Mechanical response of surrounding rock under various mining modes in continuous mining and continuous backfilling

Abstract Continuous mining and continuous backfilling effectively alleviates the conflict between resource extraction and environmental protection. However, under different mining modes, the surrounding rock undergoes progressive fracture failure during repeated loading–unloading cycles, while the associated energy evolution and deformation-settlement mechanisms have not yet been fully elucidated. Taking a representative continuous mining and continuous backfilling panel as the engineering background, this study adopts the stress deviator triggering rock mass fracture–failure as an evaluation index to investigate the mechanical behavior of different mining modes. Through a combined approach involving numerical simulation, theoretical derivation, and field application, the distortion energy evolution characteristics of surrounding rock, overburden deformation and settlement, and the working efficiency of each mining mode are systematically analyzed. The results indicate that, under all mining modes, the stress deviator progressively increases with the advancement of the mining cycle and gradually concentrates toward the unmined coal, reaching its peak in the single-coal pillar stage. Consequently, during later stages of continuous mining and continuous backfilling, the coal on both sides of the mining roadway are particularly susceptible to failure induced by stress deviator concentration. Among the different mining modes, the four-step mining mode demonstrated superior control over surrounding rock deformation and settlement, whereas the three-step mode exhibited greater dynamic stability. Although the two-step mode resulted in the largest and most severe settlements, it offered the highest construction efficiency.