Download or read book Effects of Void Redistribution on Liquefaction induced Deformations written by Ramachandran Kulasingam and published by . This book was released on 2003 with total page 988 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Void Redistribution on Liquefaction induced Ground Deformations in Earthquakes written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Liquefaction-induced ground failure continues to be a major component of earthquake-related damages in many parts of the world. Experience from past earthquakes indicates lateral spreads and flow slides have been widespread in saturated granular soils in coastal and river areas. Movements may exceed several meters even in very gentle slopes. More interestingly, failures have occurred not only during, but also after earthquake shaking. The mechanism involved in large lateral displacements is still poorly understood. Sand deposits often comprise of low permeability sub-layers e.g., silt seams. Such layers form a hydraulic barrier to upward flow of water associated with earthquake-induced pore pressures. This impedance of flow path results in an increase of soil skeleton volume (or void ratio) beneath the barrier. The void redistribution mechanism as the focus of this study explains why residual strengths from failed case histories are generally much lower than that of laboratory data based on undrained condition. A numerical stress-flow coupled procedure based on an effective stress approach has been utilized to investigate void redistribution effects on the seismic behavior of gentle sandy slopes. This study showed that an expansion zone develops at the base of barrier layers in stratified deposits subjected to cyclic loading that can greatly reduce shear strength and results in large deformations. This mechanism can lead to a steady state condition within a thin zone beneath the barrier causing flow slide when a threshold expansion occurs in that zone. It was found that contraction and expansion, respectively at lower parts and upper parts of a liquefiable slope with a barrier layer is a characteristic feature of seismic behavior of such deposits. A key factor is the pattern of deformations localized at the barrier base, and magnitude that takes place with some delay. In this thesis, a framework for understanding the mechanism of large deformations, and a practical.

Download or read book Effects of Layering on Liquefaction induced Deformations in Submerged Slopes written by Berna Sunman and published by . This book was released on 2000 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Issues in Nonlinear Deformation Analyses of Embankment Dams Affected by Liquefaction written by Jack Montgomery and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An examination of several potential sources of variability in nonlinear deformation analyses (NDAs) is presented. NDAs are becoming increasingly common for evaluating the effects of liquefaction on structures, such as embankment dams. Results from NDAs may be used to develop fragility curves for risk analyses, gain insights into deformation patterns and design and evaluate remediation alternatives. The use of NDA results in practice requires confidence in both the validity and repeatability of the analyses. This dissertation presents an evaluation of several potential sources of variability associated with NDAs of liquefaction effects on embankment dams. These sources of variability include the effects of overburden stresses on liquefaction, undrained strengths of compacted soils, effects of spatial variability on deformations, and numerical modeling of void redistribution. These topics were identified in part through discussion with engineers at the California Division of Safety of Dams which has funded this study. The goal of this dissertation is to evaluate and provide guidance on the above issues with the goal of reducing unnecessary variability in NDA results in practice. This work was also part of a parallel study which validates a set of NDA procedures against the observed performances of the Lower and Upper San Fernando Dams in the 1971 San Fernando earthquake and which will be published as a report from the Center for Geotechnical Modeling by Montgomery and Boulanger. First, an updated database of laboratory test results used to define the overburden correction factor (K[subscript][sigma]) is presented. This factor is used to account for the curvature of the cyclic strength envelope with increasing consolidation stress and provides part of the basis for extrapolation of liquefaction triggering correlations to large depths and stresses, such as those encountered under large embankment dams. Laboratory test results included in previous databases are reexamined in light of current understanding of factors which can affect laboratory measurements of cyclic strengths. The updated database is used to examine potential biases in the K[subscript][sigma] relationships used in two SPT-based liquefaction triggering procedures. The first relationship was found to be conservative with respect to the data for clean sands, and to be less conservative for sands with fines contents between 7% and 35%. The second relationship was found to provide a reasonably good fit to the data for clean sands, and to be slightly unconservative for sands with fines contents between 7% and 35%. Implications for practice are discussed. A recommended procedure for determining the static undrained shear strength parameters of compacted soils within an embankment dam is presented for use in Mohr-Coulomb constitutive models. The interpretation of ICU triaxial compression tests and a current method for estimating the effects of anisotropic consolidation in limit equilibrium analysis are reviewed. A method for interpolating ACU shear strengths in an NDA based on four different measures of consolidation stress is described and illustrated using a numerical example. The effects of spatial variability in soil properties on the liquefaction-induced deformations of gently sloping ground and the foundation of an embankment dam are presented. NDA results for models having uniform properties are compared to results for models having spatially correlated Gaussian random field property distributions. Results are presented for sets of non-uniform model realizations and a set of ground motions scaled to a range of peak ground accelerations. Computed deformations for these uniform and stochastic models are used to identify representative properties (as a percentile of the stochastic distributions) for which the uniform models produce reasonable agreement with the median of the stochastic model responses. The results show that the representative (N1)60[subscript]cs value can range from the 30th to the 70th percentile depending on the mean (N1)60[subscript]cs value, consolidation stresses, initial static shear stress ratio, shaking level, input ground motion, and other factors. The use of 33rd percentile values would appear reasonably conservative for deterministic evaluations, whereas the full range may be more appropriate for use in risk evaluations if such a refinement appears warranted. Finally, results are presented from numerical simulations to examine how geologic characteristics of stratigraphic interfaces may affect the mechanism of strength loss due to void redistribution. The void redistribution mechanism is briefly reviewed, followed by a discussion of how various characteristics of the stratigraphy may play a significant role. Numerical simulations of a layered infinite slope are then used to examine how undulations in the interface between liquefiable layers and overlying low permeability layers may affect the potential for strength loss due to void redistribution. Results show the loss of strength associated with void redistribution is greatest for near-planar interfaces between liquefying sands and low permeability strata and decreases significantly as the interface becomes more irregular. Challenges encountered during these analyses and potential implications of these findings for engineering practice are discussed.

