Research on Arch Model and Numerical Simulation of Critical Water and Sand Inrush in Coal Mine near Unconsolidated Layers

Table 2

Simulation results of ratio of crack width to particle diameter when the interlocking arch of different internal friction coefficient of granular buckling.

Internal friction coefficient	0.1	0.3	0.58	1
Internal friction angle	5.7°	16.7°	30°	45°
Ratio of crack and sand	4.0	4.6	4.9	5.0