Stability of Cuts in Soft Soils

For the case of excavations in normally consolidated sediments, slope-stability analyses were made for undrained and long-term conditions. Submerged slopes and dry slopes having different seepage patterns were investigated, and for long-term conditions the overconsolidation effect resulting from excavation was studied and found to be generally of negligible importance. The results of these analyses are presented in the form of design curves showing the required slope inclination for different values of s_u/p' for undrained conditions and different values of ∖a/_d for long-term conditions. Available field evidence is presented and none of this evidence conflicts with the results of the stability analyses. It is concluded that both the undrained case and the long-term case can provide the most critical conditions for slope stability of open excavations.