Download or read book Void Redistribution induced Shear Localization and Deformation in Slopes written by Erik Jon Malvick and published by . This book was released on 2005 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Liquefaction induced Shear Strain Localization Processes in Layered Soil Profiles written by Ronnie Kamai and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Void redistribution in layered soil profiles can significantly affect the residual strength of a liquefied soil and the resulting deformations. Liquefaction-induced seepage may get trapped under lower-permeability layers, leading to a localized increase in void ratio, strength loss and enhanced deformations. Since the transient changes in void ratio cannot be measured in the field or in large physical models, its effects can be inferred from shear strain localizations at permeability interfaces and from delayed failure, based on the theoretical understanding and empirical experience. The mechanisms affecting void redistribution, shear-strain localization, and their inter-relationships are examined in this study. The effects of void redistribution are typically not directly accounted for in practice, and at best can be explicitly accounted for by using the empirical case-history based relationships for residual strengths. However, physical models have shown that the effects of void redistribution depend on many parameters, such as the layer thickness, slope angle, permeability contrast between the layers, shaking intensity, duration and history, and hence cannot be directly correlated with the pre-earthquake soil properties, as implied from the case-history based relationships. The purpose of the study presented in this dissertation is two-fold: (1) to continue the characterization and advance the understanding of the void-redistribution strength-loss mechanism and related effects, and (2) to evaluate the ability of the currently available numerical tools to directly account for void-redistribution strength-loss mechanism. First, an analytical study of void redistribution is presented, based on back-analysis of two dense instrumentation arrays from the centrifuge test SSK01, which experienced lateral spreading and shear strain localization. Shear stress and strain are calculated from accelerometer recordings and volumetric strains are calculated from pore-pressure transducers. The analysis provides insight on the flow patterns and their relation to the observed displacements in the test. Second, the material model PM4Sand is presented and its response to partially-drained conditions is explored through single-element FLAC simulations under different patterns of loading. The PM4Sand model is then used to simulate two boundary-value problems in which void redistribution and shear strain localization were important mechanisms in the overall model response - the centrifuge tests SSK01 and EJM02. The simulations are performed to evaluate the ability of the currently available numerical tools to capture the full observed mechanism, including shear strain localization and delayed failure. Simulation results are compared to the centrifuge tests measurements and observations, as well as with the back analyses on the instrumentation arrays. Parametric studies on cyclic strength, permeability and other uncertain factors are presented. For the simulations of the centrifuge test EJM02, two constitutive models are compared (PM4Sand and UBCSand), both capturing some aspects of the observed response but not all. Finally, the limitations in predicting the effects of void redistribution and shear strain localization are discussed.

