主余震序列作用下土质边坡力学性状演化及失稳机理研究

Aftershocks occur after a mainshock in a few hours to several years, and the landslides induced by aftershocks are a major secondary disaster. Mainshock-aftershock sequences can induce the evolution of mechanical properties of earth slopes, such as strain softening of soils, variation of excess pore water pressure, and local damage accumulation of slopes. Therefore, the failure mechanism of earth slopes subjected to mainshock-aftershock sequences is more complex than that subjected to a single earthquake. Different mainshock-aftershock sequences have different combinations of seismic intensities, time intervals, and frequency contents, and their influences on the seismic response and stability of slopes are not the same. Moreover, the slope failure processes triggered by a single strong aftershock and a sequence of aftershocks are significantly different. In this project, a model will be developed to characterize the mechanical property evolution of earth slopes. Centrifuge shaking table tests will also be performed. The slope failure mechanism subjected to mainshock-aftershock sequences will be revealed and summarized through this study. Meanwhile, a space-time probability distribution model for mainshock-aftershock sequences will be proposed and incorporated into the probabilistic seismic landslide hazard analysis. The research findings from this project will provide scientific basis and technical support for the mitigation of seismic landslide hazard and the seismic design of major projects.

主震发生后数小时至数年内通常发生一系列余震，而余震诱发的滑坡是震后主要次生灾害之一。主余震序列引起边坡土体应变软化、超静孔压反复变化、边坡局部破坏累积等力学性状演化，其作用下边坡的失稳破坏机理远较单一地震复杂。不同的主余震序列之间存在场地烈度、时间间隔和频谱组合差异，其对边坡动力响应和稳定性的影响有显著不同。另外单次强余震和多次连续余震诱发边坡失稳破坏的过程和机理也有很大区别。本项目将建立主余震序列作用下边坡力学性状演化表征模型，开展相关的离心机振动台试验，并揭示和总结主余震序列作用下土质边坡的失稳机理。同时，提出主余震时空概率分布模型，建立考虑主余震时空分布规律的地震滑坡危险性概率分析方法。研究成果将为地震滑坡灾害的防治和重大工程的抗震设计提供科学依据和技术支持。

主余震序列作用下边坡的失稳破坏机理远较单一地震复杂，单次强余震和多次连续余震诱发边坡失稳破坏的过程和机理也有很大区别。本项目开展了砂土边坡和土石坝坝坡的离心机振动台试验，揭示和总结了主余震序列作用下土质边坡的失稳机理，建立了相应的地震滑坡危险性概率分析方法，并进一步拓展研究了主余震序列作用下风机单桩基础的服役性能。本项目研究了脉冲型主震作用下滑坡体的加速度响应呈现明显的截断效应，并提出了表征该效应的理论计算公式；通过试验揭示了土石坝坝坡和单桩基础在地震序列作用下的加速度分布规律和孔压响应，并评估了两者的服役性能；建立了基于Monte Carlo模拟的区域地震滑坡概率风险分析方法，并应用到实际案例评估中。依托本项目研究发表标注项目基金号论文6篇，其中SCI收录3篇、EI收录3篇，授权国家发明专利4项和软件著作权1项。培养博士研究生2名，硕士研究生2名。研究成果将为地震滑坡灾害的防治和重大工程的抗震设计提供科学依据和技术支持。