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2010

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Articles 2101 - 2130 of 5375

Full-Text Articles in Engineering

Experimental Investigation Of Plastic Demands On Piles During Lateral Spread-Induced Loads, Barbara J. Chang, Tara C. Hutchinson May 2010

Experimental Investigation Of Plastic Demands On Piles During Lateral Spread-Induced Loads, Barbara J. Chang, Tara C. Hutchinson

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

Past earthquakes have demonstrated that lateral spreading from liquefaction of the soil may cause undesirable movement and potential failure to the below ground portion of a pile foundation. For a multi-layer soil profile, the case of a dense crust layer overlying a liquefiable soil layer may create large localized plastic demands in the piles. To study this behavior and provide detailed data for use in model validation studies, a one-g shaking table experiment was conducted considering a single reinforced concrete pile embedded in a 3-layer soil system. The model pile of 10 inch diameter was tested in a sloped laminar …

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Large-Scale Shake Table Test On Lateral Spreading Of A Sheet-Pile Wall Model And Its Centrifuge Simulation, Masayoshi Sato, Kentaro Tabata, Akio Abe May 2010

Large-Scale Shake Table Test On Lateral Spreading Of A Sheet-Pile Wall Model And Its Centrifuge Simulation, Masayoshi Sato, Kentaro Tabata, Akio Abe

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

The purpose of this test was to realistically reproduce soil liquefaction and the lateral spreading of saturated sand deposits behind the sheet-pile quay walls and the consequent deformation and translation of neighboring pile foundations. Therefore, a shake table test was carried out using a large-scale laminar box on the large-scale shake table in Tsukuba. The inside dimensions of the model were 11.6 m in length, 3.1 m in width and 4.5 m in depth. Next, a dynamic centrifuge test on the behavior of a sheet-pile wall and a soil pile system was conducted to simulate that of a large-scale shake …

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Numerical Analyses Of Centrifuge Models Of The Bart Transbay Tube, Jui-Ching Chou, Bruce L. Kutter, Thaleia Travasarou May 2010

Numerical Analyses Of Centrifuge Models Of The Bart Transbay Tube, Jui-Ching Chou, Bruce L. Kutter, Thaleia Travasarou

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

Centrifuge model tests were performed to study the stability and uplift mechanisms of the BART Transbay Tube. The tube is a cut-and-cover subway tunnel located in a highly seismic area. The low relative density of the backfill material around the tunnel and the low unit weight of the tunnel might make tunnel suffer uplift movement due to buoyancy forces caused by liquefaction of the backfill material during an earthquake. Three uplift mechanisms were observed in the centrifuge model tests: (1) a cyclic ratcheting mechanism of sand moving under the tunnel associated with cyclic lateral deformations of the tunnel;(2) flow of …

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Using Tactile Pressure Sensors To Measure Lateral Spreading Induced Earth Pressures Against A Large, Rigid Foundation, Scott M. Olson, Mark R. Muszynski, Carmine Polito, Youssef M. A. Hashash, Camilo Phillips May 2010

Using Tactile Pressure Sensors To Measure Lateral Spreading Induced Earth Pressures Against A Large, Rigid Foundation, Scott M. Olson, Mark R. Muszynski, Carmine Polito, Youssef M. A. Hashash, Camilo Phillips

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

Two centrifuge tests were performed at the NEES facility at Rensselaer Polytechnic Institute (RPI) to observe lateral earth pressures mobilized against a rigid foundation element during liquefaction-induced lateral spreading, as part of a larger NEESR study aimed at developing novel approaches to mitigate the effects of seismically-induced ground failures on large, rigid foundation elements. Models were constructed in a laminar box to allow unimpeded downslope soil displacement, and the sand in the model was liquefied during the centrifuge test. Lateral pressures prior to, during, and after shaking and liquefaction were directly measured using a novel device: tactile pressure sensors. Prior …

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A Practical Approach For Implementing The Probability Of Liquefaction In Performance Based Design, Thomas Oommen, Laurie G. Baise May 2010

A Practical Approach For Implementing The Probability Of Liquefaction In Performance Based Design, Thomas Oommen, Laurie G. Baise

