考虑震源不确定性的场地地震动及反应谱研究

Based on the requirement of seismic safety evaluation for engineering sites in China, the study on the site ground motion and response spectrum considering earthquake source uncertainties will be conducted to reveal the effect of earthquake source uncertainties on site ground motion and response spectrum. For the establishment of bedrock seismic motion model which can reflect the effect of earthquake source uncertainties, a spatial random function and the Green’s function will be used to describe the earthquake source uncertainties and the path of seismic waves respectively. Then, to take the effect of site covering layer on ground motions into consideration, a Monte Carlo sampling technique will be adopted to discrete the probability space of ground motion model, and the ground motion samples can be obtained subsequently. Taking these samples as bedrock input ground motion, the site ground motion can be acquired by stochastic dynamic analysis. Finally, based on the demand of engineering seismic design, the randomness of ground motion and response spectrum on the level of probability density function will be studied, and site response spectrum with different probability levels will be established, which can provide scientific basis for geotechnical seismic design. The research results of the project, which has important scientific value and wide application prospects, will promote the development of seismic safety evaluation of engineering site, and improve the seismic performance of geotechnical engineering in China.

本项目立足我国工程场地地震安全性评价重大需求，拟围绕“考虑震源不确定性的场地地震动及反应谱研究”这一关键科学问题，开展深入研究：运用空间随机函数、Green函数分别表征震源不确定性和地震波传播路径效应，提出一种考虑震源随机特性的场地基岩地震动模型；采用蒙特卡罗抽样技术对该模型中描述地震动随机性的概率空间进行剖分，选取地震动样本时程作为基岩输入地震动对场地进行随机动力响应分析，获取考虑覆盖层影响的场地地表地震动；最后从工程抗震设计需求出发，在概率密度函数层次上把握场地地震动与反应谱的随机性，建立具有不同概率水平的场地反应谱，为岩土工程抗震设计提供科学依据。研究成果将有力推动工程场地地震安全性评价研究的发展，进一步提高我国岩土工程抗震水平，具有重要的科学理论价值和广阔的工程应用前景。

本项目立足于我国工程场地地震安全性评价的重大需求，从地震发生的物理机制出发，采用现场调研、理论分析、数值模拟等研究手段对“考虑震源不确定性的场地地震动及反应谱研究”这一科学问题展开研究，取得以下成果：①分别采用震源时间函数和格林函数量化表征震源滑动分布和传播路径的不确定性，提出了一种考虑震源不确定性和路径影响的基岩随机地震动模型；②对随机地震动模型的有效性进行验证，基于Monte Carlo方法生成随机基岩地震动时程，揭示了震源不确定性对场地地震动的影响规律；③提出了基于“震源—传播路径—场地”的全过程反应谱分析方法，通过动力响应分析获取样本点反应谱，从概率密度函数层次把握边坡场地反应谱的随机特征。项目成果突破了规范中场地反应谱的确定性分析难以表征随机震源的局限性，为基于概率分析方法的场地抗震设计提供科学依据。.相关研究成果在国际高水平期刊发表学术论文12篇，出版英文专著1部，获得国家发明专利授权1项，登记软件著作权1项。培养博士生2名，硕士生3名。项目负责人在国内外重要学术会议作特邀报告4次。在项目执行期间，项目负责人取得4项科研奖励，创办并召开第一届边坡工程抗震性能及设计国际研讨会，并多次邀请国际知名学者来华交流，促进了国际学术合作研究。