(1. State Key Laboratory of Hydraulics and Mountain River Engineering，Sichuan University，Chengdu，Sichuan 610065，China；
2. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection，Chengdu University of Technology，
Chengdu，Sichuan 610059，China)
Abstract：Laboratory experiments were carried out to study the particle segregation of rock fragments during the movement of debris avalanche. The influence of small particle contents，size differences and bed roughness were considered during the experimental process. Experimental results showed that the degree of segregation was greatly influenced by the size difference of particles and was less sensitive to the content of small particles. The particle segregation became more obvious with the increasing of the roughness of sliding bed. The formation mechanism of inverse grading during the movement of landslide was studied based on the field investigation，physical modeling tests and past studies. During the process of high speed landslide，the energy loss(relatively) of small particles was found to be larger than that of large particles，the segregation phenomenon of the larger particles in front of the small particles at the movement direction existed. After the debris avalanche entered into the stage of deceleration and accumulation，the small particles were stopped earlier than the large particles，resulted in that the large particles were moved on top of the deposits of small particles，while most of the small particles were blocked at the end of the landslide deposits. Finally，the inverse grading structure of landslide deposits was formed，where most of the larger particles were at the front of landslide deposits and most of the small particles were at the rear of landslide deposits，while the larger particles stay on top of the small particles at the middle section.
陆坤权，刘寄星. 颗粒物质(下)[J]. 物理，2004，33(10)：713-720.(LU Kunquan，LIU Jixing. Static and dynamic properties of granular matte(II)[J]. Physics，2004，33(10)：713-720.(in Chinese))
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2015, Vol. 34 
