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ENGINEERING (1197 journals)                  1 2 3 4 5 6 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Full-text available via subscription   (Followers: 5)
AASRI Procedia     Open Access   (Followers: 14)
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: 207)
Acta Geotechnica     Hybrid Journal   (Followers: 6)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 1)
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: 10)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 4)
Advanced Science     Open Access   (Followers: 4)
Advanced Science Focus     Free   (Followers: 3)
Advanced Science Letters     Full-text available via subscription   (Followers: 4)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 6)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17)
Advances in Artificial Neural Systems     Open Access   (Followers: 3)
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: 9)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 18)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 22)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 7)
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: 13)
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: 34)
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: 28)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access  
Alexandria Engineering Journal     Open Access  
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: 5)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 6)
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: 8)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 4)
Applied Sciences     Open Access   (Followers: 3)
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: 8)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 2)
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: 7)
Asian Journal of Control     Hybrid Journal  
Asian Journal of Current Engineering & Maths     Open Access  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 9)
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: 7)
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: 3)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 24)
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: 8)
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: 16)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 31)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 8)
Biomedical Science and Engineering     Open Access   (Followers: 4)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 1)
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     Full-text available via subscription   (Followers: 14)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 40)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 7)
Case Studies in Thermal Engineering     Open Access   (Followers: 4)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 3)
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: 4)
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: 10)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 13)
City, Culture and Society     Hybrid Journal   (Followers: 20)
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: 4)
Coastal Engineering     Hybrid Journal   (Followers: 10)
Coastal Engineering Journal     Hybrid Journal   (Followers: 3)
Coatings     Open Access   (Followers: 2)
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: 23)
Composite Interfaces     Hybrid Journal   (Followers: 5)
Composite Structures     Hybrid Journal   (Followers: 241)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 174)
Composites Part B : Engineering     Hybrid Journal   (Followers: 215)
Composites Science and Technology     Hybrid Journal   (Followers: 160)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 12)
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: 25)
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: 8)
Computing and Visualization in Science     Hybrid Journal   (Followers: 6)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 25)
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: 7)
Control Engineering Practice     Hybrid Journal   (Followers: 40)
Control Theory and Informatics     Open Access   (Followers: 7)
Corrosion Science     Hybrid Journal   (Followers: 24)
CT&F Ciencia, Tecnologia y Futuro     Open Access  
CTheory     Open Access  
Current Applied Physics     Full-text available via subscription   (Followers: 4)

        1 2 3 4 5 6 | Last

Journal Cover Computers and Geotechnics
  [SJR: 2.033]   [H-I: 58]   [8 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0266-352X
   Published by Elsevier Homepage  [3043 journals]
  • Discrete element modeling of the single-particle crushing test for ballast
    • 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
    • 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 analysis of the hydromechanical response of Callovo-Oxfordian
           claystone to deep excavations
    • Abstract: Publication date: May 2017
      Source:Computers and Geotechnics, Volume 85
      Author(s): Darius M. Seyedi, Antonio Gens

      PubDate: 2017-03-20T00:44:07Z
  • Fundamental aspects of the hydromechanical behaviour of Callovo-Oxfordian
           claystone: From experimental studies to model calibration and validation
    • Abstract: Publication date: May 2017
      Source:Computers and Geotechnics, Volume 85
      Author(s): Gilles Armand, Nathalie Conil, Jean Talandier, Darius M. Seyedi
      Within the framework of feasibility studies for a reversible, deep geological repository of high- and intermediate-level long-lived radioactive waste (HLW, IL-LLW), the French National Radioactive Waste Management Agency (Andra) is investigating the Callovo-Oxfordian (COx) claystone formation near Bure (northeast France) as a potential host formation for the repository. In 2000, Andra initiated construction of the Meuse Haute-Marne Underground Research Laboratory (MHM URL). Concurrently with on-site construction work, an extensive research program has been conducted, including theoretical and experimental studies and constitutive modelling. In-situ experiments provide an extensive data set for performance evaluation of models describing the thermo-hydro-mechanical behaviour of COx claystone under different conditions (excavation, heat, etc.). In 2012, a benchmark exercise was initiated to evaluate proposed models, including basic assumptions, mathematical descriptions, input variables and parameters, and to determine how these assumptions influence model outcomes with respect to in-situ experimental observations. The present paper outlines the main features of the hydromechanical behaviour of COx claystone and presents a series of laboratory test results (triaxial compression and creep tests) providing model development teams with a coherent database for model calibration and validation.

      PubDate: 2017-03-20T00:44:07Z
  • “Transverse Action” – A model benchmark exercise for numerical
           analysis of the Callovo-Oxfordian claystone hydromechanical response to
           excavation operations
    • Abstract: Publication date: May 2017
      Source:Computers and Geotechnics, Volume 85
      Author(s): Darius M. Seyedi, Gilles Armand, Aurélien Noiret
      The Callovo-Oxfordian claystone (COx) is considered as a potential geological formation to host an industrial radioactive waste repository in France. A detailed understanding of the thermo-hydro-mechanical (THM) behavior of the COx is a key issue for design of different repository structures and the safety calculations of the project. More particularly, numerical modeling of induced fracture networks around drifts excavated at the main level of the Andra’s Meuse/Haut-Marne Underground Research Laboratory (M/HM URL) and short and long term behavior of the COx around these drifts are of great interest. Several constitutive models have been developed/used in the framework of the R&D and simulation programs of Andra. A model benchmark exercise has been launched since 2012 to provide an overall view of the developed models regarding the in situ observations. In this view, two series of test cases, respectively at material point scale and at drift excavation scale are defined. Different kinds of constitutive models based on the elasto-visco-plasticity concept, continuum damage mechanics, the rigid block spring method and two-scale computational homogenized model (CHM) are used within this exercise. The obtained results show that accounting for material anisotropy and strain localization treatment techniques can improve the obtained results when elasto-visco-plastic models are used. Damage mechanics based approaches and methods accounting for discontinuities through discrete elements provide also interesting insights especially when fracturing processes must be modeled. However, more efforts are necessary to improve the robustness of these kinds of approaches in the complex context of COx response to excavation works.

