Experimental Investigation on the Shear Properties of Heterogeneous Discontinuities

Abstract

The shear behaviour of rock discontinuities is a key factor affecting the stability of rock engineering. To study the effect of heterogeneity on the shear behavior of rock joints, laboratory tests were performed on heterogeneous rock joints with different joint roughness coefficient (JRC). As a comparison, two groups of tests were also conducted on the corresponding homogeneous rock joints. Test results showed that, the shear stress–displacement curves of low strength rock joints, heterogeneous rock joints and high strength rock joints with low roughness are all in line with the trend of the typical single peak value curve, while the curves of high strength rock joints with JRC greater than 12–14 accord with the trend of strain hardening curve. The shear displacement corresponding to the peak shear strength of heterogeneous rock joints is smaller than that of the homogeneous rock joints. The shear strengths of the three types rock joints all grow exponentially with the increase of roughness. The shear strength and its growth rate of heterogeneous rock joints were between those of two corresponding homogeneous rock joints. The surface damage of rock joints increases with the increase of JRC and the damage degree of high strength rock joints is more serious than that of low strength rock joints with the same JRC. The surface damage of heterogeneous rock joints presents obvious heterogeneous characteristics.