Shahrood University of Technology Journal of Mining and Environment 2251-8592 17 1 2026 01 01 Design of Cut-Out Distance for Underground Coal Gallery Using Time-Dependent Constitutive Model 127 141 3517 10.22044/jme.2025.16087.3101 EN Sonu Saran Department of Mining Engineering, IIT (BHU), Varanasi, India Prudhvi Raju Gadepaka Central Institute of Mining and Fuel Research (CIMFR), Nagpur, India Ashok Jaiswal Department of Mining Engineering, IIT (BHU), Varanasi, India Journal Article 2025 04 25 The stability of underground coal galleries is critically influenced by time-dependent deformation behavior of surrounding rock masses, particularly in deep mining environments where long-term stress redistribution can lead to delayed failure. In continuous miner-based mining systems, determining an appropriate cut-out distance is essential to ensure productivity and safety, especially for weak rock mass. This study proposes a novel numerical–statistical framework for the optimal design of cut-out distance (COD) in room-and-pillar coal mining using continuous miners. A time-dependent viscoelastic-viscoplastic constitutive model was implemented in FLAC3D to simulate roof deformation across varying geo-mining conditions, including gallery widths (5 & 6 m), depths (100 to 400 m), and COD values (4 to 12 m). The Coal Roof Index (CRI), a composite geotechnical classification parameter, was incorporated to evaluate roof integrity. Results from the numerical simulations were used to develop two empirical models, COD₁ for depths ≤ 200 m and COD₂ for depths > 200 m, via multivariate nonlinear regression. The models demonstrated high predictive accuracy, with R² values of 0.95 and 0.90, respectively. The results reveal a strong correlation between the cut-out distance and various influencing parameters, i.e., width, depth, and CRI classification. Statistical validation through t-tests and ANOVA confirms the significance and reliability of the proposed model. Both proposed models have been validated by two field cases of the Indian coal mine. Critical CRI thresholds were quantified for safe CODs, offering actionable insights for field implementation. The proposed design approach provides a robust framework for improving the safety and sustainability of underground coal mine development, particularly under weak roof conditions. https://jme.shahroodut.ac.ir/article_3517_4f12e46109bab20b4ed8e8c0e01c17ec.pdf