Development of a Design Guideline for Pile Foundations Subjected to Liquefaction-Induced Lateral Spreading

Development of a Design Guideline for Pile Foundations Subjected to Liquefaction-Induced Lateral Spreading
Author:
Publisher:
Total Pages: 256
Release: 2021
Genre: Foundations
ISBN:

Extensive loss of stiffness and strength in liquefied soils can cause large ground deformations during strong earthquake shaking. One of the major sources of damage in pile foundations in liquefied soil is the excessive deformation due to lateral spreading. Pile-supported wharves subjected to earthquake motions are expected to accommodate inertial loads imposed at pile head from the superstructure as well as the kinematic loads imposed on piles from the lateral ground deformations. Current design codes significantly vary on how to combine inertia and kinematic demands. Recent research on soil-foundation-structure interaction suffers from lack of experiment-based data. There is a serious need to fill the knowledge gap and help designers to better evaluate risk and design cost-effective pile foundations. In this research, the interaction of inertial and kinematic demands is investigated using data from five well-instrumented centrifuge tests on pile-supported wharves. The observations from these tests were used to investigate the time- and depth-dependent nature of kinematic and inertial demands on the deep foundations during earthquake loading. The test results were analyzed to provide the relative contributions of peak inertial loads and peak soil displacements during critical cycles, and the data revealed the depth-dependency of these factors. The results were used to refine existing guidelines for design of pile-supported wharves subjected to foundation deformations. The observations from centrifuge tests were then used to evaluate the accuracy of the equivalent static analysis (ESA) procedure using p-y models for the design of pile-supported wharves subjected to lateral ground deformations during earthquake loading. The piles in these centrifuge tests were subjected to the combined effects of wharf deck inertial loads and ground deformations. The experiments included soil properties ranging from nonliquefiable to fully liquefied cases which provided a wide range of conditions against which the ESA method could be evaluated. Finally, a nonlinear dynamic model of a pile-supported wharf was created and calibrated using recorded data from a centrifuge test. The objective of the numerical modeling was to create a calibrated numerical model that captures key responses of the wharf and the soil in order to be used in subsequent studies that are too costly and time-consuming to do using physical modeling. The calibrated numerical model was then used in an incremental dynamic analysis to evaluate the effects of ground motion duration on the dynamic response of a pile-supported wharf subjected to liquefaction-induced lateral ground deformations. The analysis results provided insights on the relative contribution of inertial and kinematic demands on the response of the wharf with respect to motion duration.

Development of a Design Guideline for Bridge Pile Foundations Subjected to Liquefaction Induced Lateral Spreading

Development of a Design Guideline for Bridge Pile Foundations Subjected to Liquefaction Induced Lateral Spreading
Author:
Publisher:
Total Pages: 119
Release: 2017
Genre: Foundations
ISBN:

Effective-stress nonlinear dynamic analyses (NDA) were performed for piles in liquefiable sloped ground to assess how inertia and liquefaction-induced lateral spreading combine in long-duration vs. short-duration earthquakes. A parametric study was performed using input motions from subduction and crustal earthquakes covering a wide range of earthquake durations. The NDA results were used to evaluate the accuracy of the equivalent static analysis (ESA) recommended by Caltrans/ODOT for estimating pile demands. Finally, the NDA results were used to develop new ESA methods to combine inertial and lateral spreading loads for estimating elastic and inelastic pile demands.

Design of Pile Foundations in Liquefiable Soils

Design of Pile Foundations in Liquefiable Soils
Author: Gopal Madabhushi
Publisher: Imperial College Press
Total Pages: 232
Release: 2010
Genre: Science
ISBN: 1848163630

Pile foundations are the most common form of deep foundations that are used both onshore and offshore to transfer large superstructural loads into competent soil strata. This book provides many case histories of failure of pile foundations due to earthquake loading and soil liquefaction. Based on the observed case histories, the possible mechanisms of failure of the pile foundations are postulated. The book also deals with the additional loading attracted by piles in liquefiable soils due to lateral spreading of sloping ground. Recent research at Cambridge forms the backbone of this book with the design methodologies being developed directly based on quantified centrifuge test results and numerical analysis. The book provides designers and practicing civil engineers with a sound knowledge of pile behaviour in liquefiable soils and easy-to-use methods to design pile foundations in seismic regions. For graduate students and researchers, it brings together the latest research findings on pile foundations in a way that is relevant to geotechnical practice. Sample Chapter(s). Foreword (85 KB). Chapter 1: Performance of Pile Foundations (4,832 KB). Contents: Performance of Pile Foundations; Inertial and Kinematic Loading; Accounting for Axial Loading in Level Ground; Lateral Spreading of Sloping Ground; Axial Loading on Piles in Laterally Spreading Ground; Design Examples. Readership: Researchers, academics, designers and graduate students in earthquake engineering, civil engineering and ocean/coastal engineering.

