地震扰动区内的高山峡谷地区，斜坡易发生崩塌、滑坡，堆积在坡面或沟谷内。雨水入渗导致堆积土体饱和度增加，强度衰减，继而诱发泥石流启动。都汶公路沿线和甘肃舟曲泥石流沟汇水区松散堆积体的物理力学特性试验结果表明，两组泥石流土体细粒含量少，均为宽级配不均匀粉土质砾石土。当舟曲泥石流堆积土含水率增至15%-18%时，都汶土含水率增至12%-15%时，土体粘聚力骤减，暗示土体强度丧失存在临界含水率，这一特定含水率可作为泥石流启动的临界含水率。进一步统计分析表明，泥石流发生前1h的临界降雨量与临界含水率密切相关，利用二者的相关性拟合，可反推泥石流发生的临界降雨量，为地震扰动区泥石流灾害的防治预警提供科学依据。

In earthquake disturbance and alpine-gorge area, instability slope with crushing rock is caused by active faults and frequent earthquakes. Particle migration in the deposits is caused by water infiltration, resulting in the change of saturation， density， thus weakening its strength， which subsequently induces occurrence of debris flow initiation. Debris flow gullies in two areas including Gansu Zhouqu county in the west Qinling mountains fault zone and Duwen highway in Longmen mountain fault zone were taken as an example， physical and mechanical properties tests of the loose accumulation body were carried out. Experimental results showed that the two groups of debris flow deposits were silty gravel soil with wide and non-uniform grading. Fine grain content in Zhouqu debris deposits was relatively high， its specific gravity， liquid limit, plastic limit, liquid index，and plasticity index were greater than those of soil sample of Duwen highway. When the moisture content of Zhouqu debris flow soil and Duwen highway slope soil increased to 15%-18% and 12%-15% respectively， the soil cohesion c reduced sharply. It hinted the existence of critical moisture content in soil strength decline process. The specific moisture content could be used as the critical water content of debris flow initiation. Further statistical analysis showed one-hour critical rainfall before occurrence of debris flow and the critical moisture content was closely related. By fitting the linear relativity between them, the critical rainfall of debris flow could be deduced, which can provide technical support for the prevention and early warning of debris flow in earthquake disturbed area.

中国地质调查局项目(1212011120072)；“十二?五”国家科技支撑计划项目(2011BAK12B09)；重庆交通大学国家内河航道整治工程技术研究中心暨水利水运工程教育部重点实验室开放基金资助项目 (SLK2015B07)