Abstract
Slope stability analysis is important for the safe mining of mineral resources. The collapse of goafs in loess gullies can lead to natural disasters such as surface landslides. In this context, this study analyzes monitoring data obtained from surface observation in the Shendong mining area of the Hanjiawan coal mine based on the geological conditions therein. The monitoring results show that the working face experiences a starting period, an active period, and a declining period, from the start of mining to the end of the working face. At the initial mining stage, there is no evident surface movement or deformation in the mining area. When the advance distance of the 12106 working face is between 13 m and 109 m, the surface movement and deformation vary significantly, and the maximum subsidence reaches 1963 mm, which is enough to cause landslides. We select the physical and mechanical parameters of the rock and soil in the mine and then simulate the formation mechanism of surface landslides under different slope angles of the mining area using FLAC3D software. Because of the collapse of the mined-out area, the overlying strata structure is destroyed, the subsidence basin is shifted to the center as a whole, and the slope mass is subjected to tensile and compression deformation, resulting in plastic damage, which develops downward along the crack and leads to a collapse because of the discontinuous movement and deformation of the surface; moreover, step-type ground fissures are produced. The results also show that when the slope angle is greater than 60°, the displacement of the slope mass is not uniform, and the rock stratum in a position with large displacement loses its support, leading to landslides; when the slope angle is less than 30°, the bedrock surface forms a sliding surface and develops to the surface, thus decreasing the possibility of landslides. Based on the stability analysis of the collapsed slope in the goaf of the loess gully, a scientific basis is provided for the effective prevention and control of geological disasters in the Shendong mining area.
Highlights
Loess gullies in China are mainly distributed in the northwest region
A loess gully area mainly includes three types of landforms: a loess hilly gully area, loess remnant gully area, and loess plateau gully area. e frequency of geological disasters in loess gullies is higher than that in plains. e more serious types of hazards are landslides, ground fissures, surface subsidence, debris flow, and cavern collapses [4]. e loess gully in Shendong mining area occupies a significant portion of the entire mining area, and the surface is covered by loess, with a thickness in the range of approximately 70–80 m [5, 6]
When the surface is disturbed by external forces, there will be signs of a collapse. e mining activity causes the overlying rock layer to move and deform. e loosely accumulated soil layer is cut along the slope to become a block. e slope mass loses continuity, and a nonuniform gravity action comes into play. e slope foot loses support and forms an uneven slump
Summary
Loess gullies in China are mainly distributed in the northwest region. A loess gully is a special geological structure located in the transition zone between the plain and plateau regions. E erosion of the cover layer of loess gullies can lead to steep trenches due to rain erosion, making the geological conditions in such areas quite complex [1, 2]. Conducting coal seam mining under such geological conditions can lead to surface subsidence or even geological disasters such as landslides, collapses, and debris flows [3]. E frequency of geological disasters in loess gullies is higher than that in plains. E more serious types of hazards are landslides, ground fissures, surface subsidence, debris flow, and cavern collapses [4]. Due to external forces, such as geological movement and rain erosion, the loess exhibits some special
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