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Non-Stationary Soil-Structure Interaction Analysis Of A Sdof System Subjected To Joint Horizontal And Vertical Seismic Excitations, Pranesh Chatterjee, Biswajit Basu May 2010

Non-Stationary Soil-Structure Interaction Analysis Of A Sdof System Subjected To Joint Horizontal And Vertical Seismic Excitations, Pranesh Chatterjee, Biswajit Basu

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

In this paper a formulation has been presented to obtain the non-stationary response of a single degree of freedom system resting on a single layered soil medium and subjected to simultaneous horizontal and vertical seismic excitations. The wavelet based analytical technique using the modified Littlewood-Paley function has been adopted to characterize the seismic ground motions. Subsequently, the system equations have been solved in wavelet domain and closed form solutions for the response of the structure have been derived. The response has been calculated using wavelet based formulation and the traditional complex valued transfer function. A numerical example is also presented …

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Influence Of Soil Nonlinearities On Dynamic Soil-Structure Interaction, Ali Gandomzadeh, Luca Lenti, Maria Paola Santisi D’Avila, Fabian Bonilla, Jean-François Semblat May 2010

Influence Of Soil Nonlinearities On Dynamic Soil-Structure Interaction, Ali Gandomzadeh, Luca Lenti, Maria Paola Santisi D’Avila, Fabian Bonilla, Jean-François Semblat

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

For moderate or strong seismic events, the maximum strains can easily reach the elastic limit of the soil behavior. Considering soilstructure interaction, the nonlinear effects may change the soil stiffness at the base of the structure and the energy dissipation into the soil. To take into account the nonlinearity of the soil in the dynamic soil-structure interaction (DSSI), a 3D constitutive model, proposed by Iwan, is used to investigate DSSI in the framework of the Finite Element Method. The model accounts for the nonlinear hysteretic behavior of soils and only needs the shear modulus degradation curve to characterize the soil …

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Natural Frequency Calculation Of A Pile-Soil System In Dry Sand Under An Earthquake Loading, Eui-Kyu Yang, Sun-Yong Kwon, Jung-In Choi, Myoung Mo Kim May 2010

Natural Frequency Calculation Of A Pile-Soil System In Dry Sand Under An Earthquake Loading, Eui-Kyu Yang, Sun-Yong Kwon, Jung-In Choi, Myoung Mo Kim

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

A new method was proposed in this study to evaluate the natural frequency of a pile-soil system under earthquake loading using a simple mass-spring model. The diagonal, 4x4, mass matrix in the model consisted of concentrated masses of a pile and a superstructure. The flexural stiffness of the pile and the spring stiffness between the pile and the soil were used to construct the stiffness matrix in the model. These two matrices were then input in the frequency equation for calculating the natural frequency of the pile system. The spring stiffness between the pile and the soil, which considerably influences …

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Fixity Of Piles In Liquefiable Soils, Domenico Lombardi, Maria Giovanna Durante, Suresh R. Dash, Subhamoy Bhattacharya May 2010

Fixity Of Piles In Liquefiable Soils, Domenico Lombardi, Maria Giovanna Durante, Suresh R. Dash, Subhamoy Bhattacharya

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Recent researches have shown that piles are laterally unsupported in liquefiable soils during most strong earthquakes. If this unsupported length is significantly large, the high axial load on piles may make them more vulnerable to buckling instability. Calculation of buckling instability requires the full unsupported length of pile, which is the sum of pile length above the ground, pile length in the liquefied soil and a depth of fixity below the liquefied soil layer. In this paper, the length of fixity of pile foundations embedded in liquefiable soils has been investigated using a simple numerical method. The finite element program …

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Interaction Between Superstructure And Substructure In Railways, Konstantinos Giannakos May 2010

Interaction Between Superstructure And Substructure In Railways, Konstantinos Giannakos

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

The railway track superstructure undertakes the forces that develop during train movement and distributes them towards its seating. The track panel (sleepers with their fastenings or slab with the fastenings) plays a key role in terms of load distribution, while at the same time it ensures the stability of the geometrical distance between the rails. Earthworks and ballast (if it exists) undergo residual deformations, settlements and lateral displacements, directly influencing the deterioration of the so-called geometry of the track, which can be nevertheless described much more specifically as quality of the track. In this paper, a parametric investigation of the …

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Pile-In-Tube Foundations With Reserve Switch-Off Elements And Other Systems For Seismic Response Adaptive Control, J. M. Eisenberg May 2010

Pile-In-Tube Foundations With Reserve Switch-Off Elements And Other Systems For Seismic Response Adaptive Control, J. M. Eisenberg

