Numerical Analysis Of Trampoline Effect In Extreme Ground Motion,
2010
Kyoto University, Japan
Numerical Analysis Of Trampoline Effect In Extreme Ground Motion, Tetsuo Tobita, Susumu Iai, Tomotaka Iwata
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
Very large vertical surface acceleration of nearly four times gravity was measured at a strong motion observation station in Iwate Prefecture during the 2008 Iwate-Miyagi Inland, Japan, earthquake (Mw 6.9). The station is located about 3 km southwest of the epicenter and equipped with three-component accelerometers, installed at both the free surface and the bottom of a 260-m borehole. The wave form of the vertical acceleration shows a clearly asymmetric form with large amplitude in the upward direction. Aoi et al. (2008) reported and qualitatively explained the mechanism of this phenomenon by the analogy of bouncing a piece of …
Uniform Hazard Response Spectra Of Korea Considering Uncertainties In Ground Properties,
2010
University of California, Los Angeles, CA
Uniform Hazard Response Spectra Of Korea Considering Uncertainties In Ground Properties, Dong-Yeop Kwak, Duhee Park, Bang Woong Shin, Kwangkyun Kim
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
The seismic site coefficients derived deterministically are often used with ground motion parameters determined by probabilistic seismic hazard analysis in construction of the design response spectrum. There is, therefore, an inherent incompatibility between two approaches. New methods have been developed to resolve this incompatibility by developing probabilistic seismic site coefficients. In such approaches, the uncertainties in the properties of the ground were not systematically accounted for due to lack of measurements of the ground. In this study, an integrated probabilistic seismic hazard analysis which can quantify the nonlinear seismic site effects and account for the uncertainties in soil properties is …
1d Dynamic Non-Linear Numerical Analysis Of Earth Slopes: The Role Of Soil Ductility And Time-Sensitiveness,
2010
Politecnico di Milano, Italy
1d Dynamic Non-Linear Numerical Analysis Of Earth Slopes: The Role Of Soil Ductility And Time-Sensitiveness, Claudio Giulio Di Prisco, Federico Pisanò
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
The mechanical response of dry granular slopes subjected to dynamic perturbations is tackled from a theoretical/numerical viewpoint. A 1D geometrical/numerical scheme is adopted to analyze infinitely long strata: the dynamic activation of shallow translational failure mechanisms (as well as the displacement performance far from collapse) is analyzed by means of a self-made FEM code. The soil mechanical behavior is described by means of a simplified viscoplastic one-dimensional constitutive model, capable of reproducing both ductile (hardening) and brittle (softening) mechanical responses. The dependence of numerical results on the soil “time-sensitiveness”, as well as the differences between viscoplasticity and standard rate-independent plasticity, …
Nonlinear Site Effects: Interest Of One Directional - Three Component (1d - 3c) Formulation,
2010
Université Paris-Est, France
Nonlinear Site Effects: Interest Of One Directional - Three Component (1d - 3c) Formulation, Maria Paola Santisi D’Avila, Jean-François Semblat, Ali Gandomzadeh, Fabian Bonilla, Luca Lenti, Salvatore Martino
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
Strong ground motions generally lead to both a stiffness reduction and a larger energy dissipation in the soil layers. Thus, in order to study such phenomena, several nonlinear rheologies have been developed in the past. However, one of the main difficulties of using a given rheology is the number of parameters needed to describe the model. In this sense, the multi-surface cyclic plasticity approach, developed by Iwan in 1967 is an interesting choice since the only data needed is the modulus reduction curve. Past studies have implemented this method in one-directional SH wave-propagation (1D-1C). This work, however, aims to study …
Seismic Site Response Analysis Using Spreadsheets,
2010
G2D Resources, LLC, San Diego, CA
Seismic Site Response Analysis Using Spreadsheets, Geraldo R. Iglesia, James L. Stiady
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
A spreadsheet-based framework for quantifying local site response due to seismic excitation is presented in this paper. The main focus here is on equivalent-linear one-dimensional analysis, similar to the computer program SHAKE or its derivative kin, which by far is the most commonly used approach for performing ground response evaluation. Such analysis involves the computation of the response of a semi-infinite horizontally layered deposit overlying a uniform half-space subjected to vertically propagating shear waves. The bulk of the analysis is actually carried out in the frequency domain, which involves operations with complex-algebraic parameters. Widely available spreadsheet software is typically equipped …
