Experimental research on the mechanical properties of gypsum breccia with different water content

Abstract

This paper deals with the influence of water content on the mechanical properties of gypsum breccia with different initial water contents. The experimental research was taken on the GDS (geotechnical digital systems) tri-axial experiment system by strain rate control. The mechanical properties, including stress-strain curves, peak deviator stress, relative residual strength, elastic modulus, Poisson’s ratio, angle of internal friction and cohesion of gypsum breccia, were studied by experiment. The results showed that the water content has obvious influence on the mechanical properties of gypsum breccia. With increasing of water content, the angle of internal friction and cohesion of gypsum breccia decrease linearly. Meanwhile, the stress-strain curves go through from the declining, hump curve to the strain hardening curve. At the same confining pressure, the peak deviator stress and elastic modulus decrease exponentially, while Poisson’s ratio increases linearly with the increasing of the water content. At the same water content, with increasing of the confining pressure, the peak deviator stress, elastic modulus and the peak deviator stress increase trend but Poisson’s ratio decreases at a lower water content. While at a high water contents, the Poisson’s ratio doesn’t change much. It shows that water content plays an important role in the process of changing from the brittleness to plastic for the mechanical properties of gypsum breccia.