Optimization of Pipeline Leakage Detection System in Utility Tunnel Based on Finite Element Method

In addressing the problems of delayed detection, inefficient identification, and coverage blind spots in optical fiber-based pipeline leakage detection within pipe galleries, this study proposes a leakage detection strategy utilizing distributed optical fiber temperature measurement technology. Finite element method is employed to analyze the temperature influence radius around the pipeline leakage hole and a model test is conducted as a validation. The results show that the temperature field image at the leakage site is elliptical, influenced by temperature differences between ambient and liquid. An increase in this temperature difference accelerates changes in the temperature field's range. Adjustments to the optical fiber's winding angle and pitch demonstrated that an optimal pitch is 1/24 of the pipeline's length, with a 45 degrees winding angle. This configuration maximizes the optical fiber's distribution in detection while maintaining its cost-effectiveness. When the leakage site is constant, and only the winding mode is altered, it is observed that when the ambient temperature exceeds the liquid temperature in the pipeline, the temperature of the escaping liquid impacts the temperature-measuring fiber due to gravity, registering approximately 2 degrees C higher than the temperature measured directly at the leakage site. The temperature anomaly from field diffusion is significantly less than that caused by the water flow from the leakage impacting the fiber due to gravity. Conversely, when the ambient temperature is lower than the pipeline's liquid temperature, the opposite occurs. These research findings offer a novel approach for distributed detection in water supply and drainage pipeline leakage.