A Study Of Effective Factors On The Behavioural Characteristics Of Clayey Sands,
2010
Tarbiat Modares University, Iran
A Study Of Effective Factors On The Behavioural Characteristics Of Clayey Sands, Omid Naeemifar, S. Shahaboddin Yasrobi
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
As in recent years liquefaction phenomena have occurred in sandy soils containing different amounts of clay contents, it was concluded that in addition to silty sands, clayey sands are also vulnerable to liquefaction phenomenon. So, the urge for comprehensive study aroused to cover the issue. In this paper, the effect of clay content and its plasticity properties on behavioural characteristics of clayey sands under various density and confining pressure values have been investigated. To achieve the goal, about a hundred monotonic triaxial tests were performed on remoulded specimens of sandy soils containing different clay contents with different plasticity values. Based …
Assessment Of Liquefaction-Induced Foundation Soil Deformations,
2010
Middle East Technical University, Turkey
Assessment Of Liquefaction-Induced Foundation Soil Deformations, K. Onder Cetin, Berna Unutmaz, H. Tolga Bilge
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
Although there exist some consensus regarding seismic soil liquefaction triggering assessment of free field soil sites, estimating the liquefaction triggering potential beneath building foundations still stays as a controversial and a difficult issue. Assessing liquefaction triggering potential under building foundations requires the estimation of cyclic and static stress state of the soil medium. In the recent studies (e.g. Unutmaz 2008), the cyclic stress ratio corrected for Kα and Kσ effects under and adjacent to building foundations subjected to cyclic loading are to be estimated with the help of a series of 2-D and 3-D numerical simulations for different …
Comparison Of Three Procedures For Evaluating Earthquake-Induced Soil Liquefaction,
2010
Kleinfelder, Oakland, CA
Comparison Of Three Procedures For Evaluating Earthquake-Induced Soil Liquefaction, John Liao, Jorge Meneses, Emre Ortakci, Zia Zafir
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
Over the past decade, major advances have occurred in both the understanding and the practice with regard to the evaluation of soil liquefaction potential during earthquakes. Among these advances, there are two analytical frameworks (i.e., Seed et al. (2003) and Idriss and Boulanger (2008) procedures), which are widely accepted by the industry. The most significant achievement of the new procedures is their new criteria for assessment of liquefaction potential of low-plasticity silts and clays. These two new procedures are changing the way the design and regulatory communities consider soil liquefaction evaluation and may likely become standard-ofpractice in the near future. …
Equivalent Granular Void Ratio And Behaviour Of Loose Sand With Fines,
2010
University of Canterbury, New Zealand
Equivalent Granular Void Ratio And Behaviour Of Loose Sand With Fines, Md. Mizanur Rahman, Sik-Cheung Robert Lo, Misko Cubrinovski
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
Traditionally, void ratio is being used as a state variable for liquefaction analysis of sand with fines. However, recent publications reported that void ratio is not a good state variable for sand with fines. Thus, equivalent granular void ratio, e* instead of void ratio, e is proposed to resolve this problem. A single trend for Steady State (SS) data points for sand with fines can then be achieved in e*- log(p') space irrespective of fines contents, fc. The single trend is referred to as equivalent granular steady state line, EG-SSL. However, a parameter b, the active fraction of …
Estimating Seismic Parameters Associated With Previous Earthquakes By Scptu Soundings In The Nmsz,
2010
Bechtel Power Corporation, Frederick, MD
Estimating Seismic Parameters Associated With Previous Earthquakes By Scptu Soundings In The Nmsz, Tianfei Liao, Paul W. Mayne
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
Although the New Madrid seismic zone (NMSZ) is the most active seismic region in the eastern United States, paleoliquefaction features are often used to analyze the previous seismic activities, due to the long recurrence interval of large earthquakes. A new methodology is proposed in this paper to estimate the seismic parameters associated with previous earthquakes based on the results of seismic cone penetration tests (SCPT), using the simplified procedure of liquefaction analysis and the attenuation relationships developed for the corresponding seismic areas. This methodology is validated through the paleoliquefaction studies at two sites associated with the 1989 Loma Prieta earthquake …
