考虑地震动场地效应的潜在地震滑坡危险性预测研究

Taking Tianshui~Minxian loess hilly area with strong seismicity background as an example, seism geological background investigation & strong earthquake activity analysis are performed. On this basis, seismic inversion of Minxian earthquake and site effect under 3D terrain and stratigraphic structure are studied with regional earthquake ground motion simulation and in-situ pulse test. The results can provide real ground motion parameters for seismic landslide hazard assessment. Formation background of Minxian earthquake induced landslide and dynamic response, failure mechanism of “loess & mudstone” dual structural slope are analyzed with engineering geology survey and landslide numerical simulation. So the seismic landslides formation principle in loess hilly area can be revealed. The improve study of seismic landslide hazard assessment method based on Newmark displacement model is carried out with Minxian earthquake induced landslides, so as to develop an modified seismic landslide displacement empirical formula for loess hilly area. In Tianshui potential meizoseismal area, potential seismic hazard analyses based determined earthquake and probability analysis are carried out. The determined ground motion parameters and those with different probability levels are provided; also they are calibrated with site effects. Based on all above studies, comprehensive research on potential seismic landslide hazard prediction with ground motion site effects in Tianshui area is carried out. Through this research, with fusion of engineering seismic and engineering geology subjects, internal mechanism from earthquake happening to landslide forming is revealed; temporal and spatial probability of potential seismic landslide is predicted. The results will provide scientific basis for urban construction planning and seismic landslides disaster mitigation in loess hilly area.

围绕具有强震活动背景的天水~岷县黄土丘陵区，通过地震地质调查和强震活动分析，结合区域地震动模拟和地脉动测试，开展岷县震区的地震动反演及考虑地形和地层结构的场地效应研究，为地震滑坡危险性评估提供真实地震动参数。通过工程地质调绘和滑坡数值模拟，开展岷县地震滑坡孕灾条件和“黄土/泥岩”二元斜坡动力响应及破坏机理研究，揭示黄土丘陵区地震滑坡成灾规律；研究改进基于Newmark位移模型的地震滑坡危险性评估方法，提出适用于黄土丘陵区地震滑坡位移分析的修正经验式。开展天水地区潜在地震危险性分析，提供经过场地效应校正的确定性和不同概率水平的地震动参数；综合上述研究，开展考虑地震动场地效应的潜在地震诱发滑坡危险性预测研究。通过融合工程地质和工程地震等理论技术，揭示从地震发生到滑坡形成的内在机制，预测潜在地震滑坡的时空概率分布，为黄土丘陵区城镇建设规划和地震滑坡减灾提供科学依据。

围绕西秦岭北缘与黄土高原地貌过渡带的天水~岷县地区，综合地震工程地质调绘、原位和室内测试、区域地震动和滑坡机制数值模拟等手段，开展了考虑地震动场地效应的潜在地震滑坡危险性预测有关研究，通过融合工程地质和工程地震等方法，初步探讨了从地震发生到滑坡形成的过程，预测了潜在地震滑坡时空概率分布，为黄土丘陵区地震滑坡灾害防御和国土空间规划提供科学依据。取得主要成果如下：1.针对孕灾背景，揭示区域4类主要控滑斜坡结构，指出“黄土/泥岩”二元结构是最易滑的斜坡结构。2.从试样尺度，利用动三轴试验揭示循环动荷载和天然地震作用下的天水第四系黄土和新近系泥岩的动力学特性。3.从坡体尺度，运用离心机振动台试验和数值模拟技术，揭示了天水地区“稳定斜坡和已有滑坡”两类坡体的地震动响应及破坏特征。4.以天水郑家磨滑坡为例，探索地震作用下深层-大型泥岩滑坡运动学特征及复活机制。5.从区域尺度，融合概率地震危险性分析和基于Newmark位移模型的地震滑坡危险性评估技术，创新提出全概率和多概率潜在地震滑坡危险性评估技术，自主研发系列评估软件，评估得到天水市域在多遇、设防和罕遇地震条件下滑坡危险性分区结果。6.模拟了岷县Ms6.6级地震近断层地震动场，初步揭示地震地形效应及与同震滑坡的关系，基于此开展了同震滑坡危险性评估。7.深化了历史强震对渭河中游区域群发大型滑坡诱发效应的认识，为强震区群发大型滑坡发育规律研究提供了借鉴。8.完成九寨沟Ms7.0级地震诱发滑坡危险性应急快速评估，为地震应急救灾提供技术支撑。9.开展全国地震滑坡危险性评价及对重大战略的影响分析，编制了《全国地震滑坡危险性评价报告》（第一版），为强震山区重大工程选址和城镇规划提供支撑。在上述成果中，区域地震动地形效应分析和潜在地震滑坡危险性评估等成果具有创新意义，在支撑国土空间规划和地震地质灾害风险防控中取得良好应用成效。