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ENGINEERING (1199 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: 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: 217)
Acta Geotechnica     Hybrid Journal   (Followers: 6)
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: 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: 5)
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: 9)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 19)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 23)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
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: 35)
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   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 27)
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: 8)
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)
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: 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: 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: 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: 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: 3)
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: 13)
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: 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: 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: 6)
Composite Structures     Hybrid Journal   (Followers: 252)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 176)
Composites Part B : Engineering     Hybrid Journal   (Followers: 222)
Composites Science and Technology     Hybrid Journal   (Followers: 164)
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: 8)
Control Engineering Practice     Hybrid Journal   (Followers: 41)
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  

        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  [3031 journals]
  • An energy-based interpretation of sand liquefaction due to vertical ground
    • 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
  • A comparison of discrete element and micromechanical methods for
           determining the effective elastic properties of geomaterials
    • Abstract: Publication date: July 2017
      Source:Computers and Geotechnics, Volume 87
      Author(s): S. Geer, J.R. Berger, William J. Parnell, G.G.W. Mustoe
      Data generated from scanning electron microscopy images of oil-shale geomaterials are used to generate configurations and to acquire parameters required for use in homogenization schemes for the determination of the effective elastic properties of the samples. Two alternative homogenization methods are employed: numerical simulation using the Discrete Element Method and the Polycrystalline Self-Consistent Method from micromechanics. The schemes give rise to predictions of the effective elastic properties that are in very good agreement.

      PubDate: 2017-05-17T08:39:47Z
  • An elastoplastic model for the analysis of a driven pile extended with a
    • Abstract: Publication date: July 2017
      Source:Computers and Geotechnics, Volume 87
      Author(s): Enrique Justo, Manuel Vázquez-Boza, Jose Luis Justo, Jose Luis Arcos
      An elastoplastic model for the analysis of a driven pile extended at the bottom with a micropile under axial load is presented. The model is an extension of the integral equation method of Poulos and Davis. The finite-difference scheme used to obtain the pile displacements is reformulated to take into account the discontinuity in the stress distribution at the joint between pile and micropile. The results obtained with the proposed method are compared with the outcomes of a more sophisticated finite element simulation, and also with data from full-scale load tests. Reasonably good agreement is obtained in both cases.
      Graphical abstract image

      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
  • Parallel and scalable block system generation
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): Michael Gardner, John Kolb, Nicholas Sitar
      Generating a realistic representation of a fractured rock mass is a first step in many different analyses. Field observations need to be translated into a 3-D model that will serve as the input for these analyses. The block systems can contain hundreds of thousands to millions of blocks of varying sizes and shapes; generating these large models is very computationally expensive and requires significant computing resources. By taking advantage of the advances made in big data analytics and Cloud Computing, we have a developed an open-source program—SparkRocks—that generates block systems in parallel. The application runs on Apache Spark which enables it to run locally, on a compute cluster or the Cloud. The block generation is based on a subdivision and linear programming optimization as introduced by Boon et al. (2015). SparkRocks automatically maintains load balance among parallel processes and can be scaled up on the Cloud without having to make any changes to the underlying implementation, enabling it to generate real-world scale block systems containing millions of blocks in minutes.

      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
  • A micro-mechanics based viscoplastic model for clayey rocks
    • Abstract: Publication date: September 2017
      Source:Computers and Geotechnics, Volume 89
      Author(s): F. Farhat, W.Q. Shen, J.F. Shao
      In this study, a micro-mechanics based viscoplastic model is proposed to describe time-dependent deformation for a class of clayey rocks. The heterogeneous rock is represented as a composite material containing a porous clay matrix and mineral inclusions at a mesoscopic scale. The clay matrix is composed of a solid phase and pores at the microscopic scale. The effective plastic yield criterion is determined from a nonlinear homogenization procedure (Shen et al., 2013). This criterion is extended and used as a viscoplastic loading function. Together with a suitable hardening law and a non-associated flow rule, the viscoplastic model is completed. A series of numerical assessments are presented to investigate the influence of porosity and mineral inclusions on the time-dependent deformation of clayey rocks. Comparisons between numerical results and experimental data are also performed and presented for different loading paths.

      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
  • Efficient subset simulation for evaluating the modes of improbable slope
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): A.P. van den Eijnden, M.A. Hicks
      For analyzing low probability slope failures, a modified version of subset simulation, based on performance-based subset selection rather than the usual probability-based subset selection, is combined with the random finite element method. The application to an idealized slope is used to study the efficiency and consistency of the proposed method compared to classical Monte Carlo simulations and the shear strength reduction (SSR) method. Results demonstrate that failure events taking place without strength reduction have different modes of failure than stable slopes brought to failure by SSR. The correlation between sliding volume and factor of safety is also demonstrated.

