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Estimation of Liquefaction-induced Lateral Spread from Numerical Modeling and Its Application

Estimation of Liquefaction-induced Lateral Spread from Numerical Modeling and Its Application PDF Author: Xianhong Meng
Publisher:
ISBN:
Category : Soil liquefaction
Languages : en
Pages : 474

Book Description


Estimation of Liquefaction-induced Lateral Spread from Numerical Modeling and Its Application

Estimation of Liquefaction-induced Lateral Spread from Numerical Modeling and Its Application PDF Author: Xianhong Meng
Publisher:
ISBN:
Category : Soil liquefaction
Languages : en
Pages : 474

Book Description


Experimental Modeling and Numerical Simulation of Lateral Spreading for Validation of Constitutive Models

Experimental Modeling and Numerical Simulation of Lateral Spreading for Validation of Constitutive Models PDF Author: Trevor James Carey
Publisher:
ISBN: 9781658412421
Category :
Languages : en
Pages :

Book Description
Numerical modeling is often relied on as the most advanced approach for predicting the effects of liquefaction for complex geosystems. While numerical methods are often used to model seismic performance, little is known about how accurately constitutive models capture the physics behind liquefaction. The Liquefaction Experiments and Analysis Projects (LEAP) is an international effort among numerical and physical modelers to validate numerical models used to predict the effects of liquefaction. LEAP is conducted over a series of phases, or projects, each addressing a specific component of the overall goal of validation. The research in this dissertation presents components of LEAP, considering both experimental and numerical modeling of liquefaction. The overall goals are to: 1) provide high quality experimental data for validation of numerical constitutive models and 2) demonstrate the behavior and sensitivity of commonly used numerical liquefaction models. The goal of the first major US phase of LEAP, LEAP-GWU-2015, was to repeat the same centrifuge experiment at different research facilities, to serve as a single point for validation. The experiment consisted of a submerged slope of uniform sand. The centrifuge experiment performed at UC Davis as a part of the LEAP-GWU-2015 phase is discussed, including the experiment results, novel testing procedures, modifications to the model container, and nonconformities with experiment specifications. Prior to the second major LEAP phase, new centrifuge testing equipment was developed to characterize the initial conditions of the experiment and model response during liquefaction. A low-cost cone penetrometer device was designed and distributed to the LEAP testing facilities for improved quality control. A linear regression is presented that uses measured cone tip stresses to correct reported initial densities from mass and volume measurements. A novel hardware configuration to measure liquefaction induced deformations of a submerged slope was developed. The new configuration records displacements using five GoPro cameras attached to a submerged clear acrylic window located above the slope, which acts as a glass-bottom boat to avoid distortion due to water surface waves. The highspeed videos recorded during shaking are converted to images and using GEO-PIV displacements time histories are calculated. Time series displacements measured with the new hardware configuration were shown to produce comparable results as hand measurements and sensor data. The second major LEAP phase, LEAP-UCD-2017, consisted of twenty-four centrifuge experiments performed at nine research facilitates using the same testing geometry as the LEAP-GWU-2015 exercise. The new strategy of the LEAP-UCD-2017 phase was to intentionally vary the key input variables of motion intensity and soil density to determine the sensitivity of residual displacements to these variables. The three centrifuge experiments performed at UC Davis for LEAP-UCD-2017 are presented, including the experiment results, new procedures to estimate model specimen density, and minor nonconformities with experimental specifications. Following the LEAP-UCD-2017 and LEAP-ASIA-2019 phases an experimental displacement response surface that relates soil density, input motion intensity, and slope displacement was developed using nonlinear regression analysis of the centrifuge test data. A numerical response surface was developed using the PDMY02 constitutive model using the OpenSees finite element framework. The PDMY02 model was calibrated for three relative densities using available cyclic element test laboratory data; after considerable effort the triggering curves (cyclic stress ratio vs number of cycles to liquefaction) for the PDMY02 model cross the triggering curves developed from laboratory data, but the shapes of the numerical curves do not match the laboratory curves. A finite element mesh of the LEAP-UCD-2017 centrifuge test geometry was developed and the displacement response surface for the PDMY02 model was developed by varying the intensity of the input motion for the three calibration densities. The resulting numerical response surface is shown to match the experimental surface well, despite the fact that the numerical liquefaction triggering curves are not a good fit with the laboratory liquefaction triggering curves. Together, the results presented in this dissertation contribute to our understanding of numerical model validation and help to reconcile the different inferences produced through numerical modeling and centrifuge experiments.

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 PDF Author: National Academies of Sciences, Engineering, and Medicine
Publisher:
ISBN: 9780309440271
Category :
Languages : en
Pages : 350

Book Description
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.

