Advances in fibre optic based geotechnical monitoring systems for underground excavations

TLDR

Geotechnical stability is critical for underground infrastructures, and effective monitoring systems can warn personnel before major failures. The paper reviews conventional geotechnical monitoring sensors and emerging fibre optic sensing techniques, highlighting their unique features and differences. The review examines recent advances in fibre optic sensing systems—including Brillouin time‑domain distributed sensors and fibre Bragg gratings—focusing on laboratory and field studies, fibre packaging, temperature compensation, installation methods, and performance in underground settings. The paper discusses the advantages and limitations of each fibre optic sensing system.

Abstract

Geotechnical stability is a major concern for the long-term safety and integrity of underground infrastructures such as tunnels, railway stations, mine shafts and hydraulic power chambers. An effective geotechnical monitoring system is able to provide adequate warning to underground personnel prior to any unexpected major geotechnical failure. This paper reviews the conventional geotechnical monitoring sensors and the emerging Fibre Optic Sensing (FOS) techniques, pointing out their unique features and major differences. Recent advances in various FOS based monitoring systems, including Brillouin time domain distributed optical sensors and fibre Bragg grating (FBG) sensors, are investigated through a critical review of the laboratory studies and field applications used for underground geotechnical monitoring. Particular emphasis is given to fibre packaging, temperature compensation, installation methods and instrumentation performance in the underground environment. A detailed discussion of the advantages and limitations of each FOS monitoring system is also presented in this paper.