Distributed fiber optic sensing of lateral deformation for anti-slide piles

Anti-slide piles are key structures for stabilizing deep-seated landslides in slope engineering, and the accurate monitoring of their lateral deformation is crucial for engineering safety assessment. Traditional inclinometer methods have limitations such as low efficiency, high cost, and difficulty in achieving distributed measurement. This paper proposes a method for monitoring the lateral deformation of anti-slide piles using Brillouin Optical Time Domain Reflectometry (BOTDR) distributed optical fiber sensing technology. By establishing a cantilever beam model, a numerical calculation formula based on double integration for inverting pile displacement from distributed strain is derived. Furthermore, based on error propagation theory, the error function of the displacement calculation and its influencing factors are systematically analyzed. Combined with a case study of landslide treatment project in the Three Gorges Reservoir area, the fiber optic monitoring results are compared with traditional inclinometer data. The displacement magnitudes and variation trends show a high degree of consistency, with a maximum deviation of approximately ±0.6cm, verifying the reliability and engineering applicability of the proposed method. This research confirms the unique advantages of BOTDR technology for distributed, long-term deformation monitoring of anti-slide piles, providing a theoretical basis and practical reference for its wider application in geotechnical engineering safety monitoring.