Assessment and optimization of self-drilling pile foundations using distributed fiber optic sensors

Self-drilling micropiles can provide economic advantages over traditionally pile systems in construction of deep foundations. Owing to the specific construction process of self-drilling micropiles, the realized pile diameter may vary of the pile circumference and depth. However, the continuous measurement of temperature and strain using distributed fiber optic sensors may reduce the uncertainties related to the varying geometry. In this research project, the potential of distributed fiber optic sensors for the assessment and optimization of self-drilling micropile foundations was investigated. For this purpose, self-drilling micropiles were equipped with fiber optic and conventional sensors immediately after the construction process using different sensor layouts. In a first phase, temperature variation along the pile origination from hydration process was tried to use for retrieving information on pile geometry similar to established thermal integrity profiling method. In a second phase strain variation along the pile during pile load tests was analyzed with respect to its usage for assessing load transfer from pile to soil as well as the occurrence of potential cracks.