Table 3: Physical and mechanical parameters of rock strata.

Lithologic unitElastic modulus, Er (GPa)Poisson’s ratio, νDensity (kg/m3)Friction angle, Φ (°)Cohesion, C (MPa)Compressive strength, σc (MPa)

Mudstone #14.60.122370395.415.7
Gritstone #110.00.252652457.438.1
Mudstone #24.60.262346384.719.1
Number 9 coal3.20.251498352.711.7
Mudstone #34.60.262346384.719.1
Medium-fine sandstone13.00.212641429.336.3
Gritstone #29.00.2924504613.436.6
Mudstone #44.60.262332354.717.4
Number 11 coal3.20.251498362.711.7