Mechanical Properties of Sandstone Roof and Surrounding-Rock Control of Mining Roadways Subject to Reservoir Water Disturbance

Table 2

Characteristic parameter values during unloading seepage deformation.

Test number	Pore pressure (MPa)	Residual hoop strain	Residual axial strain	Loading stage, E (GPa)	Unloading stage (elastic), E (GPa)	Unloading stage (development), E (GPa)	Unloading stage (propagation), E (GPa)	Stress drop stage, E (GPa)
S-2	0.1	−0.0102	0.0078	7.76	6.86	6.67	5.68	2.59
S-3	0.2	−0.0106	0.0080	7.78	6.89	6.51	5.56	2.56
S-4	0.4	−0.0121	0.0085	8.07	6.90	6.14	4.53	2.12
S-5	0.6	−0.0160	0.0091	8.28	6.59	5.88	3.92	2.06