      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
  • Numerical analyses of stability and deformation behavior of reinforced and
           unreinforced tunnel faces
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): Alessandra Paternesi, Helmut F. Schweiger, Giuseppe Scarpelli
      In traditional tunneling, an analysis of the face stability is required to avoid failure mechanisms or excessive face extrusion. Face reinforcement can improve face stability and reduce deformations. In the present work a numerical study of both unreinforced and reinforced tunnel excavation faces by means of 3D FEM analyses is presented. The results are compared with those of the traditional limit equilibrium method and with an analytical solution based on previous numerical studies. It could be shown that the LEM may lead to non-conservative results. Finally, the deformation response is assessed and the benefits of face reinforcements are investigated.

      PubDate: 2017-04-17T03:21:01Z
  • 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
  • Demonstration of spatial anisotropic deformation properties for jointed
           rock mass by an analytical deformation tensor
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): Quan Jiang, Jie Cui, Xia-ting Feng, Yi-hu Zhang, Mei-zhu Zhang, Shan Zhong, Shu-guang Ran
      This paper develops a joint deformation tensor ( JD ), which considers all of the joint's mechanical and geometrical parameters that affect the deformability of the rock mass. The method based on JD ( JD method) and an elastic deformation anisotropy index (EDAI) are deduced for estimating the spatial anisotropy deformation of a jointed rock mass. The numerical modeling and in situ true triaxial compressive experiments well verified the effectiveness of the EDAI and JD method for the rock mass containing one joint set, orthogonal joint sets or the rock mass containing any types of joint network with unity stiffness ratio.

      PubDate: 2017-04-10T10:37:23Z
  • Isogeometric analysis of THM coupled processes in ground freezing
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): Yared W. Bekele, Hiroyuki Kyokawa, Arne M. Kvarving, Trond Kvamsdal, Steinar Nordal
      An isogeometric analysis (IGA) based numerical model is presented for simulation of thermo-hydro-mechanically (THM) coupled processes in ground freezing. The momentum, mass and energy conservation equations are derived based on porous media theory. The governing equations are supplemented by a saturation curve, a hydraulic conductivity model and constitutive equations. Variational and Galerkin formulation results in a highly nonlinear system of equations, which are solved using Newton-Raphson iteration. Numerical examples on isothermal consolidation in plane strain, one-dimensional freezing and heave due to a chilled pipeline are presented. Reasonably good agreements were observed between the IGA based heave simulations and experimental results.

      PubDate: 2017-04-10T10:37:23Z
  • Three-dimensional undrained tunnel face stability in clay with a linearly
           increasing shear strength with depth
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): Boonchai Ukritchon, Kongkit Yingchaloenkitkhajorn, Suraparb Keawsawasvong
      The undrained tunnel face stability in clay with a linearly increasing shear strength with depth was investigated by three-dimensional finite element analysis. Three parametric studies were performed to study the effects of the cover depth ratio, overburden stress factor and linear strength gradient ratio on the load factor of the undrained tunnel face stability. The influence of the linear strength gradient ratio on the predicted failure mechanism of the undrained face stability was discussed and examined. An approximate closed-form solution was proposed for three-dimensional undrained tunnel face stability in clays with constant or linearly increasing shear strength profiles with depth.

      PubDate: 2017-04-10T10:37:23Z
  • Application of a memory surface model to predict whole-life settlements of
           a sliding foundation
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): Riccardo Corti, Susan M. Gourvenec, Mark F. Randolph, Andrea Diambra
      In this paper a novel modelling procedure is proposed to estimate whole-life settlements of tolerably mobile sliding foundations. A new kinematic hardening-critical state-state parameter constitutive model, the Memory Surface Hardening model, is implemented in a one-dimensional analysis to predict accumulated vertical settlements under drained lateral cyclic loading. The Memory Surface Hardening model performance is compared with the Modified Cam Clay and Severn-Trent Sand models. The Memory Surface Hardening model is adopted to simulate available experimental data from centrifuge tests to predict the settlement of a sliding foundation at the final stable state (i.e. no further volume changes occur).

      PubDate: 2017-04-10T10:37:23Z
  • Dimensionless input parameters in discrete element modeling and assessment
           of scaling techniques
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): Ali Yousefi, Tang-Tat Ng
      A set of dimensionless input parameters were defined for DEM using a characteristic time which is a function of density and elastic modulus of particles and an arbitrary characteristic length. Dimensionless strain rate and mass damping ratio are inversely proportional to the characteristic time, and stress is normalized by elastic modulus to give dimensionless stress. It was demonstrated that the response of a model in the dimensionless scale is invariant with the choice of density, elastic modulus and the characteristic length if dimensionless strain rate and mass damping ratio are kept constant. Small time step is a prohibitive aspect of DEM. Scaling techniques are widely employed to enlarge the time step. Using the dimensionless scheme, it was learned that density scaling is equivalent to the use of a higher strain rate, and stiffness scaling results in a higher strain rate and an elevated stress state in the dimensionless scale.