Liquefaction Countermeasure Technique By Using Logs For Carbon Storage Against Global Warming,
2010
Fukui National College of Technology, Japan
Liquefaction Countermeasure Technique By Using Logs For Carbon Storage Against Global Warming, Masaho Yoshida, Masakatsu Miyajima, Atsunori Numata
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
Global warming is one of the most serious problems which faced by civil engineers in this century. Because a wood can store carbon within itself, the utilization of wood in the construction projects may contribute to the mitigation of global warming. The technique of ground improvement by installing logs into loose sand layer as a countermeasure against soil liquefaction was proposed in this study. The logs had been used as pile foundation until 1950's in Japan. However, as the wood has high possibility of a decrease in strength by decay, the utilization of wood become minority in the construction projects. …
Liquefaction Mitigation Of Three Projects In California,
2010
Farrell Design Build Cos., Inc., Placerville, CA
Liquefaction Mitigation Of Three Projects In California, Tom M. Farrell, Kyle Wallace, John Ho
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
Ground displacements resulting from earthquake-induced soil liquefaction and dynamic densification can cause moderate to severe structural damage during and after an earthquake. Geotechnical construction methods of mitigating these potential ground displacements include mass excavation and replacement with engineered fill, ground improvement such as soil mixing, jet grouting, compaction piers, vibro compaction, vibro stone columns, and deep dynamic compaction, or deep foundations such as driven piles. The ground improvement methods rely on altering the soil properties to resist the seismically-induced shear stresses and soil grain redistribution while deep foundation methods bypass liquefiable soil deposits to found in deeper competent soil or …
Microscale Characterization Of Energy Dissipation Mechanisms During Liquefaction,
2010
Southern Methodist University, Dallas, TX
Microscale Characterization Of Energy Dissipation Mechanisms During Liquefaction, Usama El Shamy, Christina Denissen
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
This study utilizes the discrete element method (DEM) to present a microscopic energy monitoring approach to characterize energy dissipation mechanisms in seismically loaded soils. Numerical simulations were conducted on saturated deposits of granular particles subjected to seismic excitations, modeled using a transient fully-coupled continuum-fluid discrete-particle model. The onset of liquefaction is illustrated through macroscopic and microscopic response patterns. An in-depth look at the individual microscale energy components both before and after the onset of liquefaction is presented. Prior to liquefaction, energy is dissipated mainly through inter-particle sliding (friction energy), but after liquefaction particle-to-particle impact damping also plays a major role …
Recent Advances In Liquefaction Of Fine Grained Soils,
2010
Missouri University of Science and Technology
Recent Advances In Liquefaction Of Fine Grained Soils, Shamsher Prakash, Vijay K. Puri
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
Paper reviews present literature recommendations on liquefaction of soils with fines starting with the experimental evidence previously published by the authors. The liquefaction behavior of silts and silt clay mixers was investigated over a range of plasticity index values of interest by conducting cyclic triaxial tests on reconstituted samples and their behavior was compared with that of sand. It was found that saturated silts with plastic fines behave differently from sands both with respect to rate of development of pore water pressure and axial deformations with number of load cycles. The results also showed that liquefaction susceptibility of silts shows …
Residual Shear Strengths Of Cohesionless Soils From Energy Approach,
2010
Indian Institute of Technology, India
Residual Shear Strengths Of Cohesionless Soils From Energy Approach, Raghvendra Singh, Debasis Roy
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
The residual shear strength of the non plastic soils are generally estimated from the correlations between residual shear strength estimated from the laboratory tests or from the back analyses of post failure geometries of case histories distressed during static or seismic loading and penetration resistances. The post failure shear strength of large deformed structures like debris flow, mud flow and avalanches in which the post deformed soil mass gain large distance after the failure, depends on the strain rate behavior of shear (viscous) resistance, frictional resistance, inertial effect, three dimensional effect of geometry, flexibility of failed material and void redistribution …
