Mitigating geohazards in underground goafs: a review of detection technologies, risk assessment, and treatment methods

With the continuous exploitation of mineral resources, numerous underground goafs have been formed. These mined-out voids may induce surface subsidence, shaft blockage, water inrush, landslides, and mine tremors, posing serious threats to personnel safety, equipment operation, and surface infrastructure. This paper systematically reviewed the research trends and frontiers of goaf studies since the 21st century, focusing on publication patterns, major contributing countries, and key research themes. Relevant technological advances and innovations are mainly concentrated in four aspects: (1) the failure mechanisms of goafs have been progressively clarified, with current studies focusing on rock-material properties, spatial structure, and the surrounding environment; (2) detection technologies play a fundamental role in obtaining key goaf parameters, and geophysical methods have made substantial progress in multi-physical-field characterisation, gradually evolving towards an integrated air – space – ground – borehole exploration framework; (3) hazard assessment and early-warning technologies, supported by parameters obtained from detection and monitoring, enable risk classification of goafs and timely disaster warnings; (4) backfilling and remediation technologies can effectively constrain goaf deformation and improve long-term stability. Owing to their remarkable treatment effects, various novel backfilling and remediation technologies have emerged in recent years and are developing towards greener, more efficient, intelligent, and economically feasible solutions.