A tailings dam failure can lead to disastrous impacts on people’s livelihood and the surrounding ecological environment. Due to interactions among water, tailings and ground, the mechanism of a tailings flow is more complicated than that of a flood flow. In this paper, the tailings flow is regarded as a homogeneous and incompressible non-Newtonian fluid. Its rheological properties were studied through rheological tests conforming to the Bingham model. The rheological parameters were further used in a Computational Fluid Dynamics (CFD) simulation over complex terrain to explore the tailings flow characteristics. The method was validated with experimental results of a non-Newtonian dam-break flow from literature. The flow characteristics, including flow velocity, runout distance, inundation area and depth, were analyzed in the case of the Dagangding tailings dam. The results showed that the downstream railway and village would not be affected in a conservative scenario. Finally, the effects of two measures for preventing tailings flow hazards were discussed. Setting the check dam and planting grasses and trees can effectively mitigate the damage of tailings flow.

Granite residual soil (GRS) has prominent disintegration characteristics which have induced various geological disasters and engineering problems. The initial moisture content is believed to affect the disintegration of GRS significantly. To explore the effects of the initial moisture content on the soil disintegration characteristics and disintegration mechanism, disintegration tests were performed on remolded GRS with different initial moisture contents via the balance method, and the quantitative disintegration indices were corrected, considering the effects of water-absorption weight gain, in combination with a parallel water-absorption test. The disintegration characteristics and mechanism were thoroughly investigated, starting with the disintegration process curves and disintegration morphology, and combined with strength theory, X-ray diffraction (XRD) and X-ray fluorescence (XRF), the matric suction test, and the triaxial shear test. The results are as follows. (1) The corrected method improves the accuracy of the quantitative disintegration evaluation. (2) During the two disintegration stages, the forms of disintegration are dispersive fragmentation and progressive or block separation, and the soil matric suction and weakening of intergranular joining forces, respectively, are the drivers of disintegration. The first stage is usually completed within 1.5–2 min, and the disintegration ratio is usually within 20%. (3) The trends of change within the disintegration during the two stages show opposite water-content-dependent modes, and the soil samples with lower moisture contents have better water stability and slower disintegration in the second stage. The average disintegration rate of the soil with a moisture content of 24.4% in the first and second stages was approximately 1/5 and 13 times, respectively, that of the soil with a moisture content of 6.1%; these values can be rendered as 0.049%/s and 0.82%/s, respectively. The results provide some theoretical references for soil and water conservation and engineering applications in the GRS field.

Combined with the spatial data processing capability of the Geographic Information Systems (GIS), the Pan Jiazheng method is extended from two-dimensional (2D) to three-dimensional (3D), and a 3D landslide surge height calculation method is proposed based on grid column units. First, the data related to the landslide are rasterized to form grid columns, and a force analysis model of 3D landslides is established. Combining the vertical strip method with Newton's laws of motion, dynamic equilibrium equations are established to solve the surge height. Moreover, a 3D landslide surge height calculation expansion module is developed in the GIS environment, and the results are compared with those of the 2D Pan Jiazheng method. Comparisons showed that the maximum surge height obtained by the proposed method is 24.6% larger than that based on the Pan Jiazheng method. Compared with the traditional 2D method, the 3D method proposed in this paper better represent the actual spatial state of the landslide and is more suitable for risk assessment.

This study presents a stability analysis of an extended berm reinforced by geotextiles, with a steep slope of 1V:1.1H (vertical: horizontal). Finite element (FE) analyses were carried out to explore the failure mechanism and factor of safety (FOS) of the berm, on which the effect of the strength of geotextiles, leachate level, and anti-slide pile arrangement located at the toe of the berm were considered. It was found that: (1) failure surfaces developed along the interface between the new and the existing berms; (2) the FOS decreased as the leachate increased, and an FOS value of 1.42 could be obtained if the leachate level was controlled at a height of 20 m; (3) the tensile force of geotextiles was far lower than the available strength, which suggested that the geotextile had enough of a safety reserve; and (4) one row of longer piles at the toe of the berm performed better than two rows of shorter piles if the total length of piles was the same. The design and analysis of this project can be used as a reference for landfill expansion. Especially for a site condition with limited space, a geosynthetic-reinforced soil (GRS) berm is a safe, reliable and promising alternative.