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  Subjects -> EARTH SCIENCES (Total: 634 journals)
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EARTH SCIENCES (462 journals)            First | 1 2 3 4 5     

Marine Geodesy     Hybrid Journal   (Followers: 2)
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Marine Geophysical Researches     Hybrid Journal   (Followers: 6)
Marine Georesources & Geotechnology     Hybrid Journal   (Followers: 1)
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Momona Ethiopian Journal of Science     Open Access   (Followers: 4)
Moscow University Geology Bulletin     Hybrid Journal  
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Mountain Research and Development     Open Access   (Followers: 3)
Natural Hazards     Hybrid Journal   (Followers: 108)
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Natural Hazards Review     Full-text available via subscription   (Followers: 9)
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Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen     Full-text available via subscription   (Followers: 3)
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Open Journal of Earthquake Research     Open Access  
Open Journal of Soil Science     Open Access   (Followers: 4)
Ore Geology Reviews     Hybrid Journal   (Followers: 3)
Organic Geochemistry     Hybrid Journal   (Followers: 7)
Osterreichische Wasser- und Abfallwirtschaft     Hybrid Journal  
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Physics of the Earth and Planetary Interiors     Hybrid Journal   (Followers: 11)
Physics of the Solid State     Hybrid Journal   (Followers: 3)
Physics of Wave Phenomena     Hybrid Journal   (Followers: 1)
Physics World     Full-text available via subscription   (Followers: 3)
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Planet     Open Access   (Followers: 1)
Plasma Physics and Controlled Fusion     Hybrid Journal   (Followers: 3)
Plasma Physics Reports     Hybrid Journal   (Followers: 2)
Polish Polar Research     Open Access   (Followers: 4)
Positioning     Open Access   (Followers: 1)
Pramana     Open Access   (Followers: 9)
Precambrian Research     Hybrid Journal   (Followers: 5)
Preview     Hybrid Journal  
Procedia Earth and Planetary Science     Open Access   (Followers: 5)
Proceedings in Marine Science     Full-text available via subscription   (Followers: 2)
Proceedings of the Geologists' Association     Full-text available via subscription   (Followers: 3)
Proceedings of the Linnean Society of New South Wales     Full-text available via subscription   (Followers: 1)
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Progress in Earth and Planetary Science     Open Access   (Followers: 1)
Pure and Applied Geophysics     Hybrid Journal   (Followers: 9)
Quarterly Journal of Engineering Geology and Hydrogeology     Hybrid Journal   (Followers: 5)
Quaternary Australasia     Full-text available via subscription  
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Rajshahi University Journal of Life & Earth and Agricultural Sciences     Open Access   (Followers: 1)
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Research & Reviews : Journal of Space Science & Technology     Full-text available via subscription   (Followers: 1)
Resource Geology     Hybrid Journal   (Followers: 4)
Reviews in Mineralogy and Geochemistry     Full-text available via subscription  
Reviews of Modern Physics     Full-text available via subscription   (Followers: 17)
Revista Boletín Ciencias de la Tierra     Open Access   (Followers: 2)
Revista Brasileira de Geofísica     Open Access   (Followers: 4)
Revista de Ingenieria Sismica     Open Access  
Revista de Teledetección     Open Access  
Revista Eletrônica Científica Inovação e Tecnologia     Open Access  
Revista Geológica de Chile     Open Access   (Followers: 2)

  First | 1 2 3 4 5     

Journal Cover   Soil Dynamics and Earthquake Engineering
  [SJR: 1.482]   [H-I: 45]   [8 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0267-7261
   Published by Elsevier Homepage  [2812 journals]
  • A simplified 3 D.O.F. model of A FEM model for seismic analysis of a silo
           containing elastic material accounting for soil–structure
           interaction
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Ayşegül Durmuş , Ramazan Livaoglu
      The purpose of this study is the evaluation of dynamic behavior induced by seismic activity on a silo system, containing bulk material, with a soil foundation. The interaction effects between the silo and bulk material, as well as the effects produced between the foundation of the silo and the soil, were taken into account. Proposed simplified approximation, as well as the finite model, were used for analysis. The results, from the presented approximation, were compared with a more rigorous obtainment method. Initially, the produced simplified approximation, with elastic material assumption for the grain, could determine the pressures on the dynamic material along with displacements along the height of the silo wall and base shear force, etc., with remarkable precision. Some comparisons, via a change of soil and/or foundation conditions, were also made regarding the seismic pressure of the dynamic material pressure, displacement and base shear forces for both squat and slender silos. Comparing the analytical predictions to results from the numerical simulations produced good results. It can be concluded that the model can be used effectively to perform a broad suite of parametric studies, not only at the design stage but also as a reliable tool for predicting system behavior under the limit state of the system. The results and comprehensive analysis show that displacement effects and base shear forces generally decreased when soil was softer; however, soil structure interaction (SSI) did not have any considerable effects on squat silos and therefore need not be taken into practice.


      PubDate: 2015-07-01T13:49:11Z
       
  • Determining anti-plane responses induced by oblique-truncated semicircular
           canyon using systematic hybrid method with mapping function
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Wen-Shinn Shyu , Tsung-Jen Teng , Chuen-Shii Chou
      This paper proposes a novel strategy for the investigation of displacement amplitude ( u y ) near and along an oblique-truncated semicircular canyon subjected to shear horizontal (SH) waves. Transfinite interpolation (TFI) was used to obtain the coordinates of nodes and determine the sequence of node numbering in the inner finite region including the canyon. The hybrid method, comprising finite element method and a Lamb series, was applied in conjunction with TFI to study the effects of canyon geometry, incident angle of SH waves ( θ ), and dimensionless frequency ( η ) on u y . We detailed the amplification of u y in the illuminated zone and variations in u y due to canyon-decay-effect along the canyon surface as well as the decay of u y resulting from the shield effect in the shadow zone. Interestingly, oblique-effects play an important role in the magnification of u y along the inclined bottom of canyons, and variations in θ and η dominate the patterns of u y .
      Graphical abstract image

      PubDate: 2015-07-01T13:49:11Z
       
  • A surface seismic approach to liquefaction
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Silvia Castellaro , Riccardo Panzeri , Flaminia Mesiti , Lara Bertello
      The liquefaction potential of soils is traditionally assessed through geotechnical approaches based on the calculation of the cyclical stress ratio (CSR) induced by the expected earthquake and the ‘resistance’ provided by the soil, which is quantified through standard penetration (SPT), cone penetration (CPT), or similar tests. In more recent years, attempts to assess the liquefaction potential have also been made through measurement of shear wave velocity (V S) in boreholes or from the surface. The latter approach has the advantage of being non-invasive and low cost and of surveying lines rather than single points. However, the resolution of seismic surface techniques is lower than that of borehole techniques and it is still debated whether it is sufficient to assess the liquefaction potential. In this paper we focus our attention on surface seismic techniques (specifically the popular passive and active seismic techniques based on the correlation of surface waves such as ReMiTM, MASW, ESAC, SSAP, etc.) and explore their performance in assessing the liquefaction susceptibility of soils. The experimental dataset is provided by the two main seismic events of M L=5.9 and 5.8 (M W=6.1, M W=6.0) that struck the Emilia-Romagna region (Northern Italy) on May 20 and 29, 2012, after which extensive liquefaction phenomena were documented in an area of 1200km2. The CPT and drillings available in the area allow us to classify the soils into four classes: A) shallow liquefied sandy soils, B) shallow non-liquefied sandy soils, C) deep non-liquefied sandy soils, and D) clayey–silty soils, and to determine that on average class A soils presented a higher sand content at the depth of 5–8m compared to class B soils, where sand was dominant in the upper 5m. Surface wave active–passive surveys were performed at 84 sites, and it was found that they were capable of discriminating among only three soil classes, since class A and B soils showed exactly the same V S distribution, and it is possible to show both experimentally and theoretically that they appear not to have sufficient resolution to address the seismic liquefaction issue. As a last step, we applied the state-of-the art CSR–V S method to assess the liquefaction potential of sandy deposits and we found that it failed in the studied area. This might be due to the insufficient resolution of the surface wave methods in assessing the Vs of thin layers and to the fact that Vs scales with the square root of the shear modulus, which implies an intrinsic lower sensitivity of Vs to the shear resistance of the soil compared to parameters traditionally measured with the penetration tests. However, it also emerged that the pure observation of the surface wave dispersion curves at their simplest level (i.e. in the frequency domain, with no inversion) is still potentially informative and can be used to identify the sites where more detailed surveys to assess the liquefaction potential are recommended.