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Predominant ground motion frequencies and spectra could differ sufficiently at different earthquakes on one site. The reasons of the differences are the epicenter distance, the focal depth, and many others. As it is well known, the frequency spectral configuration and predominant frequency values influence the structural seismic response and seismic behavior of structures (Mexico earthquakes 1957, 1962; Bucharest, 1977, Spitak, Armenia, 1988 and other). The maximum seismic response depends of how close the fundamental frequency values of the structure are to the predominant ground motion frequencies. Seismoisolation as an effective approach to seismic response control became popular recent decades in …

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Seismic Performance Assessment In Dense Urban Environments: Evaluation Of Nonlinear Building-Foundation Systems Using Centrifuge Tests, Zhiqiang Chen, Tara C. Hutchinson, Nicholas W. Trombetta, Henry B. Mason, Jonathan D. Bray, Katherine C. Jones, Chandrakanth Bolisetti, Andrew S. Whittaker, Benjamin Y. Choy, Bruce L. Kutter, Gregg L. Fiegel, Jack Montgomery, Roshani J. Patel, Robert D. Reitherman May 2010

Seismic Performance Assessment In Dense Urban Environments: Evaluation Of Nonlinear Building-Foundation Systems Using Centrifuge Tests, Zhiqiang Chen, Tara C. Hutchinson, Nicholas W. Trombetta, Henry B. Mason, Jonathan D. Bray, Katherine C. Jones, Chandrakanth Bolisetti, Andrew S. Whittaker, Benjamin Y. Choy, Bruce L. Kutter, Gregg L. Fiegel, Jack Montgomery, Roshani J. Patel, Robert D. Reitherman

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

In dense urban areas, buildings are generally constructed in clusters, forming city blocks. New buildings are designed assuming their response is independent of adjacent buildings, which ignores potentially important structure-soil-structure-interaction (SSSI) effects. Although a few studies have revealed the significance of SSSI effects, validated simulation and design tools do not exist. In this paper, we present the results from the first in a series of centrifuge tests intended to investigate SSSI effects. Results herein are focused on the design and measured response of two model building-foundation systems placed on dense dry Nevada sand and tested at 55-g. The two models …

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Numerical Modeling Of Soil-Pile Interaction In Liquefying Soils For A Water Crossing Bridge, Endi Zhai May 2010

Numerical Modeling Of Soil-Pile Interaction In Liquefying Soils For A Water Crossing Bridge, Endi Zhai

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

A recent design of a water crossing bridge encountered potential liquefiable soils beyond the depth that our standard-of-practice simplified liquefaction evaluation method (NCEER, 1997, Youd et al., 2001) can apply. A field investigation including deep soil borings and cone penetration test soundings was performed and revealed that loose to medium dense sandy alluvial soils are about 80 feet thick below the mud line. To evaluate liquefaction susceptibility of deeply buried soils and liquefaction effect on the response of the abutment Cast-In-Steel-Shell (CISS) piles, nonlinear effective-stress numerical models were built that were fullycoupled with a pore pressure generation scheme. The excess …

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Seismic Behavior Of Batter Pile Foundation: Kinematic Response, Takashi Tazoh, Masayoshi Sato, Jiho Jang, Yoichi Taji, George Gazetas May 2010

Seismic Behavior Of Batter Pile Foundation: Kinematic Response, Takashi Tazoh, Masayoshi Sato, Jiho Jang, Yoichi Taji, George Gazetas

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

We carried out centrifuge tests to clarify the seismic behavior of batter-pile foundations. A vertical-pile foundation and a batter-pile foundation without the presence of a superstructure were installed parallel to each other in a soil container filled with dry sand, and were excited simultaneously. Through a comparison of the acceleration and displacement response of the footing, as well as the axial and bending strain of the piles for the two pile foundations, the kinematic response of the seismic behavior of the batter-pile foundation was experimentally investigated.

