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  Subjects -> ENGINEERING (Total: 2284 journals)
    - CHEMICAL ENGINEERING (192 journals)
    - CIVIL ENGINEERING (184 journals)
    - ELECTRICAL ENGINEERING (102 journals)
    - ENGINEERING (1208 journals)
    - ENGINEERING MECHANICS AND MATERIALS (389 journals)
    - HYDRAULIC ENGINEERING (55 journals)
    - INDUSTRIAL ENGINEERING (65 journals)
    - MECHANICAL ENGINEERING (89 journals)

ENGINEERING (1208 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Hybrid Journal   (Followers: 5)
AASRI Procedia     Open Access   (Followers: 15)
Abstract and Applied Analysis     Open Access   (Followers: 3)
Aceh International Journal of Science and Technology     Open Access   (Followers: 2)
ACS Nano     Full-text available via subscription   (Followers: 227)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 2)
Acta Scientiarum. Technology     Open Access   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Active and Passive Electronic Components     Open Access   (Followers: 7)
Adaptive Behavior     Hybrid Journal   (Followers: 11)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 6)
Advanced Science     Open Access   (Followers: 5)
Advanced Science Focus     Free   (Followers: 3)
Advanced Science Letters     Full-text available via subscription   (Followers: 6)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17)
Advances in Artificial Neural Systems     Open Access   (Followers: 4)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Engineering Software     Hybrid Journal   (Followers: 25)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 14)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 10)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 20)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 25)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 28)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 12)
Advances in Polymer Science     Hybrid Journal   (Followers: 40)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 37)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 1)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 4)
AIChE Journal     Hybrid Journal   (Followers: 29)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access  
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 28)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 11)
American Journal of Engineering Education     Open Access   (Followers: 9)
American Journal of Environmental Engineering     Open Access   (Followers: 16)
American Journal of Industrial and Business Management     Open Access   (Followers: 23)
Analele Universitatii Ovidius Constanta - Seria Chimie     Open Access  
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Regional Science     Hybrid Journal   (Followers: 7)
Annals of Science     Hybrid Journal   (Followers: 7)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applicable Analysis: An International Journal     Hybrid Journal   (Followers: 1)
Applied Catalysis A: General     Hybrid Journal   (Followers: 6)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 9)
Applied Clay Science     Hybrid Journal   (Followers: 4)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 3)
Applied Nanoscience     Open Access   (Followers: 7)
Applied Network Science     Open Access  
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 3)
Applied Sciences     Open Access   (Followers: 2)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 7)
Arid Zone Journal of Engineering, Technology and Environment     Open Access  
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 3)
Asian Engineering Review     Open Access  
Asian Journal of Applied Science and Engineering     Open Access   (Followers: 1)
Asian Journal of Applied Sciences     Open Access   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 8)
Asian Journal of Control     Hybrid Journal  
Asian Journal of Current Engineering & Maths     Open Access  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 8)
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
ATZagenda     Hybrid Journal  
ATZextra worldwide     Hybrid Journal  
Australasian Physical & Engineering Sciences in Medicine     Hybrid Journal   (Followers: 1)
Australian Journal of Multi-Disciplinary Engineering     Full-text available via subscription   (Followers: 2)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 8)
Avances en Ciencias e Ingeniería     Open Access  
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
Bangladesh Journal of Scientific and Industrial Research     Open Access  
Basin Research     Hybrid Journal   (Followers: 3)
Batteries     Open Access   (Followers: 4)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 23)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 3)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Motor Trade Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 2)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Retail : An Executive Summary     Full-text available via subscription   (Followers: 3)
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access  
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 9)
Biomedical Engineering     Hybrid Journal   (Followers: 16)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 13)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 17)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 32)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 8)
Biomedical Science and Engineering     Open Access   (Followers: 3)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 2)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription  
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 14)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 3)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 14)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 41)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 7)
Case Studies in Thermal Engineering     Open Access   (Followers: 3)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 5)
CEAS Space Journal     Hybrid Journal  
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal   (Followers: 1)
CFD Letters     Open Access   (Followers: 6)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 2)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Engineering     Open Access   (Followers: 2)
Chinese Science Bulletin     Open Access   (Followers: 1)
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencias Holguin     Open Access   (Followers: 1)
CienciaUAT     Open Access  
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 11)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 14)
City, Culture and Society     Hybrid Journal   (Followers: 21)
Clay Minerals     Full-text available via subscription   (Followers: 9)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 4)
Coatings     Open Access   (Followers: 3)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 13)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 13)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 2)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 26)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Composite Structures     Hybrid Journal   (Followers: 256)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 179)
Composites Part B : Engineering     Hybrid Journal   (Followers: 227)
Composites Science and Technology     Hybrid Journal   (Followers: 197)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 13)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 6)
Computer Science and Engineering     Open Access   (Followers: 17)
Computers & Geosciences     Hybrid Journal   (Followers: 28)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 5)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 4)
Computers and Geotechnics     Hybrid Journal   (Followers: 10)
Computing and Visualization in Science     Hybrid Journal   (Followers: 5)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 29)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 6)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 8)
Control Engineering Practice     Hybrid Journal   (Followers: 42)
Control Theory and Informatics     Open Access   (Followers: 7)
Corrosion Science     Hybrid Journal   (Followers: 25)
CT&F Ciencia, Tecnologia y Futuro     Open Access  

        1 2 3 4 5 6 7 | Last

Journal Cover Computers and Geotechnics
  [SJR: 2.033]   [H-I: 58]   [10 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0266-352X
   Published by Elsevier Homepage  [3042 journals]
  • Study of thermal migration and induced mechanical effects in double U-tube
           energy piles
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): Jin Luo, Haifeng Zhao, Shuqiang Gui, Wei Xiang, Joachim Rohn
      This paper investigates two geothermal energy piles using thermal response tests (TRTs). A set of parameters including pile wall temperature, ground temperature and strain are monitored at four different depths. The thermally induced mechanical behavior of the energy piles are then analyzed based on the monitoring data. The results show the following: (1) The temperature at the pile wall clearly varies throughout the heating and cooling cycle, and the ground temperature distribution shows a delay compared to the TRT stages. (2) The thermally induced mechanical effects are influenced by both the temperature and restraint conditions.

      PubDate: 2017-07-09T07:26:59Z
       
  • A theoretical method for determining sample mass in a sieving test
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): Sheng Zhang, Xi Li, Jidong Teng, Xinyan Ma, Daichao Sheng
      Obtaining a representative particle size distribution for soil is a common challenge in earth works and is affected by the size of sieving samples. While the current standards usually specify a minimum sample mass, there is no scientific justification for the specification. Treating the preparation of sieving samples as a process of random sampling, a new method is proposed for determining the minimum mass of a sieving test sample. The proposed method is validated via laboratory tests and will improve standard specification and engineering practice.

