地震响应下土质边坡破坏模式概率分析及防灾参量逆可靠度反演方法研究

Over the past decades China has achieved great success in infrastructural development. Large amounts of earth slopes were thereby created, and most of them are in the potential of earthquake damage. In this context, research works related to seismic slope stability and its hazard control theory are of great importance to our country. The fundamentals of seismic slope stability evaluation involve the study of earthquake induced slope failure modes as well as the prediction of earthquake induced permanent displacement. The seismic load is highly stochastic and the physical parameters of geo-materials are naturally uncertain and spatially variable. As a result, there are unavoidable uncertainties in the seismic slope stability assessment, which may bring safety issues if the seismic slope design is performed without an adequate understanding of the different sources of uncertainties and their interrelationships. This research project aims at earthquake induced slope instability prediction for hazard control, utilizing the theoretical analysis, numerical simulation and model verification as a combination. The study will start with identification of the seismic slope failure modes in different conditions and detailing the failure mechanism and seismic displacement prediction. Then the uncertainty and spatial variability characterizing the slope soil parameters will be investigated. Based on above mentioned works, the random field models for spatial variability and simplified geotechnical reliability analysis frameworks will be developed to carry out probabilistic prediction of seismic earth slope instability. Lastly, the inverse reliability theory will be used to identify the key factors potential for causing slope failure, of which the probabilistic optimization design could be used to prevent hazards. It is hoped that the proposed research would provide theoretical fundamentals and technical supports to the probabilistic slope instability prediction and its hazard control under earthquake loads.

我国基础工程量巨大而地震频发，因此边坡工程在地震响应下的失稳破坏及其防灾理论一直是岩土工程领域的重点研究内容。地震边坡的稳定性评价需要综合考虑地震破坏模式和地震永久位移量。地震荷载是一个高度的随机过程，同时岩土体材料的力学特性存在天然的随机性和空间变异性等不确定性特征，这进一步增加了地震边坡稳定性评价的不确定性，导致大量的边坡在其破坏机理未被充分认知的情况下进行抗震设计、施工和服役，埋下了严重的安全隐患。本项目以土质边坡抗震防灾为研究对象，通过理论研究、数值分析、模型试验相结合的方法，进一步明确土质边坡在地震响应下的破坏模式和失稳机理，分析典型边坡土质力学参数的空间变异性规律，基于土体随机场模型和岩土可靠度理论对地震边坡的稳定性进行概率分析，利用逆可靠度原理对其失稳致灾因素进行概率优化设计，为地震响应下的边坡稳定性概率预测和灾害控制提供理论依据和技术支持。

本项目针对地震响应下土质边坡破坏模式概率分析及防灾设计参数反演方法开展了系统性研究，探讨了地震边坡的失效机理、稳定性评价方法和边坡地震破坏防灾参量可靠性优化设计理论。在项目执行期内，围绕2个关键科学问题重点研究了以下内容：（1）针对土质边坡的局部到整体失稳模式，开发了适用不同荷载条件和不同破坏模式的边坡滑体地震位移时程分析模型，重点考察了边坡地震破坏模式同静力破坏模式的不同之处，分析了地震响应下土质边坡平动和转动破坏模式的永久位移发展规律；（2）建立了适应于地震边坡失效概率预测的可靠度分析方法，提出了相应的失效概率求解模型，着重考察概率最危险滑坡破坏面的差异并揭示其变化规律；（3）基于岩土可靠度分析框架，揭示了土质力学参数空间变异性对边坡地震位移量的影响规律，同时明确了随机地震荷载对边坡永久位移的影响；（4）提出了基于逆可靠度理论的地震边坡安全可靠性优化设计模型，对重要可控变量，开发了基于逆可靠度计算的实用分析程序，拓展了边坡抗震优化设计理念的工程应用；（5）从实用角度进行了大量地震边坡破坏模式回归分析，提出了基于极限状态线的土质边坡地震稳定性图解法。 .. 项目执行期间发表SCI收录学术论文24篇、EI收录学术论文5篇，在国内外学术会议做大会报告或邀请报告10余次。培养博士研究生在读5人，硕士生9人（其中毕业6人），多人次获得研究生国家奖学金、河海大学钱家欢奖学金等荣誉称号。