Comparative study on the deformation moduli of roadway surrounding rock in coal mines: a case study

Since deformation modulus of rock mass is an important parameter for analyzing the mechanical properties of roadway surrounding rock in coal mines, accurate acquisition of the deformation modulus of roadway surrounding rock is essential for mining design, roadway support, and disaster prevention. To achieve this aim, the roadway surrounding rock in Chahasu Coal Mine was taken as the research case. First, uniaxial compression experiments and true triaxial compression experiments were carried out on coal and rock samples. The laboratory deformation modulus of rock mass was determined by stress–strain curves, and the in situ deformation modulus of rock mass in coring boreholes was obtained with the aid of the GY-75 borehole jack. Meanwhile, based on the results of rock mass quality evaluation, the estimated values of deformation moduli of roadway surrounding rock were obtained through an empirical equation. As displayed through the comparative study on the relations between deformation moduli obtained by different methods, with the increase of rock mass depth, in situ deformation modulus increases gradually with reduced growth amplitudes, and its spatial distribution characteristics can be expressed by an exponential function. For roadway surrounding rocks at the same depth, the relation between in situ deformation modulus and deformation moduli obtained from the uniaxial compression experiment and the true triaxial compression experiment can be given by an exponential function and a linear function, respectively. The empirical equation based on the single index RMR shows strong applicability in estimating the deformation modulus of roadway surrounding rock.