Effect of micro soil properties on the macro behavior of a tunnel

Abstract

Although ground is inherently heterogeneous, layered geological structure is generally accepted. Due to the differential weathering process, geological structure is sometimes unexpectable and contains high uncertainties in it. Such micro heterogeneous geological system greatly affects macro tunnel behavior during and after construction, as well as in the long-term temporal responses. The geotechnical properties commonly used in numerical modeling tend to be representative or average of global-scale properties even though geotechnical properties are spatially distributed. Furthermore, the uncertainty and spatial variation of the geotechnical properties increase as the tunnel scale increases. Consequently, the probability of failure also increases. This study investigates the micro soil properties on macro tunnel deformation behavior. The numerical results show that the deformation around the tunnel increases with an increase in the variation of the geotechnical properties. It is found that the spatial variability of soil can affect the convergence of tunnel and also it can cause the increase in tunnel support pressure. The shear failure mechanism of tunnel can be significantly affected by a spatial correlation length. In order to achieve structural stability of tunnels, the design framework must take into account the quantitative effect of variation of soil properties on tunnel behavior