CAREER: A Framework for Integrated Computational and Physical Simulation of Dynamic Soil-Pile Interaction

Iowa State University, Ames IA

Investigators

Abstract

The goal of this Faculty Early Career Development (CAREER) Program award is to develop an integrated research and education program aimed at advancing fundamental knowledge on dynamic pile-soil interaction for pile groups. To this end, integrated full-scale physical and computational studies will be carried out in the quasi-elastodynamic and nonlinear ranges. Advancements in physical simulation methods developed for single piles in the PI's recent NEES Payload project will be extended to pile groups. Specifically, coupled vertical-horizontal-rocking tests with broadband excitation and random-vibration signal processing techniques will be used to efficiently characterize the dynamic response of soil pile-group interaction in the frequency domain. Concurrently, three-dimensional inhomogeneous disturbed-zone computational models developed for single piles in the PI's previous centrifuge studies will be extended to the more complex and practically significant, yet less well-understood, case of pile groups. The sensitivity of the theoretical pile response will be determined through parametric studies of the model parameters, including (1) modulus and damping profiles in the disturbed zones around the piles, (2) modulus and damping profiles in the far-field, (3) size and shape of the disturbed zone, and (4) pile-soil contact conditions. Upon characterizing their relative contributions to the overall elastodynamic response, these parameters will then be calibrated to the observed experimental responses in a system-identification optimization approach, to produce calibrated computational disturbed-zone models of the observed soil pile-group interaction. The research will be transformative in its use of unique multi-modal and random-vibration experimental testing techniques developed in previous centrifuge projects and a full-scale NEES project; the 3D modeling of dynamic soil-structure interaction (SSI) by advanced BEM and FEM programs with capabilities for multiple, multi-layered domains to capture both near-field and far-field soil response through the use of disturbed-zone continuum models; and by examining the link between the elastodynamically calibrated disturbed-zone models for small strains, and their performance as initial models in nonlinear time-domain analyses for large strains. In accord with the purpose of the CAREER program, this award will enable the PI to develop a research program that will build a firm foundation for a lifetime of leadership in integrating education and research. The CAREER research project will be unified with a comprehensive education, outreach and training (EOT) program aimed at strengthening the analytical and teaching skills of graduate and undergraduate students, while reaching out to K-12 students to introduce them to topics of geotechnical engineering. To maximize the impact of the EOT program, the activities will be planned in consultation with established university outreach and diversity programs with proven records of inspiring K-12 students towards STEM fields and increasing participation of underrepresented minorities in engineering. The EOT activities include development of teaching modules for dissemination via NSF's TeachEngineering web site, outreach lectures on geotechnical and earthquake engineering for an annual science festival and K-12 classrooms, NSF field days through which students will learn about the project and observe tests, and involvement of local middle school students in summer research. The project also includes a formal assessment plan to ensure the success of the EOT activities through collaboration with an evaluator from the ISU Research Institute for Studies in Education.