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Numerical Analysis Of Disconnected Spread Footing On Soft Soil During Strong Earthquake, Sascha Richter, Roberto O. Cudmani May 2010

Numerical Analysis Of Disconnected Spread Footing On Soft Soil During Strong Earthquake, Sascha Richter, Roberto O. Cudmani

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

For the design of the Golden Ears approach bridge in Vancouver (Canada) a disconnected spread footing (DSF) was considered as alternative to a conventional pile foundation. In a DSF, a spread footing rests on natural ground improved by piles. Footing and piles are separated by a layer of coarse grained material. The mechanisms governing the behavior of the DSF during strong earthquake events have been investigated in a numerical finite element (FE) analysis using a (visco-)hypoplastic constitutive relationship. The FE model consists of a soil column (height 45 m) which includes the concrete piles. The superstructure is represented by a …

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Seismic Analysis Of Pile Group Using Pseudostatic Approach, H. Elahi, M. Moradi, H. G. Poulos, A. Ghalandarzadeh May 2010

Seismic Analysis Of Pile Group Using Pseudostatic Approach, H. Elahi, M. Moradi, H. G. Poulos, A. Ghalandarzadeh

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

This paper evaluates a simple approximate pseudostatic method for estimating the maximum internal forces and horizontal displacements of pile group subjected to lateral seismic excitation. The method involves two main steps. At first the free-field soil movements caused by the earthquake are computed. Then the response of the pile group based on the maximum free-field soil movements which considered as static movements as well as a static loading at the pile head, which depends on the computed spectral acceleration of the structure being supported is analyzed. The methodology takes into account the effects of group interaction and soil yielding at …

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Seismic Performance Of Double Eps Geofoam Buffer Systems, Aurelian C. Trandafir, Steven F. Bartlett May 2010

Seismic Performance Of Double Eps Geofoam Buffer Systems, Aurelian C. Trandafir, Steven F. Bartlett

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

This paper presents the results of a dynamic finite-element analysis addressing the effectiveness of a double expanded polystyrene (EPS) geofoam buffer system in reducing the peak seismic loads on a rigid, non-yielding retaining wall during an earthquake. A double EPS geofoam buffer system involves two vertical EPS panels, i.e., one EPS panel placed against the rigid wall face and another EPS panel installed at a specific distance away from the first panel in the backfill soil. Sensitivity analyses of the seismic performance of the double EPS geofoam buffer system in relation to the spacing between the EPS panels indicate that …

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Seismic Response Of Barrage Raft Floor Under Heterogeneous Soil Medium, Kumar Venkatesh, A. D. Pandey, N. K. Samadhiya May 2010

Seismic Response Of Barrage Raft Floor Under Heterogeneous Soil Medium, Kumar Venkatesh, A. D. Pandey, N. K. Samadhiya

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Seismic analyses of a barrage raft floor resting on homogeneous and heterogeneous subsoil condition were carried out by means of finite element modeling and analysis. Three dimensional models considering soil-raft-structure system were developed for both circumstances. The soil continuum, cut-off, pier, beam and abutment were modeled using eight noded brick element whereas raft floor was modeled using four noded plate bending element. The relevant amount of soil around and bottom of the barrage raft foundation has been modeled to find the effect of homogeneous and heterogeneous soil media on the seismic behavior of barrage raft floor. The seismic analysis was …

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Seismic Soil-Pile Interaction: Physical Processes And Analytical Models, Sanjeev Malhotra May 2010

Seismic Soil-Pile Interaction: Physical Processes And Analytical Models, Sanjeev Malhotra

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Seismic soil-pile-structure interaction (SSPSI) is a complex process involving several, simultaneously occurring and, sometimes compensating phenomena. The physical processes that occur in the soil when a pile supported structure undergoes earthquake loading consist of pore-pressure generation, ground deformation and subsequent cyclic degradation, strain rate effects and gap-slap mechanism. Modeling these physical phenomena numerically is a challenge. Of the various approaches available in practice, the p-y method for evaluating lateral pile response is by far the most common. However, at present, a consensus has not been established among practitioners on the appropriateness of using p-y curves for post-liquefaction analyses. This paper …

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Soil-Structure Interaction Of Soft Clay Using Prefabricated Vertical Geodrains Under Seismic Stresses, Manish V. Shah, Arvind V. Shroff May 2010

Soil-Structure Interaction Of Soft Clay Using Prefabricated Vertical Geodrains Under Seismic Stresses, Manish V. Shah, Arvind V. Shroff

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Experimental model study was carried out on soft Kaolinite clay using modified hydraulically pressurized oedometer with vertical sandwick of different diameter using open mandrel technique to investigate consolidation characteristics based on settlement and excess pore water pressure dissipation measurements. The main aim of this paper is to know the behavior of this consolidated mass under seismic stresses for different periods of time using shaking table.Pre and post shear strength of consolidated soil mass is evaluated using vane shear apparatus under seismic stresses. The interaction phenomena between clay and sandwick drain is also studied in oedometer to know stability of vertical …

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Structure-To-Soil-Structure Interaction Analysis: A Case Study, Lisa M. Anderson, Tarek Elkhoraibi May 2010

