Types of geological structures and mechanism of karst collapses in Baishazhou, Wuhan City of Hubei Province

Most of the soluble rocks in Wuhan lie in the quaternary soil layer and the lower part of the chalk-paleogene red layer, the geological structure of the distribution area of soluble rock is closely related to the karst ground collapse, most of the happened ground collapse in the stratum with the upper clay-lower sand. The study area is on the both sides of the Yangtze River along the Baishazhou karst belt, according to the thickness and the superimposed relation of overburdened clay, sandy soil, soft soil, non-soluble rock (red bed) and surface collapse, the geological structure of the solvable rocks is classified into 3 categories and 5 types. The essence of karst collapse is soil collapse, based on the geological structure and the physical and mechanical characteristics of soil, as well as the migration mode of soil particles during collapse including the clay mass collapse, sand particle leakage and the loss of soft soil, the mechanism of karst collapse is classified into three types, such as soil cavity type, hourglass type and mud flow type, and there are 2 or 3 types of compound karst collapse.