A Laboratory Study on the Use of Optical Fibers for Early Detection of Pre-Failure Slope Movements in Shallow Granular Soil Deposits

Although landsliding is the macroscopic effect of slope failure, it is only the final stage of an often time-consuming process of soil deformation. In many cases, slope movement remains extremely slow and undetected for a long time; in other cases, failure is abrupt, preceded by small deformations and followed by rapid, destructive movements. This is the case of slope failure in granular soils of pyroclastic nature, which involve an extensive mountainous area surrounding Mt. Vesuvius in southern Italy. Given that the area around Vesuvius is highly urbanized and densely populated, the detection and interpretation of pre-failure slope deformations are of great importance for risk mitigation. To this aim, Brillouin optical time-domain analysis (BOTDA), a distributed fiber optic sensing technique, may represent an efficient new tool. This paper illustrated the results of laboratory experiments on small-scale slopes instrumented with optical fiber sensors, showing the main features of this technique for early detection of slope failure.