      PubDate: 2017-03-20T00:44:07Z
  • Hydro-elasto-viscoplastic modeling of a drift at the Meuse/Haute-Marne
           underground research laboratoratory (URL)
    • Abstract: Publication date: May 2017
      Source:Computers and Geotechnics, Volume 85
      Author(s): M. Souley, G. Armand, J.-B. Kazmierczak
      An underground research laboratory (URL) is being constructed by Andra in eastern France, in Callovo-Oxfordian claystone (COx) in which various in situ geomechanical experiments are being undertaken or are to be carried out. The aim of this URL is to characterize the in situ properties of COx claystone and to test disposal technologies in a realistic way in order to assess the short- and long-term safety of a deep radioactive waste repository. In parallel, theoretical and numerical models able to reproduce the phenomena observed under different types of loading paths must be developed. The phenomenological elastic-visco-plastic model developed by Souley et al. (2011) has been enhanced to reflect recent advances in understanding of the mechanical and hydromechanical behavior of COx claystone and the modification of the mechanical and hydraulic properties in the EDZ (Excavation Damage Zone). In particular, the influence of induced damage and fracturing on the delayed strains and strain rates of the COx claystone and the permeability changes observed at the site scale, as well as hydro-mechanical couplings, are discussed and incorporated in a new model. This model is implemented into the commercial code FLAC3D. Short- and long-term test data (Armand et al., 2016) can be used to identify possible key parameters for the model. These tests were also used to identify certain parameters of our model. Some tests were simulated to verify the numerical implementation of the proposed model. Finally, the simulation of the GCS drift excavation (Seyedi et al., 2016) has been performed. Comparisons to in situ measurements are discussed and some accordance and discrepancies were observed.

      PubDate: 2017-03-20T00:44:07Z
  • An elastoviscoplastic constitutive model for geomaterials: Application to
           hydromechanical modelling of claystone response to drift excavation
    • Abstract: Publication date: May 2017
      Source:Computers and Geotechnics, Volume 85
      Author(s): Sam Cuvilliez, Inès Djouadi, Simon Raude, Roméo Fernandes
      An isotropic elastoviscoplastic constitutive model based on a generalized Hoek-Brown criterion is proposed. The plastic mechanism is characterized by a positive and a negative hardening, and a specific non-associated flow rule allows to take into account the evolution of the dilatancy. Several hydromechanical finite element simulations corresponding to realistic configurations of drift excavations in the underground research laboratory of Bure are presented. Regularization techniques are required to avoid localization phenomena due to softening. A second gradient formulation has been used as it is well suited for dilatant materials such as claystone. Numerical results are discussed and compared with experimental measurements.

      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
  • Impact of sample size on geotechnical probabilistic model identification
    • Abstract: Publication date: July 2017
      Source:Computers and Geotechnics, Volume 87
      Author(s): Xiao-Song Tang, Dian-Qing Li, Zi-Jun Cao, Kok-Kwang Phoon
      This paper aims to investigate the impact of sample size on geotechnical probabilistic model identification. First, the copula approach is presented to model the bivariate distribution of geotechnical parameters. Thereafter, the AIC scores are adopted to identify the best-fit marginal distribution and copula. Second, the variation of AIC scores because of small sample size is investigated using simulated data. Finally, the impact of the variation of AIC scores on identification of the best-fit marginal distribution and copula is examined. The minimum sample sizes for geotechnical data are also suggested to obtain a correct identification of the probabilistic models. The results indicate that the AIC scores estimated from a small sample exhibit large variation. The variation of the AIC scores has a significant impact on probabilistic model identification. The marginal distributions and copulas have a low percentage of correct identification when sample size is small. The percentages of correct identification for the marginal distributions and copulas increase with increasing sample size. The correlation coefficient between geotechnical parameters has a much larger impact on probabilistic model identification than the COV of geotechnical parameters. The suggested minimum sample sizes for geotechnical data are useful for guiding practical geotechnical site investigation.

      PubDate: 2017-03-15T00:32:36Z
  • Effect of non-linear soil deformation on the interaction among energy
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Alessandro F. Rotta Loria, Aurélien Vadrot, Lyesse Laloui
      This study investigates the effect of non-linear soil deformation on the displacement interaction among energy piles. The work is based on interaction factor analyses of full-scale pile group tests, whose results are compared with experimental evidence. The results presented highlight the tendency of interaction factor analyses that ignore non-linear soil deformation to overestimate the interaction and the displacement of energy pile groups. This outcome, in accordance with previous studies for conventional pile groups subjected to mechanical loads, may be considered in the analysis and design of energy pile groups subjected to thermal (and mechanical) loads through the interaction factor method.

