Zonal Synergistic Control of Surrounding Rock in Deep Soft-Rock Roadways Based on Strong–Weak Bearing Structures

<title>Abstract</title> <p>Large deformation and progressive failure in deep soft-rock roadways remain difficult to control because conventional support design does not fully account for the residual self-bearing capacity of damaged surrounding rock. A layered mechanical model was developed using complex-variable theory, conformal mapping, and elastoplastic mechanics. Analytical solutions were derived for stress, strain, displacement, zonal radii, and bearing-layer thicknesses. Based on strength degradation, stress redistribution, and self-bearing capacity, the surrounding rock was divided into an inner weak bearing layer, an intermediate stable bearing layer, and an outer strong bearing layer. MATLAB analyses quantified the effects of residual strength, in-situ stress, and support resistance, while FLAC3D simulations characterized stress redistribution, roadway deformation, and plastic-zone evolution. Increasing residual strength reduced the thicknesses of all three layers, whereas increasing in-situ stress expanded the disturbed and load-bearing ranges. Higher support resistance enhanced radial confinement and narrowed the near-wall weakened region. Under the proposed support scheme, simulated roof subsidence, floor heave, and sidewall convergence were 59.19, 46.48, and 31.70 mm, corresponding to reductions of 30.37%, 30.92%, and 48.60%, respectively; the plastic-zone extent was approximately 1 m. After 60 days of field monitoring, the corresponding deformations were 48.10, 42.55, and 36.97 mm, representing reductions of 92.46%, 92.52%, and 90.23% relative to unsupported conditions. The results demonstrate that zonal synergistic support can mobilize the residual self-bearing capacity of surrounding rock and improve the stability of deep soft-rock roadways.</p>