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.