(1. State Key Laboratory of Geohazards Prevention and Geoenvironment Protection，Chengdu University of Technology，Chengdu，Sichuan 610059，China；2. China Southwest Geotechnical Investigation and Design Institute Co.，Ltd.，Chengdu，Sichuan 610052，China；3. PowerChina Northwest Engineering Corporation Limited，Xi'an，Shaanxi 710065，China)
Abstract：High-locality rockfalls occur frequently combined with strong dynamic fragmentation phenomenon. However，the insufficient understanding of rockfall fragmentation often causes a large error between the hazard assessment and the actual situation. Therefore，based on the movement characteristics analysis of typical high-locality rockfalls in Guizhou Province，the dominant factors affecting fragmentation are determined. The low-strength and high-brittleness model materials are designed for the physical model test in rockfall dynamic fragmentation. The fragments? movement and deposit features under different conditions are observed and the relationship between fragmentation and its maximum movement distance is evaluated quantitatively. The results show that：(1) The falling height，volume，impact angle and joint setting are the main factors influencing rockfall dynamic fragmentation. (2) The fragmentation phenomenon is concentrated in the first contact with the slope surface. The movement of generated fragments is characterized by stratification. There are small particle-size blocks with “ejection” movement in the upper layer. The large block is rolling in the middle layer，and the fine particle is sliding at the bottom layer. (3) The block distribution characteristics have a concentrated deposit and scattered blocks. But，there is no significant block size distribution along the movement direction. (4) The fragmentation is most sensitive to the impact angle，and the fragmentation degree is positively correlated with the maximum movement distance. The empirical formula is carried out as well. (5) The problem of energy distribution in rockfall dynamic fragmentation needs to be further studied from in-situ experiments and real-time observation.
HAUG Ø T，ROSENAU M，LEEVER K，et al. On the energy budgets of fragmenting rockfalls and rockslides：Insights from experiments[J]. Journal of Geophysical Research：Earth Surface，2016，121(7)：1 310-1 327.
[7]
BOWMAN E T，TAKE W A，RAIT K L，et al. Physical models of rock avalanche spreading behaviour with dynamic fragmentation[J]. Canadian Geotechnical Journal，2012，49(4)：460-476.
[15]
HUNGR O，LEROUEIL S，PICARELLI L. The Varnes classification of landslide types，an update[J]. Landslides，2014，11(2)：167-194.
[1]
GILI J A，RUIZ-CARULLA R，MATAS G，et al. Rockfalls：Analysis of the block fragmentation through field experiments[J]. Landslides，2022，19(5)：1 009-1 029.
[3]
ZHAO T，CROSTA G B，UTILI S，et al. Investigation of rock fragmentation during rockfalls and rock avalanches via 3D discrete element analyses[J]. Journal of Geophysical Research Earth Surface，2017，122(3)：678-695.
[4]
ZHAO T，CROSTA G B，DATTOLA G，et al. Dynamic fragmentation of jointed rock blocks during rockslide-avalanches：Insights from discrete element analyses[J]. Journal of Geophysical Research：Solid Earth，2018，123(4)：3 250-3 269.
[6]
LIN Q W，CHENG Q G，LI K，et al. Contributions of rock mass structure to the emplacement of fragmenting rockfalls and rockslides：insights from laboratory experiments[J]. Journal of Geophysical Research：Earth Surface，2020，125(4)：e2019JB019296.
[8]
DE BLASIO F V，DATTOLA G，CROSTA G B. Extremely energetic rockfalls[J]. Journal of Geophysical Research：Earth Surface，2018，123(10)：2 392-2 421.
[11]
杨仕教，彭贯军，朱忠华，等. 基于ImagePy工具的岩块图像二值化分割研究[J]. 爆破，2018，35(4)：129-135.(YANG Shijiao，PENG Guanjun，ZHU Zhonghua，et al. Binary seg-mentation of rock block image based on imagepy tool[J]. Blasting，2018，35(4)：129-135.(in Chinese))
[9]
王 翔，牌立芳，吴红刚. 拉林铁路变坡面倾角崩塌落石对桥梁结构破坏作用的模拟分析与试验研究[J]. 岩石力学与工程学报，2020，39(8)：1 622-1 633.(WANG Xiang，PAI Lifang，WU Honggang. Simulation analysis and experimental study on the damage of bridge structure caused by tilt collapse and rockfall on the slope of Lalin railway[J]. Chinese Journal of Rock Mechanics and Engineering，2020，39(8)：1 622-1 633.(in Chinese))
[13]
LOCAT P，COUTURE R J，LEROUEIL S，et al. Fragmentation energy in rock avalanches[J]. Canadian Geotechnical Journal，2006，43(8)：830-851.
[14]
BOWMAN E T，TAKE W A. The runout of chalk cliff collapses in England and France—case studies and physical model experiments[J]. Landslides，2015，12(2)：225-239.
[16]
DE BLASIO F V，CROSTA G B. Fragmentation and boosting of rock falls and rock avalanches[J]. Geophysical Research Letters，2015，42(20)：8 463-8 470.
[10]
陈陆望，白世伟. 脆性岩体岩爆倾向性的相似材料配比试验研究[J]. 岩土力学，2006，27(增2)：1 050-1 054.(CHEN Luwang，BAI Shiwei. Proportioning test study on similar material of rockburst tendency of brittle rockmass[J]. Rock and Soil Mechanics，2006，27(Supp.2)：1 050-1 054.(in Chinese))
[2]
RUIZ-CARULLA R，COROMINAS J. Analysis of rockfalls by means of a fractal fragmentation model[J]. Rock Mechanics and Rock Engineering，2019，53：1 433-1 455.
[12]
HARDIN B O. Crushing of soil particles[J]. Journal of Geotechnical Engineering，1985，111(10)：1 177-1 191.
2023, Vol. 42 
