Strength of the jointed roof of an underground mine opening in stratified rock

CIM Bulletin, Vol. 86, No. 972, 1993

P. Mottahed, CANMET, Elliot Lake Laboratory, Elliot Lake, Ontario, E.K.S. Passaris and J.Q. Ran, Department of Civil Engineering, University of Newcastle upon Tyne, Newcastle upon Tyne, England

The jointed roof of underground mine openings in stratified rock can be analyzed in terms of a voussoir beam. Because of the essential indeterminacy of the structure, previous attempts of theoretically solving the equilibrium equation have been unsuccessful. Numerical analysis by the finite element method taking the geometrical and joint non-linearity into consideration combined with the experimental method has been adopted to study the performance of the voussoir beam. Deformation and failure mechanism is analyzed in relation to the failure modes. Equations are proposed to estimate the elastic buckling strength and the crushing strength of the voussoir beam and to verify the failure mode ofshear sliding. For application of the mechanism of the voussoir beam in mining operations, methods are described to predict the stability of a jointed roof and to design the dimensions of mining openings.