Sequential excavation analysis of soil-rock-mixture slopes using an improved numerical manifold method with multiple layers of mathematical cover systems

An improved numerical manifold method (INMM) with multiple layers of mathematical cover (MC) systems is employed for a sequential excavation analysis of SRM (soil-rock-mixture) slopes. For the purpose of obtaining the FOS (factor of safety) of a SRM slope, an enhanced SSRT (shear strength reduction technique) is used in the INMM. Furthermore, two algorithms, i.e., an algorithm to identify the excavated MEs (manifold elements) and an algorithm to remove the excavated MEs, are incorporated into the INMM to study the effects of excavation of the SRM slopes. With the INMM, two examples, including a soil slope and two SRM slopes subjected to sequential excavation construction, are investigated. The simulation results show that 1) the excavation processes, as well as the FOSs of the slopes, can be accurately predicted with the INMM; 2) the higher the content of rock blocks, the larger the FOS of the SRM slope will be; and 3) the FOSs assessed from the INMM are the same as those from the traditional NMM (TNMM), but the memory consumption and computational cost of the INMM are smaller.