Karst collapse related to over-pumping and a criterion for its stability

摘要

Karst collapse, caused by natural or artificial abstraction of groundwater, has been an environmental geological problem. The origin of karst collapse has been described by the potential erosion theory and the vacuum absorption erosion theory. However, a mathematical prediction criterion for karst collapse cannot be established by these two theories. This paper, from a new perspective, attempts to explain the microcosmic mechanism of karst collapse on the basis of these two theories. At a certain point in the unconsolidated soil covered on karst caves, when shearing stress surpasses shear strength of the soil, it fails under the mechanic effects of water and gas as well as gravity pressure. With an increase in damage points, a break plane appears and the soil overlying the karst caves is completely damaged and, thus, the ground surface collapses. On the basis of Mohr-Coulomb damage theory and previous studies, a prediction criterion of karst collapse is presented. An example displays the calculating process of the model and proves its reliability by analyzing nine typical collapses caused by a pumping test in Guizhou Province, China.