Full-field monitoring of segmental joint flexural tests using digital image correlation: a continuous non-contact methodology

Abstract

With the continuous upscaling of tunnel cross-sections, the thickness of segmental linings shows progressive increasing. While increased thickness reduces overall structural failure risks, local joint damage remains a critical functional concern. However, conventional sensors struggle to capture detailed damage patterns due to their localized monitoring limitations. Digital Image Correlation (DIC) is a non-contact continuous monitoring technology and can easily realize the full-field monitoring. In this work, DIC is further developed to observe the joint deflection, joint rotational angle, crack width and damage distribution continuously. The proposed monitoring technology was applied in two flexural loading tests of segmental joints and validated by conventional sensors in the same set of test. The joint deflection and rotational angle measurements obtained from DIC agree well with those obtained from conventional displacement sensors under both positive and negative moment conditions. Additionally, the crack width measurement based on DIC offers a quantitative evaluation tool for monitoring the progression of joint damage. DIC measurements also revealed that the differences in joint design details could lead to distinct damage features under positive and negative bending moment conditions. Therefore, the utilization of DIC in joint loading tests overcomes certain limitations associated with conventional sensors and introduces new possibilities for research in this field.