Research on distributed displacement monitoring and strain inversion assessment methods for buried pipelines in fracture zones

Abstract

Underground pipelines may experience localized large deformations, which can severely impact their operational lifespan under the influence of fault displacement. Traditional pipeline monitoring techniques are constrained by their measurement range, making monitoring large deformations and assessing buried pipelines’ conditions difficult. This study proposes a distributed displacement monitoring and strain inversion assessment method for buried pipelines to address this issue. First, this study proposes a large deformation shape sensing method, simplified inverse absolute nodal coordinate formulation (iANCFs); Based on the idea of the small strain of the sensor to monitor the large deformation of the structure, a distributed deformation monitoring sensor for buried pipelines is developed by combining fiber optic sensing technology. Ultimately, a model test of a buried pipeline under the action of a fracture zone was designed to obtain the real deformation of the pipeline, and a method of pipeline strain inversion assessment based on monitoring data is proposed, which found that the pipeline entered the elastic–plastic deformation stage at the 8th loading stage. After the final loading stage, the inverse strain extremum of the pipeline reached approximately 8500 με. The method proposed in this study facilitates precise localization of underground pipelines while also enabling the inversion of pipeline strain, thereby assisting in assessing pipeline conditions. This study provides a new solution for analyzing the response of pipelines under the action of fracture zones.