Impact of bidirectional shaking on the seismic response of level and sloping ground sand deposits

在进行场地地震反应分析时，通常只考虑地震动的一个剪切方向。现有研究表明，忽略地震荷载的其他分量可能会导致对地震需求的低估。目前，工程实践通过对单向需求应用一个粗略的比例因子来松散地解决这个问题。然而，最近的研究表明，双向振动的影响可能更具挑战性和重大意义，无论是对于水平地基还是斜坡地基，都会增加诸如沉降、液化势和位移等性能指标。本项目的目的是研究双向振动对砂层地震反应的影响，并提出一个基于证据的框架来解释它在工程实践中的作用。在经过验证和验证的数值方法的基础上，将开发一个受单向和双向地震剪切影响的砂岩沉积的非线性完全耦合三维分析数据库，以评估各种情况。与行业合作伙伴BGC Engineering合作，将考虑分层水平和倾斜地面条件的不同情况。将对结果进行汇编和分析，以了解双向地震剪切对所研究实例性能的影响，并制定一种在工程实践中考虑这一影响的充分知情的简化方法。这项研究的结果，特别是拟议的框架，将供工业伙伴组织使用。这项合作研究将为加拿大工程界提供工具和手段，以提高水坝和尾矿储存设施等主要结构的抗震设计效率。

When conducting seismic site response analysis, typically only one of the shearing directions of the ground motions is considered. Existing research shows that neglecting the other components of the earthquake load can lead to an underestimation of the seismic demand. Currently, engineering practice loosely addresses this issue by a means of a rough scaling factor applied to unidirectional demand. However, recent studies have revealed that the impact of bidirectional shaking can be more challenging and significant, for both level and sloping grounds, increasing indices of performance such as settlement, liquefaction potential, and displacements, among others. The objective of this project is to investigate the effects of bidirectional shaking on the seismic response of sand deposits and to propose an evidence-based framework to account for it in engineering practice. Based on a verified and validated numerical approach, a database of nonlinear fully coupled three-dimensional analysis of sand deposits subjected to unidirectional and bidirectional seismic shearing will be developed to evaluate a wide range of scenarios. In collaboration with the industry partner BGC Engineering, different cases of the layered level and sloping ground conditions will be considered. The results will be compiled and analyzed to understand the effects of the bidirectional seismic shearing on the performance of the studied cases and to develop a well-informed simplified approach to account for that in engineering practice. The outcomes of this research and, in particular, the proposed framework, will be used by the industrial partner organization. This collaborative research will provide the engineering community in Canada with tools and means to improve the efficiency of the seismic design of major structures such as water dams and tailings storage facilities.