Bearing Capacity Analysis of the Weak Basement, Progressive Destruction Analysis, and Evaluation of the Dump on an Inclined Strip Section Using the Upper-Limit Method: A Case Study in an Anonymous Open-Cast Coal Mine

Due to terrain and transportation constraints, some open cast mines have to choose a weak basement as their tailings dumping grounds. Therefore, ensuring the bearing capacity and slope stability of dumping grounds on the weak basement is of great significance for the production capacity and economic benefits of open cast mining. To ensure the safety of surrounding facilities and the normal production of open cast mines, the bearing capacity of the dumping ground of a certain open cast mine was calculated using the oblique strip method and verified by numerical simulation. On this basis, the potential failure mode of the dumping ground base was analyzed, and the ultimate bearing capacity of the dumping ground under current conditions was calculated. The results are as follows: (1) The ultimate bearing capacity of the current dumping ground base is 3781 kPa, and the failure mode of the base is overall shear sliding along the base of the dumping ground. (2) When the slope foot increases from 12° to 18°, the stability coefficient and critical bearing capacity coefficient of the slope base decrease by about 21% and 46%, respectively. The slope angle has a greater impact on the bearing capacity of the base, and the height of the slope body has a relatively small impact, with almost no width effect. (3) Compared with the classic Terzaghi method and Prandtl method, the ultimate bearing capacity of the dumping ground base determined using the oblique strip method proposed in this paper is closer to the numerical simulation results, with an error of no more than 5%, a consistent critical sliding surface, and results that are relatively consistent with the engineering practice monitoring of the surface uplift part. The calculation results of the bearing capacity of the weak basement of open cast mine dumping grounds using the oblique strip method are reliable.