Fracture and Damage Characteristics of Granite under Uniaxial Disturbance Loads

Abstract

To investigate the mechanical properties and damage characteristics of granite under frequent disturbance loads in the process of underground engineering construction, laboratory uniaxial compression tests were conducted on granite under combined dynamic and static loading conditions. The following conclusions were reached: (1) under a dynamic disturbance, the failure stress of granite grows gradually as the initial stress and disturbance load rise due to the coupling of damage and strain-rate effect; (2) the characteristic stresses of granite specimens grow with the increasing amplitude of disturbance Δσ under the disturbing loads; with the same Δσ, the characteristic stresses show an increase trend with the increasing initial stress σm; (3) the particle size distribution of rock fragments broken under the disturbance load follows the fractal law, and the fractal dimension F gradually enlarges with the growth of Δσ, indicative of an increased degree of fragmentation; and (4) the damage variable grows rapidly at first, then steadily, and, finally, shows a rapid growth trend again under the disturbance loads. The Δσ significantly influences the number of cycles and rate of change of the damage variable during the steady increase. This research has certain theoretical significance and engineering guidance value for dynamic disaster recognition and control.

Mechanical model establishment and energy characteristics analysis for rock material considering the dynamic disturbance effect

“…In addition, the reduction of the elastic longitudinal wave velocity inside rock implied the rock damage and this damage was spatially unevenly distributed. The combined dynamic and static loading tests on the samples were carried out respectively from the perspectives of magnitude of pre-static load and amplitude of disturbance load to study the rock burst phenomenon, rock characteristic stress, crack development and rock failure mode (Tao et al (2018), Fei et al (2022), Feng et al (2018), Wang et al (2022)). Liu et al (2022) conducted a dynamic disturbance triaxial loading test on red sandstone samples via disturbance servo triaxial loading system and found that the disturbance load would cause a sudden rise of rock strain.…”