Water and mud inrush hazard in underground engineering: Genesis, evolution and prevention

•A State-of-the-art review on water and mud inrush hazard in underground engineering is presented.•Emphasis is placed on recorded geneses and evolution processes of water and mud inrush hazard.•The available prevention methods and techniques of water and mud inrush hazard are reviewed.•Research gaps of water and mud inrush hazard are discussed. Water and mud inrush is one of the most important geohazards in underground engineering. The paper presents a state-of-the-art review of the current understanding of this type of geohazard. Emphasis is placed on recorded the geneses and evolution processes of water and mud inrush, as well as relevant prevention methods. In particular, the geneses of this inrush hazard are initially discussed, by providing hazard cases during the past several decades. This is followed by a review of the various forming processes and corresponding research methods (including theoretical, numerical, experimental methods) for water and mud inrush, which can be used to pave the ways for hazard prevention and future research. Subsequently, the paper provides a summary of relevant hazard prevention methods employed by academics and practitioners, followed by a short discussion on the achievements and limitations of each method. Throughout the presentation, the current overall gaps in understanding water and mud inrush hazards are identified in an attempt to stimulate further research in these promising directions by the research community.