      PubDate: 2017-03-15T00:32:36Z
  • Performance of geosynthetic-reinforced granular piles in soft clays: Model
           tests and numerical analysis
    • Abstract: Publication date: July 2017
      Source:Computers and Geotechnics, Volume 87
      Author(s): Murtaza Hasan, N.K. Samadhiya
      The laboratory model tests and numerical analyses have been performed on reinforced granular piles installed in very soft clay. The granular piles were reinforced with geosynthetic in the form of vertical encasement, horizontal strips and combined vertical-horizontal reinforcement. The short term-displacement control model tests were carried out either only a granular pile loaded or with an entire area loaded. The laboratory results in the form of vertical load intensity-settlement behaviour were compared with that obtained from FEM software, PLAXIS 3D. The results indicated significant improvement in ultimate load intensity and stiffness of treated ground due to inclusion of geosynthetic.

      PubDate: 2017-03-08T07:40:00Z
  • Estimation of arching effect in geosynthetic-reinforced structures
    • Abstract: Publication date: July 2017
      Source:Computers and Geotechnics, Volume 87
      Author(s): Shi-Jin Feng, Shu-Gang Ai, H.X. Chen
      An analytical method is proposed to estimate arching effect in geosynthetic-reinforced structures. The method integratedly considers the stresses and deformations of soils and geosynthetics, and variation of settlement with depth in overlying soil. The stresses and deformations of soil and geosynthetics can be obtained considering equilibrium and settlement models of overlying soil, membrane effect of geosynthetics, and one-dimensional compression model of underlying soil. The method is verified using a field test, the stress reduction ratio (SRR) is precisely estimated. The results of parametric study indicate that the method has extensive applicability and is helpful for rational design of geosynthetic-reinforced structures.

      PubDate: 2017-03-08T07:40:00Z
  • System reliability analysis of soil slopes with general slip surfaces
           using multivariate adaptive regression splines
    • Abstract: Publication date: July 2017
      Source:Computers and Geotechnics, Volume 87
      Author(s): Subhadeep Metya, Tanmoy Mukhopadhyay, Sondipon Adhikari, Gautam Bhattacharya
      A data driven multivariate adaptive regression splines (MARS) based algorithm for system reliability analysis of earth slopes having random soil properties under the framework of limit equilibrium method of slices is considered. The theoretical formulation is developed based on Spencer method (valid for general slip surfaces) satisfying all conditions of static equilibrium coupled with a nonlinear programming technique of optimization. Simulated noise is used to take account of inevitable modeling inaccuracies and epistemic uncertainties. The proposed MARS based algorithm is capable of achieving high level of computational efficiency in the system reliability analysis without significantly compromising the accuracy of results.

      PubDate: 2017-03-08T07:40:00Z
  • A fast direct search algorithm for contact detection of convex polygonal
           or polyhedral particles
    • Abstract: Publication date: July 2017
      Source:Computers and Geotechnics, Volume 87
      Author(s): Fei Zheng, Yu-Yong Jiao, Michael Gardner, Nicholas Sitar
      A fast direct search (FDS) algorithm is presented to increase the efficiency of contact detection for convex polygonal and polyhedral particles. All contact types are detected using only a small subset of these contact types: vertex-to-edge for polygons while vertex-to-face and edge-to-edge for polyhedra. First, an initial contact list is generated. Then in subsequent steps the contact list is updated by checking only local boundaries of the blocks and their separation. An exclusion algorithm is applied to avoid unnecessary examination for particles that are near but not-in-contact. The benchmark tests show that the FDS produces significant speed-up in various cases.

      PubDate: 2017-03-02T08:40:36Z
  • A water retention model accounting for the hysteresis induced by hydraulic
           and mechanical wetting-drying cycles
    • Abstract: Publication date: July 2017
      Source:Computers and Geotechnics, Volume 87
      Author(s): Arash Azizi, Cristina Jommi, Guido Musso
      A comprehensive description of the water retention behaviour of unsaturated soils requires accounting for the hysteresis caused by hydraulic and mechanical wetting-drying cycles. A hysteretic water retention model is proposed by introducing the liquid-solid contact angle to account for the dependency of the response on non-monotonic changes in suction and void ratio. The proposed model reproduces main drying and wetting surfaces and also nonlinear scanning curves during hydraulic or mechanical loading. Experimental tests and numerical simulations were carried out to study the water retention behaviour of a clayey silt. The model simulations captured the experimental results well.

      PubDate: 2017-03-02T08:40:36Z
  • Efficient discrete modelling of composite structures for rockfall
    • Abstract: Publication date: July 2017
      Source:Computers and Geotechnics, Volume 87
      Author(s): Anna Effeindzourou, Klaus Thoeni, Anna Giacomini, Corinna Wendeler
      This paper presents a discrete framework for the modelling of composite structures for rockfall protection. The model is applied to analyse the dynamic response of a cylindrical damping module upon impact of a boulder. The damping module consists of a cylindrical wire mesh, two steel rings, a boundary rope, a geotextile lining and a granular filling material. The chain-link wire mesh, the steel rings and the boundary rope are represented with deformable cylinder elements. The geotextile lining is incorporated into the openings of the wire mesh by using deformable facets. The filling material is represented using spherical particles.