Analysis and Design for Inelastic Structural Response of Extended Pile Shaft Foundations in Laterally Spreading Ground During Earthquakes

Analysis and Design for Inelastic Structural Response of Extended Pile Shaft Foundations in Laterally Spreading Ground During Earthquakes
Author: Arash Khosravifar
Publisher:
Total Pages:
Release: 2012
Genre:
ISBN: 9781267402622

Experiences from past earthquakes have shown that lateral spreading associated with liquefaction of cohesionless soils can be a cause of severe damage to bridge foundations. Large diameter extended pile shafts can be an effective bridge foundation choice for areas subjected to lateral spreading because they offer greater stiffness and strength relative to the magnitude of lateral spreading loads that can develop against them. A limited degree of plastic hinging below the ground surface may be allowable in design of extended pile shafts. Issues for design for extended pile shafts include: (a) how to estimate the demands due to superstructure inertia and lateral spreading in liquefied soils, and (b) how to combine these two loads in estimating the local and global inelastic demands on the structure. Studies of the response of pile foundations and pile-supported structures in liquefiable soils using physical models, numerical models, and case studies have provided the basis for a number of design recommendations. The guidance is, however, quite varied regarding how lateral spreading and superstructure inertial loads should be combined in design. To answer the above questions a series of Nonlinear Dynamic Finite Element Analyses (NDA) have been performed to investigate inelastic response of extended pile shafts subjected to liquefaction-induced lateral spreading, covering a range of soil, pile, and ground motion conditions. The results of NDA were first used to show that combined effects of lateral spreading and superstructure inertia produce larger demands than are produced by either loading case alone, such that the combined demand cannot be enveloped by analyzing the two load cases separately. The results were then used to evaluate current equivalent static analysis (ESA) method (Caltrans, 2008), with the relatively poor agreement illustrating the limitations of methods that do not combine the two loads. The results of NDA parametric study were then used to develop and calibrate an ESA procedure. The ESA procedure addresses both the nonliquefaction and liquefaction cases, and includes criteria that identify conditions which tend to produce excessive demands or collapse conditions. Finally, a series of three-dimensional (3D) Nonlinear Dynamic Finite Element Analyses (NDA) were performed to examine inelastic behavior of large diameter extended pile shafts subjected to earthquake shaking and liquefaction-induced lateral spreading. The purpose of these analyses was to evaluate the differences between 2D and 3D simulations, understand the source of any differences, and evaluate whether those differences would affect design recommendations for Equivalent Static Analysis (ESA).

Lateral-Spreading Effects on Pile Foundations

Lateral-Spreading Effects on Pile Foundations
Author: Ahmed Amr Ebeido
Publisher:
Total Pages: 485
Release: 2019
Genre:
ISBN:

Current techniques for assessing the effects of liquefaction-induced lateral spreading on pile foundations are based on simplified analytical methods that potentially lead to estimates that vary within a wide range. This might lead to potential excessive design demands, with high expenses for pre-event mitigation. Conversely, underestimated design demands might lead to costly post-event damage remediation. The conducted study is directed towards enhancements to the assessment of liquefaction induced lateral spreading effects on bridge foundation systems. Current simplified analysis techniques have been only been developed recently in preliminary form. In addition, quantitative data sets from large-scale experimentation are needed concerning the response of such ground-foundation scenarios. An effort was undertaken to address the simplified method areas of applicability and potential for enhancements. Challenges in implementing the methodology are presented within a comparative scope contrasting results of a California bridge site from different studies. On this basis, insights are derived for improvement of the currently employed simplified analysis guidelines. Furthermore, large scale shake table testing was performed on pile foundation-ground systems, under conditions of liquefaction-induced lateral spreading. A total of 7 different experiments were conducted with varying heights, ground inclination, soil profiles, pile material and cross-section. The tested models were densely instrumented, including strain gauges, total pressure and excess pore-pressure sensors, accelerometers and displacement pots. In addition, data from 4 different experiments conducted in the NIED Japan shake table facility, including single piles and pile groups and varying soil profiles were utilized to provide additional insights and characteristics. In these tests, the laminar soil container was placed in a mildly-inclined configuration to allow for accumulation of the liquefaction-induced lateral deformations. Detailed instrumentation and data interpretation procedures enable measurement of the fundamental soil-pile interaction behavior. The loading mechanisms have large cyclic components that may act in-phase or out-of-phase along the pile embedded length. The conducted heavily instrumented tests resulted in a wealth of quantitative response data sets, to be used for: i) drawing insights and recommendations of practical significance based directly on the observed response, ii) calibration of simplified and more elaborate computational analysis tools, and iii) enhancement of our design guidelines and practical assessment procedures. Monotonic pushover analysis based on newly derived p-y curves in this study is found to provide useful design estimates in good agreement with the observed experimental results.

