Mechanism and mechanical model of karst collapse in an over-pumping area

Through geological investigation of karst collapses at Zaozhuang City, China, it was found that the mechanism of karst collapse in areas of excess water extraction is characterized by a seepage effect and that the seepage-pressure effect is the initial factor that induces karst collapse. The causation mechanisms for karst collapse can be divided into two phases: the inter-collapse phase and the surface-collapse phase. Therefore, based on the limit-equilibrium theory, this paper has established mechanical models for the surface-collapse phase and determined values for the stability of the arch formed by the soil hole in an inter-collapse phase. In addition, an evaluation of a karst collapses at Zaozhuang City, China, was completed using mechanical models. The results show that the mechanical models agree with the theory of karst collapse at Zaozhuang City. Thus, it is proved that the karst collapse models can be used for the evaluation of karst collapse in areas that are over-pumped.