      PubDate: 2017-03-02T08:40:36Z
  • A general approach to model interfaces using existing soil constitutive
           models application to hypoplasticity
    • Abstract: Publication date: July 2017
      Source:Computers and Geotechnics, Volume 87
      Author(s): H. Stutz, D. Mašín, A.S. Sattari, F. Wuttke
      The modelling of interfaces is important for the holistic simulation of geotechnical structures (e.g. piles, tunnels and geogrids). For this reason, advanced constitutive interface models and numerical techniques are needed. There are few user-friendly models, and these are rarely implemented. In this paper, a new approach for advanced interface models is proposed. This is based on the assumption that the fully rough interface can be modelled considering simple-shear behaviour at the interface. A 3D soil model is used as a constitutive driver for a frictional subroutine. This minimises the effort required, and advanced interface models are available with less effort. Two different hypoplastic models are used with the new approach. The approach was verified for several aspects (e.g. mesh size dependence), and the volumetric behaviour was studied. The user-friendliness and absence of additional parameters led to more realistic simulation results. The proposed method can be extended to other modelling techniques and will improve the modelling of contacts in soil-structure interaction analysis.

      PubDate: 2017-03-02T08:40:36Z
  • Buckling failures of reserved thin pillars under the combined action of
           in-plane and lateral hydrostatic compressive forces
    • Abstract: Publication date: July 2017
      Source:Computers and Geotechnics, Volume 87
      Author(s): Zhiguo Huang, Xingguo Dai, Longjun Dong
      The reasons that pillars with small width-to-height ratios fail remain unclear. This study established a mechanical model for the buckling failure of a thin pillar subjected to compressive forces to investigate the stability of reserved thin pillars (RTPs) on both sides of mining units during barrier pillar recovery. The critical buckling stress of the thin pillar was obtained using the energy variational method, and its relationship to the aspect ratio (length-to-width ratio) was investigated. The buckling instability of RTPs can be determined by comparing the RTP stress obtained from numerical simulations with the buckling stress derived from the mechanical model.

      PubDate: 2017-03-02T08:40:36Z
  • A pore-scale numerical model for non-Darcy fluid flow through rough-walled
    • Abstract: Publication date: July 2017
      Source:Computers and Geotechnics, Volume 87
      Author(s): Wei Zhang, Beibing Dai, Zhen Liu, Cuiying Zhou
      This paper aims at developing a pore-scale numerical model for non-Darcy fluid flow through rough-walled fractures. A simple general relationship between the local hydraulic conductivity and the flow velocity is proposed. A new governing equation for non-Darcy fluid flow through rough-walled fractures is then derived by introducing this relationship into the Reynolds equation. Based on the non-linear finite element method, a self-developed code is used to simulate the non-Darcy fluid flow through fractures. It is found that the macroscopic results obtained by the numerical simulation agree well with the experimental results. Furthermore, some interesting experimental observations can be reproduced.

      PubDate: 2017-03-02T08:40:36Z
  • Uncertainty of rainfall-induced landslides considering spatial variability
           of parameters
    • Abstract: Publication date: July 2017
      Source:Computers and Geotechnics, Volume 87
      Author(s): Jing-Sen Cai, Tian-Chyi Jim Yeh, E-Chuan Yan, Yong-Hong Hao, Shao-Yang Huang, Jet-Chau Wen
      A cross-correlation analysis is conducted to determine the impacts of the heterogeneity of hydraulic conductivity Ks , soil cohesion c′ and soil friction angle (tan φ′) on the uncertainty of slope stability in time and space during rainfall. We find the relative importance of tan φ′ and c′ depends on the effective stress. While the sensitivity of the stability to the variability of Ks is small, the large coefficient of variation of Ks may exacerbate the variability of pore-water pressure. Therefore, characterizing the heterogeneity of hydraulic properties and pore-water distribution in the field is critical to the stability analysis.

      PubDate: 2017-03-02T08:40:36Z
  • Improvements for the smooth joint contact model of the particle flow code
           and its applications
    • Abstract: Publication date: July 2017
      Source:Computers and Geotechnics, Volume 87
      Author(s): Mohammad Hadi Mehranpour, Pinnaduwa H.S.W. Kulatilake
      This paper deals with two shortcomings of the smooth-joint contact model (SJCM) used in the particle flow code (PFC). The first shortcoming is the increase of the shear strength of the joint when the shear displacement of the joint exceeds a specific value that is related to the particle size. This problem is named as the interlocking problem, which is caused by the interlocking particles. It occurs due to a shortcoming of the updating procedure in the PFC software related to the contact conditions of the particles that lie around the intended joint plane during high shear displacements. This problem also increases the dilation angle and creates unwanted fractures around the intended joint plane. To solve this problem two new approaches are proposed in this paper: (1) joint plane checking (JPC) approach and (2) joint sides checking (JSC) approach. These approaches and the regular approach are used to model: (a) the direct shear test using the PFC2D and PFC3D, (b) the biaxial test on a sample having a persistent joint with a dip angle varying from 0° to 90° at an interval of 15° using the PFC2D and (c) the polyaxial test on two samples, one of them having a joint with a dip direction of 0° and the dip angle varying from 0° to 90° at an interval of 15°, and the other sample having a joint with a dip angle of 60° and the dip direction varying from 0° to 90° at an interval of 15° using the PFC3D. All numerical results show that the JPC and JSC approaches can solve the interlocking problem. Also, they proved to be more consistent with the theory compared to the regular approach. However, the JPC approach leads to a slightly softer joint. Therefore, the JSC approach is suggested for jointed rock modeling using the PFC. The other shortcoming of the SJCM dealt within this paper is its inability to capture the non-linear behavior of the joint closure varying with the joint normal stress. This problem is solved in this paper by proposing a new modified smooth-joint contact model (MSJCM). MSJCM uses a linear relation between the joint normal stiffness and the normal contact stress to model the non-linear relation between the joint normal deformation and the joint normal stress observed in the compression joint normal stiffness test. A good agreement obtained between the results from the experimental test and the numerical modeling of the compression joint normal test shows the accuracy of this new model.