      PubDate: 2017-07-09T07:26:59Z
       
  • Soil-water retention behavior of compacted soil with different densities
           over a wide suction range and its prediction
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): You Gao, De'an Sun
      To investigate the soil-water retention behavior of a clayey silt over a wide suction range, the suction is imposed on clayey silt specimens using the pressure plate method and vapor equilibrium technique with saturated salt solutions. The test results show that the soil-water retention curves (SWRCs) in terms of gravimetric water content versus suction relation over a wide suction range are independent of the initial dry density or void ratio when the suction is higher than a specific value, which can be determined by results of the mercury intrusion porosimetry test. When the SWRC is expressed in terms of degree of saturation versus suction relation over a wide suction range, the influence of dry density or void ratio is highlighted. This behavior can be explained by the features of the pore-size distribution. Residual suction and water content of specimens with different void ratios are almost the same and the air entry values of specimens show a linear relationship in the plane of water content versus suction with the logarithmic coordinate. Finally, the Fredlund and Xing SWRC equation is used to uniformly describe the SWRCs of specimens with different void ratios by taking above features of the SWRC into consideration, and the predicted results are compared well with measured values.

      PubDate: 2017-07-09T07:26:59Z
       
  • Frost jacking characteristics of screw piles in seasonally frozen regions
           based on thermo-mechanical simulations
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): Tengfei Wang, Jiankun Liu, Bowen Tai, Chuanzhen Zang, Zhichun Zhang
      In this paper, a thermo-mechanical model is proposed to simulate the frost jacking behaviour of screw piles subjected to frost heave, and the results are further validated by laboratory tests. The calculated results show that large multi-helix piles yield the least frost jacking when the freezing depth reaches half the embedment depth of pile. Based on the modified cylindrical shear method and individual bearing method, the optimal geometric parameters of screw piles are determined by a series of numerical calculations. The numerical approach is expected to serve as a reference for designing effective and economical pile types in practice.

      PubDate: 2017-07-09T07:26:59Z
       
  • Numerical study of slurry consolidometer tests taking into account the
           influence of wall friction
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): Wei He, David Williams, Ali Shokouhi
      Three tests of slurried Jeeropilly coal tailings in a purpose-built slurry consolidometer under three different loading sequences were numerically analysed to study the friction losses quantitatively. A simplified sedimentation-consolidation theory was proposed to link the initial suspended state and soil-like state of slurries. The numerical simulations provided good agreement with the measured, and indicated the noticeable friction losses, from 11.1% to 34.2%, due to factors such as the diameter of consolidometers and loading sequences. The average coefficient of the stress (pore water pressure) stood at 1 at the beginning, and declined to a stable value around 0.55 (0.67).

      PubDate: 2017-07-09T07:26:59Z
       
  • Numerical and experimental studies of the mechanical behaviour for
           compaction grouted soil nails in sandy soil
    • Abstract: Publication date: October 2017
      Source:Computers and Geotechnics, Volume 90
      Author(s): Xinyu Ye, Shanyong Wang, Qiong Wang, Scott William Sloan, Daichao Sheng
      A model test was conducted for a newly developed soil nail, the result of which was compared to that of a 3D finite element method (FEM) simulation. The shape angle (β) and friction coefficients (μ) contributed to the difference in pull-out force between the model test and the simulation. Further verifications were conducted, during which the pull-out mechanisms of the soil nail for different β and μ were analysed. It was found that both β and μ have a positive influence on the pull-out force; β only affects the increase rate, while μ influences the overall pull-out force level. Three components were found to govern the pull-out force, with the component applied to the expanded cement bulk surface accounting for approximately 80% of the total. This study proves that the optimal approach for increasing pull-out force is to enlarge the diameter of the cement bulk rather than extend the nail length.

      PubDate: 2017-07-09T07:26:59Z
       
  • Strategy for consistent model parameter calibration for soft soils using
           multi-objective optimisation
    • Abstract: Publication date: October 2017
      Source:Computers and Geotechnics, Volume 90
      Author(s): J.-P. Gras, N. Sivasithamparam, M. Karstunen, J. Dijkstra
      Constitutive models for soft soils require a large number of parameters to model the complex material response. One set of parameters should capture the soil response for various laboratory & in situ stress paths. This requires a new method to calibrate a consistent set of model parameters using test data from different load paths of classic geomechanical tests. The feasibility of the proposed method is demonstrated with the recently developed CREEP-SCLAY1S model. After a sensitivity analysis that highlights the model parameters for optimisation, an optimisation process for two different configurations is designed. The latter is successfully verified against artificially generated laboratory data.

      PubDate: 2017-06-28T19:56:10Z
       
  • Cone penetration test in sand: A numerical-analytical approach
    • Abstract: Publication date: October 2017
      Source:Computers and Geotechnics, Volume 90
      Author(s): M.M. Ahmadi, A.A. Golestani Dariani
      Separation of the effects of initial horizontal stress and relative density on cone tip resistance in sandy soils has been a complicated issue for many years. In order to overcome this problem, a numerical modeling of CPT which has been verified by calibration chamber tests, has been used in this paper to achieve a reliable analytical solution. The analytical solution has resulted in two relationships for sleeve friction and cone tip resistance in terms of the initial conditions of sandy soil. Based on the presented solution, the initial horizontal stress and relative density can be determined according to CPT measurements.

      PubDate: 2017-06-28T19:56:10Z
       
  • A rigorous solution for the stability of polyhedral rock blocks
    • Abstract: Publication date: October 2017
      Source:Computers and Geotechnics, Volume 90
      Author(s): Qinghui Jiang, Chuangbing Zhou
      Block theory has been widely applied to stability analysis of rock engineering due to its clear concept and elegant geometrical theory. For a general block with multiple discontinuity planes, it is assumed that contact is only maintained on a single plane (single-plane sliding) or two intersecting planes (double-plane sliding) in block theory analysis. Since the normal forces and shear resistances acting on the other discontinuity planes are omitted, it can cause unreasonable estimations of block failure modes and incorrect calculation of factors of safety. In this study, a new method is presented that permits to consider the contribution of the normal forces and shear resistances acting on each discontinuity plane to the block stability. The proposed method meets all of the force-equilibrium and moment-equilibrium conditions and provides a rigorous solution for stability of general blocks with any number of faces and any shape. Some typical polyhedral blocks in rock slopes are analyzed using block theory and the proposed method. The results indicate that the traditional block theory may give a misleading conclusion for the predictions of stability and sliding direction of rock blocks when contact occurs on more than two discontinuity planes.

