Characterization of the sinkhole failure mechanism induced by concealed cave: A case study

Abstract The formation of sinkholes in karst areas has become a dangerous geohazard over the last two decades and has been increasingly studied by researchers worldwide. A concealed karst cave caused a sinkhole failure event in Ziran village of Longyan City, Fujian Province, China (N25°44′20″, E117°21′99″) on 27 June 2015. A detailed field investigation showed that the failure event was induced by the enlargement of a concealed karst cave. A numerical model based on an adaptive finite element limit analysis was implemented to determine the failure mechanism and the affected regions of the sinkhole. The critical state, critical load and failure mechanism were directly analyzed using limit theorem analysis and the discrete finite element technique. The results demonstrate that the enlargement of karst caves by the suffosion effect of groundwater played an important role in karst collapse. Gravity is predicted to induce damage to a karst cave with a critical radius r of 1.25 m, thereby destabilizing the ground surface and resulting in the appearance of a sinkhole. This study provides reliable analysis methods for sinkholes caused by concealed karst caves and serves as a reference for preventing similar geohazards around the study area.