石炭の一軸引張試験と構成方程式

Abstract

Only the very limited knowledge has been known concerning the mechanical properties of coal under uniaxial tensile stress which are very important factors in coalmines. In this study we carried out uniaxial tension tests on coal, with particular attention to find the most appropriate constitutive equation for the sample coal. Three constitutive equations were chosen and tested, among which two had been proposed by the authors and one was newly proposed in this study. Coal showed high sample-to-sample scatter in strength and Young's modulus, however, relatively small scatter in the normalized stress-strain curves in the pre-failure region. All three constitutive equations were found to represent the complete stress-strain curves in reasonable accuracy. This result presents a successful application of the authors' constitutive equations to the coal behavior under uniaxial tensile stress. Once these equations are determined, they can be incorporated into FEM software to investigate various time-dependent behaviors of coal and aid in the efficient design of coalmines and the prevention of coalmine disasters.