      PubDate: 2017-06-28T19:56:10Z
       
  • Analytical definition of collapse surface in multiaxial space as a
           criterion for flow liquefaction occurrence
    • Abstract: Publication date: October 2017
      Source:Computers and Geotechnics, Volume 90
      Author(s): Alireza Najma, Manouchehr Latifi
      Prediction of flow liquefaction occurrence in multiaxial stress space is presented in this paper. The closed-form relation analytically attained by means of Dafalias-Manzari constitutive equations gives the flow stress ratio as a function of model parameters, state parameter, direction of undrained loading and especially initial condition of consolidation. These proposed flow condition can predict the occurrence of flow liquefaction initiated by any loadings whether the soil is consolidated isotropically or anisotropically. Suggested predictions are compared with the results of triaxial tests performed on Hostun RF sand. The results show that increasing consolidation stress ratio leads to flow stress ratio increase.

      PubDate: 2017-06-21T02:47:02Z
       
  • A family of improved yield surfaces and their application in modeling of
           isotropically over-consolidated clays
    • Abstract: Publication date: October 2017
      Source:Computers and Geotechnics, Volume 90
      Author(s): Y.N. Chen, Z.X. Yang
      Recognizing the limitation of the existing yield surfaces for clays, a novel type of the yield surface is derived. The shape parameters allow for the distortion of the yield surface from an ellipse to a teardrop shape such that it provides more flexibility for better modeling the shear response for over-consolidated clays. A new bounding surface model has been proposed within a critical state framework, and can predict the realistic behavior of over-consolidated clays under both undrained and drained conditions. The capacity of the model is demonstrated by five different reconstituted clays with representative testing results in the literature.

      PubDate: 2017-06-21T02:47:02Z
       
  • Displacement interaction among energy piles bearing on stiff soil strata
    • Abstract: Publication date: October 2017
      Source:Computers and Geotechnics, Volume 90
      Author(s): Alessandro F. Rotta Loria, Lyesse Laloui
      This study presents an analysis of the displacement interaction among general configurations of energy piles bearing on stiff soil strata that are subjected to thermal loads. This work integrates recent analyses investigating the displacement interaction among predominantly floating energy piles subjected to thermal loads in deep uniform soil deposits. To address this challenge, design charts for energy piles resting on either infinitely or finitely rigid soil strata are presented, applied and validated for the analysis of the vertical displacement of predominantly end-bearing energy pile groups subjected to thermal loads using the interaction factor method.

      PubDate: 2017-06-21T02:47:02Z
       
  • An axisymmetric BNEF method of circular excavations taking into account
           soil-structure interactions
    • Abstract: Publication date: October 2017
      Source:Computers and Geotechnics, Volume 90
      Author(s): Wei He, Chaoyun Luo, Jianfeng Cui, Jianren Zhang
      An axisymmetric BNEF method was proposed to analyze circular excavations. The governing equations of embedded cylindrical diaphragm walls were derived from thin-shell theory. A hyperbolic model was proposed to account for soil-structure interactions. Then, a FEM program was coded and verified using a case study. Overall, the method caught the main trend in the measured results and provided a reasonable estimation for engineering practice. Furthermore, the development of earth pressure and the hoop stress in the walls (ring beams) can be obtained using conventional parameters, extending the ability of the classic BEF method to aid the design of circular excavations.

      PubDate: 2017-06-21T02:47:02Z
       
  • A one-dimensional integral approach to calculating the failure probability
           of geotechnical engineering structures
    • Abstract: Publication date: October 2017
      Source:Computers and Geotechnics, Volume 90
      Author(s): Yonghua Su, Yanbing Fang, Shuai Li, Ya Su, Xiang Li
      This study focuses on the geotechnical engineering structures with implicit or unknown expressions of performance functions. A one-dimensional integral approach (ODIA) consisting of sampling, evaluation of statistical moments for multivariable functions, probability density function fitting, and simple integration of failure probability was developed through system integration. A convergence study of an illustrative example was conducted, and the error analysis revealed that the accuracy of ODIA is equivalent to that of the second-order reliability method. Applications of ODIA to a slope and surrounding rock of an excavation were presented to further confirm the accuracy, efficiency, and practicability of the approach.

      PubDate: 2017-06-11T09:05:46Z
       
  • 3D polycrystalline discrete element method (3PDEM) for simulation of crack
           initiation and propagation in granular rock
    • Abstract: Publication date: October 2017
      Source:Computers and Geotechnics, Volume 90
      Author(s): X.F. Li, H.B. Li, J. Zhao
      A three-dimensional Voronoi tessellation model based on the distinct element method (DEM) is proposed to model the representative part of the microstructures of granular brittle rocks. Regularization is employed to decrease the frequency of polyhedrons with large edge ratio and contributes to a higher efficiency for element meshing. Sensitivity analyses are performed for a series of micro contact parameters in accordance with the macro responses observed in laboratory experiments (e.g. the uniaxial compression test, the Brazilian disc test and the triaxial compression test). Verifications by simulating the spalling test and plate impact test indicate that the 3D polycrystalline discrete element method (3PDEM) can be employed for efficiently simulating nonlinear mechanical behaviors, large deformation, strain softening and rock dynamics.

      PubDate: 2017-06-11T09:05:46Z
       
  • Evaluation of the performance of a breakage model for high porosity
           Haubourdin chalk
    • Abstract: Publication date: October 2017
      Source:Computers and Geotechnics, Volume 90
      Author(s): Chunshun Zhang, Jian Ji, Jayantha Kodikara, Yilin Gui
      We examine a new continuum micromechanical approach to predicting the macroscopic mechanical responses of Haubourdin chalk under various load conditions. The approach is based on a simple breakage model that accounts for an evolving microstructural degradation through coccosphere crushing with only five physically meaningful parameters and one grading index. The model correlates the intrinsic failure mechanisms including the coccosphere crushing, pore collapse and plastic shearing that are identified by corresponding internal variables within thermodynamic framework. On this basis, numerical predictions of the stresses and strains are examined against their experimental counterparts as well as the results from an existing continuum model. Parametric studies are further conducted to investigate the effect of the model parameters. The favourable agreements in various conventional and complex compression tests indicate a satisfactory performance of the breakage model, highlighting the importance of capturing the microscopic degradation mechanisms when building a constitutive model.

