Constitutive Relations of Coal and Coal Measure Rocks. Volume II. A Study of the Orthotropy of Coal and Other Rock Materials

摘要

The mechanical properties of coal are often represented by the orthotropic material model, which consists of nine elastic constants. The material symmetries involved are found in coal primarily because of the natural process by which the coal was formed. In this report, the material properties of five U.S. coals, as obtained from cubical testing, are examined using the assumption of the orthotropic material model as a basis for comparison. The material properties of two American shales are analyzed, based on the assumption that they comply with the transversely isotropic model. An analysis similar to that performed on the coal material is applied to the shale to determine the conformity of its material properties to the isotropic model.