Structure-To-Soil-Structure Interaction Analysis: A Case Study, Lisa M. Anderson, Tarek Elkhoraibi

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Current industry codes, such as ASCE 4-98 recommend consideration of Structure-to-Soil-Structure Interaction (SSSI) only when it is determined to have a significant effect on local results. In some cases, it is not computationally feasible, or too costly, to analyze an explicit model including a complex of all contributing structures. The significance of SSSI is dependent upon several variables, namely the characteristics of the soil, structures, and ground motion, as well as the spatial distance between structures. The SSSI effect is most significant for lighter structures adjacent to more massive structures that are founded on soil sites. The Hanford Waste Treatment …

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The Effect Of Step Load Moving On The Surface Of A Cylindrical Cavity Using Neural Networks, Hamed Saeidi, Mansour Nikkhah-Bahrami May 2010

The Effect Of Step Load Moving On The Surface Of A Cylindrical Cavity Using Neural Networks, Hamed Saeidi, Mansour Nikkhah-Bahrami

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Potential functions and Fourier series method in the cylindrical coordinate system are employed to solve the problem of moving loads on the surface of a cylindrical bore in an infinite elastic and isotropic medium. The steady state dynamic equations of medium are uncoupled by applying potential functions. The medium responses are obtained by using an appropriate numerical method of Laplace transform inversion. The solution has an integral form; therefore, a feedforward backpropagation neural network is designed and trained using the response evaluated numerically in a finite set of random points to approximate stress and displacement components in the medium. It …

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Times-History Finite Element Dynamic Analysis - Soil Nail Wall - San Manuel Casino - Highland, California, Pirooz Barar, Qing Liu May 2010

Times-History Finite Element Dynamic Analysis - Soil Nail Wall - San Manuel Casino - Highland, California, Pirooz Barar, Qing Liu

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

The site of the proposed Phase II Parking Facility at the San Manuel Resort Casino, Highland, California, is on a sloped terrain where there is a 35 ft. grade differential from the north to the south end of the planned structure. PB&A, Inc. was selected to design a 12,000 square foot Soil-Nailed wall with a maximum height of 37 ft. to protect the Parking Structure from the soil pressures resulting from sloping ground conditions at the site. The project site is located within 100 feet of the San Andreas Fault in the highly seismic Southern California region, characterized by numerous …

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Cyclic Instability Behaviour Of Sand-Silt Mixture Under Partial Cyclic Reversal Loading, Md. Abdul Lahil Baki, Sik-Cheung Robert Lo, Md. Mizanur Rahman May 2010

Cyclic Instability Behaviour Of Sand-Silt Mixture Under Partial Cyclic Reversal Loading, Md. Abdul Lahil Baki, Sik-Cheung Robert Lo, Md. Mizanur Rahman

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Flow liquefaction is one of the most catastrophic failure phenomena in geotechnical engineering. It is a form of instability and can be observed during monotonic loading or cyclic loading. It is referred to as static instability/liquefaction for monotonic loading and cyclic instability for cyclic loading. To investigate the link between these behaviours, a number of stress controlled cyclic triaxial tests were carried out on loose sand-silt mixture under cyclic ‘reversal’ and ‘non-reversal’ loading condition. Cyclic reversal loading was partial reversal. Its peak-trough magnitudes were chosen in such a way that cyclic instability was triggered in compression side of the stress …

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Comparison Of Three Procedures For Evaluating Earthquake-Induced Soil Liquefaction, John Liao, Jorge Meneses, Emre Ortakci, Zia Zafir May 2010

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. …

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Estimating Seismic Parameters Associated With Previous Earthquakes By Scptu Soundings In The Nmsz, Tianfei Liao, Paul W. Mayne May 2010

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 …

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Estimation Of Seismic Compression In Dry Soils Using The Cpt, P. K. Robertson, Lisheng Shao May 2010

Estimation Of Seismic Compression In Dry Soils Using The Cpt, P. K. Robertson, Lisheng Shao

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

A popular method to evaluate earthquake induced settlements in dry sands is the approach proposed by Pradel (1998) which was based on standard penetration test (SPT) results and is only applicable to clean sands. A simple modification of the Pradel (1998) method is proposed based on cone penetration test (CPT) results and is extended to cover a wide range of unsaturated soils. A key parameter in the method by Pradel (1998) is the small strain shear modulus, Go, which can be estimated from the CPT or measured using the seismic CPT. The CPT can provide a continuous evaluation …

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Evaluating Liquefaction Resistance Of A Calcareous Sand Using The Cone Penetration Test, Daniela Porcino, Vincenzo Marcianò May 2010

