Multidimensional constitutive and numerical modeling in geotechnical seismic analysis and design

岩土地震工程建模的未来将几乎完全基于基于性能的地震设计理念。PBSD要求向基于位移或变形的设计模式转变，而不是传统的基于力的设计。它比传统的分析和设计方法更合理，并导致更经济有效的施工或更安全的设计。PBSD要求对计算变形的可靠性进行足够的测量。岩土结构在不规则地震荷载作用下变形的真实模拟是非常复杂的。模拟工具应处理基于有效应力公式的3D动态分析、完全耦合的固体-孔隙流体相互作用以及用于处理大型问题的并行/云计算功能。其中最重要的问题是土体的本构模型。目前在工程实践中使用的土体模型不包括许多影响应力-应变关系的非常重要的因素。解决地震的多方向循环加载问题也是极具挑战性的。从与处理土坝的BC Hydro等主要从业人员的讨论中可以清楚地看出，他们主要关心的是现有不同模型给出的不同反应；在某些情况下，这些差异足以引起极大的关注。

The future of modeling in geotechnical earthquake engineering will be based almost exclusively on Performance-Based Seismic Design philosophy. PBSD requires a paradigm shift toward a displacement or deformation-based design as opposed to the traditional force-based design. It is more rational than the conventional analysis and design methods, and leads to more cost effective construction or safer design. PBSD demands an adequate measure of reliability of computed deformations. A realistic simulation of deformation of geo-structures subjected to irregular earthquake loading is very complex. The simulation tools should handle 3D dynamic analysis based on effective stress formulation, fully coupled solid-pore fluid interaction, and parallel/cloud computing features for handling large problems. The most important issue is proper constitutive modeling of the soil matrix. Current soil models used in engineering practice do not include many of the very important factors that affect the stress-strain relationship. It is also extremely challenging to address multidirectional cyclic loading of earthquakes. From discussion made with major practitioners, such as BC Hydro who deal with earth dams, it becomes clear that their main concern is with the different responses given by the different models that are available; in some cases these differences are significant enough to cause great concern.