Assessment of slope stability under uncertain circumstances

Slope stability assessment is a difficult geotechnical problem because of the many uncertainties involved. The uncertainties associated with soil parameters are significant, originating from limited and imprecise information, which allows for the soil parameters to be expressed as uncertain variables. The distributions of these uncertain variables are built on the basis of the structure of the soil layers of a slope, and the safety factor of slope stability is defined as a ratio of resisting and acting moments under uncertain environments. The expected value of the safety factor is therefore calculated by utilizing the operational laws of the uncertain variables. The concept of the reliability index of slope stability is also introduced in order to evaluate the risk of slope instability. Three numerical examples, including a homogeneous slope and two non-homogeneous slopes, are used to verify the proposed model; meanwhile, the results are compared with those of the Fellenius method. The numerical results indicate that the proposed model can not only improve the reliability of the calculated safety factor but also reduce the computational complexity compared to deterministic methods. Fifteen project instances taken from the literature are used to investigate the validity of reliability index, and the results illustrate that the reliability index is another useful indicator to assess the stability of a slope.