Numerical Study of Damage to Rock Surrounding an Underground Coal Roadway Excavation

Table 3

Comparison of the results of simulation and empirical calculation of the self-stabilized arch height and rib spalling depth.

Method	Simulation results	Empirical formula calculation results	Error (%)
Self-stabilized arch height of coal roadway roof (m)	2.78	[52]	0.36
		[52]	0.72
Rib spalling depth (m)	0.60	[53]	5.26

h₀ is the self-stabilized arch height of coal roadway roof; W is the coal roadway width, and the value is 5.4 m; P₀ is the vertical earth pressure, and the value is P₀ = 64.6 × 0.023 = 1.4858 MPa; σ_t is the tensile strength of rock mass, and the tensile strength of the rock masses was estimated to be one-tenth of the compressive strength, so the value is 0.92 MPa; λ is the lateral pressure coefficient, and the value is 0.15; f is the rock firmness coefficient, and the value is 1.46; L is the rib spalling depth; h_w is the coal roadway height, and the value is 2.6 m; Φ is the internal friction angle, and the value is 36°.