Dynamic interpretation of stress adjustment types in high geostress hard rock tunnels based on microseismic monitoring

Abstract

Dynamic stress adjustment in deep-buried high geostress hard rock tunnels frequently triggers catastrophic failures such as rockbursts and collapses. While a comprehensive understanding of this process is critical for evaluating surrounding rock stability, its dynamic evolution are often overlooked in engineering practice. This study systematically summarizes a novel classification framework for stress adjustment types—stabilizing (two-zoned), shallow failure (three-zoned), and deep failure (four-zoned)—characterized by distinct stress adjustment stages. A dynamic interpretation technology system is developed based on microseismic monitoring, integrating key microseismic parameters (energy index EI, apparent stress ${\sigma }_a$, microseismic activity S), seismic source parameter space clustering, and microseismic paths. This approach enables precise identification of evolutionary stages, stress adjustment types, and failure precursors, thereby elucidating the intrinsic linkage between geomechanical processes (stress redistribution) and failure risks. The study establishes criteria and procedures for identifying stress adjustment types and their associated failure risks, which were successfully applied in the Grand Canyon Tunnel of the E-han Highway to detect 50 instances of disaster risks. The findings offer invaluable insights into understanding the evolution process of stress adjustment and pinpointing the disaster risks linked to hard rock in comparable high geostress tunnels.