      PubDate: 2015-07-01T13:49:11Z
       
  • Vibration control of piled-structures through
           structure-soil-structure-interaction
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Pierfrancesco Cacciola , Maria Garcia Espinosa , Alessandro Tombari
      This paper deals with the vibration control of existing structures forced by earthquake induced ground motion. To this aim it is proposed for the first time to exploit the structure–soil–structure mechanism to develop a device, hosted in the soil but detached from the structure, able to absorb part of the seismic energy so to reduce the vibration of neighbourhood structures. The design of the device is herein addressed to protect monopile structures from earthquake induced ground motion. By modelling the ground motion as zero-mean quasi-stationary response-spectrum-compatible Gaussian stochastic process, the soil as visco-elastic medium and the target monopiled-structure as a linear behaving structure the device, herein called Vibrating Barrier (ViBa), has been designed through an optimization procedure. Various numerical and experimental results are produced to show the effectiveness of the ViBa. Remarkably, a significant reduction of the structural response up to 44% has been achieved.


      PubDate: 2015-07-01T13:49:11Z
       
  • A new expression for determining the bending stiffness of circular
           micropile groups
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Keyvan Abdollahi , Alireza Mortezaei
      Increased bending stiffness and decreased foundation rotation are two main factors which reduce the rocking motion of foundation. A micropile group in circular arrangement is an innovative technique for reducing the rocking motion of the foundation. In this paper, the effects of several parameters were numerically investigated on the rocking stiffness of circular micropile group foundations. The finite difference software FLAC3D was used to model the foundation, soil, and the structure. The micropiles used in this study varied in the diameter, but had similar length. A total of seven records were selected to cover a wide range of frequency content, duration and amplitude. The results from the numerical simulation were compared and verified against those obtained from an alternative numerical method as well as a set of experimental test results. The model was then used for parametric studies and the effects of relevant parameters were investigated. The results showed that slenderness, inclination angle and distance ratio of a micropile group are main factors which increase the soil stiffness and control the seismic motion of high-rise buildings. Based on the results, a new expression was proposed that can be used to determine the optimal moment of inertia of circular micropile groups. The proposed expression revealed that the primary factors which reduce the effective period of the buildings are the number, diameter, and injection pressure of micropiles in a circular micropile group. Using the proposed relationship, it was found that using circular micropile groups can reduce the destructive seismic effects (i.e. drift demand) in high-rise buildings by up to 60%.


      PubDate: 2015-07-01T13:49:11Z
       
  • Effects of site stiffness and source to receiver distance on surface wave
           tests׳ results
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Jyant Kumar , Tarun Naskar
      By using six 4.5Hz geophones, surface wave tests were performed on four different sites by dropping freely a 65kg mass from a height of 5m. The receivers were kept far away from the source to eliminate the arrival of body waves. Three different sources to nearest receiver distances (S), namely, 46m, 56m and 66m, were chosen. Dispersion curves were drawn for all the sites. The maximum wavelength (λ max ), the maximum depth (d max ) up to which exploration can be made and the frequency content of the signals depends on the site stiffness and the value of S. A stiffer site yields greater values of λ max and d max . For stiffer sites, an increase in S leads to an increase in λ max . The predominant time durations of the signals increase from stiffer to softer sites. An inverse analysis was also performed based on the stiffness matrix approach in conjunction with the maximum vertical flexibility coefficient of ground surface to establish the governing mode of excitation. For the Site 2, the results from the surface wave tests were found to compare reasonably well with that determined on the basis of cross boreholes seismic tests.


      PubDate: 2015-07-01T13:49:11Z
       
  • Cyclic and post-cyclic monotonic behavior of Adapazari soils
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Zulkuf Kaya , Ayfer Erken
      The August 17, 1999 Kocaeli earthquake affected the city of Adapazari, which is located in the northwest of Turkey, with severe liquefaction and bearing capacity failures causing tilting of buildings, excessive settlements and lateral displacements. To understand the stress–strain behavior and pore pressure behavior of undisturbed soils during the earthquake, the cyclic and post-cyclic shear strength tests have been conducted on soil samples obtained from Adapazari in a cyclic triaxial test system within the scope of this research. Cyclic tests have been conducted under stress controlled and undrained conditions. Post-cyclic monotonic tests have been conducted following cyclic tests. The strength curves obtained in the experiments showed that the dynamic resistance of silty sand was found to be 45% lower than those of high plasticity soils (MH). The strength of clayey soils with the plasticity index of PI=15–16% was lower compared to the strength of high plasticity soils. Also, it was observed that silty sand soils had the lowest strength. The dynamic strength of the soils increased with the increase in plasticity.


      PubDate: 2015-07-01T13:49:11Z
       
  • Real-valued modal response history analysis for asymmetric-plan buildings
           with nonlinear viscous dampers
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Jui-Liang Lin , Tze-How Liu , Keh-Chyuan Tsai
      Modal analysis, which is clear in concept and simple in computation, is widely applied to evaluate the seismic responses of elastic structures with proportional damping. Nevertheless, nonlinear viscous dampers commonly installed in real buildings result in non-proportionally damped structures, which impede the modal analysis in real number field for such structures. This study develops the approach of performing real-valued modal response history analysis for elastic two-way asymmetric-plan buildings with nonlinear viscous dampers. To this end, this study first constructs the nonlinear three-degree-of-freedom (3DOF) modal equations of motion for such structures. The nonlinear 3DOF modal equations of motion retain the non-proportional damping characteristics in the modal space. Hence, by solving the nonlinear 3DOF modal equations of motion, the total response history is effectively attained by arithmetically summing up the modal response histories. This study uses nine two-way asymmetric-plan buildings, each equipped with nonlinear viscous dampers subjected to three bi-directional ground motions to verify the proposed approach. The investigation results show that the proposed simplified analysis approach provides satisfactory estimation of the seismic responses of common asymmetric-plan buildings with nonlinear viscous dampers.


      PubDate: 2015-07-01T13:49:11Z
       
  • A synthetic formulation for the Italian seismic hazard and code
           implications for the seismic risk
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): I. Vanzi , G.C. Marano , G. Monti , C. Nuti
      The paper contains two parts. In the first one, the seismic hazard on the Italian territory, as given by the current Italian structural design code, published in 2008, is discussed. Hazard curves, given by the Italian code in a tabular form, are fitted with a single non-linear model and it is shown that a more compact, simple and user-ready territorial hazard description can be applied. The model is valid for both the bedrock and the surface seismic hazards, and is accurate. The surface seismic hazard is computed with a local amplification mapping, which is now well detailed over the entire territory. Departing from these results, in the second part the territorial seismic risk for the ultimate limit state is computed via a parametric fragility curve. From the results, it can be inferred that the codes need further factors calibration, with the aims of guaranteeing both territorially uniform reliability levels, and the traditionally assumed target reliability levels, e.g. those stated in the Eurocodes.


      PubDate: 2015-07-01T13:49:11Z
       
  • Seismic assessment and retrofit of two heritage-listed R/C elevated water
           storage tanks
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Claudia Mori , Stefano Sorace , Gloria Terenzi
      A seismic assessment and advanced retrofit study on two heritage-listed reinforced concrete (R/C) elevated water storage tanks is presented in this paper. The two structures were built between the late 1920s and the early 1930s as water suppliers for a coal power plant in Santa Maria Novella Station in Florence, and are still in service. The first, taller tank has a R/C frame supporting structure and is currently used as water supplier for trains and platform services. The second, shorter tank, with a shaft-shell supporting structure, is used as water tower for the Station. The dynamic behaviour of the fluid is simulated by means of a classical convective and impulsive mass model, for which a discrete three-dimensional schematization is originally implemented in the finite element analysis. The time–history assessment enquiry highlights numerical collapse of the frame structure in the taller tank, and unsafe tensile stress states in a large portion of the shaft structure of the shorter one, under seismic action scaled at the maximum considered earthquake level. Based on these results, two retrofit hypotheses are proposed, and namely a dissipative bracing system incorporating pressurized fluid viscous spring-dampers, for the taller tank, and a base isolation system including double curved surface sliders, for the shorter one. The mechanical parameters, design criteria and technical implementation details of the two rehabilitation strategies are illustrated. The verification time–history analyses in protected conditions show that a substantial enhancement of the seismic response capacities of both structures is attained as compared to their original configurations, with little architectural intrusion, quick installation works and competitive costs.


