A Mindlin-Based Improved Newmark Method for the Seismic Stability of Anchored Slopes with Group Anchor Effects

As the lifespan of many anchored slope reinforcements in China approaches its end, there is an increased need for secondary reinforcement. This study addresses the interaction between new and existing anchors, a critical but challenging aspect. The study introduces the Anchor Rod Modified Newmark Sliding Block Method (AMNB), which enhances the traditional Newmark Sliding Block Method (NSBM) by incorporating maximum anchor rod tension, dynamic tension changes, and group anchor effects. This improvement enhances the prediction of seismic displacement in slopes with multiple anchors. The AMNB method represents an innovation in slope stability analysis, as it is the first to integrate these dynamic and interactive factors into a unified framework. Validation through comparison with established seismic permanent displacement calculations and the analysis of three typical seismic motions show the AMNB’s effectiveness in capturing dynamic behaviors under seismic excitation. Additionally, numerical simulations using FLAC3D were conducted to validate the proposed method. The results indicate that considering group anchor effects and dynamic tension changes reduces the predicted seismic permanent displacement by up to 10% compared to traditional methods. The proposed AMNB method aligns more closely with the numerical simulation results. The findings indicate that group anchor effects negatively impact anchor forces, dynamic yield accelerations, and seismic displacements, leading to lower anchor tensions and dynamic yield accelerations. This, in turn, results in larger final slope permanent displacements under the same conditions.