(1. State Key Laboratory of Coal Mine Disaster Dynamics and Control,Chongqing University,Chongqing 400044,China;
2. Faculty of Architecture Engineering,Chongqing University of Arts and Sciences,Chongqing 402160,China)
Abstract:The loading rate dependence of class I and class II rocks was investigated with the stress-feedback method. This method was executed on the servo-controlled testing machine with varied-resistance technology. The complete stress-strain curves were obtained with the stress-feedback method,and the testing machine was very stable at the post-failure region. The tests under the constant loading-rate,alternate loading-rate and loading-unloading- reloading were carried out with the stress-feedback method for class I rocks (Tage tuff,Ogino tuff) and class II rocks (Emochi andesite,Jingkou sandstone) and the elastic and inelastic strains were successfully separated from the loading-unloading-reloading test. The relationship between the inelastic strain and stress was obtained. Experimental results indicate the notable loading rate dependency of strength,failure strain,Young?s modulus and failure life span. Three methods were proposed to calculate the constant n of loading rate dependence at the pre-failure region.
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