رفتار حرکتی غلتشی ریزش سنگ در شیب ملایم: یک رویکرد آزمایشی Rolling motion behavior of rockfall on gentle slope: an experimental approach

Introduction A huge amount of the rockfalls that led to the damage of infrastructure and death of people have been reported all over the world (e.g., Guzzetti et al. 2003; Pellicani et al. 2016). Rockfall hazards have become a major risk in the mountainous areas that endanger human lives and properties, especially after the 2008 Wenchuan earthquake, China. The physical and chemical weathering are environmental activities that contribute to the development of the rockfall (Jaboyedoff et al. 2004). Slope morphology is an essential component in determining rockfall occurrence and movement (Jomelli and Francou 2000). Rainstorm (Chau et al. 2003), the frost-thaw activities (Perret and Kienholz 2004), seismic activities (Saroglou et al. 2012), human and animal activities (Selby 1982; Apostolou et al. 2015) are the contributing factors. The information of the block velocity, jump height, run-out zone, and trajectory is the basis for the creation of accurate design and the verification of protective measures (Dorren 2003; Volkwein et al. 2011). The statistical methods (Zvelebil and Moser2001), hazard inventories (Evans and Hungr 1993; Bull et al. 1994), and mathematical formulas such as kinematics, elastic-plastic mechanics, tribology and elastic collision theory were widely used in the study of rockfall. The empirical models (Piacentini and Soldati 2008; Copons et al. 2009), process-based models (Evans and Hungr 1993; Chen et al.1994; Asteriou et al. 2016), GIS-based models, Lidar-based models (Dorren and Seijmonsbergen 2003; Lan et al. 2007; Lan et al. 2010), and Terrestrial Laser Scanner models (Abellán et al. 2006) were established for calculating the run-out zone and trajectory of rockfall. The numerical models were widely used, including distinct element method (DEM), discontinuous deformation analysis (DDA) and other related codes (such as STONE and ROCKFALL programs), varying from 2D to 3D models (Crosta and Agliardi 2004; Jaboyedoff et al. 2005; Wang et al. 2011; Chen et al. 2013; Thoeni et al. 2014). The dynamic effects of three dimension topography were ignored in 2-D model. Thus, pseudo 3-D assumptions (Jaboyedoff et al. 2005) were introduced to overcome this limitation partly. Full 3D numerical modeling had been presented to do lateral dispersion of 3D trajectories and the related effects on probability and intensity assessment (Crosta and Agliardi 2004; Thoeni et al. 2014). Lumped mass method and rigid body method were involved in numerical simulations (Basson 2012; Bourrier et al. 2012). The former method ignored the block geometry and scale, so the block mass had no effect on rockfall motion except energies. And in the rigid body method, the interaction investigation between the block and slope surface is possible.