      PubDate: 2017-03-02T08:40:36Z
  • Numerical prediction of the creep behaviour of an unstabilised and a
           chemically stabilised soft soil
    • Abstract: Publication date: July 2017
      Source:Computers and Geotechnics, Volume 87
      Author(s): Paulo J. Venda Oliveira, António A.S. Correia, Luís J.L. Lemos
      This paper examines the ability of volumetric and deviatoric creep laws associated with constitutive models to simulate the creep behaviour of a soft soil in its natural state or chemically stabilised state. Initially, the models/laws are validated by oedometer and triaxial creep tests, for the stabilised and unstabilised soils. Finally, the long-term behaviour of an embankment built on a soft soil reinforced with deep mixing columns is predicted based on the properties for a curing time of 28days. The results show that the creep phenomenon should be considered in a long-term analysis of deep mixing columns.

      PubDate: 2017-02-23T14:47:55Z
  • Three-dimensional stability analysis of a longitudinally inclined shallow
           tunnel face
    • Abstract: Publication date: July 2017
      Source:Computers and Geotechnics, Volume 87
      Author(s): LianHeng Zhao, DeJian Li, Liang Li, Feng Yang, Xiao Cheng, Wei Luo
      The tunnel inclination angle (δ) generally exists in urban and cross-river (sea) tunnels; hence, its effect should be considered in the stability analysis of a tunnel face. However, the influence of this tunnel inclination angle is rarely studied. In this paper, considering the effects of the tunnel inclination angle and the tunneling length (L), the optimal upper-bound solutions of the active and passive failure pressures were obtained using sequential quadratic programming (SQP) based on the upper-bound limit analysis. The effects of the dimensionless parameters on the pressures and failure modes were investigated. The results show that the tunnel inclination angle δ and the dimensionless parameter L/D (D is the section diameter of the tunnel) significantly affect active and passive stabilities. The difference in the results between δ =−10° and δ =10° is mostly greater than 10% and reaches 80% when the internal friction angle (φ) is large. When the value of δ is zero, L/D does not affect on the result. The maximum difference in the results between L/D =0 and L/D =5 are 92.5% (passive failure) and 36.3% (active failure). For the active failure mode, with increasing of φ, the curves, which have δ values of −10°, 0° and 10°, intersect at a particular point when φ reaches a specific value.

      PubDate: 2017-02-23T14:47:55Z
  • Parameters controlling pressure and fracture behaviors in field
           injectivity tests: A numerical investigation using coupled flow and
           geomechanics model
    • Abstract: Publication date: July 2017
      Source:Computers and Geotechnics, Volume 87
      Author(s): Yongcun Feng, K.E. Gray
      Field injectivity tests are widely used in the oil and gas industry to obtain key formation characteristics. The prevailing approaches for injectivity test interpretation rely on traditional analytical models. A number of parameters may affect the test results and lead to interpretation difficulties. Understanding their impacts on pressure response and fracture geometry of the test is essential for accurate test interpretation. In this work, a coupled flow and geomechanics model is developed for numerical simulation of field injectivity tests. The coupled model combines a cohesive zone model for simulating fluid-driven fracture and a poro-elastic/plastic model for simulating formation behavior. The model can capture fracture propagation, fluid flow within the fracture and formation, deformation of the formation, and evolution of pore pressure and stress around the wellbore and fracture during the tests. Numerical simulations are carried out to investigate the impacts of a multitude of parameters on test behaviors. The parameters include rock permeability, the leak-off coefficient of the fracture, rock stiffness, rock toughness, rock strength, plasticity deformation, and injection rate. The sensitivity of pressure response and fracture geometry on each parameter is reported and discussed. The coupled flow and geomechanics model provides additional advantages in the understanding of the fundamental mechanisms of field injectivity tests.

      PubDate: 2017-02-23T14:47:55Z
  • Effects of spatial autocorrelation structure of permeability on seepage
           through an embankment on a soil foundation
    • Abstract: Publication date: July 2017
      Source:Computers and Geotechnics, Volume 87
      Author(s): Lei-Lei Liu, Yung-Ming Cheng, Shui-Hua Jiang, Shao-He Zhang, Xiao-Mi Wang, Zhong-Hu Wu
      Theoretical autocorrelation functions (ACFs) are generally used to characterize the spatial variation of permeability due to the limited number of site investigation data. However, many theoretical ACFs are available in the literature, and there are difficulties in selecting a suitable ACF for general cases. This paper proposes using the random finite element method to investigate the effects of ACF on the seepage through an embankment. Five commonly used ACFs—the squared exponential (SQX), single exponential (SNX), second-order Markov (SMK), cosine exponential (CSX) and binary noise (BIN) ACFs in the literature—are compared systematically by a series of parametric studies to investigate their influences on the seepage flow problem. Both stationary and non-stationary random fields are considered in this study. The results show that the commonly used SQX and SNX ACFs may overestimate and underestimate the seepage flow rate, respectively. It is also known that the maximum exit gradient associated with the SNX ACF is larger than those obtained using the other four ACFs. Additionally, it is proved that the deterministic approach-based design is on the conservative side and tends to be too conservative when dealing with soils with greater variation in the properties. It is also found that the SQX ACF has a higher probability of providing a more conservative design in practice. Overall, the differences between different ACFs are not significant and are within acceptable ranges.

