Soil strain-field and stability analysis of cut slope based on optical fiber measurement

A relatively small laboratory model of soil slope was constructed, and a special strain-sensing cable was embedded in the slope soil mass. The strain at different positions of the model slope was measured using pulse-prepump Brillouin optical time-domain analysis (PPP-BOTDA) technology during slope surface loading and slope cutting. The data measurements under loading were analyzed, and the co-deformation between the sensing cable and the artificial compacted soil mass is discussed. The results show that the specially designed strain sensing cable is co-deformed well with the soil after a loading of 225 kPa. The measurement data of the cut slope were analyzed in detail to elaborate the relationship between soil strain-field and slope stability. When the slope failed, the position of the sliding surface was coordinated with the strain anomaly area of the soil strain-field. A limit equilibrium analysis was then conducted to determine safety factors during slope cutting. This analysis allowed determination of the characteristic strains, reflecting the stability of the slope, which permitted the establishment of an empirical relationship between horizontal characteristic maximum strains and safety factors. The results were most effective in validating the use of the distributed optical fiber sensing technology for soil strain-field monitoring, for the purposes of evaluating slope stability and creating a warning system for landslides.