      PubDate: 2017-06-11T09:05:46Z
       
  • A simple procedure to simulate a smooth elastic-plastic transition in
           Cam-Clay models
    • Abstract: Publication date: October 2017
      Source:Computers and Geotechnics, Volume 90
      Author(s): Gema De la Morena, Laura Asensio, Ángel Yustres, Vicente Navarro
      A simple procedure is proposed to simulate a smooth transition from elastic to elastoplastic behaviour in Cam-Clay models. The procedure consists of the definition of an external constitutive surface where full yield is assumed, and an internal one that allows the definition of the position in which plastic strains start to appear before the external yield surface is reached. The comparison of the model results with different laboratory tests shows the validity of the procedure. The method considers one additional parameter with regard to a “standard” critical state model, and it can easily be implemented in existing integration modules.

      PubDate: 2017-06-01T08:55:15Z
       
  • Dynamic soil-structure interaction: A three-dimensional numerical approach
           and its application to the Lotung case study
    • Abstract: Publication date: October 2017
      Source:Computers and Geotechnics, Volume 90
      Author(s): A. Amorosi, D. Boldini, A. di Lernia
      This paper presents a three-dimensional non-linear finite element (FE) approach to analyse the dynamic soil-structure interaction (SSI) phenomena observed at the Lotung Large-Scale Seismic Test (LSST) site. The numerical study is carried out in the time domain by a commercial FE code, taking into account the non-linear behaviour of soil and the multi-directional nature of real seismic events. The soil response is simulated by an isotropic hardening elasto-plastic hysteretic model (HSsmall) implemented in the material model library of the code. This model allows to describe the non-linear cyclic response ranging from small to large strain amplitudes and to account for the variation of the initial stiffness with depth. In the paper, the FE numerical approach is first validated through a series of parametric analyses simulating simplified cases (i.e. linear visco-elastic structures founded on a homogeneous linear visco-elastic soil deposit) for which analytical solutions exist. Then, it is adopted to back-analyse the behaviour of the 1/4-scale nuclear power plant containment structure constructed at the Lotung LSST site which was shook by several earthquakes of different intensities and frequency contents. The FE results are thus compared to the recorded in-situ free-field and structural motions, highlighting the satisfactory performance of the numerical model in replicating the observed response. The overall outcome of this research proves that nowadays complex dynamic SSI phenomena can be tackled by direct approach, overpassing the strong simplifications of the well-established substructure approaches.

      PubDate: 2017-06-01T08:55:15Z
       
  • Numerical investigation of the opening effect on the mechanical behaviours
           in rocks under uniaxial loading using hybrid continuum-discrete element
           method
    • Abstract: Publication date: October 2017
      Source:Computers and Geotechnics, Volume 90
      Author(s): Y.L. Gui, Z.Y. Zhao, C. Zhang, S.Q. Ma
      Openings including their size, shape and distribution in rock play a significant role in the performance of rock related structures. The well-established knowledge in this area can contribute to the engineering practices, for example, underground space design, planning and optimisation in Civil and Mining Engineering and wellbore stability in Drilling Engineering, among others. Thus, understanding the failure mechanism of rock with openings is theoretically and practically meaningful. Laboratory testing on rock or rock-like materials with openings have been studied extensively in the literature, which, however, primarily focuses on the cracks/fractures. In this paper, a comprehensive numerical study on the effect of non-banded openings, i.e., circular, rectangular, and triangular opening, on the rock mechanical behaviour is performed using a hybrid continuum-discrete element method. It is revealed that the proposed simulation method can reproduce reasonably the crack initiation and propagation, and predict well the change of the mechanical behaviour due to the openings. In addition, the influence of the opening shape and opening ratio (=area of opening/specimen area) on the mechanical behaviour is also investigated.

      PubDate: 2017-06-01T08:55:15Z
       
  • Algorithm for generation of stratigraphic profiles using cone penetration
           test data
    • Abstract: Publication date: October 2017
      Source:Computers and Geotechnics, Volume 90
      Author(s): Eshan Ganju, Monica Prezzi, Rodrigo Salgado
      Cone Penetration Test (CPT) data are often used directly in the design of shallow and deep foundations and many other applications. To produce more cost-effective designs, it is advantageous to use CPT data to establish stratigraphic profiles as well. Algorithms to generate a stratigraphic profile using data from an individual CPT sounding and a Soil Behavior Type (SBT) chart as inputs are presented. Two SBT charts from the literature were selected and modified to eliminate ambiguity in soil classification. Novel algorithms were developed for handling the occurrence of thin layers within a stratigraphic profile to account for the fact that the standard CPT cone cannot accurately sense layers with thickness below a certain limit and a representative cone resistance cannot be obtained if the layer is too thin. Likewise, the algorithms prevent the creation of a soil profile with adjacent layers of essentially the same soil by consolidating layers appropriately. The algorithms presented generate a design soil profile, produced using a precise classification based on soil type and state and by elimination of artificial layering, that can be more effectively used in design.

      PubDate: 2017-06-01T08:55:15Z
       
  • Experimental and theoretical investigation on the compression behavior of
           sand-marine clay mixtures within homogenization framework
    • Abstract: Publication date: October 2017
      Source:Computers and Geotechnics, Volume 90
      Author(s): X.S. Shi, Jianhua Yin
      In this paper, the compression behavior of sand-marine clay mixtures was investigated, both experimentally and theoretically. The test data reveal that the Normal Compression Line of a sand-clay mixture depends on both the sand fraction and the initial water content of the clay matrix. The local stress in the clay matrix σ′ c is approximately close to the overall stress of the sand-clay mixture σ′ for a sand mass fraction of 20%. The stress ratio, σ′c /σ′, falls significantly with increasing overall stress for a sand fraction of 60%, which may be attributed to the formation of clay bridges between adjacent sand particles. A compression model was formulated within the homogenization framework. First, a homogenization equation was proposed, which gives a relationship between the overall stiffness E and that of the clay matrix Ec. Then, a model parameter ξ was incorporated considering the sensitivity of the structure parameter on the volume fraction of the clay matrix. Finally, a simple compression model with three model parameters was formulated using the tangent stiffness. Comparisons between the experimental data and simulations reveal that the proposed model can well represent the compression curves of the sand-marine clay mixtures observed in the laboratory.

      PubDate: 2017-05-27T08:47:58Z
       
  • An energy-based interpretation of sand liquefaction due to vertical ground
           motion
    • Abstract: Publication date: October 2017
      Source:Computers and Geotechnics, Volume 90
      Author(s): Vasiliki Tsaparli, Stavroula Kontoe, David M.G. Taborda, David M. Potts
      In several recent earthquakes, high vertical ground accelerations accompanied by liquefaction were observed. Downhole records have also shown that large vertical accelerations do not necessarily originate from the source, but rather get amplified towards the ground surface. Given the advantages of energy-based interpretation of liquefaction triggering due to S-waves, this approach is used together with finite element analyses to investigate vertical motion amplification and ensuing liquefaction. The results show the importance of the post-resonance response cycles, while hysteretic damping based on total stresses, accounting for the water in the pores, is shown to be very low, explaining the observed amplification.

