Risk assessment for the cascading failure of underground pillar sections considering interaction between pillars

摘要

The cascading failure of underground pillar sections poses a risk to miners and surface structures. Assessing the risk of underground mining panels contributes to the prevention and control of the catastrophic failure. To resolve the challenge in quantifying the effect of failure of a single pillar on the risk of an entire pillar section, a new risk assessment model incorporating the stability of individual pillars and the load transfer between pillars was proposed to investigate the cascading failure of pillar sections. The load transfer process from failed pillars to adjacent ones was effectively quantified by the relationship between transferred incremental load and transferring distance. The influence of uncertainties of pillar strength, caused either by intrinsic strength variability of a single pillar (quantified by coefficient of variation COV) or the non-uniform deterioration process of pillar sections (quantified by correlation coefficient rho), was investigated on the probability of cascading failure. Risk mapping was also performed on two representative historical collapsed pillar sections using the risk evaluation method proposed to illustrate the risk level of each pillar to trigger cascading failure. The proposed model could represent realistic load transfer process and provide reliable risk assessment results for pillar sections. The results showed that the reliability of pillar sections is significantly influenced by both intrinsic variability in pillar strength and intercorrelation of strength between pillars. The probability of cascading failure increases with increasing COV, which verifies that geological uncertainties increase the risk of collapse in pillar sections. The impact of COV on probability gradually decreases to negligible levels as rho increases to 1, which means that the synchronous variation of pillar strength among a pillar section can significantly compensate for the impact of COV. The proposed approach provides a distinct perspective on understanding sudden failure of high-risk pillars and contributing to the risk control for abandoned pillar sections.