This research investigates the effect of shape and mass of falling rock blocks on various rockfall characteristics through a series of laboratory experiments. A laboratory experimental setup was developed comprising a rock block release mechanism, a granite impact surface (inclination of ~28°) and a soil-gravel mixed runout surface to replicate the field condition. Each rockfall event was recorded under high resolution cameras and a sophisticated motion tracking software (Tracker v6.3.2) was utilized to analyze different motion characteristics of the falling blocks. Four different rock types were utilized viz. quartzite, granite, sandstone and limestone which were carved into cube, sphere, cuboctahedron and cuboid, respectively. The shape of the blocks were quantified both geometrically (short/long axis vs. intermediate/long axis) and by utilizing shape factor (η). The mineralogy and physico-mechanical properties of the selected rock types were analyzed in the laboratory before testing. The rockfall characteristics, such as bounce height and runout length were corelated with uniaxial compressive strength (UCS), brazilian tensile strength (BTS), point load index (PLI), density (ρ), porosity (Φ), and mass. The results indicated that the maximum runout length (4.48 m), bounce height (36.80 cm), flight time (0.61 s) and dispersion envelope area (4.80 m2) was achieved by granite (sphere) having UCS of 76.03 MPa. While, other shapes showed scattered values. It was observed that rounder shapes such as sphere and cuboctahedron deviated less from centreline, however cube and cuboid have showed relatively higher deviation due to its morphological characteristics. The 4D trajectory reconstruction of the rockfall event has indicated that sphere have achieved the highest spatial and temporal footprint along lateral (x and z axis) and vertical (y axis) direction including time (~2.70 s) among all other shapes. This is because the energy retention capacity of sphere shaped high strength granite rock tends to travel the block further also showing highest bounce height and runout length despite having a same density value of 2.66 gm/cm3 with quartzite cube, which indicates shape have a higher control over density. Further, it was observed that the runout length of the rock blocks was showing a decreasing trend with increasing porosity. The research findings provide essential scientific knowledge on the kinematics of the falling block for the development of enhanced rockfall protection system and allow a safer development in rockfall prone region around the world.

Understanding the Influence of Block Geometry and Mass on Rockfall Kinematics under Controlled Laboratory Environment

期刊论文
发表日期：

2026年6月25日

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Debasish Mazumder,
Ratan Das

摘要

This research investigates the effect of shape and mass of falling rock blocks on various rockfall characteristics through a series of laboratory experiments. A laboratory experimental setup was developed comprising a rock block release mechanism, a granite impact surface (inclination of ~28°) and a soil-gravel mixed runout surface to replicate the field condition. Each rockfall event was recorded under high resolution cameras and a sophisticated motion tracking software (Tracker v6.3.2) was utilized to analyze different motion characteristics of the falling blocks. Four different rock types were utilized viz. quartzite, granite, sandstone and limestone which were carved into cube, sphere, cuboctahedron and cuboid, respectively. The shape of the blocks were quantified both geometrically (short/long axis vs. intermediate/long axis) and by utilizing shape factor (η). The mineralogy and physico-mechanical properties of the selected rock types were analyzed in the laboratory before testing. The rockfall characteristics, such as bounce height and runout length were corelated with uniaxial compressive strength (UCS), brazilian tensile strength (BTS), point load index (PLI), density (ρ), porosity (Φ), and mass. The results indicated that the maximum runout length (4.48 m), bounce height (36.80 cm), flight time (0.61 s) and dispersion envelope area (4.80 m²) was achieved by granite (sphere) having UCS of 76.03 MPa. While, other shapes showed scattered values. It was observed that rounder shapes such as sphere and cuboctahedron deviated less from centreline, however cube and cuboid have showed relatively higher deviation due to its morphological characteristics. The 4D trajectory reconstruction of the rockfall event has indicated that sphere have achieved the highest spatial and temporal footprint along lateral (x and z axis) and vertical (y axis) direction including time (~2.70 s) among all other shapes. This is because the energy retention capacity of sphere shaped high strength granite rock tends to travel the block further also showing highest bounce height and runout length despite having a same density value of 2.66 gm/cm³ with quartzite cube, which indicates shape have a higher control over density. Further, it was observed that the runout length of the rock blocks was showing a decreasing trend with increasing porosity. The research findings provide essential scientific knowledge on the kinematics of the falling block for the development of enhanced rockfall protection system and allow a safer development in rockfall prone region around the world.