Seismic Performance and Simulation of Pile Foundations in Liquefied and Laterally Spreading Ground

Seismic Performance and Simulation of Pile Foundations in Liquefied and Laterally Spreading Ground
Author: Ross W. Boulanger
Publisher:
Total Pages: 344
Release: 2006
Genre: Science
ISBN:

Proceedings of a workshop on Seismic Performance and Simulation of Pile Foundations in Liquefied and Laterally Spreading Ground, held in Davis, California, March 16-18, 2005. Sponsored by the Pacific Earthquake Engineering Research Center; University of California at Berkeley; Center for Urban Earthquake Engineering; Tokyo Institute of Technology; Geo-Institute of ASCE. This collection contains 25 papers that discuss physical measurements and observations from earthquake case histories, field tests in blast-liquefied ground, dynamic centrifuge model studies, and large-scale shaking table studies. Papers contain recent findings on fundamental soil-pile interaction mechanisms, numerical analysis methods, and reviews and evaluations of existing and emerging design methodologies. This proceeding provides comprehensive coverage of a major issue in earthquake engineering practice and hazard mitigation efforts.

State of the Art and Practice in the Assessment of Earthquake-Induced Soil Liquefaction and Its Consequences

State of the Art and Practice in the Assessment of Earthquake-Induced Soil Liquefaction and Its Consequences
Author: National Academies of Sciences, Engineering, and Medicine
Publisher:
Total Pages: 350
Release: 2019-01-30
Genre:
ISBN: 9780309440271

Earthquake-induced soil liquefaction (liquefaction) is a leading cause of earthquake damage worldwide. Liquefaction is often described in the literature as the phenomena of seismic generation of excess porewater pressures and consequent softening of granular soils. Many regions in the United States have been witness to liquefaction and its consequences, not just those in the west that people associate with earthquake hazards. Past damage and destruction caused by liquefaction underline the importance of accurate assessments of where liquefaction is likely and of what the consequences of liquefaction may be. Such assessments are needed to protect life and safety and to mitigate economic, environmental, and societal impacts of liquefaction in a cost-effective manner. Assessment methods exist, but methods to assess the potential for liquefaction triggering are more mature than are those to predict liquefaction consequences, and the earthquake engineering community wrestles with the differences among the various assessment methods for both liquefaction triggering and consequences. State of the Art and Practice in the Assessment of Earthquake-Induced Soil Liquefaction and Its Consequences evaluates these various methods, focusing on those developed within the past 20 years, and recommends strategies to minimize uncertainties in the short term and to develop improved methods to assess liquefaction and its consequences in the long term. This report represents a first attempt within the geotechnical earthquake engineering community to consider, in such a manner, the various methods to assess liquefaction consequences.

Earthquake Geotechnical Engineering for Protection and Development of Environment and Constructions

Earthquake Geotechnical Engineering for Protection and Development of Environment and Constructions
Author: Francesco Silvestri
Publisher: CRC Press
Total Pages: 8083
Release: 2019-07-19
Genre: Technology & Engineering
ISBN: 0429632010

Earthquake Geotechnical Engineering for Protection and Development of Environment and Constructions contains invited, keynote and theme lectures and regular papers presented at the 7th International Conference on Earthquake Geotechnical Engineering (Rome, Italy, 17-20 June 2019. The contributions deal with recent developments and advancements as well as case histories, field monitoring, experimental characterization, physical and analytical modelling, and applications related to the variety of environmental phenomena induced by earthquakes in soils and their effects on engineered systems interacting with them. The book is divided in the sections below: Invited papers Keynote papers Theme lectures Special Session on Large Scale Testing Special Session on Liquefact Projects Special Session on Lessons learned from recent earthquakes Special Session on the Central Italy earthquake Regular papers Earthquake Geotechnical Engineering for Protection and Development of Environment and Constructions provides a significant up-to-date collection of recent experiences and developments, and aims at engineers, geologists and seismologists, consultants, public and private contractors, local national and international authorities, and to all those involved in research and practice related to Earthquake Geotechnical Engineering.