Experimental study of failure forms and uniaxial compressive strength for slate under low temperature

To reveal the effect of low temperature frost on compressive strength and failure forms of slate, uniaxial compression tests under seven kinds of bedding angle β and 6 kinds of temperature t were tested by low temperature numerical control incubator DX-40 and computer-controlled electronic versatile testing machine DNS100. Stress-strain curves, uniaxial compressive strength, peak strain and failure forms varying with bedding angle and frost temperature were analyzed. Based on JAEGER's single discontinuity theory, empirical formula of uniaxial compressive strength taking bedding angle and frost temperature as control variables was established and the expressions of two limit angle of β1 and β2 that affect on failure forms of slate were given. The analysis method was verified by experimental results. The results show that the uniaxial compressive strength of slate increase exponentially with the decrease of temperature due to the effects of freezing. The uniaxial compressive strength of slate first decreases and then increases with the increase of the bedding angle. There are three kinds of failure forms under uniaxial compression, i.e., when the bedding angle β is 0°≤β<27.0°, shear failure happens along the direction which has a certain angle with vertical axis; when 27.0°≤β≤82.7°, shear failure happens along the bedding plane; when 82.7°<β≤90.0°, splitting failure happens along the vertical direction. © 2017, Central South University Press. All right reserved.