Abstract: This paper adopts laboratory experiments and numerical calculation to analyze the stability of high cutting loess slope. Taking the cutting slope in the site of Huanneng electrical plant ,which islocated in Huanxian county, Gansu province , as an example, the linear elastic finite element method is utilized to attain the stress path of soil mass on the potential failure surface under multistage excavation. Then based on this stress path, triaxial shear tests are conducted on specimens with two moisture contents. With the strength parameters obtained from these tests, elastic-plastic finite element models against different excavation ratios are made to figure out its stress field. Afterwards comparison between the shear strength and shear stress on the slide surface reveals the mechanism of slope failure. Results show that the stress path (in p-q space) of soil on the prospective failure surface displays a trend that the mean stress p decreases with excavation while the shear stress q decreases at first then increases slowly. The effect of excavation on the potential surface changes from unloading at the beginning to loading. Failure firstly occurs at the shoulder of the high slope and then expands to lower area with the excavation process until a connecting yield surface in the slope develops. This mechanism is typical of top-driving landslide mechanism.

Key words: loess, high slope, excavation, stress path, triaxial shear tests, finite elements, top-driving landslide mode