Analysis of foundation selection of a water-transmission aqueduct across a karst area in Guizhou Province

A water-transmission aqueduct crosses a karst area of Guizhou Province, which may cause engineering geological problems such as karst collapse and instability of slopes. On the basis of geological and geophysical surveys and drilling property of joints and cracks and their effects on karst are analyzed using the geological outline method, and the stability of buried karst caves is assessed. Standard semi-quantitative analysis and 2D- and 3D FEM analyses containing joints and fractures are performed to further examine the stability of karst caves under overlying loads from the perspectives of displacement, stress distribution, development of plastic zones and failure modes. Research shows that the stress of the roof of the karst cave beneath the project site is similar to that of a loaded beam at depth, in which joints and fractures can have a great impact on the stability of the roof. Shearing and extension are easy to occur along these discontinuities. Based on such analysis, a proper type of foundation is recommended for the long-term safety and stability of the planned aqueduct.