On June 11, 2016, a landslide occurred in Miaoling village, Jiujiang city, Jiangxi Province, China, following continuous rainfall. An engineering geological profile indicated that the landslide consisted of a stiff crust of residual Quaternary deposits overlying a water-sensitive gravelly clay layer with a soft-plastic consistency. A geotechnical field investigation and physical models of rainfall-induced landslides were carried out in situ and in the laboratory and included the use of a new sensors to develop a geotechnical model of the cut slope. During the rainfall process in the physical simulation experiments, automatic rainfall, three-dimensional scanning, and multiparameter monitoring were conducted to analyze the resulting landslides. The results showed that the increase in moisture and the generation of pore water pressure led to changes in soil pressure and the development of plastic deformation. An analysis performed after rainfall using a strain-softening behavior model showed the initiation and propagation of plastic zones, as well as the development of landslide cracks close to the observed ones. Therefore, it was proposed that the Miaoling-Jiujiang landslide could be explained by a progressive failure mechanism.

The shear behavior of backfill-rock composites is crucial for mine safety and the management of surface subsidence. For exposing the shear failure mechanism of backfill-rock composites, we conducted shear tests on backfill-rock composites under three constant normal loads, compared with the unfilled rock. To investigate the macro- and meso-failure characteristics of the samples in the shear tests, the cracking behavior of samples was recorded by a high-speed camera and acoustic emission monitoring. In parallel with the experimental test, the numerical models of backfill-rock composites and unfilled rock were established using the discrete element method to analyze the continuous-discontinuous shearing process. Based on the damage mechanics and statistics, a novel shear constitutive model was proposed to describe mechanical behavior. The results show that backfill-rock composites had a special bimodal phenomenon of shearing load-deformation curve, i.e. the first shearing peak corresponded to rock break and the second shearing peak induced by the broken of aeolian sand-cement/fly ash paste backfill. Moreover, the shearing characteristic curves of the backfill-rock composites could be roughly divided into four stages, i.e. the shear failure of the specimens experienced: stage I: stress concentration; stage II: crack propagation; stage III: crack coalescence; stage IV: shearing friction. The numerical simulation shows that the existence of aeolian sand-cement/fly ash paste backfill inevitably altered the coalescence type and failure mode of the specimens and had a strengthening effect on the shear strength of backfillrock composites. Based on damage mechanics and statistics, a shear constitutive model was proposed to describe the shear fracture characteristics of specimens, especially the bimodal phenomenon. Finally, the micro- and meso-mechanisms of shear failure were discussed by combining the micro-test and numerical results. The research can advance the better understanding of the shear behavior of backfill-rock composites and contribute to the safety of mining engineering. (c) 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).