), research on analytical methods have shown greater potential for success [26]. In recent years, more studies have been conducted on fractured slope stability by employing the upper bound theorem of limit analysis. Based on the log-spiral failure mechanism of clay slopes, [PERSON] [27] studied the adverse effects of open cracks on slope stability during drying and water filling. [PERSON] [28] considered not only open cracks but also the effects of cracks formed as part of the failure mechanism (formation cracks). The research by [PERSON] et al. [29] showed that disregarding the influence of formation cracks will underestimate the safety of clay slopes. In addition, some scholars have studied the anisotropy of strength parameters [30], pore water pressures [31], earthquakes [32; 33], three-dimensional slopes [34], and other situations, which have promoted the development of slope stability assessment methods. Nevertheless, the upper-bound analysis method has also some shortcomings: (1) the method regards the soil as an ideal rigid, perfectly plastic body and considers that the deformation of the soil mass only occurs in the thin shear zone (failure surface) [35], which cannot reflect the internal deformation mechanism of the soil; (2) the method considers instantaneous failure where the yield condition is reached simultaneously along the entire failure surface [28], which can hardly reflect the progressive failure process widely existing in clay slopes; and (3) crack development cannot be simulated by limit analysis [36]. Furthermore, cracks in clay slopes may take on nonvertical plane shapes. For example, diagonal cracks are one of the common distribution patterns of clay cracks in Chengdu, Hefei, and Nanjing in China [37; 38]. Unfortunately, in previous stability analyses of fractured slopes, the crack was assumed as vertical, so the nonvertical crack mode in clay is still poorly understood [27; 39]. There is a close relationship between the stress field, displacement field, and slope stability [40]. By not giving sufficient stress to this fact, previous studies on the stress and deformation characteristics of slopes have been limited [41]. In the literature of stability assessment of fissured clay slopes, little attention has been paid to the coupling analysis of the initiation and development of cracks and the macroscopic progressive failure process of slopes. The mechanism leading to cracking involves the reduction of soil stress level [20; 42], and the occurrence of landslide is always related to the perturbation of the equilibrium relationship between the stress and strength of the slope materials [43]. Previous studies have rarely paid attention to internal stress variations of fractured clay slopes in the progressive failure process. The main purpose of this work was to study (1) the relationship between the initiation and development of major cracks and stress changes in clay slopes under static loads; (2) the internal relationship between major cracks, stress, and displacement variations during the progressive failure process of clay slopes. To this end, the stress mechanism of major crack initiation and development in unsaturated clay under tensile and shear failure is firstly derived in Section 2. Section 3 describes the model test conducted on a large-scale clay slope with arc-shaped slip surface to monitor changes in horizontal and vertical stresses in the slip mass and the development of slope shoulder displacement under the action of the set load sequence. Finally, the experimental and monitoring results are analyzed and discussed in Section 4.