Abstract
In view of the inclined occurrence of coal seam in Heishan open-pit coal mine, in the longitudinal exploitation process of the first mining area, the height of the slope at the west end is increasing, and the occurrence of weak interlayer in the slope is in production. The failure mechanism and stability of the end slope of the inclined composite coal seam, which is typical of the West end slope of Heishan open-pit mine, are studied by means of field investigation, theoretical analysis, limit equilibrium analysis, and numerical simulation. The factors affecting the stability of the western side slope and the potential landslide mode are analyzed. The residual thrust method and simplified Bishop method were used to study the stability of two potential landslide modes on the western slope, and the landslide mode, final slope angle, and slope morphology were determined. FLAC3D was used to simulate the western end of the slope, reveal its landslide mechanism, and clarify the evolution law of the slope rock mass displacement. The results show that the landslide mode at the west end of the first mining area is the combined sliding mode of “cutting and bedding.” With the decrease of longitudinal mining depth, the final slope angle functions from 40° to 37°. The stress and strain are concentrated at the weak layer of the coal floor of the western side slope 13-2 and at the foot of the slope. Meanwhile, the failure also occurs inside the slope. The internal cracks connect through the weak layer of the coal floor and slide along the weak layer of the coal floor 13-2. The displacement evolution law of the slope monitoring point shows that the deformation of the slope is mainly horizontal displacement, the maximum displacement deformation is at the foot of the slope, and the degree of displacement deformation of the slope surface is obviously greater than that of the inside of the slope.
Highlights
With the increase of the number of open-pit coal mines in China and the increase of the production scale, the slope increases and steepens, and the service life increases [1,2,3]
Considering that the potential landslide mode of the westend slope of the slope in Heishan open-pit mine is either the combined sliding of “cutting bed and bedding” or the circular slide, the stability of the west-end slope in the first mining area is analyzed by the residual thrust method and the simplified Bishop method
When the potential landslide mode of the west end is “cutting and bedding” sliding, it meets both the safety factor requirements and the actual engineering requirements. e stable slope angles of sections I∼VI are 40°, 39°, 38°, 38°, and 37°, respectively. e width of the corresponding transport flat plate is 20 m, 20.5 m, 22.4 m, 22.3 m, 23.9 m, and 25 m, that is, the final slope angle of the west-end slope stability decreases from 40° to 37° with the decreasing depth of the longitudinal mining in the first mining area
Summary
With the increase of the number of open-pit coal mines in China and the increase of the production scale, the slope increases and steepens, and the service life increases [1,2,3]. For open-pit coal mine with inclined composite coal seam, with the development of mining, the height of end-side slope keeps increasing, and the exposure number of weak interlayer gradually increases. Scholars at home and abroad have done a lot of research work on the landslide mechanism and slope stability under the influence of the weak layer in composite coal seam open-pit coal mine [4,5,6]. E results provide a reference for the failure mechanism and stability analysis of the end slope of inclined composite coal seam under similar conditions [11,12,13]. E research results can provide guidance for the production of open-pit mine and have reference significance for slope failure mechanism and stability analysis under similar inclined composite coal In order to eliminate the safety threat caused by landslide to the development of mining and stripping engineering in the first mining area of Heishan open-pit mine, in this paper, the stability of the western mining area of Heishan open-pit mine is studied in depth. e research results can provide guidance for the production of open-pit mine and have reference significance for slope failure mechanism and stability analysis under similar inclined composite coal
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