Abstract
The lithology of the strata in the Gobi region of the Xinjiang autonomous region of China is mainly composed of mudstone, silty mudstone, and other soft rocks. Because of the low strength of the rock mass and the serious effects of physical weathering in this area, the slope stability in open-pit mines is poor, and creep deformation and instability can readily occur. Taking the Dananhu No. 2 open-pit mine as a typical example, the creep test of a mudstone sample under different stress levels was studied. Then, based on a bottom friction experiment and a FLAC3D numerical simulation, the deformation and failure processes of the slope were analyzed. The stress–displacement curve and the displacement–time curve for the monitoring points were plotted to obtain the relationship between the stress and displacement for the slope of the soft rock. The results showed that the long-term strength of the mudstone was between 8.0 and 8.8 MPa, and that stable creep occurred when the slope was under low stress. The potential failure mode for this type of slope is that the front edge creeps along the weak layer and then a crack is formed at the trailing edge of the slope. When the crack penetrates the weak layer, cutting bedding and bedding sliding occur. The deformation process of the stable creep slope includes an initial deformation stage, an initial creep stage, a constant velocity creep stage and a deceleration creep stage.
Highlights
Soft rock is widely distributed in China
The lithology of the strata in the Gobi region of the Xinjiang autonomous region of China is mainly composed of mudstone, silty mudstone, and other soft rocks
A large amount of monitoring data concerning slope engineering studies in open-pit mines show that the mechanical response of the formation during mining often displays a clear time effect, and the time effect of the deformation will affect the deformation of the slope, which is caused by the rheological properties of the rock layer
Summary
Soft rock is widely distributed in China. Given a relative depletion of shallow resources in the country, the depth and scale of open-pit mining have been increasing recently. Researchers in China have studied creep deformation and the instability mechanism (Wang 2009; Wang et al 2010) in soft rock slopes, and the failure mechanisms (Li et al 1998; Wang et al 2013) and reinforcement and treatment measures (Wang et al 2007). These studies have provided a theoretical basis for the prevention and control of failures of soft rock slopes. In combination with the topography and engineering profile of the slope of the mining area, the creep deformation law for the soft rock slope was examined using a simulation test and numerical simulation of the bottom friction, the aim being to provide a theoretical basis for the safe and efficient operation of open-pit mines
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