Abstract：Reliable test data constitutes the basis of studying rock strength and deformation features. In this paper，conventional triaxial compression(CTC) tests were performed systematically upon silty sandstone in order to study the size effect of rock samples by analyzing the influences of sample size on rock strength and deformation behaviors under different confining pressures. We consider first CTC tests on samples of the same diameter by varying the sample height. It is shown that given the confining pressure，as the height-diameter ratio increases，both the failure stress and the Poisson?s ratio decrease while the Young?s modulus increases. Particularly，when the height-diameter ratio is beyond the value of 2.2，the measured material strength，Young?s modulus and the Poisson?s ratio become stable. Further，an additional set of CTC tests with different confining pressures are carried out upon samples of 37 mm in diameter and with the height-diameter ratio of 2.0. We analyze the characteristics of rock strength and deformation and compare the results with those issued from the tests on the samples of 50 mm in diameter and with the height-diameter ratio of 2.0. It is concluded that in CTC tests the size effect on relatively uniform rocks like silty sandstone is mainly attributed to the influence of rock height-diameter ratio.
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2019, Vol. 38 
