Evaluation of Deep-Seated Slope Stability of Embankments over Deep Mixed Foundations

When embankments are constructed over soft foundations, deep-seated slope stability often becomes one of the controlling factors in design. Deep mixing methods have been commonly used as an alternative to solve the deep-seated slope stability problem. Bishops modified method is a commonly adopted approach for analyzing the slope stability of embankments on deep mixed foundations. Bishops modified method assumed slopes fail along a circular slip surface and the soils along this slip surface provide shear resistance. However, experimental studies have showed that deep mixed columns under a combination of vertical and horizontal forces could fail due to shearing or bending. The possible failure modes depend on the combination of the forces, the strengths of soft soils and deep mixed columns, dimensions and arrangements of deep mixed columns. Since deep mixed columns are formed by mixing a certain amount of admixture (cement or lime or a combination) with soil, they can have a wide range of strengths. A numerical method was used in this study to evaluate the factors of safety varying with the strengths of deep mixed columns an