A new testing method for investigating the loading rate dependency of peak and residual rock strength

抄録

One of the important methods for investigating time-dependency is to measure the loading-rate dependency of peak strength, however, no experimental method has been established for accurately measuring it from a small number of samples. In this study we propose such a method. A single sample is loaded at alternating strain rates to obtain stress-strain curves for both strain rates.The loading-rate dependency of peak strength obtained via this method was nearly identical to previous results obtained using conventional methods, including results obtained under confining pressure. We also investigated the loading-rate dependency of the stress-strain curve for the post-failure region for which few results have been published. Under confining pressure, the corrected stress-strain curve, obtained by multiplying the stress of the complete stress-strain curve obtained at the fast strain rate by a constant determined by the ratio between the fast strain rate and slow strain rate, is nearly coincident with the stress-strain curve for the slow strain rate. This is an interesting result and represents new knowledge that may help elucidate failure mechanisms in the post-failure region.