Engineering

Anthracite

Classification of discontinuities

Statistics

Geotechnical engineering

Petroleum engineering

Coal mining

Rock mass classification

Joint (building)

Discontinuity (linguistics)

Geology

Coal

Waste management

Mathematics

Mining engineering

Mathematical analysis

Geometry

Parametric statistics

Structural engineering

Modulus

International Journal of Rock Mechanics and Mining Sciences

This paper presents a new criterion for assessing top coal cavability in Longwall Top Coal Caving mining technology. Top coal Cavability Index (TCI) criterion was developed through a parametric study, statistical analysis and validation against field monitoring data. A discontinuum modelling technique with plastic rock material was used to quantify the impact of parameters on top coal cavability in a more realistic manner. The study demonstrated that an increase in the value of parameters such as immediate rock strength, coal strength, coal elastic modulus, coal vertical joint spacing, coal discontinuity friction angle and top coal thickness causes a decrease in top coal cavability, whereas an increase in the value of cover depth leads to an increase in the cavability. Coal elastic modulus was found to have a minor impact, while coal vertical joint spacing has the most significant impact on the cavability. The TCI criterion successfully incorporates the impacts of coal strength, rock strength and discontinuity friction angle into the evaluation of top coal cavability. The proposed criterion can thus be utilised to explicitly assess top coal cavability taking into account coal seam characteristics, surrounding rock mass properties and the nature of discontinuities, which contributes to improving reliability of the criterion.

A new cavability assessment for Longwall Top Coal Caving from discontinuum numerical analysis