Investigation of Soil Nonlinearity at Very Small Strains Using Ground Buried Fiber Optic Sensors

Abstract

Effects of small strain nonlinearity on deformation behaviour of geotechnical structures have been extensively studied in the literature. This paper offers a slightly different perspective, looking at effects of the small strain non-linearity on the identification of surface loads caused by pedestrians and vehicles. Due to the small load magnitudes caused by these objects, the corresponding strains in the ground are extremely small, making them difficult to detect using conventional strain measurements. An experimental field study as been carried out to investigate deformation behaviour of soil using ground buried distributed fibre optic sensors (FOS). FOS has been proven an adequate tool for measuring extremely small strains in soils and capturing accurately the small strain nonlinearity of soil behaviour. In contrast to conventional discrete strain measurements at the surface, FOS provides a large array of strain data at higher accuracy. The deformation of soils at very low stresses and strains has been shown to be highly nonlinear, affecting the surface load identification.