Effects of the Loading and Unloading Conditions on Crack Propagation in High Composite Slope of Deep Open-Pit Mine

Table 1

Properties of each geologic layer.

Stratum	Young’s modulus (GPa)	Poisson’s ratio	Mass density (kg/m^3)	Cohesion (MPa)	Angle of internal friction (°)
Topsoil	1.80 × 10^−2	0.3	1786	13.4	21.3
Sandstone	8.30	0.214	2245	28.6	25.6
Coal	0.65	0.36	1540	13.0	20
Limestone	6.11	0.224	2130	27.0	22.5