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

这个教师早期职业发展（CAREER）计划奖的目标是开发一个综合的研究和教育计划，旨在推进桩群动态桩土相互作用的基础知识。为此，将在准弹性动力学和非线性范围内进行综合全面的物理和计算研究。PI最近的NEES有效载荷项目中为单桩开发的物理模拟方法的进步将扩展到桩群。具体而言，耦合垂直水平摇摆试验与宽带激励和随机振动信号处理技术将被用来有效地表征土桩群相互作用在频域中的动态响应。同时，三维非均匀扰动区计算模型开发的单桩在PI以前的离心研究将扩展到更复杂的和实际意义，但不太好理解，桩群的情况下。将通过模型参数的参数研究确定理论桩响应的灵敏度，包括（1）桩周围扰动区的模量和阻尼分布，（2）远场的模量和阻尼分布，（3）扰动区的大小和形状，以及（4）桩土接触条件。在表征它们对整体弹性动力响应的相对贡献后，这些参数将被校准到系统识别优化方法中观察到的实验响应，以产生观察到的土桩群相互作用的校准计算扰动区模型。该研究将在其使用独特的多模态和随机振动实验测试技术在以前的离心机项目和一个全面的NEES项目开发的变革;三维建模的动态土-结构相互作用（SSI）通过先进的边界元法和有限元程序，具有多个，多层域捕捉近场和远场土壤响应通过使用扰动区连续模型的能力;并通过检查小应变的弹性动力学校准的扰动区模型之间的联系，和它们作为大应变的非线性时域分析中的初始模型的性能。在与职业计划的目的雅阁，这个奖项将使PI开发一个研究计划，将建立一个坚实的基础，在整合教育和研究的领导终身。职业生涯研究项目将与旨在加强研究生和本科生的分析和教学技能的综合教育，推广和培训（EOT）计划相结合，同时向K-12学生介绍岩土工程主题。为了最大限度地发挥EOT计划的影响，这些活动将与既定的大学外展和多样性计划进行协商，这些计划具有激励K-12学生走向STEM领域和增加代表性不足的少数民族参与工程的良好记录。EOT的活动包括开发教学模块，通过NSF的TeachEngineering网站进行传播，为年度科学节和K-12教室举办关于岩土工程和地震工程的外联讲座，NSF实地考察日，学生将通过该项目了解并观察测试，以及当地中学生参与夏季研究。该项目还包括一项正式的评估计划，通过与执行支助大学教育研究所的一名评估员合作，确保EOT活动取得成功。

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.