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ENGINEERING (1206 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Hybrid Journal   (Followers: 6)
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: 234)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 2)
Acta Scientiarum. Technology     Open Access   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Active and Passive Electronic Components     Open Access   (Followers: 7)
Adaptive Behavior     Hybrid Journal   (Followers: 11)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 6)
Advanced Science     Open Access   (Followers: 5)
Advanced Science Focus     Free   (Followers: 3)
Advanced Science Letters     Full-text available via subscription   (Followers: 7)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17)
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: 15)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 10)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 21)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 28)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 12)
Advances in Polymer Science     Hybrid Journal   (Followers: 41)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 37)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 1)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 4)
AIChE Journal     Hybrid Journal   (Followers: 30)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access  
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 28)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 11)
American Journal of Engineering Education     Open Access   (Followers: 9)
American Journal of Environmental Engineering     Open Access   (Followers: 16)
American Journal of Industrial and Business Management     Open Access   (Followers: 23)
Analele Universitatii Ovidius Constanta - Seria Chimie     Open Access  
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Regional Science     Hybrid Journal   (Followers: 7)
Annals of Science     Hybrid Journal   (Followers: 7)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applicable Analysis: An International Journal     Hybrid Journal   (Followers: 1)
Applied Catalysis A: General     Hybrid Journal   (Followers: 6)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 15)
Applied Clay Science     Hybrid Journal   (Followers: 5)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4)
Applied Nanoscience     Open Access   (Followers: 8)
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: 3)
Asian Engineering Review     Open Access  
Asian Journal of Applied Science and Engineering     Open Access   (Followers: 1)
Asian Journal of Applied Sciences     Open Access   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 8)
Asian Journal of Control     Hybrid Journal  
Asian Journal of Current Engineering & Maths     Open Access  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 8)
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
ATZagenda     Hybrid Journal  
ATZextra worldwide     Hybrid Journal  
Australasian Physical & Engineering Sciences in Medicine     Hybrid Journal   (Followers: 1)
Australian Journal of Multi-Disciplinary Engineering     Full-text available via subscription   (Followers: 2)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 8)
Avances en Ciencias e Ingeniería     Open Access  
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
Bangladesh Journal of Scientific and Industrial Research     Open Access  
Basin Research     Hybrid Journal   (Followers: 5)
Batteries     Open Access   (Followers: 4)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 23)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 4)
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: 10)
Biomedical Engineering     Hybrid Journal   (Followers: 16)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 13)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 17)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 31)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 9)
Biomedical Science and Engineering     Open Access   (Followers: 4)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 2)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription  
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 14)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 3)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 14)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 41)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 8)
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: 8)
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: 10)
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: 5)
Coatings     Open Access   (Followers: 3)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 13)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 13)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 2)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 26)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Composite Structures     Hybrid Journal   (Followers: 259)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 181)
Composites Part B : Engineering     Hybrid Journal   (Followers: 236)
Composites Science and Technology     Hybrid Journal   (Followers: 216)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 14)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 6)
Computer Science and Engineering     Open Access   (Followers: 17)
Computers & Geosciences     Hybrid Journal   (Followers: 28)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 5)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 4)
Computers and Geotechnics     Hybrid Journal   (Followers: 10)
Computing and Visualization in Science     Hybrid Journal   (Followers: 5)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 30)
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: 9)
Control Engineering Practice     Hybrid Journal   (Followers: 42)
Control Theory and Informatics     Open Access   (Followers: 8)
Corrosion Science     Hybrid Journal   (Followers: 25)
CT&F Ciencia, Tecnologia y Futuro     Open Access  
CTheory     Open Access  
Current Applied Physics     Full-text available via subscription   (Followers: 4)
Current Science     Open Access   (Followers: 58)