      PubDate: 2015-07-01T13:49:11Z
       
  • Engineering behavior and correlated parameters from obtained results of
           sand–silt mixtures
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Darn-Horng Hsiao , Vu To-Anh Phan , Yi-Ting Hsieh , Hsin-Yi Kuo
      The results of an experimental study on sands with low-plastic silt content are presented. Flexible wall permeameter tests, drained and undrained triaxial compression tests, one-dimensional consolidation tests, and undrained cyclic triaxial tests were performed on specimens with a low plastic silt content of 0%, 15%, 30%, 40%, 50% and 60% by weight. The soil specimens were tested under three different categories: (1) at a constant void ratio index; (2) at the same peak deviator stress in a triaxial test; and (3) at a constant relative density. The results were observed to be somewhat different from previous studies with non-plastic silt content and plastic fine content. Cyclic triaxial tests showed that an increase in silt content causes a decrease in the cyclic resistance ratio with a silt content up to 40–50% and thereafter causes an increase in the cyclic resistance ratio with further increases in silt content. The results of triaxial tests indicated that the value of the peak deviator stress changed with different types of specimens, and the greater internal friction an angle has, the stronger is the liquefaction resistance. Flexible wall permeameter tests concluded that the saturated hydraulic conductivity slowly decreases with an increase in silt content in the range from 0% to 30% and considerably decreases with a silt content greater than 30%. A one-dimensional consolidation test postulated that increasing silt content decreases the coefficient of consolidation. In addition, the global void ratio did not appear to be a pertinent parameter in explaining the behavior of sand–silt mixtures, while fine content and intergranular void ratio were suitable parameters for explaining the behavior of sand–silt mixtures. Finally, correlated parameters from obtained results were also presented in this study.


      PubDate: 2015-07-01T13:49:11Z
       
  • Characterizing the process of liquefaction initiation in Anzali shore sand
           through critical state soil mechanics
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Amirabbas Mohammadi , Abbas Qadimi
      A series of monotonic drained and cyclic undrained triaxial tests were conducted to study the cyclic behavior of a shore sand mainly formed of silica and carbonate, under critical state soil mechanics framework. The main focus of the study was on simplifying the process of approaching to liquefaction, and predicting it using the concept of “state”. The results indicated that generation of pore water pressure from the start of cycling to liquefaction can be simplified into a bilinear-shaped trend in a semi-logarithmic space. The pore pressure response, the number of cycles needed for liquefaction and the cyclic resistance ratio were shown to depend on the initial state relative to the critical state line in space of specific volume against logarithm of mean effective stress. Analysis of the results also indicated that the bilinear trend of approaching to liquefaction and the liquefaction resistance of the soil with various densities and stress levels could be well characterized in terms of the state parameter and the cyclic stress ratio, using logarithmic, exponential and quadratic formulations. Liquefaction curves were derived in terms of the state parameter, independent of soil density and stress level.


      PubDate: 2015-07-01T13:49:11Z
       
  • A note on peak accelerations computed from sliding of objects during the
           1969 Banja Luka earthquakes in former Yugoslavia
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): M.I. Manić , B.Ð. Bulajić , M.D. Trifunac
      Peak ground accelerations, computed from sliding of objects during the 1969 Banja Luka earthquakes in Bosnia and Herzegovina (former Yugoslavia) are computed assuming that the ground motion consists of simple rectangular or sinusoidal pulses. The results show good agreement with observed macroseismic estimates of shaking based on the Mercalli–Cancani–Sieberg (MCS) intensity scale. The results are also in compliance with recorded accelerations during the 1973–1986 period and with recent probabilistic hazard analyses for the Banja Luka region.


      PubDate: 2015-07-01T13:49:11Z
       
  • Determination of traffic-load-influenced depths in clayey subsoil based on
           the shakedown concept
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): LianSheng Tang , HaoKun Chen , HaiTao Sang , SiYang Zhang , JieYi Zhang
      The determination of the depth of traffic load influence is significant for pavement and embankment design on soft soil. In this study, a method based on strain-controlled criteria is presented to estimate the depths within which the behavior of a saturated clayey subsoil is affected by cyclic traffic loads. Based on the shakedown concept, the following depths of influence can be defined: (1) the threshold depth, beyond which the dynamic effect of the traffic loads is insignificant; (2) the plastic shakedown limit depth, within which the subsoil experiences noticeable and continuous deformation; and (3) the critical failure depth, within which the soil fails due to the accumulation of strain. This method for determining the depths of influence is advantageous because it is applicable to various soil types. The data required for this method consist of vertical stress responses along the soil profile and three cyclic stress limits of the soil. Based on the development of pore pressure and the dynamic strain behaviors during undrained cyclic triaxial tests, the following cyclic stress limits of the soft clay subsoil are determined: a threshold cyclic stress ratio CSRt of 0.03, a plastic shakedown limit stress ratio CSRp of 0.33 and a critical cyclic stress ratio CSRc of 0.44. These cyclic stress limits are used to determine the corresponding depths of influence, which are then used to implement ground improvements and strengthen the dynamic carrying capacity of the road structures.


      PubDate: 2015-07-01T13:49:11Z
       
  • Nonlinear incremental analysis of fire-damaged r.c. base-isolated
           structures subjected to near-fault ground motions
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Fabio Mazza
      Amplification of structural response of r.c. base-isolated structures is expected under near-fault ground motions, yet there is a lack of knowledge of their behavior in the case of fire. To investigate the nonlinear seismic response following a fire, an incremental dynamic analysis is carried out on five-storey r.c. base-isolated framed buildings with fire-protected High-Damping-Laminated-Rubber Bearings (HDLRBs), designed in line with the Italian seismic code. Horizontal components of near-fault ground motions characterized by forward-directivity or fling-step pulse-type are considered. The nonlinear seismic response of base-isolated structures in a no fire situation is compared with that in the event of fire, at 45 (i.e. R45) and 60 (i.e. R60) minutes of fire resistance, assuming both damaged (i.e. DS) and repaired (i.e. RS) stiffness conditions. Five fire scenarios are considered assuming the fire compartment confined to the area of the first level (i.e. F1), the first two (i.e. F1/2) and the upper (i.e. Fi, i=3–5) levels, with the parametric temperature–time fire curve evaluated in accordance with Eurocode 1. The nonlinear seismic analysis is performed by using a step-by-step procedure based on a two-parameter implicit integration scheme and an initial-stress-like iterative procedure. At each step of the analysis, plastic conditions are checked at the critical (end) sections of the girders and columns, where thermal mapping with reduced mechanical properties is evaluated with the 500°C isotherm method proposed by Eurocode 2. A viscoelastic model with variable stiffness properties in the horizontal and vertical directions, depending on the axial force and lateral deformation, simulates the response of an HDLRB.


      PubDate: 2015-07-01T13:49:11Z
       
  • Seismic pressures on rigid cantilever walls retaining linear poroelastic
           soil: An exact solution
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): G.A. Papagiannopoulos , D.E. Beskos , T. Triantafyllidis
      The dynamic response of a water-saturated linear poroelastic soil layer over bedrock retained by a pair of rigid cantilever walls to a horizontal seismic excitation is obtained analytically–numerically under plane strain conditions. Hysteretic damping in the soil skeleton may also be present. The problem is solved in the frequency domain and its exact solution is obtained analytically. This is accomplished with the aid of Fourier series along the horizontal direction and solution of the resulting system of ordinary differential equations to obtain the amplitudes of the soil skeleton displacements and the pore water pressure. Soil displacements and stresses, pore water pressure as well as wall pressures and resultant forces are explicitly presented. Their variation with frequency, hysteretic damping, porosity and permeability is numerically obtained and compared against an approximate solution, to assess the degree of validity of the assumptions.


