and thereby advancing the state of the practice. Natural soils and hydraulically deposited fills (e.g. tailings) are often characterized by layering of finer and coarser material (silt and sand). Instrumented seismic table testing will be used to characterize the dynamic response of such deposits and provide recommendations for their evaluation in engineering practice. Due to conflicting research on the effect of confining stress on liquefaction, the effect of confining pressure on normally and over-consolidated hydraulically-deposited soils will be evaluated using cyclic triaxial testing. This research may lead to revised correction factors for the evaluation of liquefaction in such soils. Topic B: Due to advances in the state of the practice and regulations, numerical analysis is increasingly to evaluate the seismic stability of earth structures. The utility of these analyses are restricted by the limitations of the constitutive models used to simulate material behaviour. A constitutive model that incorporates critical aspects of dynamic behaviour will be developed and implemented. The model will be based on correlations with widely used laboratory and in situ testing procedures and will consider: a hyperbolic stress-strain relationship, the effects of fines content, initial static shear and degree of consolidation, and post-liquefaction strength loss. Numerical and analytical methods will be compared to validate the use of the pseudo-static method and the Newmark displacement method for earth structures composed of materials subject to strength loss and liquefaction. Basic guidelines for dynamic numerical analysis will be developed.