Protection measures in order to increase safety of unstable clay slopes by unconventional pore pressure release techniques

摘要

Regarding submerged soil as a three-phase medium (gas, water and solids), measurements and calculations suggest barometric pressure to be a new and important factor in slope stability. A further application of this concept suggests pore water pressure release techniques to stabilise instable slopes in low permeable soil. This new method is presented in order to stabilise endangered cut slopes in clay. A solution has been found by installing horizontal and inclined drain bore holes to increase slope stability. Thus pore water pressure is reduced directly in the shear zone and around the overall region of the shear zone. The calculation of the pore water pressure release is based on a three-phase model, which is used to design an adequate layout of the bore holes. Pore water pressure may be released up to the mean barometric pressure level and even beyond. Thus slope stability may increase significantly with time.