(1. Institute of Solid Mechanics，Ningxia University，Yinchuan，Ningxia 750021，China；
2. School of Physics and Electrical Information，Ningxia University，Yinchuan，Ningxia 750021，China)
Abstract：A tensorial measure，called the crack fabric，defines the geometric distribution of cracks in rock. Based on the theoretical framework for fabric description with the principle of stereology，a quantitative method describing the crack fabric in rock was proposed. The crack tensor was redefined with the normalized quantities. The trace of the redefined tensor is a constant，which brings a great convenience for determining the crack fabric. The plane crack tensor of rock was defined with the test line. The amplitude parameters and the component angle defined with the second invariant and third invariant of the plane crack tensor respectively，which described the degree and the direction of crack anisotropy. The plane distribution of cracks was described with two defined scalar quantity. The three-dimensional orthotropic crack tensors were deduced uniquely with any two amplitude parameters of three orthogonal planes. With the geometry changes of the crack distribution，the orthotropic fabric tensor degenerated naturally into the form of transversely isotropic and isotropic. Verification of coal CT test results showed that the tensor described better the plane distribution of cracks.
2015, Vol. 34 
