Water Inrush from Pregrouting Fractures Induced by Mining Activities and Its Engineering Control Method Optimization

Table 1

Mechanical parameters of rock and floor rock masses.

Rock strata	Poisson’s ratio	Elastic modulus (GPa)	Internal friction angle (°)	Cohesive force (MPa)	Tensile strength (MPa)
Coal seam	0.25	4.0	21	1.3	1.3
Mudstone	0.25	10.0	31	8.5	1.4
Limestone	0.30	47.0	38	36	5.3
Sandy mudstone	0.27	30.0	35	8.2	2.1
Fine-grained sandstone	0.40	17.2	33	7.0	1.6
Medium-grained sandstone	0.26	28.5	35	8.5	1.7
Coarse-grained sandstone	0.24	23.0	36	6.5	1.5
Roof rock	0.24	26.0	33	8.2	1.4
Floor rock strata	0.30	50.0	39	3.6	5.3