Distributed fiber optic shape sensing along shotcrete tunnel linings: Methodology, field applications, and monitoring results

Abstract Deformation monitoring and structural reliability assessment are key components in modern conventional tunneling. The state-of-the-art design is usually based on displacement measurements of geodetic targets using total stations paired with pointwise geotechnical sensors inside the tunnel lining. In recent years, distributed fiber optic sensing (DFOS) has become more popular tunneling applications. DFOS basically deliver internal strain temperature distributions, but no direct relation to shape’s behavior. This paper introduces a novel evaluation concept, which combines readings for shape along curved structures, such as cross-sections. designed system was implemented into shotcrete cross-sections well shaft linings enables determination profiles high spatial resolution range centimeters. Evaluations continuous campaigns over several weeks epoch-wise performed by different units combination stochastic analysis demonstrate potential developed approach its capability extend traditional methods