      PubDate: 2017-05-22T08:44:05Z
       
  • Reliability bearing capacity analysis of footings on cohesive soil slopes
           using RFEM
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): Ning Luo, Richard J. Bathurst
      Reliability analysis of bearing capacity of a strip footing at the crest of a simple slope with cohesive soil was carried out using the random finite element method (RFEM). Analyses showed that the coefficient of variation and the spatial correlation length of soil cohesion can have a large influence on footing bearing capacity, particularly for slopes with large height to footing width ratios. The paper demonstrates cases where a footing satisfies a deterministic design factor of safety of 3 but the probability of design failure is unacceptably high. Isotropic and anisotropic spatial variability of the soil strength was also considered.

      PubDate: 2017-05-17T08:39:47Z
       
  • System reliability analysis and risk assessment of a layered slope in
           spatially variable soils considering stratigraphic boundary uncertainty
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): Lei-Lei Liu, Yung-Ming Cheng, Xiao-Mi Wang, Shao-He Zhang, Zhong-Hu Wu
      Due to complex geological deposition, post-deposition processes and limited site investigation data in engineering practice, soil properties are often spatially variable and the stratigraphic boundary in layered soils is generally characterized by uncertainty. The spatial variability of soil properties has been well investigated in past years, whereas the question of how the stratigraphic boundary uncertainty affects the slope stability remains unanswered. This paper attempts to investigate the effects of the stratigraphic boundary uncertainty on the system reliability and risk of a layered slope in spatially variable soils. In this paper, the spatial variability of soil properties is simulated by non-stationary random fields that are generated by an extended Cholesky decomposition technique, while the stochastic nature of the stratigraphic boundary location is simulated by a discrete random variable. Monte Carlo simulation (MCS) is suggested for evaluating the system failure probability and risk. Various comparisons between probabilistic analysis results obtained from considering and neglecting the stratigraphic boundary uncertainty have been made for different statistics of soil properties. Results show that the stratigraphic boundary uncertainty plays an important role in identifying the slope failure mechanism. Moreover, neglecting the stratigraphic boundary uncertainty would generally overestimate the slope failure risk for different statistics, except at small coefficients of variation of the friction angle, where the results are underestimated.

      PubDate: 2017-05-17T08:39:47Z
       
  • Size-dependent mechanical behavior of an intergranular bond revealed by an
           analytical model
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): Huaning Wang, Hao Gong, Fang Liu, Mingjing Jiang
      The size of intergranular bonds significantly affects the macroscopic mechanical properties of geomaterials. A size-dependent bond contact model is desired in the distinct element method (DEM) for geomaterials formed by aggregates of bonded particles. This paper proposes an analytical solution of highly-precise stress fields of a biconcave bond between two identical disc-shaped particles under different loading paths based on Dvorkin’s solution. The Unified Strength theory is then introduced to obtain the initial failure domain in the bond. The proposed solution is consistent with results predicted by finite element simulations and experimental observations. The functions of bond stiffness with respect to all influencing parameters, i.e. bond width/thickness, particle radius and elastic parameters of bond material, are provided by the solution and empirically formulated by fitting a large number of analytical results. Additionally, the failure criterion or envelope under different combined loads is formulated for typical brittle bonds. The resulting failure criterion, approximated as an ellipsoid, depends on the size and material properties of the bonds. The proposed solution and equation can be implemented into a bond contact model used in DEM simulations of a geomaterial, where variation of bond sizes is significant and size-dependent contact model is important.

      PubDate: 2017-05-12T08:32:45Z
       
  • Computational framework for obtaining volumetric fracture intensity from
           3D fracture network models using Delaunay triangulations
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): Jiewei Zhan, Jianping Chen, Peihua Xu, Xudong Han, Yu Chen, Yunkai Ruan, Xin Zhou
      Fracture intensity, the degree of fracturing in rock masses, is one of the fundamental parameters used in characterizing rock mass as a fracture network. Among fracture intensity measures, volumetric fracture intensity (P32) is the most useful, since it directly reflects the degree of rock mass fracturing, independent of fracture orientation and size distribution. P32 represents the total area of fractures per cubic meter, and it can simultaneously reflect the spacing and size component of fractures. Because P32 cannot be directly measured in the field, previous works have developed various inference methods based on available 1D and 2D measures collected from field surveys. At present, discrete fracture network (DFN) models are deemed to be a suitable method for the characterization of fractured rock mass. Hence, calculating P32 from a DFN model is also a widely accepted approach. However, the geometry-based method cannot effectively address the irregular simulation space, and the methods employed are ill-suited if polygonal fractures appear in the DFN model. To solve these deficiencies, a computational framework based on the Delaunay triangulation of 3D uniformly distributed random points is introduced, and a detailed description is presented. The proposed computational framework is suitable for various types of DFN models, such as Baecher disk models, elliptical disk models and Dershowitz polygon models. A simulated example was generated to verify the proposed computational framework. Finally, a DFN model is built based on fracture data acquired from the Songta hydropower station, and the proposed computational framework was used to calculate P32 for the DFN model.

      PubDate: 2017-05-12T08:32:45Z
       
  • Effect of compressible parameters on vertical vibration of an elastic pile
           in multilayered poroelastic media
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): Zhi Yong Ai, Li Hua Wang
      This paper mainly investigates the influences of compressible parameters on the vertical vibration of a pile embedded in layered poroelastic soil media. The pile is treated as a 1D elastic bar by the finite element method, and fundamental solutions for the layered poroelastic soils due to a vertical dynamic load are obtained by the analytical layer element method. Based on the compatibility conditions, the pile-soil dynamic interaction problem is solved. The numerical scheme has been compiled into a Fortran program for numerical calculation. Influences of the pile-soil stiffness ratio, compressible parameters, vibration frequency and the soil stratification are discussed.

