The classifications of water and mud/rock inrush hazard: a review and update

Water and mud/rock inrush has been recognized as one of the major geological hazards in underground engineering, which resulted in huge casualties, financial losses, or environmental disruption. Classification of hazard types plays an important role in understanding hazard behavior and guiding corresponding treatment measures. Various classifications of water and mud/rock inrush have been widely discussed. This paper reviewed the available classifications and considered the applicability of those classifications for numerous hazard cases since the 1950s. However, the current classifications were incompatible with occurred cases. The mainly used three classifications based on criteria of material type, hazard size, and geological feature, therefore, were updated to eliminate the incompatibility. A classification was first presented to distinguish between various materials of water and mud/rock inrush, utilizing five terms including water flow, diluent mud flow, viscous mud flow, water-rock flow, and mud-rock flow, followed by presenting the definition and description. Second, this paper differentiated between small, moderate, large, and extremely large water and mud/rock inrush concerning the gushing water flux and mud/rock volume. Subsequently, four terms, including karst terrain, geological structure, differential weathering zone, and unconsolidated sediments, were used to make up a classification system that distinguishes hazard types through geological features. Sixteen subclasses were also subsequently defined and described. Moreover, to describe the hazard class in a shorthand way, a classification code was developed for each class of three updated classifications. Finally, the treatment technology for each hazard type was included in this paper. The updated classifications eliminated their incompatibility with numerous hazard cases, and targeted approaches for dealing with the hazards can now be quickly located, thereby saving time.