The UC Berkeley team participated in a full-scale field test of grout piles using Distributed Fiber Optic Sensing (DFOS) to measure strain and temperature development throughout the project. The project involved the construction and load testing of 5 drilled grout columns for a Caltrans embankment construction project in Indianola, CA. The types of monitoring performed by the UC Berkeley team included Distributed Strain and Temperature Sensing (DSTS) of temperature development during curing and for strain monitoring during load testing. An Optical Frequency Domain Reflectometry (OFDR) is used for collecting extremely fine strain and temperature profiles, which has a spatial resolution of 2.6 mm with 10 Hz measuring frequency per channel. The fine temperature profiles measured during the grout curing process reveal potential groundwater flows at multiple depths. The strain profiles measured during the load test show the zones where the shaft friction was mainly mobilized. Research goals of the deployment include characterizing the cause for measured strain fluctuations with depth along the pile as well as developing a simplified data analysis framework for DFOS data for conventional pile design methods.
Set-up of fiber optic sensors for the full-scale field test of grout piles