Three-dimensional stability calculation method and application of intermediate bridge supporting consequent bedding slope in open-pit mine

Abstract

Solving the dynamic synergistic design challenge of slope and intermediate bridge during parallel stripping of multi-pits is crucial to realizing both safe production and economic benefits of mines. Based on the analysis of the failure mode of the intermediate bridge supporting consequent bedding slope, constructed a 3D mechanical model of the intermediate bridge, and analyzed the 3D supporting effect quantitatively. Combined with Mohr-Coulomb shear strength theory, a 2D equivalent method considering the 3D supporting effect of intermediate bridge under different failure modes is proposed, and a 3D stability calculation method of slope under this effect is established. In addition, the main influencing factors of the intermediate bridge supporting effect are analyzed. The 3D stability coefficient regression model is constructed by using the response surface method, and the validity of the model for solving practical engineering problems is verified by engineering application. The results show that when considering the combined sliding failure mode, the design bottom width d should be given priority in the establishment of supporting structures such as dump bridges, for the intermediate bridge demolition design project, the design bridge length should be given priority b. The interaction between the bottom width d and the bridge height h has a significant effect on the 3D stability of the slope; For the shear dilatancy failure mode, the supporting and demolition engineering should give priority to the design of bridge height h and bottom width d respectively. The interaction between bridge height h and bridge length b has the most significant effect on the 3D stability of the slope. The error rate between the 3D stability calculation results and the predicted value of the regression model is 1.9–3.3%, and the regression model can fully meet the actual needs of the project. This study lays a theoretical and application foundation for the dynamic collaborative design, stability control and engineering implementation of slope and intermediate bridge in multi-pit parallel stripping open-pit coal mine.