Mechanical Characteristics and Mesostructural Damage of Saturated Limestone under Different Load and Unload Paths

Table 7

Distributions of bound water and free water before and after loading and unloading.

Loading and unloading path		Pretest or posttest	Pore proportions for IA			Pore proportions for RIA			Pore proportions for DIA
			Bound water/%	Free water/%	Bound-water reduction/%	Bound water/%	Free water/%	Bound-water reduction/%	Bound water/%	Free water/%	Bound-water reduction/%
At σ0 = 2.5 MPa, as the loading rate increases	= 0.15	Pre	94.67	5.33	1.53	99.39	0.61	22.79	97.23	2.77	46.40
	mm/min	Post	93.14	6.86		76.60	23.40		50.83	49.17
	= 0.2	Pre	99.79	0.21	25.56	97.76	2.24	52.61	97.87	2.13	33.38
	mm/min	Post	74.23	25.77		45.15	54.85		64.49	35.51
	= 0.3	Pre	95.93	4.07	36.03	95.86	4.14	53.18	96.50	3.50	2.28
	mm/min	Post	59.90	40.10		42.68	57.32		94.22	5.78
At  = 0.2 mm/min, as the initial peak stress σ0 increases	σ0 = 2.5 MPa	Pre	99.79	0.21	25.56	97.76	2.24	52.61	97.87	2.13	33.38
		Post	74.23	25.77		45.15	54.85		64.49	35.51
	σ0 = 7.5 MPa	Pre	95.93	4.07	24.93	99.01	0.99	52.15	96.94	3.06	30.83
		Post	71.00	29.00		46.86	53.14		66.11	33.89
	σ0 = 12.5 MPa	Pre	98.14	1.86	0.84	97.48	2.52	51.79	96.83	3.17	18.54
		Post	97.30	2.70		45.69	54.31		78.29	21.71
Average reduction of bound water					17.78			46.50			26.49