      PubDate: 2017-05-12T08:32:45Z
       
  • A new procedure for ground response curve (GRC) in strain-softening
           surrounding rock
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): Jin-feng Zou, Chao Li, Feng Wang
      A new procedure for the ground response curve (GRC) is investigated in strain-softening surrounding rock for a circular opening. The procedure started each step with a radius increment and the analytical solutions of stress and strain in each annulus were presented. The plastic region is divided into a finite number of concentric annuli, whose thickness is uniformly determined by a small radius increment. Combining the equilibrium equation and failure criterion, stress for each annulus can be obtained analytically. The displacement for each step can be calculated analytically through solving the differential equation by invoking flow rule and Hooke’s law. The strains for each annulus can be obtained by the strain-displacement relationship. In the successive manner, the distributions of stress and displacement can be found. It should be noted that the finial stress and displacement at radial direction are the internal support pressure and deformation at the excavation surface, respectively. By assuming different plastic radii (using a plastic radius increment), GRC, the evolution curve of plastic radii and internal support pressure can be obtained analytically. Some numerical and engineering examples are performed to demonstrate the validity of the proposed procedure. It is shown that the results of the proposed procedure at the tunnel crown are basically consistent with field measuring data. The influence of the annulus number, plastic radius increment and dilation on the accuracy of the proposed approach is investigated. Results show that the solutions are more accurate and the calculation efficiency is higher.

      PubDate: 2017-05-07T03:54:03Z
       
  • DEM study on the effect of particle breakage on the macro- and
           micro-behavior of rockfill sheared along different stress paths
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): Ming Xu, Juntian Hong, Erxiang Song
      The behavior of crushable rockfill sheared along different stress paths is studied using the discrete element method. Rockfill particles are modeled as breakable agglomerates, and reasonable consistency is found between the predicted and experimental results. The simulation highlights the influence of agglomerate breakage on both the macro- and micro-behavior of the assembly. The evolution of both the number and mode of agglomerate breakage during shearing is significantly influenced by the confining pressure, deviator stress ratio, and loading direction. The relationship between the deviator stress ratio on the macro-scale and the deviator fabric on the micro-scale along different stress paths is explored.

      PubDate: 2017-05-07T03:54:03Z
       
  • Micromechanics of undrained response of dilative granular media using a
           coupled DEM-LBM model: A case of biaxial test
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): Daniel H. Johnson, Farshid Vahedifard, Bohumir Jelinek, John F. Peters
      In this paper the Discrete Element Method (DEM) is coupled with the Lattice-Boltzmann Method (LBM) to model the undrained condition of dense granular media that display significant dilation under highly confined loading. DEM-only models are commonly used to simulate the micromechanics of an undrained specimen by applying displacements at the domain boundaries so that the specimen volume remains constant. While this approach works well for uniform strain conditions found in laboratory tests, it doesn’t realistically represent non-uniform strain conditions that exist in the majority of real geotechnical problems. The LBM offers a more realistic approach to simulate the undrained condition since the fluid can locally conserve the system volume. To investigate the ability of the DEM-LBM model to effectively represent the undrained constraint while conserving volume and accurately calculating the stress path of the system, a two dimensional biaxial test is simulated using the coupled DEM-LBM model, and the results are compared with those attained from a DEM-only constant volume simulation. The compressibility of the LBM fluid was found to play an important role in the model response. The compressibility of the fluid is expressed as an apparent Skempton’s pore pressure parameter B. The biaxial test, both with and without fluid, demonstrated particle-scale instabilities associated with shear band development. The results show that the DEM-LBM model offers a promising technique for a variety of geomechanical problems that involve particle-fluid mixtures undergoing large deformation under shear loading.

      PubDate: 2017-05-07T03:54:03Z
       
  • Fixed point automatic interpretation of bender-based G0 measurements
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): Ionuţ Dragoş Moldovan, António Gomes Correia
      We present a new model updating technique for the automatic calculation of the small strain shear modulus of geomaterials, based on bender element experiments. The technique searches for the shear modulus that maximizes the correlation between the output signal obtained from the experiment and the output signal acquired from its computational simulation. Instead of conventional extremum finding algorithms, a fixed point technique is used to update the shear modulus at each iteration. This option increases substantially the attraction basin of the absolute maximum correlation and improves the convergence of the algorithm.

      PubDate: 2017-05-07T03:54:03Z
       
  • The effect of backfill cohesion on seismic response of cantilever
           retaining walls using fully dynamic analysis
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): Abdolreza Osouli, Siavash Zamiran
      The analyses of retaining walls in California showed many backfills are coarse material with some cohesion. In this investigation, seismic response of cantilever retaining walls, backfilled with dirty sandy materials with up to 30kPa cohesion, is evaluated using fully dynamic analysis. The numerical simulation procedure is first validated using reported centrifuge test results. The validated methodology is then used to investigate the effects of three earthquake ground motions including Kobe, Loma Prieta, and Chi-Chi on seismic response of retaining walls. In addition, the input peak ground acceleration values are varied to consider a wide range of earthquake acceleration intensity.

      PubDate: 2017-05-07T03:54:03Z
       
  • Bearing capacity computation for a ring foundation using the stress
           characteristics method
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): Amin Keshavarz, Jyant Kumar
      The stress characteristics method (SCM) has been used to compute the bearing capacity of smooth and rough ring foundations. Two different failure mechanisms for a smooth footing, and four different mechanisms for a rough footing have been considered. For a rough base, a curvilinear non-plastic wedge has been employed below the footing. The analysis incorporates the stress singularities at the inner as well as outer edges of the ring footing. Bearing capacity factors, Nc , Nq and Nγ are presented as a function of soil internal friction angle (ϕ) and the ratio (ri /ro ) of inner to outer radii of the footing.

      PubDate: 2017-05-01T03:48:34Z
       
  • Site response analysis using one-dimensional equivalent-linear method and
           Bayesian filtering
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): Rodrigo Astroza, César Pastén, Felipe Ochoa-Cornejo
      Site response analysis is crucial to define the seismic hazard and distribution of damage during earthquakes. The equivalent-linear (EQL) is a numerical method widely investigated and used for site response analysis. Because several sources of uncertainty are involved in this type of analysis, parameters defining the numerical models need to be identified from in-situ measurements. In this paper, a Bayesian inference method to estimate the expected values and covariance matrix of the model parameters is presented. The methodology uses data from downhole arrays recorded during earthquakes. Two numerical applications show the good performance and prediction capabilities of the proposed approach.

      PubDate: 2017-05-01T03:48:34Z
       
  • Numerical investigation of multi-directional site response based on
           KiK-net downhole array monitoring data
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): Bo Han, Lidija Zdravkovic, Stavroula Kontoe, David M.G. Taborda
      The multi-directional site response of a well-documented downhole array in Japan is numerically investigated with three directional (3-D) dynamic hydro-mechanically (HM) coupled Finite Element (FE) analysis. The paper discusses the challenges that 3-D modelling poses in the calibration of a cyclic nonlinear model, giving particular emphasis on the independent simulation of the shear and volumetric deformation mechanisms. The employed FE model is validated by comparing the predicted site response against the recorded motions obtained from the KiK-net downhole array monitoring system in Japan. The results show that, by employing the appropriate numerical model, a good agreement can be achieved between the numerical results and the monitored acceleration response in all three directions simultaneously. Furthermore, the comparison with the recorded response highlights the significance of the independent modelling of the shear and volumetric deformation mechanisms to the improvement of the numerical predictions of multi-directional site response.

