Geo-material erosion and its effects on concrete tunnel lining

Water seepage in tunnels often results in adverse effects both on the serviceability and stability of the tunnels. Inter alia, water tends to bring fines from the soil/rock matrix leaking into the tunnel, which will cause erosion in the surrounding geo-materials. Depending on the geological structure and geotechnical properties of the geo-materials surrounding the tunnel, the erosion may take the form of voids or suffosion which will weaken the stiffness of geo-materials around the tunnel lining. Consequently it will affect the stress distributions on the tunnel lining. In this paper, the geo-material erosion mechanisms were reviewed, and the stress redistributions affected by the erosion in the tunnel lining was analyzed. For this purpose, finite element modeling techniques was used for the analysis of additional stresses and bending moment on the lining as results of the erosion effects. The analytical results from finite element modeling showed that the water-leaking induced erosion will have significant effects on the stress distribution and bending movement in the tunnel lining and hence impact on the stability of the tunnel.