      PubDate: 2015-07-01T13:49:11Z
       
  • Ductility damage indices based on seismic performance of RC frames
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Mohammad S. Alhaddad , Khalid M. Wazira , Yousef A. Al-Salloum , Husain Abbas
      This paper presents an analytical procedure for determining ductility damage indices using static collapse mechanism analysis for ductile reinforced concrete (RC) frames subjected to prescribed drift limits corresponding to different seismic performance levels. This assessment benefits from performance-based seismic design (PBSD) concept that employs rotation ductility factors, pre-defined target damage indices and beam sidesway mechanism as key performance objectives to estimate curvature ductility demands at pre-designated plastic hinges of beam sidesway mechanism. The proposed ductility-based damage indices (DBDI) assessment procedure considers regular frames with secondary effects such as P-Delta and soil–structure interaction (SSI) within a simple non-iterative process suitable for practical applications. A 12-story RC moment frame was chosen to implement the proposed procedure considering P-Delta effect. Pushover analysis using SAP 2000 was carried out for the frame to verify the results of the DBDI method. The results show that the DBDI seismic assessment procedure can be used to quantify the damage potential at different performance levels and relate that to local flexural ductility of critical frame members. The research presented in this paper provides a simple yet conservative damage assessment tool for use by practicing engineers.


      PubDate: 2015-07-01T13:49:11Z
       
  • Experimental and numerical evaluation of the effectiveness of a stiff wave
           barrier in the soil
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): P. Coulier , V. Cuéllar , G. Degrande , G. Lombaert
      This paper discusses the design, the installation, and the experimental and numerical evaluation of the effectiveness of a stiff wave barrier in the soil as a mitigation measure for railway induced vibrations. A full scale in situ experiment has been conducted at a site in El Realengo (Spain), where a barrier consisting of overlapping jet grout columns has been installed along a railway track. This barrier is stiff compared to the soil and has a depth of 7.5m, a width of 1m, and a length of 55m. Geophysical tests have been performed prior to the installation of the barrier for the determination of the dynamic soil characteristics. Extensive measurements have been carried out before and after installation of the barrier, including free field vibrations during train passages, transfer functions between the track and the free field, and the track receptance. Measurements have also been performed at a reference section adjacent to the test section in order to verify the effect of changing train, track, and soil conditions over time. The in situ measurements show that the barrier is very effective: during train passages, a reduction of vibration levels by 5dB is already obtained from 8Hz upwards, while a peak reduction of about 12dB is observed near 30Hz immediately behind the barrier. The performance decreases further away from the jet grouting wall, but remains significant. The experimental results are also compared to numerical simulations based on a coupled finite element–boundary element methodology. A reasonable agreement between experiments and predictions is found, largely confirming the initially predicted reduction. This in situ test hence serves as a ‘proof of concept׳, demonstrating that stiff wave barriers are capable of significantly reducing vibration levels, provided that they are properly designed.


      PubDate: 2015-07-01T13:49:11Z
       
  • Numerical modeling of the dynamic lateral behavior of
           geosynthetics-reinforced pile foundation system
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Ahmed Taha , M. Hesham El Naggar , Alper Turan
      This paper presents a finite-element (FE) analysis for simulating the dynamic performance of geosynthetics-reinforced pile foundation system. The (FE) models were constructed using commercial FE program Plaxis 3D Dynamic. The numerical models were verified against the results of a reduced scale model test of geosynthetics-reinforced pile foundation system. A numerical parametric study was carried out to investigate the effect of different design parameters on the effectiveness of the proposed geosynthetics-reinforced pile foundation system. The studied parameters include: the frequency and amplitude of ground motion; the stiffness and strength of the geosynthetic reinforcement, the location of the reinforcement within the backfill material and the thickness of the backfill material. The numerical results indicated that the geosynthetics-reinforcement greatly reduced the maximum lateral acceleration response of the pile cap.


      PubDate: 2015-07-01T13:49:11Z
       
  • Bound of earthquake input energy to building structure considering shallow
           and deep ground uncertainties
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): M. Taniguchi , I. Takewaki
      The bound of earthquake input energy to building structures is clarified by considering shallow and deep ground uncertainties and soil–structure interaction. The ground motion amplification in the shallow and deep ground is described by a one-dimensional wave propagation theory. The constant input energy property to a swaying–rocking model with respect to the free-field ground surface input regardless of the soil property is used effectively to derive a bound. An extension of the previous theory for the engineering bedrock surface motion to a general earthquake ground motion model at the earthquake bedrock is made by taking full advantage of the above-mentioned input energy constant property. It is shown through numerical examples that a tight bound of earthquake input energy can be derived for the shallow and deep ground uncertainties.


      PubDate: 2015-07-01T13:49:11Z
       
  • Numerical modelling of drop load tests
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): R. Colombero , S. Kontoe , S. Foti , D.M. Potts
      Assessment of the attenuation of induced vibrations in the ground plays an important role in evaluating comfort and structural safety. Analytical and empirical wave attenuation relationships of increasing complexity and detail are presented in the paper, as well as a numerical model that accurately reproduces wave attenuation for a well-documented site, namely the one of the Tower of Pisa, Italy. A new source model is calibrated on near-field data and used as input for the dynamic coupled consolidation finite element analysis to achieve a satisfactory simulation. The accuracy of simpler analytical and empirical approaches is then comprehensively assessed through comparison with the validated numerical model and the field data obtained from geophones at various distances from the impact source.


      PubDate: 2015-07-01T13:49:11Z
       
  • Pre-shear effect on liquefaction resistance of a Fujian sand
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Bin Ye , Jiafeng Lu , Guanlin Ye
      Pre-shear history has been shown to be a critical factor in the liquefaction resistance of sand. By contrast to prior experimental studies in which triaxial shear tests were used to examine the effects of pre-shear on the liquefaction resistance of sand, hollow cylinder torsional shear tests were used in this study to avoid the influence of the inherent anisotropy that is inevitably produced during the sample preparation process because of gravitational deposition. A series of cyclic undrained shear tests were performed on sand samples that had experienced medium to large pre-shear loading. The test results showed that the liquefaction resistance of sand can be greatly reduced by its pre-shear history, and a pre-shear strain within the range from 0.1% to 5% can cause sand to be more prone to liquefaction. During the cyclic shear tests, the samples that had experienced pre-shear loading exhibited different behaviors when cyclic shear loading started in different directions, i.e., the clockwise direction and the counterclockwise direction. If the cyclic loading started in the identical direction as the pre-shear loading, then the mean effective stress of the sand was almost unchanged during the first half of the loading cycle; if the cyclic loading started in the direction opposite to that of the pre-shear loading, then the mean effective stress decreased significantly during the first half of the loading cycle. However, this anisotropic behavior was only remarkable during the first loading cycle. From the second cycle onward, the speeds of the decrease in the mean effective stresses in the two types of shear tests became similar.


      PubDate: 2015-07-01T13:49:11Z
       
  • Vertical vibration of an elastic pile embedded in poroelastic soil
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Changjie Zheng , George P. Kouretzis , Scott W. Sloan , Hanlong Liu , Xuanming Ding
      We present an analytical study on the vertical vibration of an elastic pile embedded in poroelastic soil. The poroelastic soil is divided into a homogeneous half-space underlying the pile base and a series of infinitesimally thin independent layers along its shaft. The dynamic interaction problem is solved by extending a method originally proposed for an embedded rigid foundation. The validity of the derived solution is verified via comparison with existing solutions. Arithmetical examples are used to demonstrate the sensitivity of the vertical pile impedance to the relative rigidity of the two soil parts.


