以野外调查为基础,选取坡度、地表起伏度、岩石抗剪强度指标(内摩擦角与粘聚力)、距断裂距离、地震烈度、岩体风化程度、最大24 h降雨量、年平均气温、土地利用类型等10项指标作为基本判别因子,分析泥石流对影响因子的敏感程度.研究表明,G318川藏公路最有利于泥石流发育的条件为:1.坡度:20°～35°；2.地表起伏度:100 ～300 m;3.岩石抗剪强度指标:内摩擦角＜35°,粘聚力＜25 MPa;4.岩体风化程度:＞0.4；5.距断层距离:0～10km;6.地震烈度:大于Ⅶ度；7.土地利用:荒漠草原、冰川、裸岩砾石、坡草地；8.年平均气温:＜8°与10°～12°；9.最大24 h降雨量:＞40 mm.结合GIS与信息量模型分析G318川藏公路段沿线泥石流危险性,研究结果表明:公路大部分路段处于中度、高度与极高度危险区,三者面积之和占总面积的71.99％,范围较大,主要分布在大渡河、金沙江、澜沧江、怒江、帕隆藏布江等大江大河的深切峡谷区；基本无危险区范围较小,主要位于成都平原和高原面路段,仅占总面积的4.21％.研究成果与实际灾情吻合,可为川藏公路泥石流风险评估及新路选线提供科学依据.%This article analyzes the susceptibility of debris flows along G318 Sichuan-Tibet highway,and the results show the favorable geological and geomorphological conditions for debris flow occurrence,which includes:1.hill slopes from 20° to 35°,2.relative elevation between 100 m and 300 m,3.for rocks' shear strength indexes,angle of internal friction is lower than 35 ° and cohesive force is below 25 MPa,4.weathering degree of rock stratum should be above 0.4,5.the distances to faults within 10 km,6.the earthquake magnitude is above 7.0,7.land use types including desert steppe,glacier area,bare rock land,and slope grassland,8.annual mean temperature is located below 8° and between 10° and 12°,9.maximum daily rainfall is larger than 40 mm.Through adopting information acquisition analysis method for the above selected factors,the hazard degree of debris flow was evaluated,and debris-flow hard mapping of Sichuan-Tibet highway was completed with support of GIS technique.The proposed method divides the hazard degree along the highway into 5 levels:very low,low,medium,high and very high.The high hazardous areas along G318 Sichuan-Tibet highway are mainly located in the medium,high,very high levels,which account for 71.99％ of the whole highway area.They are located in the canyon area of Dadu River,Jinsha River,Lanchang River,Nu River and Palongzangbu River.Referring to these areas,the debris-flow prevention project should be strengthened in road construction and land designing.While the very low hazardous areas are relatively small,accounting for only 4.21％,which are located in the sections of Chengdu plain area and Tibetan plateau area.The analyzed results above are consistent with results from the actual debris flows situation along Sichuan -Tibet highway.Thus,this hazard evaluation results are suitable for providing debris flow risk analysis and line selection for new road.
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