Evaluating Liquefaction Resistance Of A Calcareous Sand Using The Cone Penetration Test, Daniela Porcino, Vincenzo Marcianò

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

An experimental study based on Static Cone Penetration Tests (CPT) performed in Calibration Chamber (CC) and cyclic Simple Shear (SS) tests was undertaken in order to establish a correlation for estimating cyclic resistance ratio (CRR) of calcareous sands. CPT’s in CC were carried out on an uncemented calcareous sand, dug out from Brittany in France (Quiou sand) in the context of a previous research. Test results were thus re-analysed by the authors, considering the specific purposes of the paper. SS tests were conducted on specimens reconstituted by water sedimentation method that, according to the authors’ previous studies is capable of …

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Ground Motions And Liquefaction Potential, Roger L. Torres May 2010

Ground Motions And Liquefaction Potential, Roger L. Torres

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Strong earthquakes have the potential to produce liquefaction of saturated and loose soils or to produce shear strength loss on sensitive clays, which may produce embankment failure with uncontrolled release of the reservoir. Earthfill Dam 101 has been classified as a high risk dam and this study attempts to determine the extent of the risk. It retains a 60,000 acre-feet reservoir with population downstream of the embankment. The analysis of the earthquake through a bracketed accelerogram provides insight into how the embankment will respond to the seismic loading and to the soils properties. In the case study, the peak response …

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Examination Of Existing Dmt-Based Liquefaction Evaluation Methods By Side-By-Side Dmt And Cpt Tests, Gordon Tung-Chin Kung, Der-Her Lee, Pai-Hsiang Tsai May 2010

Examination Of Existing Dmt-Based Liquefaction Evaluation Methods By Side-By-Side Dmt And Cpt Tests, Gordon Tung-Chin Kung, Der-Her Lee, Pai-Hsiang Tsai

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

This study employed the field measurements of flat dilatometer test (DMT) and cone penetration test (CPT) presented by a recent study (Tsai et al. 2009) and additional DMT and CPT data conducted in this present study to examine the existing DMT-based liquefaction evaluation methods. Specifically, the DMT and CPT were conducted side-by-side at each of six in-situ sites and thus it is feasible to incorporate those test results into validating the existing DMT-based methods such as Grasso and Maugeri (2006), Monaco et al. (2005), and Rena and Chameau (1991). The DMT parameter, horizontal stress index (KD), is used …

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Liquefaction Countermeasure Technique By Using Logs For Carbon Storage Against Global Warming, Masaho Yoshida, Masakatsu Miyajima, Atsunori Numata May 2010

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. …

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Evaluation Of Gravel Drains Effectiveness Against Liquefaction In Shaking Table Utilizing Energy Method, Hadi Bahadori, Gholi Asadzadeh May 2010

Evaluation Of Gravel Drains Effectiveness Against Liquefaction In Shaking Table Utilizing Energy Method, Hadi Bahadori, Gholi Asadzadeh

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Liquefaction is one of the major causes of damage to civil engineering structures. The shear strength of sandy soil during strong earthquakes is reduced due to exerted energy that is related to increasing of pore water pressure. The absorbed energy calculated through hysteretic stress-strain loops as compared with the exerted earthquake energy is an alternative method to study the liquefaction susceptibility of saturated sandy soil. There are several numbers of remediation methods which reduce the excess pore water pressure such as gravel drains. In the current study seven precisely performed 1-g shaking table tests are conducted. Synthetic Firouzkooh sand was …

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Liquefaction Mitigation Of Three Projects In California, Tom M. Farrell, Kyle Wallace, John Ho May 2010

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 …

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Liquefaction Mitigation Using Air Injection, William M. Camp Iii, Hugh C. Camp, Ronald D. Andrus May 2010

Liquefaction Mitigation Using Air Injection, William M. Camp Iii, Hugh C. Camp, Ronald D. Andrus

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Soils most susceptible to liquefaction are loose, non-plastic and saturated. Because the compressibility of air is orders of magnitude greater than the compressibility of water, un-saturation or partial saturation can significantly increase the liquefaction resistance of a soil deposit. Nakazawa et al. (2004) have shown that cyclic strength in laboratory test specimens can be more than twice as high in partially saturated soil than fully saturated soil. It is hypothesized that sufficient de-saturation to increase the liquefaction resistance can be induced by injecting air or gas into the subsurface. Simple, qualitative shake-table experiments demonstrate the increase in liquefaction resistance as …

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Microscale Characterization Of Energy Dissipation Mechanisms During Liquefaction, Usama El Shamy, Christina Denissen May 2010

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 …

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