      PubDate: 2015-07-01T13:49:11Z
       
  • Seismic response of high plasticity clays during extreme events
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Juan M. Mayoral , Ernesto Castañon , Neftalí Sarmiento
      Mexico City high plasticity clays exhibit a small degree of nonlinearity for shear strains as large as 0.1%, which leads to both moderate shear stiffness degradation and small to medium damping increment, even for long duration subduction strong ground motions, such as the 8.1M w 1985Michoacan earthquake. Nonetheless, current seismic design criteria of strategic infrastructure used worldwide have striven for having larger return periods for establishing the seismic environment, considering recent large magnitude (M>8.5M w) events. This paper presents the study of the seismic response of typical high plasticity clays found in the so-called Texcoco Lake, in the surrounding of Mexico City valley, for larger to extreme earthquakes. The shear wave velocity profile was characterized using a down-hole test. The seismic environment was established from a set of uniform hazard response spectra developed for a nearby rock outcrop for return periods of 125, 250, 475 and 2475 years. A time-domain spectral matching was used to develop acceleration time histories compatible with each uniform hazard response spectrum. Both frequency and time domain site response analyses were carried out considering each seismic scenario. Ground nonlinearities were clearly observed in the soil response during extreme ground shaken, which increases rapidly with the return period. This fact must be taken into account to avoid costly and potentially unsafe seismic designs.
      Graphical abstract image

      PubDate: 2015-07-01T13:49:11Z
       
  • Theoretical modeling and numerical simulation of seismic motions at
           seafloor
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Chao Li , Hong Hao , Hongnan Li , Kaiming Bi
      This paper proposes a modeling and simulation method of seafloor seismic motions on offshore sites, which are composed of the base rock, the porous soil layers and the seawater layer, based on the fundamental hydrodynamics equations and one-dimensional wave propagation theory. The base rock motions are assumed to consist of P- and S-waves and are modeled by the seismological model in southwest of Western Australia (SWWA). The transfer functions of the offshore site are calculated by incorporating the derived dynamic-stiffness matrix of seawater layer into the total stiffness matrix. The effect of water saturation on the P-wave velocity and Poisson׳s ratio of subsea soil layers are considered in the model. Both onshore and seafloor seismic motions are stochastically simulated. The comparison results show that the seafloor vertical motions are significantly suppressed near the P-wave resonant frequencies of the upper seawater layer, which makes their intensities much lower than the onshore vertical motions. The simulated seafloor motions are in compliance with the characteristics of available seafloor earthquake recordings and can be used as inputs in the seismic analyses of offshore structures.


      PubDate: 2015-07-01T13:49:11Z
       
  • Numerical prediction of ground vibrations induced by high-speed trains
           including wheel–rail–soil coupled effects
    • Abstract: Publication date: October 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 77
      Author(s): Guangyun Gao , Jian Song , Gongqi Chen , Jun Yang
      A simplified analytical model including the coupled effects of the wheel–rail–soil system and geometric irregularities of the track is proposed for evaluation of the moving train load. The wheel–rail–soil system is simulated as a series of moving point loads on an Euler–Bernoulli beam resting on a visco-elastic half-space, and the wave-number transform is adopted to derive the 2.5D finite element formulation. The numerical model is validated by published data in the literature. Numerical predictions of ground vibrations by using the proposed method are conducted at a site on the Qin-Shen Line in China.


      PubDate: 2015-07-01T13:49:11Z
       
  • Editorial Board / Aims and Scope
    • Abstract: Publication date: September 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 76




      PubDate: 2015-07-01T13:49:11Z
       
  • Forward to: Recent development of earthquake engineering and soil dynamics
           for large-scale infrastructure
    • Abstract: Publication date: September 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 76
      Author(s): Xianzhang Ling , Xiuli Du , Yunmin Chen , Hanlong Liu , Quan Gu , Gang Wang



      PubDate: 2015-07-01T13:49:11Z
       
  • Seismic response of a pile-supported excavation on Santiago gravel
    • Abstract: Publication date: September 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 76
      Author(s): E. Sáez , G.S. Pardo , C. Ledezma
      Non-secant anchored piling support is one of the most frequent earth-retaining systems for temporary deep excavations in Santiago, Chile. The main advantages of using non-secant piling support are their relatively low cost and ease of installation. This system is particularly efficient on stiff soils with deep groundwater table, conditions usually found in Santiago. This paper presents the results of a numerical investigation aimed to study the characteristics of earthquake-induced lateral pressures on a recent pile-supported excavation 26m deep. The estimated static deformations of the piles were compared against some measurements performed during the excavation. The dynamic pressures, and their influence on the piles׳ internal forces, were evaluated using a synthetic Ricker wavelet in the numerical FE model. Two kinds of FE models were developed, an approximate 2D-plain strain model and a fully 3D model. The accuracy of the 2D model on predicting static and dynamic lateral pressures was also investigated.


      PubDate: 2015-07-01T13:49:11Z
       
  • Shaking-table tests and numerical simulations on a subway structure in
           soft soil
    • Abstract: Publication date: September 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 76
      Author(s): Chen Guoxing , Chen Su , Zuo Xi , Du Xiuli , QI Chengzhi , Wang Zhihua
      Shaking table tests were performed to investigate the damage mechanisms of a subway structure in soft soil while experiencing strong ground motions. The seismic responses of the structure and soil were found to be more sensitive to input motions with richer low-frequency components. The excess pore pressure ratio of soil increased slightly, and the distribution of the excess pore pressure surrounding the structure showed clear spatial effects. The frequency spectrum characteristics of input ground motions clearly influenced the lateral displacement of the structure. In addition, the structure was most severely damaged at the top or the bottom of the interior columns. Finite element analyses were conducted by using the modified Martin–Seed–Davidenkov viscoelastic and the rate-independent plastic-damage constitutive models for soil and concrete, respectively. Satisfactory agreement was observed between the simulation and test results, the difference between these results was discussed in detail. The results provide insight into how the characteristics of strong ground motion might influence and present a simplified analysis method to quantitatively evaluate the damage of subway structures in soft soil.


      PubDate: 2015-07-01T13:49:11Z
       
  • Track and ground vibrations generated by high-speed train running on
           ballastless railway with excitation of vertical track irregularities
    • Abstract: Publication date: September 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 76
      Author(s): Xuecheng Bian , Hongguang Jiang , Chao Chang , Jing Hu , Yunmin Chen
      Track irregularities generated during the running service of high-speed railways aggravate vibrations of the track and the surrounding ground environment. To better understand the propagation of vibrations induced by high-speed train running on irregular tracks, a 2.5-dimensional (2.5D) finite element model combining with thin-layer elements was applied to establish a vehicle–track–foundation coupled dynamic analysis model. A quarter-car model was used to derive the equation for wheel–rail interaction force considering track irregularity. The track structure and the underlying foundation were simulated using the 2.5D finite element model, and the subsoil boundary was simulated using thin-layer elements. Compared with the field measurements of the Beijing–Shanghai high-speed railway, the reliability of the established numerical model in analyzing vibration response was verified. A spectrum analysis of the response data obtained from the field measurements reveals that for a newly constructed high-speed railway, track alignment is in good condition due to the operation of grinding and leveling, and vehicle parameters dominate the vibration response of the track structure. Then influences of track irregularities of four typical wavelengths on the vibrations of the track and the surrounding ground environment were investigated. It is found that track irregularities of smaller wavelengths induce higher vibration frequencies and significantly higher vibration responses from the track and the ground compared to track irregularities of longer wavelengths. However, the low-frequency vibrations induced by the latter propagate to a longer distance compared to the former. The critical velocity of the ballastless slab track–ground system is greater than the Rayleigh wave velocity of the soft layer of the subsoil. When train speed is lower than the critical velocity, track irregularity substantially affects the vibrations of the track and the surrounding ground. When the train speed exceeds that critical velocity, the ground vibration is determined by the train wheel weight.


