Dynamic buckling mechanism of pillar rockbursts induced by stress waves

Abstract

Rockbursts are sudden and violent rock failures that can lead to huge production and equipment losses, injury or death of mining workers. Buckling has been regarded as one of the key mechanisms of rockbursts, which are often induced by dynamic loads from mining excavations, such as drilling and blasting in underground mining. The paper attempts to investigate the dynamic buckling mechanism of pillar rockbursts in underground mining, by considering rockbursts as a dynamic stability problem of underground rock structures. The results include: (1) A new explanation of the “sudden and violent” phenomenon of rockbursts, characterized by exponential growth of the amplitudes of transverse displacement responses, even in the presence of rock damping; (2) Identification of the critical role in inducing rockbursts of dynamic loads that bear frequencies approximately double the natural pillar frequency; (3) The greater influence on rockburst occurrence of the amplitude of dynamic component relative to the static component of loads; and (4) Quantification of the relative effects of stress waveform of dynamic loads on pillar rockbursts, which are in decreasing order if other parameters remain constant: rectangular, sinusoidal, and exponential waveforms. Application examples are provided and limitations of the approach are discussed. This research is motivated by the on-going and ubiquitous occurrence of rockbursts in underground excavations all around the world. In contrast to conventional methods that use rock specimens or rock materials to study rockbursts, this investigation emphasizes the structural effects on rockbursts, which has potential applications in hard rock mining engineering. Keywords: Pillar rockbursts, Buckling mechanism, Stress waves, Structural rock mechanics