Experiment on Influence of End Friction on Size Effect of Sandstone

To investigate the influence of the end friction on the size effect of sandstone, a new test method was proposed to reduce the end friction. Uniaxial compression tests were carried out on sandstone samples with different height-diameter ratios. The results show that: the proposed test method in this paper has good inhibiting effect on the end friction. Due to the hoop constraint of end friction, the damage mode of samples experience the evolution from splitting failure to tension-shear hybrid failure and shear failure with the increase of the height-diameter ratio in the traditional uniaxial compression, while the failure patterns are always shear failure when the end friction has been eliminated. Under the influence of end friction, the experimental uniaxial compressive strength is greater than its true strength. The test strength comprises the true strength and the contribution value of end friction, and the contribution value decreases gradually with the increase of the height-diameter ratio.