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

Empirical Liquefaction Models (ELMs) are the usual approach for predicting the occurrence of soil liquefaction. These ELMs are typically based on in situ index tests, such as the Standard Penetration Test (SPT) and Cone Penetration Test (CPT), and are broadly classified as deterministic and probabilistic models. The deterministic model provides a “yes/no” response to the question of whether or not a site will liquefy. However, Performance-Based Earthquake Engineering (PBEE) requires an estimate of the probability of liquefaction (PL) which is a quantitative and continuous measure of the severity of liquefaction. Probabilistic models are better suited for PBEE but …

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Application Of Concave-Up P-Y Elements In Static Analysis Of Piles In Laterally Spreading Ground, Pirooz Kashighandi, Scott J. Brandenberg May 2010

Application Of Concave-Up P-Y Elements In Static Analysis Of Piles In Laterally Spreading Ground, Pirooz Kashighandi, Scott J. Brandenberg

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

Concave-up p-y behavior in liquefied sand has been observed by many researchers due to the dilatant tendency of sand that is dense of its critical state being suppressed in undrained loading. However, static analysis method often scale down the concave-down p-y curves that characterize drained loading, thereby missing the potentially important influence of concave-up behavior on pile response. For lateral spreading problems, large shear strains are typically assigned to the liquefied layer, which presupposes that the liquefied sand is soft and weak. This assumption is incompatible with the strengthening, stiffening concave-up p-y material. This paper presents a static lateral spreading …

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Compaction Grouting For Seismic Mitigation Of Sensitive Urban Sites, Richard C. Wakeman, Alan Evenson, Thomas Morgan, Joseph Pastore, J. Tanner Blackburn May 2010

Compaction Grouting For Seismic Mitigation Of Sensitive Urban Sites, Richard C. Wakeman, Alan Evenson, Thomas Morgan, Joseph Pastore, J. Tanner Blackburn

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

For moderately loaded structures founded on liquefiable soils, spread footings on improved ground can provide considerable cost savings over deep foundation options. Liquefaction mitigation by ground improvement must be properly designed and executed; and should include a field verification program. Although densification is the most effective method of achieving verifiable mitigation of liquefaction susceptible soils, vibro-densification methods are often disregarded for urban sites due to concern for adjacent structures and utilities. An alternative to vibratory methods is compaction grouting, which can achieve densification of cohesionless materials while avoiding excessive vibration of adjacent structures. Recently, compaction grouting was successfully applied to …

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Determination Of The Proper Thickness Of Sublayers For Analyzing Post-Liquefaction Deformation Associated With Seepage Of Pore Water After Earthquake, Ramez Alchamaa, Mitsutoshi Yoshimine May 2010

Determination Of The Proper Thickness Of Sublayers For Analyzing Post-Liquefaction Deformation Associated With Seepage Of Pore Water After Earthquake, Ramez Alchamaa, Mitsutoshi Yoshimine

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

The estimation of the large flow deformation in the liquefiable layered ground and its effects on a variety of civil structures and infrastructures is considered to be a significant concern in recent earthquakes. This paper proposes a new practical approach for estimating the appropriate thickness of sub-layers within a soil profile (soil element size) for simulating the post-liquefaction deformation considering the seepage flow of pore water after an earthquake. The findings of recent numerical analysis and extensive series of triaxial tests were utilized to develop the ability to analyze such fundamental issue. The study was conducted based on to the …

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Liquefaction Potential Evaluation Based On Site Classes – A Performance Based Approach, T. G. Sitharam, K. S. Vipin May 2010

Liquefaction Potential Evaluation Based On Site Classes – A Performance Based Approach, T. G. Sitharam, K. S. Vipin

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

Lots of research work is being carried out in evaluating the liquefaction susceptibility. The main objectives of these studies are to identify the regions which are vulnerable to liquefaction. In the present study, an attempt has been made to predict the liquefaction susceptibility based on corrected SPT values required to prevent the liquefaction for given return periods. The evaluation of liquefaction susceptibility requires the calculation of two parameters, seismic loading and the soil resistance. In most of the studies, the seismic loading will be evaluated based on probabilistic methods and the evaluation of soil resistance will be done based on …

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Calibrated 3d Computational Modeling Of Soil-Structure Systems And Liquefaction Scenarios, Ahmed Elgamal May 2010

Calibrated 3d Computational Modeling Of Soil-Structure Systems And Liquefaction Scenarios, Ahmed Elgamal

