An innovative approach for recognizing deformation patterns of a built circular tunnel

This manuscript established an innovative approach for recognizing deformation patterns of a built tunnel, which benefits for diagnosing possible causes for lining anomalies. Demonstrating with a circular tunnel, the deformation of a tunnel lining is first assumed to be composition of specific deformation patterns. These patterns are numerically approved as linearly independent to each other with sufficient degrees of freedom, and are thus regarded as characteristic modes which can assemble all deformation situations by multiplying various constants. Several simple examples with load variation on boundaries are introduced to demonstrate the proposed method. Lining displacements in each example are decomposed as linear combination of characteristic modes. Diagrammatic illustrations indicate these deformation patterns posing different physical meaning including translation, rotation, and several types of deformation for tunnel lining.