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Tunnel failure caused due to geologic heterogeneity and variability in both mining processes and tunnel arrangement in deep metal mines is very complex. In this paper, a quantitative risk assessment for deep tunnel failure was conducted using clustering and logistic regression. The study was performed by considering various representative evaluation indexes of geological conditions, mining disturbance, and microseismic (MS) data. Comprehensive Seismic Event Clustering (CSEC) methodology was used to analyse the MS data to filter noise data and identify seismic sources. Additionally, peak particle velocity (PPV) was used to quantitatively evaluate the influence of MS activities on the response of tunnel which would aid in determining the PPV distribution characteristics of a large regional tunnel. Furthermore, Excavation Vulnerability Potential (EVP) index was used to quantitatively evaluate the effect of site conditions on response of the tunnel. Thus, based on logistic regression, PPV and EVP were used to establish a risk assessment model to determine the tunnel damage levels and probability of damage occurrence. The successful application of the proposed method at the Ashele copper mine demonstrates that it is capable of conducting a risk assessment for tunnel failure in deep metal mines. [ABSTRACT FROM AUTHOR]

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In the mining process of deep metal mines, different types of rock mass instability failures are caused by strong mining disturbance. It is beneficial to master the fracture mechanism of rock mass in time to effectively prevent and control the ground pressure disasters. Microseismic signals are generated by the propagation and expansion of cracks inside the rock mass that contain plentiful information about the structural changes of rock mass. The ratio of the radiated energy of S and P waves (Es/Ep) of microseismic events can fast and effectively calculate the rock fracture mechanism, which is widely used for ground pressure hazard risk assessment. In this paper, this method was used to analyze the fracture mechanism of rock mass around deep stope in Hongtoushan copper mine and Ashele copper mine. Furthermore, the spatial distribution characteristics and proportion changes of microseismic events with different fracture mechanisms along with the mining process were studied. The results show that tensile cracks play a dominant role, accounting for 62% of the total events, during non-shear fracturing of the rock mass caused by the stoping unloading effect, while shear cracks occupy 68% of the total events during orebody slip failure. When the physical and mechanical properties of the orebody and rock mass are significantly different, slip failure along their contact zone is prone to occur under blasting disturbance. During deep mining, it is necessary to control the exposed area of the roof by each stoping, especially during the earlier mining stage, to avoid tensile stress concentration. The temporal and spatial variation of tension cracks and shear cracks induced by roof damage obtained in this paper can guide the prevention and control of ground pressure disasters in deep mining effectively. [ABSTRACT FROM AUTHOR]