Research on Seepage Properties and Pore Structure of the Roof and Floor Strata in Confined Water-Rich Coal Seams: Taking the Xiaojihan Coal Mine as an Example

Table 1

Comparison of the water probing holes construction.

Drill	#1	#2	#3	#4	#5	#6	#7	Remarks
Orifice height (m)	914.148	914.637	913.270	901.937	897.344	907.657	907.486	—
Initial water elevation (m)	—	896.847	897.501	893.437	891.801	899.657	896.286	—
Water quantity increase position (m)	894.928	895.997	894.341	892.327	891.436	894.537	895.786	—
Roof of the coal seam (m)	891.048	892.437	891.941	891.107	891.119	892.261	894.966	—
Sudden increase in the water volume (m)	890.248	891.937	891.641	890.387	890.961	890.607	894.766	Enter the coal seam for 0.2∼1.65 m
Floor of the coal seam (m)	Not tested	891.537	Not tested	889.457	Not tested	889.877	894.486	—
Final hole height (m)	889.748	888.537	890.941	889.297	890.618	889.797	894.086	—
Water inflow (m^3/h)	>40	20	>93	29.4	>60	45	Flooded	Measured after drilling
Hydraulic pressure (MPa)	2.6	2.5	2.6	2.4	—	—	—	Measured after drilling