      PubDate: 2017-05-01T03:48:34Z
       
  • Semi-analytical solutions to one-dimensional consolidation for unsaturated
           soils with symmetric semi-permeable drainage boundary
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): Lei Wang, De'an Sun, Linzhong Li, Peichao Li, Yongfu Xu
      This paper presents semi-analytical solutions to Fredlund and Hasan’s one-dimensional consolidation for unsaturated soils under symmetric semi-permeable drainage boundary conditions. Two variables are introduced to transform two coupled governing equations of pore-air and pore-water pressures into an equivalent set of partial differential equations, which are easily solved by the Laplace transform. Then, the pore-air and pore-water pressures, and soil settlement are obtained in the Laplace domain. Crump’s method is adopted to perform the inverse Laplace transform in order to obtain semi-analytical solutions in time domain. It is shown that the present solution is more applicable to various types of drainage boundary conditions, and in a good agreement with existing solutions from the literature. Furthermore, several numerical examples are provided to investigate the consolidation behavior of an unsaturated single-layer soil with traditional drainage boundary (single or double), and single-sided and double-sided semi-permeable drainage boundaries. Finally, it illustrates the changes in pore-air and pore-water pressures and soil settlement with time at different values of symmetric semi-permeable drainage boundary conditions parameters. In addition, parametric studies are conducted by the variations of pore-air and pore-water pressures at different ratios of air-water permeability coefficient and the depth.

      PubDate: 2017-05-01T03:48:34Z
       
  • Analytical study of fluid flow modeling by diffusivity equation including
           the quadratic pressure gradient term
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): Mahdi Abbasi, Mojtaba Izadmehr, Masoud Karimi, Mohammad Sharifi, Alireza Kazemi
      Diffusivity equation which can provide us with the pressure distribution, is a Partial Differential Equation (PDE) describing fluid flow in porous media. The quadratic pressure gradient term in the diffusivity equation is nearly neglected in hydrology and petroleum engineering problems such as well test analysis. When a compressible liquid is injected into a well at high pressure gradient or when the reservoir possess a small permeability value, the effect of ignoring this term increases. In such cases, neglecting this parameter can result in high errors. Previous models basically focused on numerical and semi-analytical methods for semi-infinite domain. To the best of our knowledge, no analytical solution has yet been developed to consider the quadratic terms in diffusivity PDE of one-dimensional unsteady state fluid flow in rectangular coordinates and finite length. Due to the resulting errors, the nonlinear quadratic term should also be considered in the governing equations of fluid flow in porous media. In this study, the Fourier transform is used to model the one-dimensional fluid flow through porous media by considering the quadratic terms. Based on this assumption, a new analytical solution is presented for the nonlinear diffusivity equation. Moreover, the results of linear and nonlinear diffusivity equations are compared considering the quadratic term. Finally, a sensitivity analysis is conducted on the affecting parameters to ensure the validity of the proposed new solution. The results demonstrate that this nonlinear PDE is also applicable for hydraulic fractured wells, and well test analysis of fractured reservoirs.

      PubDate: 2017-04-24T03:39:44Z
       
  • Load-settlement behavior modeling of single piles using artificial neural
           networks and CPT data
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): F. Pooya Nejad, Mark B. Jaksa
      Pile foundations are usually used when the conditions of the upper soil layers are weak and unable to support the super-structural loads. Piles carry these super-structural loads deep into the ground. Therefore, the safety and stability of pile-supported structures depends largely on the behavior of the piles. In addition, accurate prediction of pile behavior is necessary to ensure appropriate structural and serviceability performance. In this paper, an ANN model is developed for predicting pile behavior based on the results of cone penetration test (CPT) data. Approximately 500 data sets, obtained from the published literature, are used to develop the ANN model. The paper compares the predictions obtained by the ANN with those given by a number of traditional methods and it is observed that the ANN model significantly outperforms the traditional methods. An important advantage of the ANN model is that the complete load-settlement relationship is captured. Finally, the paper proposes a series of charts for predicting pile behavior that will be useful for pile design.

      PubDate: 2017-04-24T03:39:44Z
       
  • Stochastic response surface method for reliability problems involving
           correlated multivariates with non-Gaussian dependence structure: Analysis
           under incomplete probability information
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): Fan Wang, Heng Li
      This paper aims to provide a stochastic response surface method (SRSM) that can consider non-Gaussian dependent random variables under incomplete probability information. The Rosenblatt transformation is adopted to map the random variables from the original space into the mutually independent standard normal space for the stochastic surrogate model development. The multivariate joint distribution is reconstructed by the pair-copula decomposition approach, in which the pair-copula parameters are retrieved from the incomplete probability information. The proposed method is illustrated in a tunnel excavation example. Three different dependence structures characterized by normal copulas, Frank copulas, and hybrid copulas are respectively investigated to demonstrate the effect of dependence structure on the reliability results. The results show that the widely used Nataf transformation is actually a special case of the proposed method if all pair-copulas are normal copulas. The effect of conditioning order is also examined. This study provides a new insight into the SRSM-based reliability analysis from the copula viewpoint and extends the application of SRSM under incomplete probability information.

      PubDate: 2017-04-24T03:39:44Z
       
  • A simple critical state interface model and its application in prediction
           of shaft resistance of non-displacement piles in sand
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): Ali Lashkari
      A simple semi-hyperbolic state-dependent constitutive model for sand-structure interfaces is proposed. The model formulation is consistent with critical state soil mechanics since void ratio evolves continuously with shear strain from initial state towards asymptotic critical state at extremely large shear strains. The model takes into account influence of normal stiffness on volume change and stress path. The proposed interface model is implemented in a pile segment analysis scheme for simulation of shaft resistance mobilization in non-displacement piles. Results reveal that the proposed pile segment analysis can well predict shaft resistance of model piles embedded in different sands.

      PubDate: 2017-04-10T10:37:23Z
       
  • Discrete element modeling of the single-particle crushing test for ballast
           stones
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): Bo Wang, Ullrich Martin, Sebastian Rapp
      In this paper, a discrete element modeling approach for the single-particle crushing test for irregularly shaped ballast stones is presented. Bonded spherical particles are used to represent test specimens. Parametric studies focusing on particle size, axial strain rate, particle aggregate size and number of bonds are performed. The selection criteria of these parameters are discussed from the perspective of railway engineering. The results indicate that the proposed modeling approach is reliable for simulating railway ballast stones and can thus be further used for simulations of ballast aggregations.

