Scale effect on equivalent continuum elastic modulus of columnar jointed rock masses by distinct element method

Scale effects play an important role in evaluating mechanical properties of jointed/fractured rock masses. These phenomena were studied through use of the distinct element method. The Voronoi diagram was introduced to simulate stochastic joints, and the coefficient of variation (CV) was used to estimate the resolution of a certain property from numerical tests. A large number of numerical tests with different geometric sizes were carried out. Then, the scale effects of equivalent continuum elastic modulus, Eeq and equivalent continuum elastic compliance, 1/Eeq were statistically analyzed. The investigation shows that: the estimated deformation REV size is about 4 times of average side length of a Voronoi polygon with acceptable variations for CV of 5%; the mean value of specimen's Eeq obviously decreases as size increases, and the mean value of specimen's 1/Eeq increases slightly with increasing size. In discussing the applicability of the results, it is better to adopt the reciprocal of a mean specimen's 1/Eeq as the lower bound of Eeq, while the mean specimen's Eeq should be used as the effective Eeq in engineering. This method was finally applied to analysis deformation data from in situ tests of Baihetan Hydropower Station. ©, 2015, Tsinghua University. All right reserved.