Abstract:During the long-term operation of urban tunnel, due to the defects of tunnel construction or its inadequate maintenance, it is easy to cause the tunnel structure deformation, disease and other problems, which will bring out the hidden dangers to tunnel structure. Therefore, it is necessary to clarify the safety state of tunnel structure so as to take the control measures of structural safety and to ensure the operation safety of urban tunnel. As an important part of urban expressway, the importance of urban underpass is self-evident. Based on the underpasses of Runyang North Road and Taizhou Road in Yangzhou, the structural deformation monitoring and disease investigation of tunnel are carried out. The tunnel structural safety status is assessed and the corresponding maintenance measures are put forward. It is hoped to provide a certain reference for the structural safety monitoring and evaluation of similar urban underpasses.