      PubDate: 2017-03-27T00:52:29Z
       
  • High pressure jet-grouting column installation effect in soft soil:
           Theoretical model and field application
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): Hanlong Liu, Hang Zhou, Gangqiang Kong, Hongyu Qin, Yahui Zha
      This paper presents a theoretical model for investigating the installation effect of high pressure jet grouting column in soft clay. The model is formulated by assuming the installation process as a series of pressure-controlled spherical cavity expansion in semi-infinite soil, of which the approximate solutions are derived by combining use of two fundamental solutions of spherical cavity expansion in finite spherical symmetry soil and displacement-controlled spherical cavity expansion in semi-infinite soil. The approximate solutions are then validated by comparing the predictions with FEM results as well as published results. The comparison results show that the presented approximate solutions are suitable for the problem of pressure-controlled spherical cavity expansion in semi-infinite soil, particularly in evaluating the limit expansion pressure as well as the expansion pressure-ground surface displacement relation. Subsequently, the proposed approximately solutions are applied to interpret the limit injection pressure and the grouting pressure-ground surface displacement during the installation process of HPJ-GC. Some parametric studies are also conducted. Furthermore, an instrumented field test study of HPJ-GC is conducted in the thick soft soils comprising quaternary alluvial and marine deposits of the Lianyungang-Yancheng Highway located in Jiangsu Province, China. The measured ground heave is compared with the analytical predictions using the proposed theoretical model. Reasonable agreement is achieved.

      PubDate: 2017-03-27T00:52:29Z
       
  • Particulate material fabric characterization by rotational haar wavelet
           transform
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): Junxing Zheng, Roman D. Hryciw
      A Rotational Haar Wavelet Transform (RHWT) method is developed to characterize the fabric of particulate assemblies from two-dimensional images. A Maximum Energy Ratio Ψ reveals the fabric direction and its intensity. The method is implemented on 12 sand and 3 rice specimens of various shapes. It was shown that Ψ may be expressed in terms of a material's aspect ratio and relative density. A material fabric classification system based on Ψ is proposed. The parameter also defines the fabric tensor for cross anisotropic material. Scanning electron microscope images of kaolinite clay and several rock images are also analyzed.

      PubDate: 2017-03-20T00:44:07Z
       
  • Numerical 3D modeling of the effects of strain rate and confining pressure
           on the compressive behavior of Kuru granite
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): Timo Saksala, Mikko Hokka, Veli-Tapani Kuokkala
      This paper deals with numerical modeling of the compressive behavior of granite rock under high strain rate dynamic loading and wide range of confining pressure. For this end, a constitutive model based on damage mechanics and viscoplasticity for rock is formulated and implemented in explicit dynamics FEM. The viscoplastic part is based on a simple power law type yield criterion that incorporates the rate-dependency with a linear viscosity term. Moreover, a Rankine type of tensile cut-off is employed. The damage part of the model is formulated with separate scalar damage variables in tension and compression. The model is calibrated for Kuru granite and validated with the experimental data from dynamic compression tests at the strain rate of 600 1/s up to 225MPa of confining pressure. The numerical simulations demonstrate that, despite the underlying continuum modeling approach, the model captures the correct experimental failure modes, including the transition from single-to-multiple fragmentation, as well as the dynamic compressive strengths at different confining pressures.

      PubDate: 2017-03-15T00:32:36Z
       
  • Wind-induced dynamic amplification effects on the shallow foundation of a
           horizontal-axis wind turbine
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): Qian-Feng Gao, Hui Dong, Zong-Wei Deng, Yi-Yue Ma
      Wind loads are random variables, which induce significantly greater responses in structures than do static loads. We develop a finite-infinite element model of a 2MW wind turbine using ABAQUS and then verify it with in situ data. The adopted dynamic constitutive model of the soil is based on the Davidenkov skeleton curve. The results demonstrate that the dynamic amplification factors (DAFs) strongly depend on wind speed and spatial position. Considerable values of the DAFs, ground acceleration, and ground velocity are observed, suggesting that the responses of the shallow foundation of a wind turbine are affected by dynamic wind loads.

      PubDate: 2017-03-15T00:32:36Z
       
  • Multi-laminate non-coaxial modelling of anisotropic sand behavior through
           damage formulation
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): S.A. Sadrnejad, Sh. Shakeri
      A modified multi-laminate model, to predict non-coaxiality in anisotropic sand, is proposed in this paper. The model can easily be extended to other geo-materials only with implementing some minor provisions. To consider anisotropy of sand, two ellipsoids are utilized to summarize shear and compressive stiffness of material in different directions. Damage concept is used to take into account degradation of material through loading procedure. Ellipsoid of rigidity factors is being changed in both size and dimension, under applied strain path. Variation of ellipsoids results in change of stiffness distribution over different planes. In other words, fabric evolution in material is considered through variation of ellipsoids of rigidity factors. A simple rule is proposed for shear stress-strain relationship in loading-unloading and reloading, which captures most of the natural characteristics of sand behavior. In multi-laminate models, depending on stiffness distribution over sampling planes, stress and strain are not coaxial essentially. To achieve better results, non-coaxiality of shear stress and strain on sampling planes is considered by applying vector field concept. Shear stress in different directions of a sampling plane is considered as a vector field. This field is obtained from strain field, considering shear stiffness in various orientations. The model parameters are calibrated using uniaxial compressive test data in different directions, with respect to bedding plane on an anisotropic sand sample. To investigate capability of the model to predict non-coaxiality, results of the model are compared to experimental results obtained from pure principal stress rotation. Ultimately, good accuracy is observed in results.

      PubDate: 2017-03-15T00:32:36Z
       
  • Assessing the impacts of a large slope failure using 3DEC: The
           Chiu-fen-erh-shan residual slope
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): Jian-Hong Wu, Wei-Kang Lin, Hsuan-Teh Hu
      This paper assesses the impact of Chiu-fen-erh-shan residual slope failure using a three-dimensional distinct element program. The simulation results indicate that rocks will severely damage the Lung-Nan path. The Taanshan syncline generates a depression zone adjoining to the slope toe and acts as a buffer zone to trap failing rocks. Some rocks will travel through the syncline, which poses a risk to visitors at the monument and the Shihmen observation deck. Few rocks will pass though the memorial park near the northern boundary of the slope. Visitors should be evacuated out of the impact area during a heavy rainfall event.

      PubDate: 2017-03-15T00:32:36Z
       
 
 
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