      PubDate: 2017-04-10T10:37:23Z
  • Numerical analysis of lateral movements and strut forces in deep cement
           mixing walls with top-down construction in soft clay
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): Pitthaya Jamsawang, Sittisak Jamnam, Pornkasem Jongpradist, Pornpot Tanseng, Suksun Horpibulsuk
      This article presents the observed and simulated lateral movements and strut forces induced in deep cement mixing walls under deep excavation using top-down construction techniques in soft Bangkok clay. The walls are supported laterally by permanent concrete slabs and temporary struts. A three-dimensional numerical model is first calibrated with observed data from a case study. Then, a parametric study is performed to compare this construction method with the bottom-up method and investigate the influence of the DCM wall thickness on lateral movements and strut forces of the wall.

      PubDate: 2017-04-10T10:37:23Z
  • Strength failure behavior and crack evolution mechanism of granite
           containing pre-existing non-coplanar holes: Experimental study and
           particle flow modeling
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): Yan-Hua Huang, Sheng-Qi Yang, P.G. Ranjith, Jian Zhao
      In this study, uniaxial compression tests were conducted on granite specimens containing three non-coplanar holes. The relationships between the stress, acoustic emission (AE) and crack evolution process were analyzed using AE measuring and photographic monitoring techniques. Particle flow code (PFC) was then used to simulate the strength failure behaviors of the specimens with three non-coplanar holes under uniaxially loading. Four typical crack coalescence patterns were identified, i.e., shear, mixed tensile and shear, and tensile. The crack evolution mechanisms around the pre-existing holes in the granite specimens were revealed by an analysis of the force and displacement fields.

      PubDate: 2017-04-10T10:37:23Z
  • The combined scaled boundary finite-discrete element method: Grain
           breakage modelling in cohesion-less granular media
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): T. Luo, E.T. Ooi, A.H.C. Chan, S.J. Fu
      A computational technique combining the scaled boundary finite element method (SBFEM) and the discrete element method (DEM) is developed. Both methodologies work in tandem to model two mechanisms i.e. grain-to-grain interaction via DEM; and breakage of individual grains via SBFEM. Both play important roles in characterising the response of granular soils. The combination of the two methods results in some advantages in computational flexibility and implementation in modelling grain breakage in granular materials. Parametric studies demonstrate the method’s ability to reproduce stress-strain curves in bi-axial tests of granular rock-fills; and qualitatively predicts characteristics of grain breakage observed in laboratory tests.

      PubDate: 2017-04-10T10:37:23Z
  • The role of uncertainty in bedrock depth and hydraulic properties on the
           stability of a variably-saturated slope
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): Guilherme J.C. Gomes, Jasper A. Vrugt, Eurípedes A. Vargas, Julia T. Camargo, Raquel Q. Velloso, Martinus Th. van Genuchten
      We investigate the uncertainty in bedrock depth and soil hydraulic parameters on the stability of a variably-saturated slope in Rio de Janeiro, Brazil. We couple Monte Carlo simulation of a three-dimensional flow model with numerical limit analysis to calculate confidence intervals of the safety factor using a 22-day rainfall record. We evaluate the marginal and joint impact of bedrock depth and soil hydraulic uncertainty. The mean safety factor and its 95% confidence interval evolve rapidly in response to the storm events. Explicit recognition of uncertainty in the hydraulic properties and depth to bedrock increases significantly the probability of failure.

      PubDate: 2017-04-10T10:37:23Z
  • Numerical simulation of fracture path and nonlinear closure for
           simultaneous and sequential fracturing in a horizontal well
    • Abstract: Publication date: August 2017
      Source:Computers and Geotechnics, Volume 88
      Author(s): Wan Cheng, Guosheng Jiang, Yan Jin
      Reservoir stimulation requires a model to evaluate the fracture path and closure for the simultaneous or sequential propagation of the hydraulic fracture (HF). This paper presents a fluid-solid coupled model to simulate multi-stage HF propagation. A non-linear joint model is proposed to evaluate the fracture closure when the created fractures are elastically propped. HF closure continues until the balance of external stress matches the proppant's resistance. The reservoir along the horizontal wellbore is not stimulated equally by the multi-stage fracturing. The HFs in the subsequent stage are ‘repelled’ and restrained by the HFs in the previous stage.

      PubDate: 2017-04-10T10:37:23Z
  • 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 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
  • 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
  • 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
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