Study on dynamic failure behavior of cracks in elliptical tunnel surrounding rock under dynamic load

• Published in: Theoretical and applied fracture mechanics Vol. 133; p. 104541
• Main Authors: Peng, Tao, He, Fanmin, Ren, Dongxing, Zhou, Changlin, Xu, Rongxin, Wang, Chao
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-10-2024
• Subjects: Crack; Crack propagation speed; Dynamic fracture toughness; Impact load; Dynamic fracture toughness; Crack propagation speed; Impact load; Crack
• ISSN: 0167-8442
• DOI: 10.1016/j.tafmec.2024.104541

•The dynamic experiment of rock with different crack inclination angles was carried out by using the drop hammer system.•The dynamic propagation behavior of boundary cracks in elliptical surrounding rock is analyzed by experiment and numerical simulation.•The universal function is used to modify the static stress intensity factor to solve the dynamic stress intensity factors of mode I and I / II composite cracks.
Elliptical cross-section underground holes are widely present, and the shock waves generated during construction can disturb the existing cracks and defects around them, affecting the surrounding rock’s stability. A series of impact experiments were executed utilizing crack propagation gauges to analyze the behavior of boundary cracks in the surrounding rock that contains elliptical holes under dynamic loading conditions. The fracture time and the crack propagation velocity for the elliptical hole model were determined across a spectrum of prefabricated crack angles. A good agreement was achieved between the simulation and experimental results. It was concluded that for crack angles α equal to 0° and 90°, the initiation time for crack formation in the specimens is extended compared to the initiation time observed in mode I/II composite cracks, concurrent with an accelerated crack propagation rate. For a crack angle of α at 30°, there is a heightened propensity for tensile failure to manifest along both sides of the short half-axis of the elliptical hole. In contrast, when the crack angle is inclined at 60°, the region at the base of the longer semi-axis of the elliptical hole becomes more vulnerable to tensile failure.