A new empirical chart for rockburst analysis in tunnelling: Tunnel rockburst classification (TRC)

Rockburst is defined as a phenomenon with immediate dynamic instability under excavation unloading conditions of deep or high geostress areas. Inadequate knowledge and lack of characterizing information prevent engineers and experts from achieving appropriate prediction results related to the rockburst behaviour. In this study, a data set including 220 rockburst instances was collected for rockburst classification via the geostatistical method. An update of the 2D graph, the tunnel rockburst classification (TRC) chart, was introduced based on analysing three indicators, namely, elastic energy index (W-et), tangential stress in rock mass (sigma(theta)), and uniaxial compressive strength (sigma(c)). Distribution and correlation of data were drawn on 2D plot, and the boundaries of rockburst were distinguished according to the achieved interpolate points by kriging method. Hierarchically, the validation phase was performed using an additional set of 28 case histories obtained from several projects around the world. The results showed that the TRC chart with an average error percentage of 3.6% in the prediction of rockburst had a significant and effective implementation in comparison to the exiting heuristic systems. Despite the initial character of the prediction, the described chart may be a helpful tool in the first steps of design and construction. (C) 2021 Published by Elsevier B.V. on behalf of China University of Mining & Technology.

Automated summary

Rockburst is defined as an immediate dynamic instability under excavation unloading conditions in deep or high geostress areas. An updated TRC chart based on elastic energy index, tangential stress in rock mass, and uniaxial compressive strength was introduced for rockburst prediction, showing a significant improvement in accuracy compared to existing heuristic systems.