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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]

The purpose of this ISRM Suggested Method is to describe a methodology for in situ microseismic monitoring of the rock mass fracturing processes occurring as a result of excavations for rock slopes, tunnels, or large caverns in the fields of civil, hydraulic, or mining engineering. In this Suggested Method, the equipment that is required for a microseismic monitoring system is described; the procedures are outlined and illustrated, together with the methods for data acquisition and processing for improving the monitoring results. There is an explanation of the methods for presenting and interpreting the results, and recommendations are supported by several examples. [ABSTRACT FROM AUTHOR]

The evolutions of stress and deformation inside of rock is highly important in studies of the rock failure mechanism but is difficult to obtain via the traditional stress measurement methods due to limited measuring points. Thus, studies of the stress and displacement evolution within rock were conducted based on acoustic emission (AE) monitoring in laboratory experiments. The differences in the distributions and evolution characteristics of the stress field and deformation field before caving in a deep stope were also examined based on in-situ microseismic (MS) monitoring. The results show that the distributions of micro-cracks, apparent stress and deformation inside the rock are highly consistent and can reflect the spatial-temporal evolution characteristics of the stress field and deformation field within the rock. The accumulated apparent volume is more accurately than the strain to reflect the changes in inelastic deformation inside the rock. Based on in-situ MS monitoring, MS activities were found to be closely related to blasting disturbances during the caving process. Before a caving of the deep stope, the distributions of stress and displacement showed obvious differences, reflecting the loosening process of the rock mass. The non-uniformity and the differences in the stress and deformation can deepen the understanding of the rock (mass) failure process. [ABSTRACT FROM AUTHOR]