基于简化Newmark位移模型的区域地震滑坡危险性快速评估——以汶川M_S8.0级地震为例

CASE STUDY ON RAPID ASSESSMENT OF REGIONAL SEISMIC LANDSLIDE HAZARD BASED ON SIMPLIFIED NEWMARK DISPLACEMENT MODEL: WENCHUAN M_S 8.0 EARTHQUAKE

以汶川MS8.0级地震重灾区的11县市为例,初步提出了基于简化Newmark位移模型的地震滑坡危险性应急快速评估方法。利用汶川地震即时地震动参数、工程地质岩性经验分组及地形坡度数据,借助ArcGIS空间数据建模工具编制了地震滑坡危险性快速评估流程模块。计算了区域浅表层饱和岩土体斜坡的静态安全系数Fs、临界加速度ac,并借此分析了地震滑坡易发性。利用经验式获得了汶川地震Arias强度和区域滑坡位移DN分布,实现了汶川地震重灾区地震滑坡危险性的快速评估,为应急救灾决策提供了参考。通过对比评估结果和震后滑坡调查成果,可知数十处灾难性滑坡绝大部分位于-高危险区的龙门山主中央断裂带两侧约20km地带中,显示了评估方法的可靠性;同时,分析指出了空间数据精度及更新不足导致局部评估结果欠佳的局限性,并提出了改进建议。

The rapid assessment method on seismic landslide hazard based on simplified Newmark displacement model is preliminarily developed, in Wenchuan Ms 8.0 earthquake severely afflicted 11 counties. With the real- time earthquake ground motion parameters, empirical engineering geology lithology formations, topographic slope data, the module of seismic landslide hazard rapid assessment is produced based on ArcGIS spatial data modeller tools. Static safety factor F~ and critical acceleration ac of regional shallow saturated rock and soil mass slope are calculated, according to which seismic landslide susceptibility is assessed. The Arias intensity of Wenchuan earth- quake and regional landslide displacement DN distribution are calculated with empirical formula, based on which rapid assessment of seismic landslide hazard in Wenchuan earthquake severely afflicted area is realized. The assess-ment results can be reference for emergency response decision-making. It is indicated that tens of catastrophic land- slides are almost totally located in extreme high-high hazard zone, which within both sides about 20km of Longmen- shan central fault belt through comparing the seismic landslide investigation and assessment results. The comparing result indicates the well reliability of assessing model. Meanwhile, the limitation is also analyzed that local assess- ment result is inaccurate due to poor spatial data accuracy and update. Some improvement suggestion is provided.