In Situ and Laboratory Mechanical Characterization Using High-Resolution Fiber Optic Distributed Sensing Assaf KLAR a,1 , Shun UCHIDA b , and Eyal LEVENBERG a a Technion – Israel Institute of Technology, Haifa, Israel. b Rensselaer Polytechnic Institute, Troy, United States. Abstract. This paper explores the potential use of high-resolution fiber optic distributed sensing technology for in situ moduli profiling and in laboratory element testing. In recent times, strain measurement using fiber optics has been employed in innovative civil engineering applications such as in the health monitoring of ageing infrastructures. Through recent developments, in particular Rayleigh backscatter optical frequency domain reflectometry technique, the fiber optic sensing technology is nowadays capable of providing continuous distributed strain measurement with a higher spatial resolution of the order of millimeters. As a result, the technology can potentially serve as a viable alternative to conventional strain gauges (i.e. high-spatial resolution yet localized measurement devices) or seismic geophysical measurement (i.e. distributed yet low-spatial resolution). This paper provides two examples of its applicability to both in situ and laboratory mechanical characterization. Keywords. Fiber optics sensing, Mechanical characterization, Load tests, Small strain modulus, Stiffness profile, Strain Measurements, Element testing. 1. Introduction Distributed fiber optic sensing has received a considerable focus over the last decade from both the fiber optic and civil engineering communities, resulting in substantial advances in both fundamental developments and field integration and interpretation. These include structural health monitoring [1,2], pipeline integrity evaluation [3,4,5], and tunneling and tunneling induced ground displacement evaluation [6,7,8]. Recent fiber optic developments have increased significantly the spatial resolution of distributed sensing, resulting in sub-centimeter strain measurements capabilities [9,10]. This paper explores the potential of distributed sensing for both in situ and laboratory characterization of soils. In specific, the paper covers recent trials to evaluate the in situ stiffness profile using vertically installed fiber optic cable, together with surface loading, and the full-field view of strain profile in laboratory uniaxial tests. The demonstrated cases in the paper utilized the Rayleigh backscatter optical frequency domain reflectometry technique. 1 Corresponding Author. Email: klar@technion.ac.il. Deformation Characteristics of Geomaterials V.A. Rinaldi et al. (Eds.) IOS Press, 2015 © 2015 The authors and IOS Press. All rights reserved. doi:10.3233/978-1-61499-601-9-382 382