【作者】 王涛；

【导师】 吴树仁；

【作者基本信息】 中国地质科学院 ， 地质工程， 2010， 博士

【摘要】 地震触发区域地质灾害危险性评估是地质灾害风险评估中的重点问题之一,论文依托973项目课题专题“汶川地震重大次生山地灾害风险管理系统研究”和十一五科技支撑课题“重大地质灾害监测预警及应急救灾关键技术研究”,以汶川Ms8.0级强烈地震重灾区的11县市作为研究区,针对强烈地震触发地质灾害的应急快速评估和震后降雨及潜在地震诱发地质灾害危险性进行了评估研究,并主要取得了下列进展和成果：1.建立并初步改进了基于简化Newmark累积位移模型的地震滑坡危险性评估模块,探索提出地震地质灾害损失快速评估的技术方法。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,进行了汶川地震重灾区地质灾害危险性及其损失快速评估,为应急救灾决策提供了实用的科技支持。2.初步揭示了汶川地震重灾区地质灾害分布规律：汶川地震地质灾害的区域空间分布明显受龙门山断裂带、地形地貌及水系沟谷等要素控制。地质灾害类型以崩塌、滑坡、泥石流、碎屑流(群)及崩滑-碎屑流为主,其次包括砂土液化和地面塌陷等；其中前3种以及崩滑-碎屑流危害相对严重,而碎屑流(群)分布面积最广；在震后恢复重建过程中,大量结构松动的岩土体及堆积于坡体表层或河谷两岸的松散崩滑流碎屑物,极易被强降雨或河流搬运形成泥石流灾害,成为最具威胁性的地质灾害隐患形式,也明确指示了地震地质灾害滞后性及链生性的时间序列分布特征。3.以文家沟地震滑坡-碎屑流研究为例,初步揭示典型地震高速远程滑坡-碎屑流的基本特征、成因机理和演化过程；指出汶川地震广泛诱发的高速远程滑坡-碎屑流不仅造成了重大的损失,而且易于在暴雨期间再次产生泥石流灾害,需要在重建过程中引起高度注意；该灾难性滑坡事件分析为潜在强震地区重大隐患地质灾害调查及危险性评估提供了参考。4.以平武县水观乡石坎河流域作为示范区,利用震后2.5m分辨率的SPOT5即时遥感影像,进行了基于影像分类技术的地震滑坡快速制图技术的比选分析；提出面向对象特征提取与人工判识结合的方法,对北川县湔江等4条灾害多发流域进行了地震滑坡精准解译；进一步修改完善了地震地质灾害强度评估的技术方法,分别利用地质灾害面密度和快速解译灾点密度,对重点流域和重灾区地质灾害强度进行了评估和等级划分,为地质灾害强度快速评估奠定了基础。5.利用简化Newmark模型,对汶川地震诱发滑坡易发性、危险性和损失进行快速反演评估,结果显示在高损失区域内包括了映秀镇、北川县、南坝镇等地,青川县处于高中损失水平过渡区,而平武县和叠溪镇处于中低损失水平地区,这些结论在现场调查过程中均得到了较好的验证。6.利用信息量模型进行了震后地质灾害易发性评估,指出了震后潜在滑坡及泥石流物源的区域分布特征。利用Weibull概率模型预测了2年内累积概率密度为90%(即超越概率为10%)的日最大降雨量分布,进而利用安全系数Fs的计算方法对降雨诱发地质灾害的危险性进行了评估；利用改良的Newmark位移模型对50年超越概率10%的潜在地震诱发地质灾害危险性进行了评估,结果表明地质灾害高危险区主要沿发震断裂带所控制的地质灾害密集发育区分布,评估结果对汶川地震灾区灾后重建和减灾防灾具有重要的指导意义。更多还原

【Abstract】 Seismic landslides hazard assessment is one of the key issues in landslide risk assessment framework. This thesis takes Wenchuan Ms 8.0 earthquake severely afflicted 11 counties as study area. Emergency response rapid assessment of landslides triggered by intensive earthquake and post-earthquake hazard assessment of due to future rainfall and potential earthquake is researched; main progresses and resulrts is achieved as following:1. Seismic landslide hazard assessment model based on simplified Newmark cumulative displacement is preliminarily developed and improved using Arcgis spatial analysis modeling function, the method of seismic landslide loss rapid assessment is provided. With the real-time earthquake ground motion parameters of Wenchuan earthquake, empirical engineering geology lithology formations, topographic slope data, rapid back analysis assessment of landslide hazard and the loss due to Wenchuan earthquake is carried out; the results provide scientific and technological support for emergency response dicision-making.2. Spatial distribution of seismic landslides triggered by Wenchuan earthquake is significantly affected by Longmenshan fracture zone, topography and stream valleys. The seismic geohazards mainly consist of collapses, landslides, debris flows, debris slide (s) and debris-avalanches, followed by sandy soil liquefaction and ground subsidence. The former 3 geohazard types and debris-avalanches usually cause more damage, and debris flow (s) distribute most widely. In the post-earthquake reconstruction, lots of loose structural rock & soil mass and landslide debris deposits located in slope surface and valley banks can be easily carried by heavy rainfall or river flow to transform into debris flows, to become the most threatening geohazard type. This evolutionary process indicates the post-earthquake lag and chain characters of seismic landslides.3. Taking Wenjiagou seismic debris-avalanche for case study, the inducing context, ground motion triggering mechanism, spatial characteristics and evolution process of high-speed and long runout of debris-avalanche are analyzed. It is indicated that widely spread debris-avalanches triggered by Wenchuan earthquake do not only cause lots of damage, but also be easy to transform into new debris flows due to rainfall, which should be paid more attention to in reconstruction after the earthquake. At the same time, this case study provides reference for investigation and hazard assessment of major hidden landslides in potential intensive earthquake zone similar to Longmenshan structural zone.4. With 2.5m-resolution SPOT5 remote sensing image of Shikanhe river basin shot immediately after the earthquake, rapid identification and extraction methods of seismic landslide based on image classification techniques are comparatively analyzed. With the method of composing object-oriented feature extraction and artificial interpretation, seismic landslides in Shikanhe river, Jianjiang river, Mianyuanhe river and Minjiang river basins is accurately interpreted. The seismic landslide intensity levels of typical river basins and whole study area is assessed using area and point density respectively.5. Results of seismic landslides susceptibility, hazard and loss rapid invesion assessment in Wenchuan earthquake with simplified Newmark model show that Yingxiu township, Beichuan county, and Nanba township etc. locate in heavy loss zone, Qingchuan county lies in transition zone from heavy to moderate loss zone, Pingwu county and Diexi township lie in light loss zone; these results are well validated in field investigation.6. Post-earthquake landslide susceptibility is assessed using information model; the result indicates regional distribution of potential landslides and substance source for debris-flows. The daily maximum rainfall value with 90%’s cumulative probability density (10% probability of exceedance) in 2 years is predicted using Weibull probability density function model; then the landslide hazard assessment due to future rainfall is carried out with the safety factor Fs calculation. Consequently, the landslide hazard assessment due to potential earthquake with 10% probability of exceedance in 50 years is assessed with the improved Newmark displacement model; the result shows that highly landslide hazard zone mainly locate in landslide clustering area controlled by the seismic faults, and provides valuable guidance for reconstruction in Wenchuan earthquake severly afflicted area and hazard mitigation and prevention.This thesis is supported by 973 Project subject "Study on risk management system of major secondary landslides triggered by Wenchuan earthquake" and 11th 5-year Science and Technology Support program "Study on monitoring & warning of major landslides and key technology of emergency response".更多还原