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

Three-dimensional (3D) computational simulation is increasingly allowing for insights into the mechanics of seismic soil-structure system response. Calibration is being facilitated by field, full-scale, and centrifuge model laboratory data. Computational algorithms and scenario-specific graphical user-interfaces are gradually permitting the routine adoption of such geometrically realistic simulation environments. This paper presents an overview of salient recent 3D soil-foundation-structure earthquake response simulations. Developments related to graphical user-interfaces (OpenSeesPL, http://cyclic.ucsd.edu/openseespl) are summarized, demonstrating the current and evolving capabilities towards performance-based earthquake engineering (PBEE). From an OpenSeesPL-generated lateral push-over analysis of a large pile-group, it is shown that corner piles may shoulder a significantly …

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Case Histories And Energy-Based Evaluation On Travel Distance Of Slope Failures During Recent Earthquakes, Takaji Kokusho, Tomohiro Ishizawa May 2010

Case Histories And Energy-Based Evaluation On Travel Distance Of Slope Failures During Recent Earthquakes, Takaji Kokusho, Tomohiro Ishizawa

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

An energy approach evaluating travel distance of debris in slope failures is proposed here, in which earthquake energy and gravitational potential energy are dissipated in flow deformations. Shake table model tests of dry sand slopes are carried out in which the earthquake energy dissipated in slope failure can be successfully quantified. The model tests indicate that measured slope displacements can be reliably evaluated by the proposed energy approach based on a rigid block model if an appropriate friction coefficient of the slope is specified. The energy approach is then applied to a number of slopes failed during recent earthquake in …

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Estimation Of Displacement Demand For Seismic Design Of Bridges With Rocking Shallow Foundations, Bruce L. Kutter, Lijun Deng, Sashi Kunnath May 2010

Estimation Of Displacement Demand For Seismic Design Of Bridges With Rocking Shallow Foundations, Bruce L. Kutter, Lijun Deng, Sashi Kunnath

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

Rocking foundations provide many desirable characteristics for a yielding dynamic system; they are economical, they provide a ductile (energy dissipating) moment limiting hinge, and they have a natural re-centering tendency. In order to take advantage of these characteristics in routine practice, simplified design procedures for bridge systems with rocking foundations are required. Two performance targets for deterministic seismic bridge design are: collapse should not occur during the “Maximum Credible Earthquake”, and, the serviceability of the bridge should not be compromised during smaller events that are expected during the lifetime of the structure (Functional Evaluation Earthquakes). The crux of the design …

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Integrated Earthquake Resistant Design Of Structure-Foundation Systems, Michael J. Pender May 2010

Integrated Earthquake Resistant Design Of Structure-Foundation Systems, Michael J. Pender

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

In this paper the case is made for an integrated approach to the earthquake resistant design of structure-foundation systems. Emphasis is placed on the need to analyse the response of a system that has the foundation and structure modelled with comparable levels of sophistication. The paper gives examples which illustrate what can be achieved with simplified models that represent the essence of the structural and foundation behaviour. However, to achieve a truly integrated structure-foundation design the investigation of the soil in which the foundation will be constructed needs to receive effort comparable to that expended in modelling the structurefoundation system. …

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Modeling The Observed Site Response From Istanbul Strong Motion Network, Atilla Ansal, Gökçe Tönük, Aslı Kurtuluş, Mustafa Erdik, Stefano Parolai May 2010

Modeling The Observed Site Response From Istanbul Strong Motion Network, Atilla Ansal, Gökçe Tönük, Aslı Kurtuluş, Mustafa Erdik, Stefano Parolai

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

An extensive site investigation study was carried out in the European side of Istanbul as part of the large-scale microzonation project for the Istanbul Metropolitan Municipality. 2912 borings mostly down to 30m depth with approximately 250m spacing were conducted within an area of 182 sqkm to investigate local site conditions. 55 stations of the Istanbul Rapid Response Network and Ataköy vertical array are located in this area. There have been few small earthquakes in the recent years with local magnitude slightly over M=4. One of these earthquakes took place on 12/3/2008 in Yalova with local magnitude of M=4.8. Vertical array …

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Seismic Response Of Deep Foundations Subjected To Liquefaction-Induced Lateral Spreading: Integrated Research And Practical Implications, Ricardo Dobry, Tarek Abdoun May 2010

Seismic Response Of Deep Foundations Subjected To Liquefaction-Induced Lateral Spreading: Integrated Research And Practical Implications, Ricardo Dobry, Tarek Abdoun

