汶川震区成兰铁路关键段多尺度滑坡危险性评估

以穿越汶川震区的成兰铁路龙门山关键段为例,探索提出了强震扰动背景下重大工程场区多尺度滑坡危险性评估方法。利用信息量模型反演评估了汶川地震诱发的同震滑坡空间分布特征,以此为前提开展了区域和局地两种空间尺度的滑坡危险性预测评估。在区域廊带尺度上,分别利用可能最大降雨量预测方法和信息量模型,进行了日超越概率10%的最大降雨量时空分布预测及其诱发滑坡的危险性评估;同时,结合地震危险性区划成果,开展了50年超越概率10%的基本地震动诱发滑坡的危险性评估。在局地场站尺度上,利用基于崩塌运动过程模拟的Rockfall Analyst软件,开展了柿子园大桥周边崩塌运动学特征(Runout)模拟和危险性评估。滑坡和崩塌危险性评估的结果分别为铁路规划选线和场站防护设计提供了不同尺度的地质安全依据。

MULTI-SCALE LANDSLIDE HAZARD ASSESSMENT FOR KEY SECTION OF CHENGDU-LANZHOU RAILWAY, WENCHUAN SEISMIC REGION

Taking Longmenshan key section of Chengdu-Lanzhou railway in Wenchuan seismic region as an example, we explore a sort of multi-scale landslide hazard assessing method for major project site in strong earthquake afflicted area. The spatial distribution characteristics of coseismic landslides induced by Wenchuan M_s 8.0 earthquake are inverted assessed with information value model. On this basis, landslide hazard assessments in regional and local scale are carried out. In regional railway corridor scale, the temporal and spatial distribution of daily maximum precipitation of 10% exceedance probability is predicted by Probable Maximum Precipitation method. Due to such probable precipitation, the landslide hazard is assessed with information value model. Also, combining seismic hazard zoning result, the landslide hazard is assessed due to basic earthquake ground motion of 10% exceedance probability in 50 years. In local railway station scale, with Rockfall Analyst software based on rolling stone kinematics simulation, runout characteristics and hazard of rockfall around Shiziyuan bridge site are simulated and assessed. All of the landslide and rockfall hazard assessment results above provide geological safety references in different scales for railway plan and line selection, site landslide defense design respectively.