Experimental Study on Physicomechanical Properties of Deep Sandstone by Coupling of Dry-Wet Cycles and Acidic Environment

Table 5

Mechanical parameters of sandstone specimens under various conditions.

Stage of A-D-W cycles	Before immersion			pH = 4			pH = 5			pH = 6			pH = 7
	σ (MPa)	E (GPa)	ε (‰)	σ (MPa)	E (GPa)	ε (‰)	σ (MPa)	E (GPa)	ε (‰)	σ (MPa)	E (GPa)	ε (‰)	σ (MPa)	E (GPa)	ε (‰)
Stage I	97.96	20.75	11.04	56.03	11.29	10.99	68.28	11.15	12.30	67.50	13.19	11.80	86.46	16.94	12.30
Stage II	—	—	—	34.83	7.16	13.90	40.26	6.54	12.10	48.30	13.11	10.61	66.91	13.33	10.09
Stage III	—	—	—	31.99	3.36	15.36	37.37	4.81	11.70	44.74	7.39	12.55	60.79	8.23	8.08
Stage IV	—	—	—	29.15	2.46	18.27	29.07	3.21	11.99	33.83	4.02	12.49	45.80	11.42	7.10