      PubDate: 2015-07-01T13:49:11Z
       
  • A practical and efficient coupling method for large scale
           soil–structure interaction problems
    • Abstract: Publication date: September 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 76
      Author(s): Surong Huang , Ozgur Ozcelik , Quan Gu
      A practical and efficient coupling method for performing nonlinear static pushover or time history analysis for soil–structure interaction (SSI) systems is presented. The method combines the advantages of efficient analysis of a half-space soil medium represented as discrete filters and powerful modeling capabilities of finite element analysis (FEA) software for large scale nonlinear structural systems, thus is potentially useful for solving large scale realistic civil infrastructure problems. The boundary conditions of displacement continuity and force equilibrium between soil and structure are satisfied by using Newton׳s method. The coupling between the two substructures is based on a real-time data communication technique called the client–server (CS) integration technique. A comprehensive study is made regarding the newly developed coupling method by using a single- and a multi- degree of freedom structure and soil systems, as well as a real world SSI example. Several details are discussed, including the effect of simulation time step sizes, comparison of implicit and explicit methods, effects of increasing nonlinearity in the SSI system, and the nonlinear seismic responses of the SSI systems in cases of considering vs. not considering SSI effect. This paper proposes a practical and efficient method for nonlinear static pushover or seismic analysis of large scale SSI systems, and part of the research results provides valuable insight for engineering practice.


      PubDate: 2015-07-01T13:49:11Z
       
  • Fines-content effects on liquefaction hazard evaluation for infrastructure
           in Christchurch, New Zealand
    • Abstract: Publication date: September 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 76
      Author(s): B.W. Maurer , R.A. Green , M. Cubrinovski , B.A. Bradley
      To assess soil liquefaction hazards for civil infrastructure, several competing liquefaction evaluation procedures (LEPs) are used to estimate the potential for liquefaction triggering, often for use in a liquefaction potential index (LPI) framework. However, due to the relatively uncertain effects of fines-content (FC) on liquefaction behavior, LPI hazard assessments may be less accurate at sites with high FC. Accordingly, this study investigates “fines-content effects” on the accuracy of LPI hazard assessment during the 2010–2011 Canterbury Earthquake Sequence (CES). These effects are resolved into: (1) criteria based on the soil-behavior-type index (I c ) for identifying liquefaction-susceptible soils; (2) FC-corrections inherent to each LEP, used to adjust liquefaction resistance for the presence of fines; and (3) the potential for non-liquefied, high-FC soils to inhibit liquefaction manifestation. This investigation is performed using 7000 liquefaction case studies from the CES, wherein LPI hazard assessments computed with the Robertson and Wride [50], Moss et al. [41], and Idriss and Boulanger [30] LEPs are compared to field observations. For the assessed dataset, LPI hazard assessments were significantly and uniformly less accurate at sites with silty and clayey soil mixtures. For these sites, the existing LPI framework has inherent limitations, such that all LEPs produce erroneous hazard assessments. In particular, the capacity of plastic soils to inhibit liquefaction manifestation by affecting pore pressure development and redistribution should be further evaluated.


      PubDate: 2015-07-01T13:49:11Z
       
  • Response of a RC pile behind quay wall to liquefaction-induced lateral
           spreading: A shake-table investigation
    • Abstract: Publication date: September 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 76
      Author(s): Liang Tang , Xianzhang Ling , Xiaoyu Zhang , Lei Su , Chunhui Liu , Hui Li
      Response of pile foundations to liquefaction-induced lateral spreading still continues to be a complex problem. A shake-table experiment was carried out to explore the response of a reinforced concrete pile behind a sheet-pile quay wall due to liquefaction-induced lateral soil flow. The quay wall was used to trigger liquefaction-induced large lateral ground deformation. The representative features of the pile and the soil are recorded and analyzed. Particular attention is paid to monotonic lateral pile response. A pressure distribution scenario with a triangular lateral pressure from the non-liquefied crust layer and a uniform lateral pressure from the upper liquefied stratum was proposed. A simplified analytical model based on the classical equation for beam on elastic foundation was adopted to evaluate nonlinear behavior of the pile. On this basis, the model was calibrated to represent the experimental observations. Then, key parameters influencing nonlinear pile response were determined. The simulations demonstrated that the model underestimates lateral pile deformation and negligibly influences the moments when linear pile behavior was assumed. Larger pile diameter while holding a constant stiffness could greatly increase the moments and displacements of the pile. Nevertheless, the axial force from the superstructure has a tendency to increase the pile responses to a certain extent. This study further enhances the current understanding of the pile behavior under lateral spreading. Finally, additional large-scale experimental studies are needed in order to provide more data for calibration of soil flow pressure and evaluate inelastic response of piles due to lateral spreading of liquefied soils.


      PubDate: 2015-07-01T13:49:11Z
       
  • Physical modeling of lateral spreading induced by inclined sandy
           foundation in the state of zero effective stress
    • Abstract: Publication date: September 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 76
      Author(s): Yumin Chen , Chengxiang Xu , Hanlong Liu , Wengang Zhang
      The state of zero effective stress is a situation at which the effective stress of saturated sand decreases to zero in the process of liquefaction. In the state of zero effective stress, sand particles suspend in water and the foundation is vulnerable to much large lateral deformation. The state of zero effective stress can be achieved through dynamic loading tests, but the obtained state is difficult to sustain a steady situation. To simulate the suspended sand in water under fully liquefied condition, plastic sand, characterized by small specific gravity, is used instead of quartz sand to build an inclined foundation. Salt water with similar density is used to pass in slowly near bottom of the foundation. As observed in tests, the plastic sand is able to suspend in sodium chloride solution (salt water) of a specific density and thus this model can be used to simulate the lateral spreading of a foundation under zero effective stress state. Lateral deformation occurs within a certain depth beneath the ground and the magnitude increases from the bottom up, showing nonlinear behaviors. This paper presents a physical modeling approach for achieving the state of zero effective stress under static laboratory condition.


      PubDate: 2015-07-01T13:49:11Z
       
  • Seismic dynamics of offshore breakwater on liquefiable seabed foundation
    • Abstract: Publication date: September 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 76
      Author(s): Jianhong Ye , Gang Wang
      Offshore structures, such as composite breakwaters, are generally vulnerable to strong seismic wave propagating through loose or medium-dense seabed foundation. However, the seismically induced failure process of offshore structures is not well understood. In this study, seismic dynamics of a composite breakwater on liquefiable seabed foundation is investigated using a fully coupled numerical model FSSI-CAS 2D. The computation results show that the numerical model is capable of capturing a variety of nonlinear interaction phenomena between the composite breakwater and its seabed foundation. The numerical investigation demonstrates a three-stage failure process of the breakwater under seismic loading. In this process, the far-field seabed can become fully liquefied first, inducing excessive settlement of the structure, followed by significant lateral movement and tilting of the structure when the near-field soil progressively liquefies. The study demonstrates great promise of using advanced numerical analysis in geotechnical earthquake design of offshore structures.


      PubDate: 2015-07-01T13:49:11Z
       
  • Measurement of small strain shear modulus of clean and natural sands in
           saturated condition using bender element test
    • Abstract: Publication date: September 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 76
      Author(s): Yuanqiang Cai , Quanyang Dong , Jun Wang , Chuan Gu , Changjie Xu
      Bender element (BE) tests of saturated sand have increased interest to researchers currently. However, the measurement of small strain modulus from BE tests shows large difference between saturated and dry conditions. In this study, BE tests of a type of clean sand (Fujian sand) and two types of natural sands (Hangzhou sand and Nanjing sand) were performed. For the purposes of comparison, resonant column (RC) test and torsional shear (TS) test were also carried out on the same specimen. The factors that influence the determination of the travel time of shear wave in BE tests are discussed and a reliable method for the determination of the shear-wave velocity is obtained. It is found that the shear-wave velocities V s of saturated Fujian sand (clean sand) and Hangzhou sand (natural sand) obtained from BE tests are 5–10% greater than those obtained from RC and TS tests. However, the V s of saturated Nanjing sand (natural sand) obtained from BE, RC and TS tests show good agreement with a maximum difference of about 3%. Sands with various fines contents were also tested in an attempt to explain the differences between the two saturated natural sands. Biot׳s theory accounting for the dispersion of shear wave was employed to interpret the results of BE tests. The results indicate that the fines content of natural sand plays an important effect on the hydraulic conductivity, which affects the relative motion between soil particles and fluid when a high frequency shear wave propagates in the specimen. Based on this, a method for the determination of small strain shear modulus in BE test was proposed for both saturated clean sands and natural sands.


