Multi-parameter monitoring for steel pipe structures using monolithic multicore fibre based on spatial-division-multiplex sensing

In recent years, great importance has been put upon the safety monitoring towards pipelines. In this paper, multi-core optical fibre and the spatial-division-multiplex sensing technique were developed and applied to monitor the working condition and health status of the steel pipes. In order to validate the feasibility of the proposed method, a scale model of the steel pipe as the test specimen was experimentally investigated, and the static and dynamic test were conducted respectively. 7-core fibre and the spatial-division-multiplex sensing techniques were employed to monitor the structural response including the deformation and vibration. With the help of the proposed multi-core fibre based recognition techniques, the ambient temperature can be accurately evaluated with the error of ±0.5 °C, and the structure vibration can be monitored with the maximum error of 3.8% compared with the results of accelerator and displacement meter. All results show that the 7-core fibre has excellent performance on detecting the structural strain and mode frequency. The accuracy and reliability of the experiment results prove that the multi-parameter hybrid measurement based on spatial multiplexing of multi-core optical fibres has wide application prospects in the structural health monitoring of underground pipelines as well as pipes in buildings and other infrastructures.