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

Integrated research is described on the response of pile foundations subjected to lateral ground deformations associated with sand liquefaction. Field evidence, experiments and analysis have indicated that pile bending and other response aspects depend on a complex manner on – and are very sensitive to - several parameters including the specific foundation and structural system, the free field ground deformation, and soil aspects such as layering and properties of nonliquefied and liquefied soil strata. The research presented focuses on sites where the liquefiable soil reaches the ground surface (especially important to bridge foundations), showing that in this case the permeability …

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Architecture As An Expression Of Identity: Abbas Hilmi Ii And The Neo-Mamluk Style, Nadania Idriss May 2010

Architecture As An Expression Of Identity: Abbas Hilmi Ii And The Neo-Mamluk Style, Nadania Idriss

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

This paper examines the religious architecture that was built at the end of the nineteenth, beginning of the twentieth century, during the rule of Abbas Hilmi II (1892-1914). The architecture is examined in light of the political and cultural climate of the time period. European influences brought new tastes for building styles, and the Neo-Mamluk became popularized for mosque architecture.

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Sand Plasticity Model For Nonlinear Seismic Deformation Analyses, Ross W. Boulanger May 2010

Sand Plasticity Model For Nonlinear Seismic Deformation Analyses, Ross W. Boulanger

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

A sand plasticity model for nonlinear seismic deformation analyses is presented. The model follows the basic framework of the stressratio controlled, critical state compatible, bounding surface plasticity model for sand presented by Dafalias and Manzari (2004). Modifications to the model were implemented to improve its ability to approximate the stress-strain responses important to geotechnical earthquake engineering applications; in essence, the model was calibrated at the equation level to provide for better approximation of the trends observed across a common set of experimentally- and case history-based design correlations. An overview of the model formulation and example simulations of element loading tests …

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Liquefaction-Induced Movements Of Buildings With Shallow Foundations, Jonathan D. Bray, Shideh Dashti May 2010

Liquefaction-Induced Movements Of Buildings With Shallow Foundations, Jonathan D. Bray, Shideh Dashti

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

Seismically induced settlement of buildings with shallow foundations on liquefiable soils has resulted in significant damage in recent earthquakes. In Adapazari, Turkey multi-story buildings punched into, tilted excessively, and slid laterally on softened ground. The state-of-the-practice still largely involves estimating building settlement using empirical procedures developed to calculate postliquefaction consolidation settlement in the free-field. This approach cannot possibly capture shear-induced and localized volumetricinduced deformations in the soil underneath shallow mat foundations. Geotechnical centrifuge experiments were performed recently to identify the dominant mechanisms involved in liquefaction-induced building settlement. The centrifuge tests revealed that considerable building settlement occurs during earthquake strong shaking. …

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Recent Advances In Non-Linear Site Response Analysis, Youssef M. A. Hashash, Camilo Phillips, David R. Groholski May 2010

Recent Advances In Non-Linear Site Response Analysis, Youssef M. A. Hashash, Camilo Phillips, David R. Groholski

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

Studies of earthquakes over the last 50 years and the examination of dynamic soil behavior reveal that soil behavior is highly nonlinear and hysteretic even at small strains. Non-linear behavior of soils during a seismic event has a predominant role in current site response analysis. The pioneering work of H. B. Seed and I. M. Idriss during the late 1960’s introduced modern site response analysis techniques. Since then significant efforts have been made to more accurately represent the non-linear behavior of soils during earthquake loading. This paper reviews recent advances in the field of non-linear site response analysis with a …

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Recent Advances In Seismic Design Of Geosynthetically-Lined Waste Containment Facilities, Neven Matasovic May 2010

Recent Advances In Seismic Design Of Geosynthetically-Lined Waste Containment Facilities, Neven Matasovic

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

Geosynthetic materials are essential elements of almost all modern landfill barrier systems. Materials such as geomembranes and geosynthetic clay liners are widely used as resistive barrier elements while geotextiles, drainage nets, and geocomposites are widely employed in modern composite barrier systems for both landfill liners and covers. The ability of these geosynthetic elements to maintain their integrity when subject to deformations due to waste settlement and seismic loading is a major uncertainty with respect to the performance of modern landfills. Over past years, advances have been made in understanding of material behavior under cyclic loading, modeling of modern landfill response …

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Zero-Gravity Triaxial Shear Tests On Mechanical Properties Of Liquefied Sand And Performance Assessment Of Mitigations Against Large Ground Deformation, Ikuo Towhata, Trinh Thi Lan Anh, Suguru Yamada, Ramin Motamed, Yoshikazu Kobayashi May 2010

Zero-Gravity Triaxial Shear Tests On Mechanical Properties Of Liquefied Sand And Performance Assessment Of Mitigations Against Large Ground Deformation, Ikuo Towhata, Trinh Thi Lan Anh, Suguru Yamada, Ramin Motamed, Yoshikazu Kobayashi

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

This paper concerns prediction of liquefaction-induced large deformation of geotechnical structures that will play major roles in practice of seismic performance design. To do this prediction, it is essential to establish a mechanical model for liquefied sand in which effective stress is null or extremely low. Although past model tests suggested that liquefied sand behaves similar to viscous liquid, there is an opinion against it that pore water pressure distribution in embedded structures produces an apparent rate-dependent behavior. This opinion was examined precisely and quantitatively by analyzing a full-scale model test to find that the pore pressure theory cannot account …

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Geotechnical Aspects Of Recent Pakistan Earthquakes, Sarfaraz Ali, Liaqat Ali, Muhammad Ammar May 2010

Geotechnical Aspects Of Recent Pakistan Earthquakes, Sarfaraz Ali, Liaqat Ali, Muhammad Ammar

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

Geologically, Kashmir and northwestern areas of Pakistan are located in most active seismic zones of sub-continent. In Kashmir area, earthquakes had been triggered by a continuous subduction phenomenon of Indian plate under Eurasian plate; a collision zone that created Himalaya Mountain range and still giving it a rise of 1 cm each year. The Quetta earthquake occurred on part of the left-lateral Chaman Fault System and was measured 8.1 on Richter scale with focal depth of 17 km. The earthquake completely devastated the city of Quetta, leaving 35000-60000 dead and injuring thousands of people in affected areas. The Kashmir earthquake …

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Strong Ground Motion In The Epicentral Region Of The MW 6.3, Apr 6 2009, L’Aquila Earthquake, Italy, Roberto Paolucci, Chiara Smerzini May 2010

Strong Ground Motion In The Epicentral Region Of The MW 6.3, Apr 6 2009, L’Aquila Earthquake, Italy, Roberto Paolucci, Chiara Smerzini

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

In the night of Apr 6 2009, a Mw 6.3 earthquake struck the Abruzzi region and the whole Central Italy, causing about 300 deaths and vast destructions in the town of L'Aquila, one of the largest urban centres in Central Italy, and its surroundings. As most destructive earthquakes in the Italian Central and Southern Apennines mountain chain, this was caused by a normal fault rupture, the epicenter of which was estimated at less than 5 km from the center of L'Aquila. Several 3-components digital strong motion instruments were installed around L'Aquila at few km distance from the epicenter: 3 …

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The Non-Regularity Of Earthquake Recurrence In California: Lessons From Long Paleoseismic Records From The San Andreas And San Jacinto Faults In Southern California, And The North Anatolian Fault In Turkey, Thomas Rockwell May 2010

The Non-Regularity Of Earthquake Recurrence In California: Lessons From Long Paleoseismic Records From The San Andreas And San Jacinto Faults In Southern California, And The North Anatolian Fault In Turkey, Thomas Rockwell

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

A long paleoseismic record at Hog Lake on the central San Jacinto fault in southern California documents evidence for 18 surface ruptures in the past 3.8-4 ka. This yields a long-term recurrence interval of about 210 years, consistent with its slip rate of ~15 mm/yr and field observations of 3-3.5 m of displacement per event. However, during the past 3800 years, the fault has switched from a quasiperiodic mode of earthquake production, during which the recurrence interval is similar to the long-term average, to clustered behavior with the inter-event periods as short as a few decades (five surface ruptures occurred …

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A Structural Engineer’S Approach To Efficient Sfsi: Towards Performance Based Design, M. Hesham El Naggar May 2010

A Structural Engineer’S Approach To Efficient Sfsi: Towards Performance Based Design, M. Hesham El Naggar

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

Performance-based design (PBD) involves designing structures to achieve specified performance targets under specified levels of seismic hazard. This involves analyzing the entire soil-structure system and requires structural and geotechnical expertise. This paper is focused on soil-foundation-structure interaction (SFSI) in relation to PBD. A Beam-on-Nonlinear-Winkler- Foundation (BNWF) model is developed to incorporate important SFSI aspects into structural analysis software. The model accounts for: nonlinearity due to soil yield and/or footing uplift; cyclic degradation of stiffness and strength due to variable-amplitude loading; distribution of soil resistance underneath the footing for different loading conditions; reduction in radiation damping with increased nonlinearity; and coupling …

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Corps Of Engineers Practice In The Evaluation Of Seismic Deformation Of Embankment Dams, Vlad G. Perlea, Michael H. Beaty May 2010

Corps Of Engineers Practice In The Evaluation Of Seismic Deformation Of Embankment Dams, Vlad G. Perlea, Michael H. Beaty

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

Guidance for the Corps of Engineers requires the use of seismic deformation analysis in the evaluation of existing dams for seismic loads and in the validation of remediation design for seismically deficient embankment dams. The Corps uses a phased approach for evaluating the seismic safety. For dams with significant seismic loads, problem soils, high risk, or those where simple analyses identified seismic concerns, a more advanced deformation analysis is generally required. A major challenge in these analyses is the selection of a reliable constitutive model when liquefiable materials are present. The computer program FLAC, in conjunction with a modified version …

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Ground Improvement To Reduce Liquefaction Potential Using Vibrocompaction And Stone Columns, Sanjeev Kumar, Tim Holcomb, Shahram Pezeshk May 2010

Ground Improvement To Reduce Liquefaction Potential Using Vibrocompaction And Stone Columns, Sanjeev Kumar, Tim Holcomb, Shahram Pezeshk

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

With the rapid pace of industrialization, structures are being designed and constructed in the flood plains of major rivers. In earthquake prone areas, a fundamental issue in the design and construction of structures on saturated sandy soils is weather or not the design earthquake could initiate liquefaction in the form of lateral spreading, sand boils, settlement, or cracking. Many different methods, including vibrocompaction, deep dynamic compaction, compaction piles, geopiers, deep mixing, vibratory probes, displacement/compaction grout, etc., have been used to reduce the liquefaction potential at various sites. Use of vibrocompaction to densify cohesionless soil is becoming more common and cost …

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Practical Seismic Design Considering Non-Linear Soil-Pile-Structure Interaction, Y. C. Han, Shin – Tower Wang May 2010

Practical Seismic Design Considering Non-Linear Soil-Pile-Structure Interaction, Y. C. Han, Shin – Tower Wang

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

A substructure approach is proposed for the seismic analysis considering the soil-pile-structure interaction. Two software packages are available for practical applications, DYNAN program and SAP 2000 program. The nonlinearity of soil is considered approximately using a boundary zone model with non-reflective interface. The validation of model is confirmed with dynamic tests on piles in the field, and the results for a single pile are used to compare with the predictions in this study. The liquefaction for sand soil layer can be accounted for, and a case of liquefaction is discussed. The seismic response of a vacuum tower structure supported on …

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Recent Advances In Predicting Earthquake-Induced Sliding Displacements Of Slopes, Ellen M. Rathje, George Antonakos May 2010

Recent Advances In Predicting Earthquake-Induced Sliding Displacements Of Slopes, Ellen M. Rathje, George Antonakos

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

This paper summarizes recent research related to predicting earthquake-induced sliding displacements of earth slopes. Recently developed empirical models for the prediction of sliding displacements for shallow (rigid) failure surfaces are discussed, and comparisons of the different models demonstrate that including peak ground velocity, along with peak ground acceleration, reduces the median displacement prediction and the standard deviation of the prediction. Thus, peak velocity provides important information regarding the level of sliding displacement. A framework is developed such that the recently developed empirical displacement models for rigid sliding can be used for deeper, flexible failure surfaces, where the dynamic response of …

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Seismic Response Of Columnar Reinforced Ground, C. Guney Olgun May 2010

Seismic Response Of Columnar Reinforced Ground, C. Guney Olgun

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

Ground improvement using stiff columnar reinforcement, such as stone, jet-grout and soil-mix columns, is commonly used for mitigation of seismic damage in weak ground. Seismic shear stress reduction in the reinforced soil mass is often counted on for reducing liquefaction potential. Current design methods assume composite behavior of the reinforced soil, where the shear stress reduction is based on the ratio of the columnar stiffness relative to the soil as well as the area replacement ratio. This implicitly assumes that the stiff columns will deform in pure shear along with the surrounding soft soil. Three dimensional dynamic finite element analyses …

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