Experimental Investigation of Water–Sand Mixed Fluid Initiation and Migration in Porous Skeleton during Water and Sand Inrush

Table 4

The porosity and porosity change rate data.

Time (s)	Porosity (%)					Porosity change rate (min^-1)
	0.095 MPa	0.17 MPa	0.23 MPa	0.25 MPa	0.377 MPa	0.095 MPa	0.17 MPa	0.23 MPa	0.25 MPa	0.377 MPa
0	30.94	30.94	30.94	30.94	30.94	0	0	0	0	0
3	32.1388	32.35723	33.01252	33.34017	35.19683	0.23976	0.28345	0.4145	0.48003	0.85137
6	34.84917	35.52447	36.28898	37.27191	39.56543	0.54207	0.63345	0.65529	0.78635	0.87372
9	37.74518	38.82093	39.47622	40.58838	42.73267	0.5792	0.65929	0.63745	0.66329	0.63345
12	40.00229	40.714	41.42209	42.99112	45.85072	0.45142	0.37861	0.38917	0.48055	0.62361
15	41.64052	42.33221	43.51718	45.61228	47.21049	0.32765	0.32364	0.41902	0.52423	0.27195
18	43.06032	43.95405	44.69271	46.83366	48.19343	0.28396	0.32437	0.2351	0.24428	0.19659
21	44.04325	44.91697	45.90991	47.81659	48.86873	0.19659	0.19259	0.24344	0.19659	0.13506
24	45.02619	46.33677	47.41308	48.56109	49.13885	0.19659	0.28396	0.30063	0.1489	0.05402
27	47.03208	47.86578	48.38018	48.75951	49.20638	0.40118	0.3058	0.19342	0.03968	0.01351
30	48.7395	48.84872	49.02034	49.17636	49.28558	0.34148	0.19659	0.12803	0.08337	0.01584