Evaluation of Drilled Shaft Capacity Using Embedded Sensors and Statnamic Testing

• Published in: Journal of bridge engineering 2016-11, Vol.21 (11)
• Main Authors: Tran, Khiem T, McVay, Michael, Nguyen, Trung Dung, Wasman, Scott J
• Format: Article
• Language: English
• Subjects: Assessments; Dynamical systems; Loads (forces); Nonlinear dynamics; Nonlinearity; Piles; Segments; Skin friction; Technical Papers
• ISSN: 1084-0702; 1943-5592
• DOI: 10.1061/(ASCE)BE.1943-5592.0000944

AbstractThis paper presents an application of the embedded data collector (EDC) approach using strain and acceleration measurements at the top and bottom of a pile (drilled shaft) during dynamic loading (Statnamic) for estimation of static side and tip resistance. For assessment of the skin friction, wave propagation along the pile was modeled as a one-dimensional (1D) wave equation with nonlinear static skin friction and viscous damping. The soil–pile system was divided into segments, and each segment was characterized with independent multilinear skin friction. The skin friction of each segment was determined by least-squares fitting of computed particle velocities to the measured data at the top and bottom of the pile. For assessment of the tip resistance, the pile tip was modeled as a single—degree-of-freedom nonlinear system. A nonlinear stiffness–displacement relationship was determined by balancing force and energy from inertia, damping, and stiffness against the measured tip data. The technique was applied to a side- and tip-grouted drilled shaft 7.8 m in length with various cross sections (1.05-m diameter for top segment and 1.20-m diameter for bottom segment). The estimated static resistance was compared to results from top-down static compression loading and the segmental unloading point approach during Statnamic testing.