Mechanical Properties of Sandstones under Initial Unloading Damage

Table 2

Statistical table of the deformation modulus at the unloading stage.

Confining pressure (MPa)	Unloading capacity (%)	0.00%	40.00%	66.67%	73.33%	80.00%	86.67%	93.33%	100%
12.5	100.00	21.47	20.97	20.58	20.36	19.90	19.54	18.89	16.71
13.0	93.33	22.45	22.21	21.89	21.61	21.15	20.61	19.70	—
13.5	86.67	23.17	22.72	22.27	22.07	21.85	21.07	—	—
14.0	80.00	23.13	22.96	22.64	22.47	21.82	—	—	—
14.5	73.33	22.99	22.80	22.54	22.25	—	—	—	—
15.0	66.67	23.27	23.12	22.78	—	—	—	—	—
17.0	40.00	22.77	22.54	—	—	—	—	—	—