This study aims to investigate rockfall failure mechanism and its movement characteristics. For that, a series of rockfall experiments were conducted on sedimentary rocks of Mizoram at laboratory scale to understand their motion characteristics. An experimental setup was made with hard base of gneissic and granitic rocks with an impact angle of 40°. Three different rock types Sandstone, Shale, and Sandy-Shale of Bhuban Formation of four different mass classes were prepared. The samples were allowed to free fall from a height of 1.5 meter and each rockfall test was repeated five times and the mean runout length was recorded. A high-resolution camera was setup to capture each falling event. The recorded videos were used to analyze initial failure and post-impact motion characteristics (i.e., motion trajectory and kinetic energy) in a motion tracking software. Our study showed that the trajectory of a block is a combination of four basic block movement types: free falling, bouncing, rolling, and sliding. Results indicated that the slope morphology of the base significantly influences the kinetic energy (KE) during its falling path. Steeper slopes increase the kinetic energy of the falling rock blocks while gentle slopes reduce the kinetic energy. It was noted that the bouncing behavior of the falling rock blocks were highly unpredictable and extremely complex, significantly affecting the post-impact motion trajectory. The runout lengths of falling rock blocks were significantly influenced by their shape and elastic modulus, with a higher modulus of elasticity leading to an extended runout distance. The outcome of this study may help in determining the most appropriate and effective rockfall mitigation measures, such as catch fences, barriers, and rockfall attenuators.

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Laboratory Simulation of Rockfall Hazard in Different Sedimentary Rocks of Mizoram, India

  • Debasish Mazumder,
  • Ratan Das,
  • Sourav Das

摘要

This study aims to investigate rockfall failure mechanism and its movement characteristics. For that, a series of rockfall experiments were conducted on sedimentary rocks of Mizoram at laboratory scale to understand their motion characteristics. An experimental setup was made with hard base of gneissic and granitic rocks with an impact angle of 40°. Three different rock types Sandstone, Shale, and Sandy-Shale of Bhuban Formation of four different mass classes were prepared. The samples were allowed to free fall from a height of 1.5 meter and each rockfall test was repeated five times and the mean runout length was recorded. A high-resolution camera was setup to capture each falling event. The recorded videos were used to analyze initial failure and post-impact motion characteristics (i.e., motion trajectory and kinetic energy) in a motion tracking software. Our study showed that the trajectory of a block is a combination of four basic block movement types: free falling, bouncing, rolling, and sliding. Results indicated that the slope morphology of the base significantly influences the kinetic energy (KE) during its falling path. Steeper slopes increase the kinetic energy of the falling rock blocks while gentle slopes reduce the kinetic energy. It was noted that the bouncing behavior of the falling rock blocks were highly unpredictable and extremely complex, significantly affecting the post-impact motion trajectory. The runout lengths of falling rock blocks were significantly influenced by their shape and elastic modulus, with a higher modulus of elasticity leading to an extended runout distance. The outcome of this study may help in determining the most appropriate and effective rockfall mitigation measures, such as catch fences, barriers, and rockfall attenuators.