Identification of arbitrarily shaped critical 3D failure surface of a slope based on the sliding direction

Abstract The determination of critical failure surface and stability evaluation of 3D slopes have been a hot and difficult problem in geotechnical engineering. The conventional method defines the critical failure surface using the safety factor (SF) whereas it is powerless for some special problems, such as two different failure surfaces with equal SFs. So far, many studies on the critical failure surface of a 3D slope have mainly focused on rotational ellipsoid, while less research has been done on the arbitrary shape. To solve the above problems, we develop a model for constructing a arbitrarily shaped failure surface and ascertain the critical failure surface by the sliding direction (SD). To verify rationality of the introduced theory, the critical failure surfaces of two benchmark symmetric slopes and corresponding SFs are reanalyzed, and the results are compared with the reference solutions. Meanwhile, the results obtained by the proposed method are also consistent with the reference solutions for the complex slope with the asymmetric failure surface. The parametric analysis explores the relationships between the mechanical properties of soil and the SD as well as the SF. Furthermore, influence factors of the spatial characteristics of sliding mass are also revealed. The proposed method is used as a helpful complement to the existing methods.