Experimental Validation of an Empirical Model for Computing the Diameter of Drilled Shafts during Construction Using CSL Signal Processing

Abstract

Drilled shaft foundations are increasingly being used to support various types of buildings and infrastructure facilities. The load carrying capacity of these drilled shafts is largely dependent on their diameter. The large loads carried by such structural elements make quality control and assurance of their diameters during construction extremely critical. Current methods adopted by the industry for measuring drilled shaft diameters during construction depend on discrete points of concrete volumetric measurements that lack both accuracy and continuity. An empirical model is developed and presented in this paper for computing the diameter of drilled shaft foundations that overcomes these limitations. The model is developed using signal processing performed on cross-hole sonic logging (CSL) experimental data obtained from three drilled shaft specimens. The model is validated using experimental data obtained from two separate specimens. The research reported in this paper demonstrates that there exists a high correlation between the maximum amplitude of CSL signal frequency and thickness of concrete. The results show that the model is capable of accurately computing the diameter of drilled shafts, with an absolute average error of 2.42%.