Objective Percussion bored piles are widely used in pile foundation engineering in karst areas owing to their strong adaptability to complex geological conditions and high hole-forming efficiency. However, the dynamic impact generated during percussion boring can readily induce karst collapse hazards, leading to construction suspension, damage to buildings and farmland, and even substantial economic losses and casualties. To effectively prevent such hazards, it is necessary to systematically reveal the dynamic factors, hazard-causing modes, and prevention and control countermeasures of karst collapses induced by percussion bored pile construction, thereby providing a basis for safe pile foundation construction in karst areas.

Methods Based on an analysis of the action modes and collapse-inducing conditions of dynamic factors such as vibro-impact, suction, and water hammer effects during percussion bored pile construction, and combined with the geological conditions of typical construction sites in karst areas, this study established modes of karst collapse induced by percussion bored pile construction. Typical cases of different collapse types were selected to analyze their development processes, dynamic action mechanisms, and evolution characteristics, thereby revealing the formation mechanisms of each collapse type.

Results Three modes of karst collapse induced by percussion bored pile construction were established: vibro-impact–suction type, water-hammer type, and slurry-loss type. These modes differed significantly in dynamic triggering conditions, development processes, influence scope, and hazard severity. Analyses of typical cases showed that vibro-impact and suction effects often act in a coupled manner on shallow overburden layers, whereas water hammer effects propagate along karst conduits and cause relatively extensive damage; slurry-loss-type collapse is closely related to rapid slurry loss in pile holes. Among these modes, water-hammer-type collapse is characterized by large scale, numerous occurrences, wide distribution, and severe damage, making it a key type requiring prevention and control during percussion bored pile construction in karst areas.

Conclusions Based on the hazard-causing mechanisms and development characteristics of different collapse modes, corresponding prevention and control countermeasures were proposed for each mode. These findings provide a reference for safe and economical construction of percussion bored piles and for the prevention and control of karst collapse hazards in karst areas.