Study of the Rotation of Blocks in a Two-Dimensional Blocky Rock Mass under the Impact Load and Torque

Abstract

Rock masses have complex block-hierarchical structures involving various scale levels, which should be considered in dynamic and static conditions. Because the interlayer has weak mechanical properties, the deformation of rock masses is primarily concentrated at the interlayers, which provides the possibility of translation and rotation for rock blocks. In situ experimental data have shown that the blocky rock masses undergo significant angular deformation under a dynamic impact, and the rotation of blocks can significantly affect the wave propagation and dynamic behavior of rock masses. Consequently, to investigate the rotation of blocks, a two-dimensional dynamic model of blocky rock masses was established based on the accurate consideration of the rotation effect. This research revealed the mechanism of the rotation of blocks and determined the characteristics of energy transfer and the influence of block rotation on the inhomogeneous deformation of interlayers. The findings showed that the rotation of blocks is caused by the nonequilibrium shear between the interfaces in the absence of external torques, resulting in inhomogeneous deformation of interlayers. The blocky rock masses can produce additional tension and compression deformation caused by the rotation of blocks at local positions in addition to the deformation caused by the translation. The energy transfer and influence of the rotation of blocks under an external torque are inconsistent with those under a horizontal impact load. This study theoretically solves the problems of wave propagation in block media under arbitrary loads and torques and is helpful for the research of seismic wave propagation in block media with inhomogeneous complex structures.