Download or read book Proceedings of the 16th International Conference on Soil Mechanics and Geotechnical Engineering written by The Organizing Committee of the 16th ICSMGE and published by IOS Press. This book was released on 2005-09-12 with total page 3742 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 16th ICSMGE responds to the needs of the engineering and construction community, promoting dialog and exchange between academia and practice in various aspects of soil mechanics and geotechnical engineering. This is reflected in the central theme of the conference 'Geotechnology in Harmony with the Global Environment'. The proceedings of the conference are of great interest for geo-engineers and researchers in soil mechanics and geotechnical engineering. Volume 1 contains 5 plenary session lectures, the Terzaghi Oration, Heritage Lecture, and 3 papers presented in the major project session. Volumes 2, 3, and 4 contain papers with the following topics: Soil mechanics in general; Infrastructure and mobility; Environmental issues of geotechnical engineering; Enhancing natural disaster reduction systems; Professional practice and education. Volume 5 contains the report of practitioner/academic forum, 20 general reports, a summary of the sessions and workshops held during the conference.

Download or read book State of the Art and Practice in the Assessment of Earthquake Induced Soil Liquefaction and Its Consequences written by National Academies of Sciences, Engineering, and Medicine and published by . This book was released on 2019-01-30 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Physical Modelling in Geotechnics written by P. Guo and published by Taylor & Francis. This book was released on 2022-11-22 with total page 1046 pages. Available in PDF, EPUB and Kindle. Book excerpt: Papers cover topics including: physical modelling facilities; experimental advances; seismic experimental advances; education; soil behaviour; offshore systems; cold regions; geo-environment; dynamics; earthquake effects; and strategies for disaster reduction.

Download or read book Innovative Earthquake Soil Dynamics written by Takaji Kokusho and published by CRC Press. This book was released on 2017-07-28 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt: Innovative Earthquake Soil Dynamics deals with soil dynamics in earthquake engineering and includes almost all aspects of soil behavior. Both generally accepted basic knowledge as well as advanced and innovative views are accommodated. Major topics are (i) seismic site amplification, (ii) liquefaction and (iii) earthquake-induced slope failure. Associated with the above, basic theories and knowledge on wave propagation/attenuation, soil properties, laboratory tests, numerical analyses, and model tests are addressed in the first part of the book. A great number of earthquake observations in surface soil deposits as well as case histories with new findings are addressed in the later chapters, together with associated laboratory test data. Most of the research results originate from Japan, which is rich in earthquake records and case histories, although mostly isolated from the outside world because of the language barrier. Another important feature characterizing this book is an energy perspective in addition to the force-equilibrium perspective, because it is the author’s strong belief that energy is a very relevant index in determining seismic failures, particularly of soils and soil structures. Innovative Earthquake Soil Dynamics is written for international readers, graduate students, researchers, and practicing engineers, interested in this field.

Download or read book Physics and Mechanics of Soil Liquefaction written by PoulV. Lade and published by Routledge. This book was released on 2018-04-27 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt: The workshop aims to provide a fundamental understanding of the liquefaction process, necessary to the enhancement of liquefaction prediction. The contributions are divided into eight sections, which include: factors affecting liquefaction susceptibility and field studies of liquefaction.

Download or read book Canadian Geotechnical Journal written by and published by . This book was released on 2007 with total page 564 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physical Modelling in Geotechnics Two Volume Set written by Sarah Springman and published by CRC Press. This book was released on 2010-06-17 with total page 1530 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book results from the 7th ICPMG meeting in Zurich 2010 and covers a broad range of aspects of physical modelling in geotechnics, linking across to other modelling techniques to consider the entire spectrum required in providing innovative geotechnical engineering solutions. Topics presented at the conference: Soil – Structure – Interaction; Natural Hazards; Earthquake Engineering: Soft Soil Engineering; New Geotechnical Physical; Modelling Facilities; Advanced Experimental Techniques; Comparisons between Physical and Numerical Modelling Specific Topics: Offshore Engineering; Ground Improvement and Foundations; Tunnelling, Excavations and Retaining Structures; Dams and slopes; Process Modelling; Goenvironmental Modelling; Education

Download or read book Pile Foundations in Liquefied and Laterally Spreading Ground During Earthquakes written by Ross W. Boulanger and published by . This book was released on 2003 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aspects of the Cyclic Loading Behavior of Saturated Soils written by James Nathaniel Dismuke and published by . This book was released on 2003 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Soil and Rock America 2003 written by Patricia J. Culligan and published by . This book was released on 2003 with total page 1266 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Simulation of Liquefaction induced Deformations written by Kandiah Arulanandan and published by . This book was released on 2000* with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: