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Articles 2521 - 2550 of 4583

Full-Text Articles in Engineering

Numerical Study On The Behaviour Of Structures In The Near-Field Of Sheet-Pile Driving Work, H. Meissner, A. Becker Mar 2001

Numerical Study On The Behaviour Of Structures In The Near-Field Of Sheet-Pile Driving Work, H. Meissner, A. Becker

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

The process of sheetpile-driving is investigated. Emphasis is placed on the influence of actual pile driving depth and the transfer of pile driving energy from the sheetpile to the surrounding soil. The propagation of waves caused by the pile driving and its effects on the soil and structures founded in and on the ground are discussed. Horizontal and vertical displacements of structures on the surface as well as in half space (e.g. buried pipelines) are presented. The results were obtained using the finite element method. The central point of these first studies is to show the effect of sheetpiling works …

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Comparison And Modeling Of Sand Behavior Under Cyclic Direct Simple Shear And Cyclic Triaxial Testing, J.-F. Vanden Berghe, A. Holeyman, R. Dyvik Mar 2001

Comparison And Modeling Of Sand Behavior Under Cyclic Direct Simple Shear And Cyclic Triaxial Testing, J.-F. Vanden Berghe, A. Holeyman, R. Dyvik

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

Constant volume cyclic shear (DSS) tests were performed on Brusselian sand using the new NGI simple shear apparatus and a special control system for cyclic strain controlled testing. Test results are compared with those from cyclic triaxial (TXS) tests. The tests investigated the degradation of the cyclic shear modulus for different relative densities (from 60% to 90%), different consolidation pressures (from 5OkPa to 200kPa) and different shear strain amplitudes (from 0.1% to 9%). The comparison of the soil specimen behavior in the two different test types shows that soil degradation is mainly function of (1) the dilative or contractive behavior …

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Dynamic Interaction Between Rail Track Systems And The Layered Subsoil Solutions In The Frequency-And Time Domain, S. Savidis, S. Bergmann, C. Bode, R. Hirschauer Mar 2001

Dynamic Interaction Between Rail Track Systems And The Layered Subsoil Solutions In The Frequency-And Time Domain, S. Savidis, S. Bergmann, C. Bode, R. Hirschauer

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

For the numerical simulation of dynamic soil-structure interaction problems both a frequency and a time domain formulation are presented. In order to be capable to consider more sophisticated models of the structure, the frequency domain algorithms for homogeneous and layered halfspaces have been coupled to the Finite Element Program ANSYS. Flexibility functions are presented for a concrete slab track system. Furthermore the stress distribution in the subsoil is calculated and visualized. The time domain formulation is applied for demonstrating the basic phenomena of a moving load passing by with sub- and supercritical speed. Besides that, a nonlinear, tension-free condition of …

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Vertical Earthquake Response Analysis Of Xiaolangdi Earth-Rock Dam With 3-D Shear Wedge Model, Zhenzhong Shen, Zhiying Xu Mar 2001

Vertical Earthquake Response Analysis Of Xiaolangdi Earth-Rock Dam With 3-D Shear Wedge Model, Zhenzhong Shen, Zhiying Xu

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

The constructing Xiaolangdi dam is the highest earth-rock dam in China. Its maximum height is about 154 m, and the length of dam axis is about 1500 m. In this paper, by application of the three-dimensional shear wedge theory and the Bubnov-Galerkin approach method, the vertical earthquake response analysis is performed for the earth dam. Its dynamic behaviors such as maximum dynamic displacement, velocity, acceleration and stress etc. are obtained. Under the action of the designed earthquakes, the fundamental period of the vertical vibration of the Xiaolangdi earth-rock dam is about 0.803 s, the maximum acceleration response is about 0.976 …

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Surface Waves In Evaluation Of Damping In Layered Systems, Nenad Gucunski, Ali Maher Mar 2001

Surface Waves In Evaluation Of Damping In Layered Systems, Nenad Gucunski, Ali Maher

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

The Spectral analysis of surface waves (SASW) method has been successfully used in evaluation of elastic moduli profiles of layered systems. Recently, there have been attempts to implement the SASW method and surface waves in evaluation of damping/attenuation properties of layered systems. Results of numerical simulations are presented for the purpose of explanation of effects of damping properties of individual layers on the overall attenuation properties, as measured during actual SASW testing. A parametric study conducted examines effects of a number of parameters, including the system stratification that may lead to dominant wave propagation in terms of higher Rayleigh modes. …

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Vibration Of Synchrotron Foundation Due To Ground-Transmitted Excitation, M. Hesham El Naggar, Bruce F. Sparling Mar 2001

Vibration Of Synchrotron Foundation Due To Ground-Transmitted Excitation, M. Hesham El Naggar, Bruce F. Sparling

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

The Canadian Light Source (CLS) is a third generation synchrotron that will be capable of generating a wide spectrum of electromagnetic radiation used in the study of the atomic and sub-atomic structure of materials. The CLS facility will feature a 50 m diameter vacuum storage ring used to contain a highly focused stream of electrons. The accuracy required in aiming the electron beam and resulting radiation necessitates very stringent operational tolerances on foundation vibrations, with peak dynamic displacements being limited to less than 0.35 μm. To assess the level of seismic excitation at the site due to traffic on an …

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Vertical Vibrations Of Block Foundations, Vijay K. Puri, Braja M. Das Mar 2001

Vertical Vibrations Of Block Foundations, Vijay K. Puri, Braja M. Das

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

Steady state vertical vibration tests were conducted on test blocks measuring 1.5m x 0.75m x 0.7 m and 3m x 1.5m x 0.7m resting on ground surface. The amplitudes of vibration the blocks were measured at different frequencies. Dynamic shear modulus of the soil at site was also determined by conducting in-situ tests. The natural frequencies and amplitudes of vibration were calculated by (i) elastic half space method and (ii) impedance function method. A comparison was then made of the observed and the computed values natural frequencies and the vibration amplitudes. The data obtained shows that for this case the …

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Partially Embedded Rectangular Foundations: A Simplified Approach To Compute Dynamic Stiffnesses, Toyoaki Nogami, Ham Shean Chen Mar 2001

Partially Embedded Rectangular Foundations: A Simplified Approach To Compute Dynamic Stiffnesses, Toyoaki Nogami, Ham Shean Chen

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

Partially embedded rectangular foundations are considered. Soil at the side of the foundation is decoupled from that at the base and is treated as a stack of horizontal layers of unit thickness that are mutually uncoupled. The side soil stiffnesses/depth are formulated from the vibration of a massless rigid rectangular disc in an individual layer. In the development of formulations, the layer medium is further simplified with a column-spring system. All these simplifications lead to simple expressions suitable for practical use. The two parameters in these expressions are defined by iteration using two coupled simple equations. Dynamic soil stiffesses at …

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Evaluating The Response Of Soils To Seismic Tremors By Recording Background Noise, Rabah Iddir, Nadir Laradi Mar 2001

Evaluating The Response Of Soils To Seismic Tremors By Recording Background Noise, Rabah Iddir, Nadir Laradi

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

At 29/10/1989, Tipaza’s region situate in the west of Algiers, was vibrate below a Chenoua earthquakes. A distance between the centre of this earthquakes and Algiers the capital, wasn’t a to make a damages for the constructions (Casbah, Bab El Oued, Hamma, Tagara...). Because this one is dating for the colonial era, and haven’t a para-seismic structures. Then determination of zonal effects is one of the essential components of para-seismic prevention, having recourse to macro-zoning. The conventional method of measuring zonal effects experimentally is based on seismic recording. It is admittedly reliable, but it is laborious We suggest in this …

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Behavior Of Dune Sands Of The Thar Desert Under Dynamic Loading, Sanjay Gupta, Ravi Sundaram Mar 2001

Behavior Of Dune Sands Of The Thar Desert Under Dynamic Loading, Sanjay Gupta, Ravi Sundaram

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

Forced vibration test were conducted on concrete blocks for a power project in north-western Rajasthan (India). The site is in the Thar desert and has meta-stable aeolian sand deposits. At shallow depth, the amplitude versus frequency curves shows two peaks, suggesting that the soil structure was probably collapsing and settling under the dynamic load. Tests conducted on the deeper, relatively more stable soils confirm a good response to dynamic loads. The instability under static loading conditions is also highlighted and correlated to the dune morphology.

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Site Effect Evaluation Using Combination Of Source Scaling Models And Ground Motion Records, Vladimir Sokolov, Chin-Hsuing Loh, Kuo-Liang Wen Mar 2001

Site Effect Evaluation Using Combination Of Source Scaling Models And Ground Motion Records, Vladimir Sokolov, Chin-Hsuing Loh, Kuo-Liang Wen

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

We analyze site response of the Taipei basin using the records obtained by the Taiwan Strong Ground Motion Instrumentation Program (TSMIP) network. Records of 66 earthquakes of M=2.6-6.5 with a hypocentral depth varying from 1 km to 118 km and hypocentral distances of up to 150 km are studied for 35 stations located within this triangle shaped alluvium structure. The site response is obtained in terms of spectral ratios calculated by dividing of the site spectrum by the reference spectrum estimated for a hypothetical “very hard rock” site. The recently developed empirical source scaling and attenuation models are used for …

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Site Response Analysis Using Forced-Vibration Tests On Hydraulic-Filled Soil Deposit, Dong-Soo Kim, Jin-Sun Lee Mar 2001

Site Response Analysis Using Forced-Vibration Tests On Hydraulic-Filled Soil Deposit, Dong-Soo Kim, Jin-Sun Lee

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

Forced vibration tests and detailed site characterization were performed at a geotechnical experimental site in Yong-jong Island where Inchon International Airport being constructed. The vibratory motions generated by the combination of hydraulic hammer compaction and dynamic compaction were monitored by 3-component velocity transducers in the down hole array as well as on the ground surface. Spectral analyses of the recorded vibratory motions were performed to evaluate the resonant frequencies of the experimental site. The linear analysis and simplified method were also performed to evaluate the resonant frequencies of the experimental site based on the results of detailed site investigation. The …

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New-Generation Objective And Reproducible Isoseismals, And Tests Of Source Inversion Of The Usgs "Felt Reports", Franco Pettenati, Livio Sirovich Mar 2001

New-Generation Objective And Reproducible Isoseismals, And Tests Of Source Inversion Of The Usgs "Felt Reports", Franco Pettenati, Livio Sirovich

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

We present two new techniques for treating earthquake intensity data objectively and reproducibly. First, our natural-neighbor, n-n, isoseismals (program: ConVor) are used to draw objective and reproducible isoseismals of the Whittier Narrows ML=5.9, 1987 earthquake from the earthquake damage (“felt reports”) sparsely observed in the region by the U.S.G.S. ConVor uses the n-n coordinates to weight and interpolate the observations; thus, the weights of the experimental sites which are natural neighbors to a new point are proportional to the areas of the intersections of their Voronoi polygons. It is shown that the n-n isoseismals: 1) honour the experimental …

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Simple Power-Law Characterization Of Transient Ground-Borne Vibrations, Michael L. Rucker, Otto C. Holmquist Mar 2001

Simple Power-Law Characterization Of Transient Ground-Borne Vibrations, Michael L. Rucker, Otto C. Holmquist

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

Practical characterization of transient ground-borne vibrations in civil and geotechnical engineering problems is often a difficult and frustrating task. Some modem engineering seismographs now routinely permit the collection of histogram-type data where the peak vibration for a pre-set time interval can be measured and stored for significant time periods. Such data is amenable to analysis utilizing concepts of fractal geometry and self-ordered criticality. Resulting data trends tend to follow power-law relationships that plot as essentially straight lines in log-log space. This application is similar to the Gutenberg-Richter relationship for earthquakes where the relationship between magnitude and frequency is fractal. However, …

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Influences Of S-Wave Velocity To The Seismic Response Of Silt Ground, Yufeng Gao, Hanlong Liu, Wei Zhu, Tugen Feng Mar 2001

Influences Of S-Wave Velocity To The Seismic Response Of Silt Ground, Yufeng Gao, Hanlong Liu, Wei Zhu, Tugen Feng

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

By using of one-dimension equivalent linearzation seismic response analysis method, the study is performed to the different silt grounds. The influences of s-wave velocity uncertainty to the seismic acceleration peak, duration, response spectrum of silt ground are discussed in the paper. Following conclusions will he expected. (1) The relationship between the difference of seismic peak acceleration and the difference of s-wave velocity is in linear distribution approximately. The seismic peak acceleration is changed with the S-wave velocity. The seismic peak acceleration is much effected by the uncertainty of S-wave velocity. (2) The uncertainty of shear wave velocity has little influence …

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Characterisation Of Site Effects By Means Of Energy Spectra, Luis D. Decanini, Giuseppe Lanzo, Fabrizio Mollaioli Mar 2001

Characterisation Of Site Effects By Means Of Energy Spectra, Luis D. Decanini, Giuseppe Lanzo, Fabrizio Mollaioli

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

The effects of subsoil conditions on surface ground motion are evaluated in terms of energy spectra. Near-field and far-field strong ground motion recorded during recent destructive earthquakes at nearby rock and soil sites characterized by a comprehensive knowledge of the geotecbnical properties are considered. The study suggests that energy spectra at soil sites are amplified with respect to those on rock sites. The maximum spectral amplification is usually well correlated to the natural periods of the sites. The most striking difference between traditional response spectra and energy spectra is the high soil amplification at longer periods, which is not apparent …

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Characterization Of Microtremor Records Using Simulated Microtremors, Juan Carlos Tokeshi Nagamine, Yoshihiro Sugimura, Madan B. Karkee Mar 2001

Characterization Of Microtremor Records Using Simulated Microtremors, Juan Carlos Tokeshi Nagamine, Yoshihiro Sugimura, Madan B. Karkee

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

The paper attempts to illustrate the potential application of simulation techniques for interpretation and characterization of microtremors. Simulations are performed with two types of source distribution models, both involving a large number of Dirac wave type sources randomly activated on the surface of a horizontally layered ground underlain by the half-space. Attempt is made to utilize the technique for the interpretation of microtremors at KASAI site in Chiba prefecture (Japan). The site has a deep base layer and weak impedance contrast. The parameter RF, defined as the ratio between horizontal and vertical input forces at the source, is used as …

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A Seismic Site-Amplification Map For Memphis, Shelby County, Tennessee From Geophysical, Geotechnical, And Geological Measurements, C. Cramer, R. Williams, K. Tucker Mar 2001

A Seismic Site-Amplification Map For Memphis, Shelby County, Tennessee From Geophysical, Geotechnical, And Geological Measurements, C. Cramer, R. Williams, K. Tucker

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

As a part of the U.S. Geological Survey’s (USGS) Memphis, Shelby County Seismic Hazard Mapping project, geophysical and geotechnical subsurface data are being collected into a subsurface database for Shelby County, Tennessee. Memphis is a major urban area near the New Madrid Seismic Zone in the central U.S. and has a building stock that is largely vulnerable to even moderate ground shaking from earthquakes. The subsurface geological, geotechnical, and geophysical information gathered will be used to construct a three-dimensional model of the geology and seismic velocity structure of the area down to Paleozoic bedrock (up to 1 km deep) for …

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Influence Of Seismic Noises Background Intensity On Waves Propagation Speed, S. I. Kerimov Mar 2001

Influence Of Seismic Noises Background Intensity On Waves Propagation Speed, S. I. Kerimov

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

A research of the previous years has shown that on processes taking place in ground has a sufficient influence a background level of own ground microvibrations - microseism. This fact changes a view about ground model, explaining a difference in ground behavior at its studying in laboratorial and field conditions. In connection with that there was offered a new mechanical ground model that detects not only and influence of mechanical behavior of ground skeleton but also wave processes occurring in it. Conducted calculations of models shoved that offered ground model allows to describe processes observed in practice and not fitting …

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Numerical And Experimental Simulation Of Seismic Site Responses, Xian Tao, Takaaki Kagawa, Akio Abe Mar 2001

Numerical And Experimental Simulation Of Seismic Site Responses, Xian Tao, Takaaki Kagawa, Akio Abe

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

Prediction of seismic site responses has been one of the most important tasks in geotechnical earthquake engineering. Since Kanai used the multiple wave reflection theory to compute horizontal ground movements against seismic shaking, a number of researchers have extended the basic concept proposed by Kanai. Performance of seismic site response methods, however, has always invited open questions for problems involving extreme seismic shaking and large deformation of soils due, for example, to liquefaction and lateral spreading. A new numerical method SRANG3D (Site Response Analysis of Non-linear Ground in 3 Dimensions) has been developed to improve our prediction capabilities for seismic …

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Evaluation Of Mexico City Clay Dynamic Properties Using A Parameter Identification Approach, Juan C. Carvajal U., Víctor M. Taboada U., Miguel P. Romo O. Mar 2001

Evaluation Of Mexico City Clay Dynamic Properties Using A Parameter Identification Approach, Juan C. Carvajal U., Víctor M. Taboada U., Miguel P. Romo O.

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

Laboratory-determined soil dynamic properties are always (to different degrees) affected by sample disturbance, scale effects, deficient modeling of in situ conditions, and so on. The installation of vertical arrays of strong motion instruments and the ensuing records obtained during various seismic events, have opened the opportunity to explore other alternatives to evaluate soil dynamic properties by solving the inverse problem. In this paper, an analytical procedure that allows the solution of this problem in a simple way is presented and applied to a case history in Mexico City. The model assumes 1-D propagation of shear waves throughout homogeneous viscoelastic soil …

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Site Dependent Spectra For The Umbro-Marchigiano Earthquake (Italy) Of September-October 1997, Paolo Carrubba, Michele Maugeri Mar 2001

Site Dependent Spectra For The Umbro-Marchigiano Earthquake (Italy) Of September-October 1997, Paolo Carrubba, Michele Maugeri

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

Free-field ground motion during earthquake can be conveniently represented by response spectrum for a given level of damping and ductility. Typical response spectra have been established in several seismic codes, as the Eurocode EC8, but for real seismic events some disagreements may be still encountered. The disagreements come from the presence of soil formations or local site conditions which can differ G-om those provided by seismic codes. During the recent Umbro-Marchigiano earthquake, happened in Italy in the September-October 1997, 198 records ofhorizontal acceleration have been collected from more than 30 accelerometric stations. Soil conditions have been known in detail for …

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Comparison Of Liquefaction Potential Of Loess In China, Usa, And Russia, Lanmin Wang, H. Hwang, Y. Lin, T. G. Ryashenko, V. V. Akulova Mar 2001

Comparison Of Liquefaction Potential Of Loess In China, Usa, And Russia, Lanmin Wang, H. Hwang, Y. Lin, T. G. Ryashenko, V. V. Akulova

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

Loess is extensively distributed in many parts of the world, including China, the United State and Russia. Based on experimental study of loess obtained from the three countries, the liquefaction potential of loess are investigated. It is found though loess in the three country all have liquefaction potential, their peak ground acceleration of triggering liquefaction and their behavior during liquefaction vary significantly. Further study of microstructure of loess reveals that the microstructure of the loess in the three countries differs each other in many ways. This factor, combined with the different of gradation, physical index and formation materials, accounts for …

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A Critical State Evaluation Of Fines Effect On Liquefaction Potential, Konstantinos I. Andrianopoulos, George D. Bouckovalas, Achilleas G. Papadimitriou Mar 2001

A Critical State Evaluation Of Fines Effect On Liquefaction Potential, Konstantinos I. Andrianopoulos, George D. Bouckovalas, Achilleas G. Papadimitriou

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

Published results from laboratory tests show that an increase in the percentage of fines generally leads to a reduction of the cyclic liquefaction resistance of a sand, while empirical correlations from in-situ tests consider the presence of fines as beneficial. In order to study this seemingly not univocal effect of tines content, this paper involves the integrated framework of Critical State Soil Mechanics. For this purpose, firstly the effect of tines on the location of the Critical State Line (CSL) is studied through statistical analysis of a large data set of triaxial element tests. Results show that fines affect the …

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Correlation Between Liquefaction Potential Using Spt And Cpt Data In A Specific Site In Iran, S. M. Mir Mohammad Hosseini Mar 2001

Correlation Between Liquefaction Potential Using Spt And Cpt Data In A Specific Site In Iran, S. M. Mir Mohammad Hosseini

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

The geotechnical characteristic of the soil layers is one of the main factors influencing liquefaction potential of the ground. The standard penetration test (SPT), had been extensively used to measure the in-situ soil properties due to its simplicity and availability all over the world in the majority of the liquefaction studies. Nevertheless, it suffers horn some shortcomings in comparison with another in-situ test called cone penetration test (CPT). In order to compare the liquefaction potential evaluated based on the SPT data with those based on the CPT data, a specific site in the southern parts of Iran, have been selected …

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Non-Linear Site Response Analysis For Deep Deposits In The New Madrid Seismic Zone, Youssef M. A. Hashash, Duhee Park, Jungsuk Lee Mar 2001

Non-Linear Site Response Analysis For Deep Deposits In The New Madrid Seismic Zone, Youssef M. A. Hashash, Duhee Park, Jungsuk Lee