      PubDate: 2015-07-01T13:49:11Z
       
  • Dynamic shear modulus and damping ratio of frozen compacted sand subjected
           to freeze–thaw cycle under multi-stage cyclic loading
    • Abstract: Publication date: September 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 76
      Author(s): X.Z. Ling , F. Zhang , Q.L. Li , L.S. An , J.H. Wang
      Frozen soil plays an important role on the stability of railway and highway subgrade in cold regions. However, the dynamic properties of frozen soil subjected to the freeze–thaw cycles have rarely been investigated. In this study, cryogenic cyclic triaxial tests were conducted on frozen compacted sand from Nehe, Heilongjiang Province in China which was subjected to the closed-system freeze–thaw cycles. A modified Hardin hyperbolic model was suggested to describe the backbone curves. Then, dynamic shear modulus and damping ratio versus cyclic shear strain were analyzed under the different freeze–thaw cycles, temperatures, initial water contents, loading frequencies and confining pressures. The results indicate that the freeze–thaw process plays a significant effect on the dynamic shear modulus and damping ratio, which slightly change after one freeze–thaw cycle. Dynamic shear modulus increases with increasing initial water content, temperature, loading frequency and confining pressure. Damping ratio increases with increasing initial water content, while decreases with increasing temperature and loading frequency. The effect of confining pressure on the damping ratio was found not significant. Furthermore, the empirical expressions were formulated to estimate dynamic shear modulus and damping ratio of the frozen compacted sand. The results provide guidelines for evaluating the infrastructures in cold regions.


      PubDate: 2015-07-01T13:49:11Z
       
  • Seasonal differences in seismic responses of embankment on a sloping
           ground in permafrost regions
    • Abstract: Publication date: September 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 76
      Author(s): Shuangyang Li , Yuanming Lai , Mingyi Zhang , Wenbing Yu
      Because of its direct influence on the amount of unfrozen water and on the strength of intergranular ice in a frozen soil, temperature has a significant effect on all aspects of the mechanical behavior of the active layer in which temperature fluctuates above and below 0°C. Hence seismic responses of engineering structures such as embankment on a sloping ground in permafrost regions exhibit obvious differences with seasonal alternation. To explore the distinctive seismic characteristics of a railway embankment on the sloping ground in permafrost regions, a coupled water-heat-dynamics model is built based on theories of heat transfer, soil moisture dynamics, frozen soil mechanics, soil dynamics, and so on. A well-monitored railway embankment on a sloping ground in Qinghai–Tibet Plateau is taken as an example to simulate seismic responses in four typical seasons in the 25th service year. The numerical results show that seismic acceleration, velocity and displacement responses are significantly different in four typical seasons, and the responses on October 15 are much higher among the four seasons. When the earthquake is over, there are still permanent differential deformations in the embankment and even severe damages on the left slope on October 15. Therefore, this position should be monitored closely and repaired timely to ensure safe operation. In addition, the numerical model and results may be a reference for maintenance, design and study on other embankments in permafrost regions.


      PubDate: 2015-07-01T13:49:11Z
       
  • Simulation of broadband seismic ground motions at dam canyons by using a
           deterministic numerical approach
    • Abstract: Publication date: September 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 76
      Author(s): Chun-Hui He , Jin-Ting Wang , Chu-Han Zhang , Feng Jin
      As a deterministic numerical approach for simulation of earthquake ground motions, the spectral element method (SEM) is applied to generate a broadband acceleration array for dam-canyons instead of the traditional empirical or stochastic methods. Specifically, the SEM analysis model with an extra fine mesh is used for the Pacoima Canyon to simulate the entire path starting from earthquake source rupture via the propagation medium to the local site. The source and the 3D earth model (velocity structure) are validated through the modeling of the Newhall earthquake on 28 October 2012 at a frequency of up to 8Hz. Subsequently, the San Fernando earthquake records on 13 January 2001 are further used to study the effects of propagation path in simulation. Finally, the spatially varying ground motions at the Pacoima Canyon are obtained for different source mechanisms. The results show that the source mechanism and the local site topography significantly affect the distribution of the peak accelerations along the canyon.
      Graphical abstract image

      PubDate: 2015-07-01T13:49:11Z
       
  • Geotechnical aspects and seismic damage of the 156-m-high Zipingpu
           concrete-faced rockfill dam following the Ms 8.0 Wenchuan earthquake
    • Abstract: Publication date: September 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 76
      Author(s): Jian-Min Zhang , Zeyan Yang , Xizhang Gao , Jianhong Zhang
      Damage to the Zipingpu concrete-faced rockfill dam (CFRD) with the maximum height of 156m was induced by the great May 12, 2008 Wenchuan earthquake with a magnitude of Ms 8.0. The dam is the first CFRD over 150m high experiencing the strong shallow earthquake of IX degree in the world. The seismic damage to the dam raised a number of questions concerning the safety of the dam as well as the adequacy of design criteria. Extensive investigation has been carried out accordingly and is summarized in this paper. The purpose of this paper is to document geotechnical aspects of the design and seismic damage during earthquake, and in particular to highlight key experiences and lessons learned. Analysis of the instrumental records during the earthquake and results of the subsequent surveys following the quake yield three key conclusions as follows. (1) The earthquake motion mainly caused significant seismic non-uniform deformation of the embankment and damage to the face slabs, structures on the crest and downstream stone masonry. The predominantly longitudinal seismic motion intensified the interaction between the embankment and the abutments. The seismic deformation of the embankment and the strong interaction between the abutments and embankment were believed to have been responsible for damage to face slabs. Seepage through the dam increased, but was not significant, due to water-seal damage in the concrete face and peripheral joints. In general, the damage to the dam, although serious in some parts, was minor as a whole and was reparable. (2) Several design considerations contributed to the safety of the Zipingpu dam. Shallow-angle slopes on the downstream dam face were used to enhance the stability of the dam. Most significantly, the adequate zoning and well-compacted rockfill enabled effective deformation control of the embankment, thus greatly reducing the seismic deformation during ground shaking and ensuring the safety of the seepage control system. The performance of the Zipingpu dam during the earthquake evidenced the success of the design. (3) Overall, the Zipingpu CFRD was structurally stable and safe even though it was subjected to seismic shaking at a greater magnitude than the design seismicity. High CFRDs are feasible in seismic regions of western China if adequate design considerations are implemented to alleviate as much damage as possible during major earthquakes.


      PubDate: 2015-07-01T13:49:11Z
       
  • Editorial Board / Aims and Scope
    • Abstract: Publication date: August 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 75




      PubDate: 2015-07-01T13:49:11Z
       
  • The near-field method for dynamic analysis of structures on soft soils
           including inelastic soil–structure interaction
    • Abstract: Publication date: August 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 75
      Author(s): M. Ghandil , F. Behnamfar
      The problem of soil–structure interaction analysis with the direct method is studied. The direct method consists of explicitly modeling the surrounding soil to bedrock and the structure resting on the soil. For the soil medium, usually the traditional equivalent linear method with a reduced shear modulus and an increased damping ratio for the soil is used. However, this method does not work in the vicinity of foundation where the soil behavior is highly nonlinear because of presence of large strains. This research proposes a modified equivalent linear method with a further reduction of the soil shear modulus in the near-field of foundation that results in validity of using the equivalent linear method throughout. For regular short, intermediate and tall structures resting on such soft soils, a series of dynamic time-history analysis is implemented using earthquake records scaled to a sample design spectrum and the nonlinear structural responses are compared for different assumptions of soil behavior including the elasto-plastic Mohr–Coulomb, the traditional equivalent linear, and the proposed modified equivalent linear method. This analysis validates the proposed method.


      PubDate: 2015-07-01T13:49:11Z
       
  • Bayesian analysis on earthquake magnitude related to an active fault in
           Taiwan
    • Abstract: Publication date: August 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 75
      Author(s): J.P. Wang , Su-Chin Chang , Yih-Min Wu , Yun Xu
      It is understood that sample size could be an issue in earthquake statistical studies, causing the best estimate being too deterministic or less representative derived from limited statistics from observation. Like many Bayesian analyses and estimates, this study shows another novel application of the Bayesian approach to earthquake engineering, using prior data to help compensate the limited observation for the target problem to estimate the magnitude of the recurring Meishan earthquake in central Taiwan. With the Bayesian algorithms developed, the Bayesian analysis suggests that the next major event induced by the Meishan fault in central Taiwan should be in M w 6.44±0.33, based on one magnitude observation of M w 6.4 from the last event, along with the prior data including fault length of 14km, rupture width of 15km, rupture area of 216km2, average displacement of 0.7m, slip rate of 6mm/yr, and five earthquake empirical models.