      PubDate: 2017-02-23T14:47:55Z
  • Bearing capacity of rectangular footings in uniform clay with deep
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Jun Liu, Mingzhi Li, Yuxia Hu, Congcong Han
      This letter is concerned with the undrained bearing capacity of rectangular footings with various aspect ratios and embedment ratios in uniform clay. It covers thin plate foundations with low aspect ratios and high embedment depth with embedment ratio up to 150. The work is based on small strain finite element analysis (FEA). After verification of the FEA model against existing solutions of the bearing capacity factors of rectangular footings, a series of FEA results are obtained. Based on the FEA results, a simple formulation is proposed to calculate the bearing capacity factor for rectangle footing with different aspect ratio in any embedment depth, extending the existing solutions to cover a wider ranges of footing aspect ratios and embedment ratios.

      PubDate: 2017-02-15T14:32:57Z
  • Modelling the non-coaxiality of soils from the view of cross-anisotropy
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Yu Tian, Yang-Ping Yao
      Material anisotropy is widely recognized as the fundamental reason that causes non-coaxiality between principal directions of stress and plastic strain increment. In order to model the non-coaxiality of soils from the view of cross-anisotropy, the anisotropic transformed stress method is introduced. By replacing the ordinary stress with the anisotropic transformed stress, and adopting a normal flow rule in the transformed stress space, non-coaxiality can be reflected simply within the framework of conventional elastoplastic constitutive theory. As an example, the unified hardening model is extended to be cross-anisotropic by this method, and then used to predict the non-coaxiality.

      PubDate: 2017-02-15T14:32:57Z
  • Failure probability assessment and parameter sensitivity analysis of a
           contaminant’s transit time through a compacted clay liner
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Liang-tong Zhan, Cheng Chen, Yu Wang, Yun-min Chen
      This paper presents failure probability assessment and parameter sensitivity analysis of a contaminant’s transit time through a compacted clay liner. Monte Carlo simulation (MCS) was used to assess failure probability, and the failure samples generated in the MCS were used to investigate the sensitivity of various uncertain parameters to the failure probability. To facilitate the MCS, a database on various transport parameters was developed by collecting and analyzing measurement data reported in literature. Failure probability assessment and parameter sensitivity analysis showed that the uncertainties in adsorption parameters, longitudinal dispersivity, and hydraulic conductivity have the most significant effects on failure probability.

      PubDate: 2017-02-15T14:32:57Z
  • The importance of accurate time-integration in the numerical modelling of
           P-wave propagation
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Vasiliki Tsaparli, Stavroula Kontoe, David M.G. Taborda, David M. Potts
      The numerical dissipation characteristics of the Newmark and generalised-α time-integration schemes are investigated for P-wave propagation in a fully saturated level-ground sand deposit, where higher frequencies than those for S-waves are of concern. The study focuses on resonance, which has been shown to be of utmost importance for triggering liquefaction due to P-waves alone. The generalised-α scheme performs well, provided that the time-step has been carefully selected. Conversely, the dissipative Newmark method can excessively damp the response, changing radically the computed results. This implies that a computationally prohibiting small time-step would be required for Newmark to provide an accurate solution.

      PubDate: 2017-02-09T14:25:07Z
  • Estimating water retention characteristic parameters using differential
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Sabino Maggi
      The water retention curve has a key role for the hydraulic characterization of porous media. A new method, based on the differential evolution algorithm, for the determination of the characteristic parameters of several water retention models from the experimental data is proposed. We present the details of the method and its application to the calculation of water retention curves of soils. We show that our method can find the optimal model parameters without any prior information on the characteristics of the medium under investigation. The errors associated to the calculated parameters are evaluated through the random perturbation of the data.

      PubDate: 2017-02-04T14:14:25Z
  • Rigid block based lower bound limit analysis method for stability analysis
           of fractured rock mass considering rock bridge effects
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Jianfeng Zhou, Qingsheng Chen, Junxing Wang
      A rigid block based lower bound limit analysis method for analyzing stability of fractured rock mass in 2D and 3D conditions is proposed. The rock bridge effects are considered in the general formation. No assumptions are imposed on the inter-element forces, and the solution obtained is statically admissible. The proposed method is theoretically rigorous and simple. The validation and efficiency of the proposed method have been demonstrated through three typical types of slopes, indicating that apart from the fractures, rock bridge plays a key role in stabilizing rock blocks, which should be greatly concerned in stability analysis of rock mass.

      PubDate: 2017-02-04T14:14:25Z
  • Modelling the settlement behaviour of a strip footing on sloping sandy
           fill under cyclic loading conditions
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Md. Jahid Iftekhar Alam, C.T. Gnanendran, S.R. Lo
      This paper investigates the settlement behaviour of a strip footing seating on the crest of an embankment and subjected to cyclic loading. The embankment fill is a dense sand and the issue is the gradual accumulation of settlement over a large number of load repetitions. Cyclic triaxial tests were first conducted to develop a consistent but simple material model for numerical implementation. Particular emphasis was placed on linking the stress-strain behaviour of an unload-reload cycle to the accumulation of permanent strain, with only five input parameters required to model the cyclic behaviour. The material model was implemented in a numerical analysis to compute the settlement behaviour obtained from model tests conducted by another researcher. It is pertinent to highlight that the same soil, compacted to same density at same moisture content, was used for both the cyclic triaxial tests and model tests. Reasonable to good agreement between the experimental and numerical results was achieved.

