Deformation-Based Seismic Analysis and Design of Waterfront Retaining Structures

滨水建筑物包括重力墙、板桩墙和桩承式码头等，这些建筑物在地震作用下的响应主要取决于复杂的地基-结构-基础相互作用以及地基和回填土的不排水特性。 目前这种系统的设计理念旨在将支撑结构的变形限制在可接受的水平。 本研究的目的是发展一套以变形为基础的分析方法，以供滨水建筑物的抗震评估与设计之用。 将研究典型的二维重力墙和板桩墙的抗震性能和破坏，这些墙容易受到超孔隙水压力的积累和液化的影响。 各种地基加固技术的性能使用作为标准的预测永久变形为不同水平的地面震动强度，并将提供指导方针，修复优化。 将采用有效应力、非线性有限元法，并结合边界元，对传出波的能量辐射进行精确建模。 地基、回填土和近场土采用严格、有效的临界状态模型进行建模，该模型可以预测砂土中的密实化、孔隙水压力恢复、液化和循环流动性。 该模型能够较好地模拟超孔隙水压力的产生、重新分布和消散过程，并揭示了可能导致破坏的变形机制。 该研究将与日本清水公司和希腊NTUA的研究人员密切合作进行。 这是一个由NSF 98-36“美日城市地震减灾研究”第二年计划资助的奖项。"

Waterfront structures include gravity walls, sheet pile walls, and pile supported wharfs which are vulnerable to earthquake damage the response of such structures to strong ground shaking depends primarily on the complex soil-structure-foundation interaction and the undrained behavior of the foundation and backfill soils. Current philosophy in the design of such system aims at limiting deformations of the supported structures to acceptable levels. Depending on their importance and function.The objective of this research is to develop a deformation-based method of analysis for the seismic evaluation and design of waterfront structures. The seismic behavior and damage of typical two-dimensional gravity walls and sheet pile walls that are vulnerable to excess pore water pressure buildup and liquefaction, will be investigated. The performance of various ground improvement techniques using as criterion the predicted permanent deformation for different levels of ground shaking intensity and will provide guidelines for remediation optimization. An effective-stress, nonlinear finite element method, coupled with boundary elements for accurate modeling of the energy radiation through outgoing waves will be used. The foundation, backfill and near-field soils are modeled with a rigorous, efficient critical state model, that can predict densification, pore water pressure buildup, liquefaction and cyclic mobility in sands. The numerical model can simulate successfully the generation, redistribution and dissipation of excess pore water pressures and reveal the deformational mechanisms leading to possible failure. The investigation will be performed in close collaboration with researchers from Shimizu Corporation, Japan and NTUA, Greece. This is an award supported under the 2nd year initiative, NSF 98-36 "US-Japan Urban Earthquake Disaster Mitigation Research."