Discrete Element Simulation of Roadway Stability in an Efflorescent Oxidation Zone

Table 1

Coal seam roof and floor lithology and the characteristics of efflorescent-oxidised rock mass.

Classification	Lithology	Thickness (m)	Characteristics of efflorescent-oxidised rock mass	RQD (%)	Drill core photographs
Main roof	Gritstone	10.6	Faint yellow colour, weak lustre, fractured, loose structure	45.4–56.7
Immediate roof	Mudstone	1.48	Weak lustre, water-swelling clays, fractured, high level of efflorescent oxidation in clay	5.2–18.5
Number 9 coal	Coal	9	Soil lustre, sepia, water-swelling clay, high level of efflorescent oxidisation in clay	0
Immediate floor	Medium sandstone	2.3	Faint yellow colour, weak lustre, fractured, unconsolidated structure	45.4–56.7
Main floor	Mudstone	2.7	Sepia, soil lustre, fractured, unconsolidated structure	5.2–18.5