Vol20 No.3: 688-704

【Title】Laboratory-scale investigation of the material distribution characteristics of landslide dams in U-shaped valleys

【Author】JIAN Fu-xian¹;CAI Zheng-yin¹;GUO Wan-li^1,2*

【Addresses】1 Geotechnical Engineering Department, Nanjing Hydraulic Research Institute, Nanjing 210024, China; 2 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing 210024, China

【Corresponding author】GUO Wan-li

【Citation】Jian FX, Cai ZY, Guo WL, et al. (2023) Laboratory-scale investigation of the material distribution characteristics of landslide dams in U-shaped valleys. Journal of Mountain Science 20(3). https://doi.org/10.1007/s11629-022-7664-3

【DOI】https://doi.org/10.1007/s11629-022-7664-3

【Abstract】Material distribution characteristics during sliding and depositing is particularly significative to investigate the internal structure and spatial variation of landslide dams, which are fundamentally determining the mechanical and hydraulic behavior and the susceptibility to cause dam failure. However, limited by longevity shortages and special geographic environments, the material distribution characteristics and their formation mechanisms are difficult to observe in the field. Therefore, an experimental apparatus modeling a landslide dam was developed in this paper, designing three sampling methods with two valley states. The internal deposit characteristics, void ratio variation and relative content of the particle size range (PSR) were analyzed, and the mechanics of deposit structure were also delicately ascertained. The results indicate that granular material deposited in valley shows a structure of inverse grain size accumulation in both vertical and horizontal directions, exhibiting spatial variability of particle gradation and void ratio. The characteristic PSR decreases from 22 - 30 mm in the two-dimensional state to 10 - 14 mm in the three-dimensional state. Vibration excitation and vibration sieve are the intrinsic mechanisms of granular flow segregation, intrinsically inducing the formation of inverse grading deposit structures. Consequently, spatial variability in size is mainly triggered by segregation, whereas coarse particle content and deposition boundaries merely exacerbate the difference degree.

【Keywords】Landslide dam; Inverse grading structure; Granular flow segregation; Material spatial variability; Deposit characteristics