Probabilistic Models for Engineering Assessment of Liquefaction-induced Lateral Spreading Displacements

Probabilistic Models for Engineering Assessment of Liquefaction-induced Lateral Spreading Displacements PDF Author: Allison Theresa Faris
Publisher:
ISBN:
Category :
Languages : en
Pages : 912

Book Description


Liquefaction-induced Lateral Spread Displacement

Liquefaction-induced Lateral Spread Displacement PDF Author: T. Leslie Youd
Publisher:
ISBN:
Category : Shear strength of soils
Languages : en
Pages : 62

Book Description


Development of Numerical Tools for the Evaluation of Pile Response to Laterally Spreading Soil

Development of Numerical Tools for the Evaluation of Pile Response to Laterally Spreading Soil PDF Author: Alborz Ghofrani
Publisher:
ISBN:
Category :
Languages : en
Pages : 367

Book Description
Problems in geotechnical earthquake engineering often involve complex geometries and boundary conditions prohibiting the use of simple models. Although very useful, empirical models are sometimes not applicable to the problem at hand and performing experimental tests is costly and difficult. Improvements in computer technology have made advanced numerical modeling an essential tool for analysis and design of systems in the field of geotechnical earthquake engineering. In this context, there is a need for a robust numerical framework capable of handling different aspects of the engineering problems in this field. In this study, several of these aspects for 3D dynamic finite element analysis of such engineering problems are addressed. Particularly, constitutive modeling of granular soil to capture liquefaction, and soil-pile interaction are considered and tools are developed and implemented in OpenSees to address the problem of bridge foundations subjected to liquefaction induced lateral spreading loads. Several 3D static, quasi-static and dynamic examples are included for verification and validation of the tools implemented as part of this research.

Model Tests and Numerical Simulations of Liquefaction and Lateral Spreading

Model Tests and Numerical Simulations of Liquefaction and Lateral Spreading PDF Author: Bruce L. Kutter
Publisher: Springer Nature
ISBN: 3030228185
Category : Electronic books
Languages : en
Pages : 660

Book Description
This open access book presents work collected through the Liquefaction Experiments and Analysis Projects (LEAP) in 2017. It addresses the repeatability, variability, and sensitivity of lateral spreading observed in twenty-four centrifuge model tests on mildly sloping liquefiable sand. The centrifuge tests were conducted at nine different centrifuge facilities around the world. For the first time, a sufficient number of experiments were conducted to enable assessment of variability of centrifuge test results. The experimental data provided a unique basis for assessing the capabilities of twelve different simulation platforms for numerical simulation of soil liquefaction. The results of the experiments and the numerical simulations are presented and discussed in papers submitted by the project participants. The work presented in this book was followed by LEAP-Asia that included assessment of a generalized scaling law and culminated in a workshop in Osaka, Japan in March 2019. LEAP-2020, ongoing at the time of printing, is addressing the validation of soil-structure interaction analyses of retaining walls involving a liquefiable soil. A workshop is planned at RPI, USA in 2020. .

Model Tests and Numerical Simulations of Liquefaction and Lateral Spreading II

Model Tests and Numerical Simulations of Liquefaction and Lateral Spreading II PDF Author: Tetsuo Tobita
Publisher: Springer Nature
ISBN: 3031488210
Category :
Languages : en
Pages : 448

Book Description


Liquefaction-induced Lateral Spreading and Its Effects on Pile Foundations

Liquefaction-induced Lateral Spreading and Its Effects on Pile Foundations PDF Author: Liangcai He
Publisher:
ISBN:
Category :
Languages : en
Pages : 886

Book Description


Single Piles in Liquefiable Ground

Single Piles in Liquefiable Ground PDF Author: Rui Wang
Publisher: Springer
ISBN: 3662496631
Category : Science
Languages : en
Pages : 131

Book Description
This thesis focuses on the seismic response of piles in liquefiable ground. It describes the design of a three-dimensional, unified plasticity model for large post-liquefaction shear deformation of sand, formulated and implemented for parallel computing. It also presents a three-dimensional, dynamic finite element analysis method for piles in liquefiable ground, developed on the basis of this model,. Employing a combination of case analysis, centrifuge shaking table experiments and numerical simulations using the proposed methods, it demonstrates the seismic response patterns of single piles in liquefiable ground. These include basic force-resistance mode, kinematic and inertial interaction coupling mechanism and major influence factors. It also discusses a beam on the nonlinear Winkler foundation (BNWF) solution and a modified neutral plane solution developed and validated using centrifuge experiments for piles in consolidating and reconsolidating ground. Lastly, it studies axial pile force and settlement during post-earthquake reconsolidation, showing pile axial force to be irrelevant in the reconsolidation process, while settlement is process dependent.