Loading‐Rate Dependence of Rocks in Postfailure Region under Triaxial Compression

Abstract

To study the loading-rate dependence of four types of rocks in the peak and postfailure regions, the alternative strain rate test method is employed in conducting triaxial compressive tests under different confining pressure and moisture conditions. An index of the loading-rate dependence in the postfailure region is proposed, and the effects of confining pressure and moisture condition on the index are analyzed. The reliability of the test results is verified by comparing the experimental and calculated results of stress relaxation. Following are the results. (1) The peak strength and postfailure behavior significantly depend on the loading rate. The indices (nc and nd) of the loading-rate dependence in the postfailure region obtained based on the elastic and unloading moduli show a good linear relationship. It is feasible to use nc to evaluate the loading-rate dependence of rocks in the postfailure region. (2) The loading-rate dependence of the rock strength increases with the increase in the confining pressure. The effect of confining pressure on the loading-rate dependence in the postfailure region is related to the moisture condition state. (3) Water-saturation treatment will increase the loading-rate dependence in the peak and postfailure regions, and the effect of water is greater than that of the confining pressure. (4) The experimental and calculated results of stress relaxation in the postfailure region are in good agreement, thus validating the experimental results.

Literature survey and application of a full-field 3D-DIC technique to determine the damage characteristic of rock under triaxial compression

“…Next all specimens were removed from the oven and put into a desiccator for 24 hours as “dried specimens”. The density of Ogino tuff is 1.81 g/cm 3 , the uniaxial compression strength is 27.35 MPa, the Young’s modulus is 4.02 MPa, and Poisson’s ratio is 0.31 (Tang et al., 2018).…”

Loading Rate Dependence of Rock Strength Under Triaxial Compression

“…The loading rate dependency of rock is one of the fundamental mechanical properties, which is essential in understanding the mechanism of earthquake and geological tectonic movements (Wasantha et al, 2015) and estimating the long-term stability of underground structures, e.g., mining roadway and underground storage (Mahanta et al, 2017;Tang et al, 2018;Wang et al, 2020). In the past few years, loading rate dependency of rock strength has been studied by many researchers, and Hashiba and Fukui (2015) provided a literature review regarding the loading rate dependence of rock strength.…”