Seismic Analysis Of Saturated Sand Deposits With Silt Layers,
2010
Yildiz Technical University, Turkey
Seismic Analysis Of Saturated Sand Deposits With Silt Layers, Murat Tonaroglu, Kutay Ozaydın, S. Umit Dikmen
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
Liquefaction of saturated sands during earthquakes is known to be the cause of significant earthquake related damages, including loss of bearing capacity, lateral flow and spreading, slope failures. In recent earthquakes including the1999 Marmara Earthquake in Turkey, field observations have indicated that silt inclusions or silt layers in the sandy deposits can have significant effects on development of liquefaction. The objective of this work is to analytically study the behavior of saturated sand deposits with silt layers. For this purpose, a hypothetical soil profile in which silt layers exist has been selected. The selected profile was then modeled and analyzed …
Undrained Response And Liquefaction Behaviour Of Non-Plastic Silty Sands Under Cyclic Loading,
2010
National Institute of Technology Calicut, India
Undrained Response And Liquefaction Behaviour Of Non-Plastic Silty Sands Under Cyclic Loading, K. Ranga Swamy, A. Boominathan, K. Rajagopal
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
The undrained response and liquefaction behaviour of fine sand and silty sands consisting of 30% and 50% non-plastic fines were investigated in the present study. The effect of consolidation stress level, cyclic stress amplitude and amount of non-plastic fines on soil liquefaction have been studied through a systematically planned stress controlled cyclic triaxial tests. To examine the effect of consolidation pressure on liquefaction behaviour, the sand-silt specimens were prepared at 40% relative density and consolidated at pressures of 50, 100 and 200 kPa. To investigate the effect of fines content on liquefaction resistance of sands at constant postconsolidation void ratio, …
3d Analysis Of The Seismic Response Of Seven Oaks Dam,
2010
URS Corporation, Oakland, CA
3d Analysis Of The Seismic Response Of Seven Oaks Dam, Lelio Mejia, Ethan Dawson
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
Procedures for the three-dimensional (3-D) dynamic analysis of earth dams have been available for over 25 years. However, additional case histories are needed to assess whether such procedures are capable of simulating the seismic response of dams in narrow canyons, and to further evaluate the effects of 3-D behavior on the response of such dams. This study was aimed at identifying the vibration characteristics of Seven Oaks Dam during the 2005 Yucaipa and 2001 Big Bear Lake earthquakes, and at evaluating the applicability of 3-D and 2-D numerical procedures to simulate the response of the dam. Accelerograms recorded on the …
Behavior Of Nailed Steep Slopes In Laboratory Shake Table Tests,
2010
IIT-Kharagpur, India
Behavior Of Nailed Steep Slopes In Laboratory Shake Table Tests, Aniruddha Sengupta, Debabrata Giri
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
This paper presents results of laboratory shake table tests performed to study the dynamic behavior of nailed steep slopes. The surface displacements, settlement of the crest and the acceleration responses along with the behavior of the facing wall are examined during the tests. Two 18 cm high 60° and 70° steep soil slopes reinforced with nine hollow aluminum nails placed in three rows are considered. Three strain gauges are glued to each nail to measure the tensile force developed in the nails. Four strain gauges are fixed at the center of the facing wall to measure the development of strains …
Centrifuge Model Tests Of Tieback Anchors And Drainage Pipes For Stabilization Of Slopes Under Earthquake Loads,
2010
Nippon Koei Co., LTD. Research and Development Center, Japan
Centrifuge Model Tests Of Tieback Anchors And Drainage Pipes For Stabilization Of Slopes Under Earthquake Loads, Keiichi Ota, Koji Takeya, Keiichi Itoh, Senro Kuraoka, Yuichi Ueno, Takaya Hiroshima
International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
Tieback anchors are widely used for the stabilization of natural and manmade slopes in Japan. The interactions between tieback anchors and slopes under seismic loading need to be understood to develop rational design concepts and installation methods in earthquake prone areas. We conducted centrifuge model tests to examine the characteristics of dynamic and residual loads on tieback anchors installed in slopes subjected to seismic loads. If the model slope contained a saturated zone, circular failure occurred even with pre-tensioned tieback anchors, and the amplitude of the oscillating loads on the tieback anchors was very high. This suggested that excess pore …