      PubDate: 2015-07-01T13:49:11Z
       
  • Estimation of liquefaction potential from dry and saturated sandy soils
           under drained constant volume cyclic simple shear loading
    • Abstract: Publication date: August 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 75
      Author(s): M.Murat Monkul , Cihan Gültekin , Müge Gülver , Özge Akın , Ece Eseller-Bayat
      Understanding the liquefaction mechanism of sandy soils still remains as one of the challenges in geotechnical earthquake engineering, since clean sands, silty sands and clayey sands do not necessarily show identical reactions under seismic loading. This study investigates the cyclic simple shear responses of three sandy soils: clean sand (Sile Sand 20/55), silty sand (Sile Sand 20/55 with 10% IZ silt) and clayey sand (Sile Sand 20/55 with 10% kaolin) based on many dry and saturated specimens. Drained constant volume cyclic simple shear tests on clean and silty sand specimens have shown that liquefaction potential of those soils could also be determined via dry samples. This is an important observation, since dry specimens are much easier to prepare and less time consuming compared to their saturated counterparts, as the demanding saturation process is eliminated. However, cyclic responses of dry and saturated clayey sand specimens were shown to be quite different, and therefore saturation of these specimens is still a must for liquefaction assessment. For both silt and kaolin, adding 10% fines to the base sand increased the liquefaction potential of resulting sandy soils considerably compared to the clean sand at the same void ratio. But this difference relatively decreased as the specimens became looser.


      PubDate: 2015-07-01T13:49:11Z
       
  • Characterisation of shear wave velocity profiles of non-uniform bi-layer
           soil deposits: Analytical evaluation and experimental validation
    • Abstract: Publication date: August 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 75
      Author(s): Maria Giovanna Durante , Dimitris Karamitros , Luigi Di Sarno , Stefania Sica , Colin A. Taylor , George Mylonakis , Armando Lucio Simonelli
      A crucial aspect of physical geotechnical model tests (under both 1-g and n-g conditions) is the evaluation of the initial (low-strain) stiffness of the soil layers of the sample test deposit, especially in the case of coarse materials. While for uniform soil deposits this issue can be addressed in a straightforward manner, e.g. by determining the fundamental frequency through the transfer function of an applied white-noise excitation, the problem becomes cumbersome for multi-layered deposits. After reviewing a number of available theoretical solutions, this paper illustrates a simplified yet reliable analytical procedure for determining the shear wave velocity profile (V s) in a single or bi-layer deposit, taking into account the inhomogeneity of the individual soil layers, under the hypothesis of vanishing shear modulus at ground surface. The fundamental natural frequency of the inhomogeneous bi-layer deposit is analysed using the Rayleigh quotient procedure. The associated shape function is evaluated by considering the equilibrium of the soil column under a pseudo-static lateral inertial excitation imposed at its base, accounting for both layering and inhomogeneity. A validation of the proposed method is provided by comparing numerical results obtained from both time- and frequency- domain analyses against experimental data on Leighton Buzzard sand, from a recently-completed research project conducted on the shaking table facility at BLADE Laboratory, University of Bristol (UK).


      PubDate: 2015-07-01T13:49:11Z
       
  • A simplified analysis model for determining the seismic response of buried
           steel pipes at strike-slip fault crossings
    • Abstract: Publication date: August 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 75
      Author(s): E. Uckan , B. Akbas , J. Shen , W. Rou , F. Paolacci , M. O’Rourke
      The seismic response analysis of buried pipelines at fault crossings is a complex problem requiring nonlinear 3D soil-structure and large deformation analyses. Such analyses are computationally expensive and the results are hard to evaluate. Therefore, a simple numerical model is needed for engineering and design offices to determine the seismic demand of steel pipes at fault crossings. This paper presents a simplified numerical model for buried steel pipes crossing strike-slip faults and oriented perpendicular to the fault. Two pipes with different diameter to thickness (D/t) ratios and steel grades are used in the study. The proposed model permits plastic hinge formations in the pipe due to incrementally applied fault movements, allows determination of the critical length of the pipeline and measure strains developed on the tension and compression sides in the pipe. The model also considers the effect of bending as well as axial strains due to stretching.


      PubDate: 2015-07-01T13:49:11Z
       
  • Development of an empirical correlation for predicting shear wave velocity
           of Christchurch soils from cone penetration test data
    • Abstract: Publication date: August 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 75
      Author(s): Christopher R. McGann , Brendon A. Bradley , Merrick L. Taylor , Liam M. Wotherspoon , Misko Cubrinovski
      Following the companion study of McGann et al. [1], seismic piezocone (SCPTu) data compiled from sites in Christchurch, New Zealand area are used with multiple linear regression to develop a Christchurch-specific empirical correlation for use in predicting soil shear wave velocities, V s , from cone penetration test (CPT) data. An appropriate regression functional form is selected through an evaluation of the residuals for regression models developed with the Christchurch SCPTu database using functional forms adopted by previous empirical correlations between V s and CPT data. An examination of how the residuals for the chosen regression form vary with the predictor variables identifies the need for non-constant depth variance in the regression model. The performance of the model is assessed through comparisons of predicted and observed V s profiles and through forward predictions with synthetic CPT data. The new CPT–V s correlation provides a method to estimate V s from CPT data that is specific to the non-gravel soils of the Christchurch region in their current state (caution should be used for western portions of the Springston Formation where SCPTu data were sparse). The correlation also enables the utilization of the large, high-density database of CPT logs ( > 15 , 000 as of 1/1/2014) in the Christchurch region for the development of both site-specific and region-wide models of surficial V s for use in site characterization and site response analysis.


      PubDate: 2015-07-01T13:49:11Z
       
  • Applicability of existing empirical shear wave velocity correlations to
           seismic cone penetration test data in Christchurch New Zealand
    • Abstract: Publication date: August 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 75
      Author(s): Christopher R. McGann , Brendon A. Bradley , Merrick L. Taylor , Liam M. Wotherspoon , Misko Cubrinovski
      Seismic piezocone (SCPTu) data compiled from 86 sites in the greater Christchurch, New Zealand area are used to evaluate several existing empirical correlations for predicting shear wave velocity from cone penetration test (CPT) data. It is shown that all the considered prediction models are biased towards overestimation of the shear wave velocity of the Christchurch soil deposits, demonstrating the need for a Christchurch-specific shear wave velocity prediction model (McGann et al., 2014) [1]. It is hypothesized that the unique depositional environment of the considered soils and the potential loss of soil ageing effects brought about by the 2010–2011 Canterbury earthquake sequence are the primary source of the observed prediction bias.


      PubDate: 2015-07-01T13:49:11Z
       
  • Torsional vibration of a finite cylindrical cavity in a two-layer
           transversely isotropic half-space
    • Abstract: Publication date: August 2015
      Source:Soil Dynamics and Earthquake Engineering, Volume 75
      Author(s): Azizollah Ardeshir-Behrestaghi , Morteza Eskandari-Ghadi , Bahram Navayi neya , Javad Vaseghi-Amiri
      The aim of this paper is to present a rigorous investigation for a two-layered transversely isotropic linear elastic half-space containing a circular cylindrical cavity of length equal to the top layer undergoing mono-harmonic ring shape shear stress applied either on the vertical cylindrical surface or on the base of the cavity. To this end, a combination of Fourier cosine integral transform for depth and Hankel integral transform for radial distance are used, which translate the boundary value problem to a singular integral equation for the shear stress comes out from the continuity of two layers. The integral equation is solved for some collocation points with a smoothed variable of distance, which is adapted with the use of a free parameter. It is shown that, although the shear stress is highly singular, it does not highly depend on this free parameter. Both the analytical and numerical results are verified with both the static isotropic and dynamic transversely isotropic homogeneous cases. In addition, some new graphical results are presented for more understanding in engineering point of view.


      PubDate: 2015-07-01T13:49:11Z
       
 
 
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