      PubDate: 2017-02-04T14:14:25Z
  • Effects of soil anisotropy on a soil structure interaction in a heat
           exchanger pile
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Dunja Perić, Tri V. Tran, Marta Miletić
      A coupled thermal-hydro-mechanical computational modeling of actual field tests, which had been conducted on an end bearing heat exchanger pile, has been carried out. Results of a conventional triaxial test program, which was performed during the site investigation, indicated that two soil layers were anisotropic. A simplified form of a transverse isotropy was used to model the response of these layers. Additional analyses were carried out for completely isotropic soil layers. Comparisons between the measurements obtained during the field testing and predictions of the computational models showed a very good to excellent agreement. Overall the anisotropic model performed better than the isotropic model.

      PubDate: 2017-02-04T14:14:25Z
  • Developing a 3D elastoplastic constitutive model for soils: A new approach
           based on characteristic stress
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Chao Ma, Dechun Lu, Xiuli Du, Annan Zhou
      This paper presents a new approach for the development of an elastoplastic constitutive model to predict the strength and deformation behaviour of soils under general stress conditions. The proposed approach was based on characteristic stress, which considers the effect of the intermediate principal stress on the material strength. Referring to the Cam-clay model, the shear dilatancy equation, plastic potential function and hardening parameter for the developed model were all derived using the characteristic stress. The model predictions indicated that the established model could quantitatively reproduce the negative dilatancy behaviour, positive dilatancy behaviour, and three-dimensional strength properties of soils.

      PubDate: 2017-01-28T06:05:19Z
  • Assessment of strut forces for braced excavation in clays from numerical
           analysis and field measurements
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Anthony T.C. Goh, Fan Zhang, Wengang Zhang, Otard Y.S. Chew
      One important consideration in the design of a braced excavation system is to ensure that the structural bracing system is designed both safely and economically. The forces acting on the struts are often determined using empirical methods such as the Apparent Pressure Diagram (APD) method developed by Peck (1969). Most of these empirical methods that were developed from either numerical analysis or field studies have been for excavations with flexible wall types such as sheetpile walls. There have been only limited studies on the excavation performance for stiffer wall systems such as diaphragm walls and bored piles. In this paper, both 2D and 3D finite element analyses were carried out to study the forces acting on the struts for braced excavations in clays, with focus on the performance for the stiffer wall systems. Subsequently, based on this numerical study as well as field measurements from a number of reported case histories, empirical charts have been proposed for determining strut loads for excavations in stiff wall systems.

      PubDate: 2017-01-28T06:05:19Z
  • Influence of single flaw on the failure process and energy mechanics of
           rock-like material
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Jin Jin, Ping Cao, Yu Chen, Chengzhi Pu, Dawei Mao, Xiang Fan
      This paper investigates the influence of a flaw on crack initiation, the failure mode, deformation field and energy mechanism of the rock-like material under uniaxial compression. The results of laboratory test and numerical simulation demonstrate the flaw inclination effect can be classified into three groups: 0–30°, 30–60° and 75–90°. The characteristic stresses increase as the flaw angle increases. The tensile cracks initiate from gentle flaws (α ⩽30°) and shear cracks appear at tips of steep flaws (α ⩾45°). The input energy, strain energy and dissipation energy of a specimen show approximate increasing trends as the flaw angle increases.

      PubDate: 2017-01-28T06:05:19Z
  • GPU-based parallel computation for discontinuous deformation analysis
           (DDA) method and its application to modelling earthquake-induced landslide
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Yixiang Song, Da Huang, Bin Zeng
      Graphic Processing Unit (GPU), as a computing device, has upgraded from single-subject graphical processors to multi-core processors with tremendous computational horsepower. This paper proposes to accelerate the DDA using parallel Jacobi Preconditioned Conjugate Gradient (JPCG) technique on GPUs. Based on the results of two numerical examples, the calculation accuracies of the DDA with serial and parallel solvers are validated, and we found that the DDA with parallel solvers exhibits a much higher execution efficiency. The movement process of Daguangbao landslide triggered by the Wenchuan earthquake is replicated and the modeled deposit pattern coincides well with the actual topography after earthquake.

      PubDate: 2017-01-22T05:50:28Z
  • Generation of multivariate cross-correlated geotechnical random fields
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): H. Zhu, L.M. Zhang, T. Xiao, X.Y. Li
      A geotechnical problem that involves several spatially correlated parameters can be best described using multivariate cross-correlated random fields. The joint distribution of these random variables cannot be uniquely defined using their marginal distributions and correlation coefficients alone. This paper presents a generic methodology for generating multivariate cross-correlated random fields. The joint distribution is rigorously established using a copula function that describes the dependence structure among the individual variables. The cross-correlated random fields are generated through Cholesky decomposition and conditional sampling based on the joint distribution. The random fields are verified regarding the anisotropic scales of fluctuation and copula parameters.

