Abstract: The engineering properties of mucky silty clay have the following features: high compressibility, high moisture content, high sensitivity, easily to be disturbed and low shear strength. A proposed site is located at the outlet area of the Baiquan Springs. The thick Quaternary mucky silty clay overlays the silt soil and karst rock cavities and pinnacles which the slight artesian groundwater flows. The lower silt layer is a medium permeable artesian aquifer which receives the water head from lower groundwater flows. If the appropriate engineering measures are not applied in the mucky silty clay layer during the foundation construction, the occurrence of the groundwater gushing hazard is relatively high. It is concluded that the engineering properties of the mucky silty soils are changed under this special hydrological condition and therefore, the supporting structure for the deep excavation and the bottom soils improvement need to be appropriately considered.

Key words: mucky silty clay, slight artesian groundwater, baiquan spring, groundwater in karst rock cavities and pinnacles