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| PHYSICAL MODELING TESTS ON INVERSE GRADING OF PARTICLES IN HIGH SPEED LANDSLIDE DEBRIS |
| HAO Minghui1，XU Qiang2，YANG Xingguo1，PENG Tao1，ZHOU Jiawen1，2 |
(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) |
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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.
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Received: 13 May 2014
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| [1] 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))
[2] 孙其诚，王光谦. 颗粒物质力学导论[M]. 北京：科学出版社，2009：1–5.(SUN Qicheng，WANG Guanqian. The mechanics of granular material[M]. Beijing：Science Press，2009：1–5.(in Chinese))
[3] CRUDEN D M，HUNGR O. The debris of the Frank slide and theories of rockslide-avalanche mobility[J]. Canadian Journal of Earth Sciences，1986，23(3)：425–432.
[4] 王玉峰，程谦恭，朱 圻. 汶川地震触发高速远程滑坡–碎屑流堆积反粒序特征及机制研究[J]. 岩石力学与工程学报，2012，31(6)：1 089–1 106.(WANG Yufeng，CHENG Qiangong，ZHU Qi. Inverse grading analysis of deposit from rock avalanches triggered by Wenchuan earthquake[J]. Chinese Journal of Rock Mechanics and Engineering，2012，31(6)：1 089–1 106.(in Chinese))
[5] 张 明，殷跃平，吴树人，等. 高速远程滑坡–碎屑流运动机理研究发展现状与展望[J]. 工程地质学报，2010，18(6)：805–817. (ZHANG Ming，YIN Yueping，WU Shuren，et al. Development status and prospects of studies on kinematics of long run out rock avalanche[J]. Journal of Engineering Geology，2010，18(6)：805–817.(in Chinese))
[6] NAYLOR M A. The origin of inverse grading of muddy debris flow deposits-a review[J]. Journal of Sedimentary Petrology，1980，50(4)：1 111–1 116.
[7] PUDASAINI S P，HUTTER K. Avalanche dynamics：dynamics of rapid flows of dense granular avalanches[M]. Berlin：Springer-Verlag，2007：60–70.
[8] ZHOU J，CUI P，FANG H. Dynamic process analysis for the formation of Yangjiagou landslide-dammed lake triggered by the Wenchuan earthquake，China[J]. Landslide，2013，10(3)：331–342.
[9] STROM A L. Rock avalanches of the Ardon River valley at the southern foot of the Rocky Range，Northern Caucasus，North Osetia[J]. Landslides，2004，3(1)：237–241.
[10] LUZIO E D，BIACHI-FASANI G，ESPOSITO C，et al. Massive rock-slope failure in the Central Apennines(Italy)：the case of the Campo di Giove rock avalanche[J]. Bulletin of Engineering Geology and the Environment，2004，63(1)：1–12.
[11] BOULTBEE N，STEAD D，SCHWAB J，et al. The Zymoetz river rock avalanche，June 2002，British Columbia，Canada[J]. Engineering Geology，2006，83(1/3)：76–93.
[12] ZHOU J，CUI P，YANG X. Dynamic process analysis for the initiation and movement of the Donghekou landslide-debris flow triggered by the Wenchuan earthquake[J]. Journal of Asian Earth Sciences，2013，76(1)：70–84.
[13] BAGNOLD R A. Experiments on a gravity-free dispersion of large solid spheres in a Newton fluid under shear[J]. Proceedings of the Royal Society of London(Series A)：Mathematical and Physical Sciences，1954，225：49–63.
[14] BERTRAN P. The rock-avalanche of February 1995 at Claix(French Alps)[J]. Geomorphology，2003，54(3)：339–346.
[15] STROM A L. Mechanism of stratification and abnormal crushing of rockslide deposits[C]// OLIVEIRA R，ERODRIGUES L，COELHO A G，et al ed. Proceedings of the 7th International IAEG Congress. Rotterdam：A. A. Balkema.1994：1 287–1 295.
[16] DUFRENSE A. Granular flow experiments on the interaction with stationary run out path materials and comparison to rock avalanche events[J]. Earth Surface Process and Landforms，2012，37(14)：1 527–1 541.
[17] LEGROS F. Can dispersive pressure cause inverse grading in grain flows?[J]. Journal of Sedimentary Research，2002，72(1)：166–170. |
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2015, Vol. 34 
