Multi-objective inversion of mining-induced subsidence and rock mass mechanical parameters based on degradation zoning: a case study of Longwanggou coal mine

Inverting rock mass mechanical parameters from mining-induced subsidence is challenging due to the complex stratigraphy and numerous parameters involved. This study developed a collaborative inversion framework that integrates orthogonal experiments, numerical simulations, and response surface methodology, based on rock movement monitoring data, the mine geometry, and the concept of mining-induced degradation zoning. The method establishes response relationships and functions between key indicators (maximum subsidence \({W}ₘₐₓ\) , major influence range \(B\) , roof deformation \({h}c\) , floor deformation \({h}b\) , and goaf deformation \(Δ h\) ) and the mean values of rock mass parameters (elastic modulus \(E ̄\) , Poisson’s ratio \(ν ̄\) , cohesion \(c ̄\) , internal friction angle \(φ ̄\) , and tensile strength \({{σ }ₜ}\) ). Through multi-objective optimization, the mean values of parameters for mined ( \(E ̄, ν ̄, c ̄, φ ̄, {{σ }ₜ}\) ) and unmined zones ( \(E ̄^{}, ν ̄^{}, c ̄^{}, φ ̄^{}, {{σ }ₜ}^{}\) ) were inverted, thereby obtaining the zone mechanical parameters of rock masses with different lithologies. Compared with field measurement data, the deviations between the key response values ( \({W}ₘₐₓ\) , \(B\) ) obtained from numerical simulations based on response functions and inverted parameters, and the measured values were [0.00% and 0.00%] and [0.59% and 0.1%], respectively. This study presents a scientifically rigorous and effective optimization approach for determining rock mass parameters in coal mining, with major implications for water-preserved mining, and subsidence prediction.