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A landslide occurred on November 24, 2019, in weathered phyllite at the western longwall of Yabaling open pit of Anqian iron mine in Anshan City, Liaoning Province, China. The landslide was estimated to be 3.0 × 104 m3 in volume and caused severe damage to the road of transporting waste materials. This landslide was a typical jointed rock mass landslide, and the cause of the landslide was related to four factors: open-pit mining activity, the weak rock, discontinuities, and the high rainfall. According to the failure characteristics, the landslide area was divided into three parts: the tension-cracking area, the sliding-deformation area, and the colluvium area. The failure mechanism of the landslide was investigated through a back analysis combining nonlinear Hoek–Brown criterion and FLAC3D program with a parameter reduction technique. The results showed that the predicted sliding surface at the critical state matched closely the field observations. A remedial scheme of landslide stabilization including four rows of micropiles was proposed and the stabilization mechanism of the micropiles was discussed. The shear strain increment contours show that the micropiles arrested the original sliding surface and controlled the movement of the sliding mass behind them, and thereby significantly improved the stability of the landslide. This paper also presents the results obtained from the parametric analysis in order to understand the impact of strength parameters on the long-term stability of the stabilized slope. The findings improved understanding of the failure characteristics and mechanism of jointed rock mass landslides may be used for evaluating the stability of slopes and early identification for both active and inactive open-pit mines. [ABSTRACT FROM AUTHOR]

A rainfall-induced landslide occurred in the north highwall of the Fushun west open pit at 5:00 (UTC + 8) on July 26, 2016, in China. The landslide was about 3.1 × 106 m3 and caused considerable destruction of houses, roads, and railways. Field investigations, laboratory tests, and numerical analyses have been performed to explore the failure characteristics and formation mechanism of the landslide. The landslide was divided into three parts: the crack area, the sliding body area, and the accumulation area. The X-ray diffraction and scanning electron microscope techniques were used to reveal the mineral composition and microstructure of the landslide material. Then, a conceptual model of the landslide mechanism was constructed and the process of the landslide was divided into four stages: unloading and cracking stage; sliding and partial locking stage; shearing out and failure stage; and flowing and accumulating stage. A combined seepage and stability analysis was performed to explore the mechanism of the landslide by numerical simulation. The relationship of volumetric water content and hydraulic conductivity to matric suction was established to describe the hydraulic characteristics of the slope material under infiltration. The results show that the maximum matric suction in the slope decreases continually with the increase of rainfall intensity and duration, and the north highwall will not be stable after 7.2 h for 16 mm/h of rainfall. The original slope was stable and heavy rainfall triggered the landslide, and the obtained critical failure surface matched the field survey closely. The findings improved understanding of the failure mechanism and process of rainfall-induced landslides may be used for evaluating the stability of slopes and early identification for both active and inactive open-pit mines. [ABSTRACT FROM AUTHOR]

Owing to the heavy rainfall, a landslide occurred at the Anqian Iron mine, at 18:00(UTC + 8) on November 24, 2019, in China. The landslide was about 3.0 × 104 m3 and caused damage to the road of transporting waste materials. Failure characteristics and the mechanism of this landslide were analyzed in this study. The landslide area was divided into three parts: the rear tension cracking area, the middle sliding deformation area, and the front colluvium area. A contact-free measuring technique using the new ShapeMetrix3D system was applied and 204 joints were analyzed based on equal-angle stereographic projection. Thus, a conceptual model of the mechanism of the landslide was constructed and the formation process of the landslide was divided into three stages: the first shearing and dislocation stage; the second sliding, front bulging, and rear tractive cracking stage; and the third local rock mass collapse and colluvium depositing stage. Numerical modeling was performed to discover the landslide mechanism by progressively reducing the shear strength of rock mass. The results showed that the original slope was stable, whereas heavy rainfall triggered the landslide, and the predicted failure surface matched closely the field investigations. The factor of safety obtained by real three-dimensional analyses was slightly higher than that obtained by plane problem analyses, and the difference was attributed to the three-dimensional effect of the landslide. This paper also presents the results obtained from the parametric analysis in order to understand the impact of shear strength parameters on the overall stability of the slope. [ABSTRACT FROM AUTHOR]