      PubDate: 2017-01-22T05:50:28Z
  • Class-A-prediction of lateral pile deformation with respect to vibratory
           and impact pile driving
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): E. Heins, J. Grabe
      Distinctions of lateral loading behavior of vibrated and impact driven piles with respect to their influence on state variables of soils exist. Based on a field test simulations of horizontal load tests subsequent to the simulation of installation processes (vibrated and impact driven) are conducted. Soil behavior and horizontal displacement of the piles are investigated. Characteristics of pile installations as dynamic processes with large deformations and horizontal load tests as static processes have to be reproduced. A link to transfer results between CEL-method used for simulations of pile installations and classic FEM used for simulation of horizontal load tests is established.

      PubDate: 2017-01-22T05:50:28Z
  • Lower bound limit analysis of wedge stability using block element method
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Jianfeng Zhou, Junxing Wang
      A lower bound limit analysis approach based on the block element method is proposed to analyze wedge stability problem. The search for the maximum value of the factor of safety is set up as a nonlinear programming problem. Sequential quadratic programming (SQP) algorithm from a reasonable initial value is applied to obtain the optimal solution. This approach provides a strict lower bound solution considering the sliding mode and rotation effect simultaneously. The deviations of the factor of safety between the present and traditional limit equilibrium methods are positively correlated with both the friction angle and the dip of the discontinuity surface.

      PubDate: 2017-01-22T05:50:28Z
  • Implementation of displacement-dependent Barton-Bandis rock joint model
           into discontinuous deformation analysis
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Shuqi Ma, Zhiye Zhao, Wen Nie, Jan Nemcik, Zhenyu Zhang, Xing Zhu
      Discontinuous deformation analysis (DDA) has been widely applied in analyzing various rock engineering problems. As the joint strength play a vital role in the stability of jointed rock mass, this paper makes an attempt to implement the Barton-Bandis rock joint model into the DDA code to replace the original Mohr-Coulomb joint model. The developed Barton-Bandis joint model which is characterized by displacement-dependent shear strength is verified by experimental direct shear tests. An example of a block sliding on an inclined plane is used to demonstrate the capacity of the DDA-BB model in predicting the dynamic motion behavior of sliding blocks.

      PubDate: 2017-01-15T05:31:08Z
  • Discrete modeling of low-velocity penetration in sand
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Jens Kristian Holmen, Lars Olovsson, Tore Børvik
      In this paper, a discrete particle method was evaluated and used in numerical simulations of low-velocity penetration in sand. Hemispherical, blunt, and ogival-nosed impactors were tested at striking velocities below 5m/s. The tests were conducted in a dropped-object-rig where the resisting force from the sand was measured continuously during the experiments. This provided a basis for comparison for the simulations. The shapes of the force-penetration depth curves were different for the various impactors, but the ultimate penetration depths were similar in all tests that were done with the same impact velocity. Three-dimensional discrete particle simulations were generally capable of describing the behavior of the sand. However, the peak resisting force was underestimated, which led to a slight overestimation of the ultimate penetration depth. This discrete particle method has previously been evaluated at high impact velocities. The results presented in this study supplement past results and show that the method can also be used to describe the overall response of sand subjected to low-velocity penetration.

      PubDate: 2017-01-15T05:31:08Z
  • Numerical modelling of the effects of consolidation on the undrained
           spudcan capacity under combined loading in silty clay
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Raffaele Ragni, Britta Bienen, Dong Wang, David Mašín, Mark J. Cassidy
      The paper shows the increase in vertical and combined horizontal and moment bearing capacity of jack-up spudcan installed in silty clay, when a load-hold period is accounted for. The numerical implementation of a hypoplastic model for structured clays, combined with large deformation coupled analyses allowed the modelling of the spudcan installation process. Results were mapped into three-dimensional small strain analyses, conducted to investigate the combined loading capacity and describe the yield surface. The underlying failure mechanisms were investigated and increases in capacity due to consolidation determined. Experimental centrifuge data on carbonate silty clay validated the qualitative trend revealed numerically.

      PubDate: 2017-01-15T05:31:08Z
  • Influence of the intermediate principal stress and principal stress
           direction on the mechanical behavior of cohesionless soils using the
           discrete element method
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Bo Li, Liangliang Chen, Marte Gutierrez
      In this paper, the Discrete Element Method (DEM) is employed to numerically explore the response of hollow cylinder specimens of granular soils under complex stress paths. Two series of numerical tests are conducted to clarify the effects of the principal stress direction α and the intermediate principal stress through the b-value on the mechanical response of granular materials. The effects of α and b-value on the non-coaxiality of the principal stress and the principal plastic strain increment directions are investigated. It is observed that b-value and α significantly affect the non-coaxial behavior of granular materials. Finally, the results are discussed and compared with those obtained from physical laboratory tests.

      PubDate: 2017-01-15T05:31:08Z
  • Empirical assessment of the critical time increment in explicit
           particulate discrete element method simulations
    • Abstract: Publication date: June 2017
      Source:Computers and Geotechnics, Volume 86
      Author(s): Masahide Otsubo, Catherine O'Sullivan, Tom Shire
      This contribution considers the critical time increment (Δtcrit ) to achieve stable simulations using particulate discrete element method (DEM) codes that adopt a Verlet-type time integration scheme. The Δtcrit is determined by considering the maximum vibration frequency of the system. Based on a series of parametric studies, Δtcrit is shown to depend on the particle mass (m), the maximum contact stiffness (Kmax ), and the maximum particle coordination number (CN, max). Empirical expressions relating Δtcrit to m, Kmax , and CN, max are presented; while strictly only valid within the range of simulation scenarios considered here, these can inform DEM analysts selecting appropriate Δtcrit values.

      PubDate: 2017-01-15T05:31:08Z
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