Profile deformation of a circular tunnel induced by ambient stress changes

Since profiles of a tunnel can be most easily and precisely measured using the current approaches such as the profile-image method, the measurement of profiles has become the standard process for evaluating the safety of a tunnel. The deformation of a profile yields important information on changes in the ambient stress of a tunnel. This study presents a method for distinguishing the two-dimensional, deformational displacement from the translational and rotational displacement. Based on this method, the net deformational displacements of a profile under various loading conditions are obtained. The studied loading conditions include ambient uniaxial and biaxial loadings, loading near the lining, inclined loading and sliding along a weak plan. The deformation patterns correspond to various loading conditions can be easily distinguished, that changes in ambient stress can be identified from the measured profile deformation. More sophisticated situations, elasto-plastic material, initial deformation, and profiles other than circular profiles are also examined to investigate the effectiveness of further extensions or application of the proposed method.