Experimental and numerical study on the mechanical properties of the rock-concrete contact surface for consideration of ground-liner interaction in rock tunnelling

The mechanical properties of the rock-concrete contact surface are vital in the study of the ground-liner interaction for the tunnels embedded in rock mass. This paper mainly investigates the shear mechanical behaviour and failure mechanisms of the ground-tunnel interface with experimental and numerical approaches. Firstly, a Brazilian test was conducted to make a rough surface that represents the rock-concrete contact surface in the rock tunnelling. The split rough surface was then scanned with a 3 D scanning technique with which the digital terrain map (DTM) model of the split surface was acquired. In conjunction of the DTM model with a 3 D printing technique, synthetical samples that represent the rock-concrete contact surface were produced. These samples were put in shear test in which the shear behaviour and failure mechanism were investigated, and the shear strength criterion of the rock-concrete contact surface was presented. Ultimately, based on the discrete element method (DEM) code 3DEC, the numerical shear tests of the contact surface were performed. A sophisticated, nonlinear, continuously yielding (C-Y) model was adopted to describe the complex shear behaviour of the contact surface during the numerical shear test. The reasonable match of laboratory data with the numerical test results demonstrated the applicability of the DEM approach in reflecting the shear mechanical behaviour of the rock-concrete contact surface of liner.