Abstract
A practical application for evaluation of rock deformability by means of the crack theory is discussed and presented. In the theoretical analysis presented in the 1st report, discontinuities of rock mass are assumed to be represented by circular cracks and to be classified into two types, i. e., theopen cracks and the closed cracks. The effective Young's modulus E of rock mass is expressed as eq.(4) and it is a function of four parameters which are the intrinsic Young's modulus E, the frictional coefficientμon the discontinuity surface, the crack densityΦand the state coefficient q of discontinuities. In this paper, the practical procedures to evaluate the four parameters are discussed and it is pointed out that E andμshould be determined from the laboratory test and the joint roughness investigation, and a combination of the scanline survey and the seismic exploration are available to evaluateΦand q .
For an application of the theory and the procedures to in-situ rock mass, the field investications have been carried out at two sites of Yanahara mine. The four parameters have been quantified and in-situ Young's moduli are determined theoretically. From the reasonable, agreements of the results with those of the back-analyses, it is concluded that the theory and the procedures proposed have a promise to estimate rock deformability quantitatively.
