Theoretical and numerical study on the block-flexure toppling failure of rock slopes.

• Two theoretical models for block-flexure toppling failure were proposed. • Detailed damage information of the joints during block-flexure was studied. • Effects of cross joint spacing on block-flexure were discussed. Block-flexure toppling failure is frequently encountered in rock slopes. In this paper, we first proposed two theoretical models to calculate the factor of safety against block-flexure toppling, namely, step by step analysis model (LEM-SSAM) and overall analysis model (LEM-OAM). Then, we developed two special MATLAB codes for a quick stability estimation based on the proposed methods, respectively. Next, the universal distinct element code (UDEC) was used to study the failure mechanisms of block-flexure toppling. In order to realistically simulate the excavation of slope and obtain the detailed damage information of joints, we developed two FISH functions in UDEC. Finally, we conducted a comparative analysis of the limit equilibrium method and the numerical simulations through twelve theoretical models. The results show that many aspects of block-flexure toppling failure have been captured using UDEC combined with the developed FISH functions. The LEM-OAM and UDEC agree well while a larger factor of safety is obtained using the LEM-SSAM. It is found that the dip angles and friction angles of the joints dipping steeply into face have a great influence on block-flexure toppling failure while the influence of the cross joint spacing is less significant. [ABSTRACT FROM AUTHOR]