<p>This study presents an innovative application of force-energy equilibrium analysis to evaluate failure extension lengths (FEL) in excavation-induced translational landslides. Utilizing a combination of field data, mechanical balance analysis, and numerical simulations, we systematically investigate the effect of excavation on landslide dynamics. Our approach incorporates the existing energy balance framework and extends its application to excavation-induced translational landslides characterized by weak interlayer. The methodology focuses on capturing the intricate interplay between unloading forces, shear displacement, stress, and strain across various stages of landslide development. A case study of the Tongzilin landslide in Yanshan Township serves as a practical example, underpinning the validation of our theoretical model with real-world data. The proposed methodology provides a valuable reference for the prevention and management of excavation-induced translational landslides.</p>