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

The New Madrid Seismic Zone, the most seismically active zone in the Eastern US, is overlain by deep unconsolidated deposits of the Mississippi Embayment. The deposits range in thickness from about 20 m in the St. Louis area to about 1 km in the Memphis Area and consist of silts, clays and sands. The influence of these deposits on the propagation of seismic waves to the ground surface remains a major source of uncertainty. A new non-linear one-dimensional site response analysis model is introduced for the vertical propagation of horizontal shear waves in deep soil deposits. The model accounts for …

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Evaluation Of Liquefaction Potential Of Gravelly Soil Layer Based On Field Performance Data, Yukihisa Tanaka, Mamoru Kanatani, Kiyotaka Sato, Hiroyuki Ishikawa, Tomoyoshi Takeda Mar 2001

Evaluation Of Liquefaction Potential Of Gravelly Soil Layer Based On Field Performance Data, Yukihisa Tanaka, Mamoru Kanatani, Kiyotaka Sato, Hiroyuki Ishikawa, Tomoyoshi Takeda

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

In general, gravelly soil layers are considered to be less susceptible to liquefy during earthquakes than sandy soil layers. However, in 1995 Hyogoken-Nambu Earthquake, sand ejection due to liquefaction was observed in Port Island and Rokkco Island, which were man-made islands reclaimed by gravelly soils. In this paper, firstly, site investigation including sampling by freezing technique was conducted in Rokko Island where lots of ejected sand was not observed during the earthquake to know liquefaction strengths of the reclaimed deposits. Secondly, earthquake response analyses were conducted for a site in Rokko Island as well as a site in Port Island …

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Motion Amplification In Horizontal And Vertical Components At Liquefiable Sites, Jun Yang, Tadanobu Sato, Xiang-Song Li Mar 2001

Motion Amplification In Horizontal And Vertical Components At Liquefiable Sites, Jun Yang, Tadanobu Sato, Xiang-Song Li

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

This paper describes an analytical study with the purpose to gain some new understandings of the behavior of motion amplification in both horizontal and vertical components at liquefiable sites. By using a verified, effective-stress based nonlinear procedure, a series of numerical tests of a liquefiable sand deposit subjected to simultaneous action of horizontal and vertical shaking of various levels are carried out. To account for the characteristics of near-source motion, realistic array records of strong motion due to the Kobe earthquake of 1995 are employed to produce a variety of intensities of input motion in horizontal and vertical components. An …

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Validation Of The Energy-Based Method For Evaluating Soil Liquefaction In Centrifuge, Hesham M. Dief, J. Ludwig Figueroa, Adel S. Saada Mar 2001

Validation Of The Energy-Based Method For Evaluating Soil Liquefaction In Centrifuge, Hesham M. Dief, J. Ludwig Figueroa, Adel S. Saada

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

Extensive research has been conducted at Case Western Reserve University to introduce and evaluate the energy concept in defining the liquefaction potential of soils when subjected to dynamic loads. Generalized relationships were obtained by performing regression analyses between the energy per unit volume at the onset of liquefaction and liquefaction affecting parameters. This study deals with evaluating and examining the suitability of these relationships using centrifuge modeling. Centrifuge liquefaction testing of several soils with different grain-size characteristics made it possible to evaluate the validity of the energy method in determining the liquefaction potential of a soil deposit. Dynamic centrifuge tests …

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Liquefaction-Induced Lateral Spreading And Dilative Soil Behavior, Ahmed Elgamal, Zhauhui Yang Mar 2001

Liquefaction-Induced Lateral Spreading And Dilative Soil Behavior, Ahmed Elgamal, Zhauhui Yang

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

During liquefaction, strength and stiffness degradation in sloping liquefied soil may lead to significant cycle-by-cycle shear strain accumulation. Accuracy in quantifying the magnitude of accumulated permanent shear strain is the key to satisfactory modeling of liquefaction-induced lateral spreading. Commonly used stress-space constitutive models may not be easily calibrated to reproduce the observed magnitudes of permanent shear deformation, since the shear flow phase is often accompanied by a minor change in shear stress magnitude. In a newly developed constitutive model, the observed large post-liquefaction shear-strain accumulation is accomplished by introducing a perfectly plastic zone into a multi-yield surface stress-space framework. After …

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