The investigation of concrete structural performance is crucial to maintain the stability of infrastructure. In order to assess structural stability, this work focuses on the development of an integrated framework to detect damaged conditions in the field and analyze their effect on mechanical performance through nondestructive testing (NDT) technology and numerical models. First, a ground penetrating radar (GPR) and an infrared camera work collaboratively to identify the damaged positions of the concrete structure, with parameters calibrated by laboratory experiments. Then, a finite element model is established to study structural mechanical performance based on field conditions and detected results. In addition, the influenced regions induced by local damage are studied under different boundary conditions. As a case study, the devised method was employed in the Nanjing Yangtze River tunnel for stability assessment and disaster prevention. The detected results of the damaged conditions agree well with the actual conditions in the field. Numerical results show that the circumferential stress component is more significant than that observed longitudinally. The effect of local damage on stress implies a positive correlation with the rise of water pressure, in which the maximum stress response to the variation of water level is 45KPa per meter.@en

Temperature variation is an essential factor to influence the stability of concrete structure. In contrast to the uniform distribution of temperature in most existing approaches, this paper aims to study the natural temperature distribution in concrete structure and analyze its impact on structural mechanical behaviors in field. As a case study, an underwater shield tunnel is investigated using the presented method. Firstly, temperature sensors are installed in different positions to achieve real-time monitoring in field. Then, a statistical model is derived by monitoring data to describe temperature variation. As a core component of the approach, the devised statistical model is integrated into our program to determine the external loads imposed on model. Finally, the mechanical behaviors of concrete structure are discussed under uneven temperature distribution. Analytical results indicated the magnitudes of temperature distribution is related to different positions of structure, in which the significant distinctions can be observed at upper and lower of tunnel as well as the inside and outside structures. Also, the tensile stress of tunnel lining increases with the rise of temperature, for instance, in this case study per temperature rising would lead to an increment 25.3 KPa of tensile stress. As a promising application, the analytical results provide an assessment of concrete structure stability.@en