        1 2 3 4 5 6 7 | Last

Journal Cover Computers and Geotechnics
  [SJR: 2.033]   [H-I: 58]   [10 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0266-352X
   Published by Elsevier Homepage  [3044 journals]
  • Undrained capacity of a surface circular foundation under fully
           three-dimensional loading
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Z. Shen, S. Bie, L. Guo
      Circular foundations are widely employed in offshore engineering to support facilities and are generally subjected to fully three-dimensional loading due to the harsh offshore environmental load and complex operational loads. The undrained capacity of surface circular foundations on soil with varying strength profiles and under fully three-dimensional loading is investigated and presented in the form of failure envelopes that obtained from finite element analyses. The combined ultimate limit state of circular foundations is defined as the two-dimensional failure envelopes in resultant H-M loading space accounting for the vertical load and torsion mobilisation. The effects of vertical load and torsion mobilisation, soil shear strength heterogeneity and loading angle from moment to horizontal load on the shape of normalised H-M failure envelopes are explored. A series of expressions are proposed to describe the shape of failure envelopes obtained numerically, enabling essentially instantaneous generation of failure envelopes and optimisation of a circular foundation design based on constraint of any input variable through implementation in an automated calculation tool. An example application is ultimately provided to illustrate how the proposed expressions may be used in practice.

      PubDate: 2017-09-02T09:26:44Z
  • Computation of the safety factor for slope stability using discontinuous
           deformation analysis and the vector sum method
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Xiaodong Fu, Qian Sheng, Yonghui Zhang, Jian Chen, Shankai Zhang, Zhenping Zhang
      This study introduces the vector sum method into discontinuum-based methods by considering the sliding vector and the stress state of the discrete block system. The sliding direction computation and force projection in the new approach are detailed, and the safety factor is solved by explicit equations. The vector sum method is implemented in the discontinuous deformation analysis (DDA) program and is used to compute the safety factors for two numerical examples. A comparison of the solutions obtained with the theoretical analysis and limit equilibrium analysis demonstrates that the new method is suitable for calculating the safety factor of a slope.

      PubDate: 2017-09-02T09:26:44Z
  • A simplified axisymmetric model for column supported embankment systems
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Lin-Shuang Zhao, Wan-Huan Zhou, Ka-Veng Yuen
      In this study, a simplified axisymmetric model is built to simulate a column supported embankment system. The model is based on a cylindrical unit cell that contains one column with the surrounding soil and a layer of overlying embankment fill. The deformation of the column with the surrounding soil is simulated using a deformed shape function. The embankment fill is divided into an inner cylinder and an outer hollow cylinder to simulate the soil arching effect. The stress continuity and volume deformation continuity are applied to combine the behavior of the embankment fill and that of the column-reinforced foundation together. A semi-analytical solution is obtained, and it is verified using a finite element analysis and a case study. After that, parametric studies are put forward to evaluate the load transfer mechanism within the embankment fill, the shear stress at the interface between the column and the surrounding soil, and the vertical stress distribution within the column. The influences of the column modulus, the spacing between columns, the height of the embankment fill, and the length of the column on the soil arching effect are investigated and discussed. It is concluded that when the column modulus becomes larger, the stress ratio between the column and the surrounding soil increases correspondingly. The height of equal settlement plane is close to the net spacing between columns, but it changes slightly with a change in the column modulus.

      PubDate: 2017-09-02T09:26:44Z
  • A comprehensive study on the parameters setting in smoothed particle
           hydrodynamics (SPH) method applied to hydrodynamics problems
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Zirui Mao, G.R. Liu, Xiangwei Dong
      Smoothed particle hydrodynamics (SPH) is a meshfree, Lagrangian particle method which has advantages in handling solids with extremely large deformation. Like any other numerical methods, cares must be taken to ensure its desirable accuracy and stability through considering several correction techniques in calculation. The selection of values for parameters in those correction approaches is a key step in SPH simulation, which is always difficult for new beginners to deal well with effectively. This paper examines the common inconsistency and instability problems in SPH method and studies its computational efficiency when applied to hydrodynamics problems with material strength like soil column collapse. We analyzed in detail how the correction techniques mitigate these inconsistency and instability problems. Also, the numerical testing results associate with different values for the parameters used in the correction techniques are provided for better understanding the influence of these parameters and for finding out the desirable values. It is found that (1) the SPH method is easily subjected to an inconsistency problem in the boundary area due to the boundary deficiency, and it can be treated well by adopting “virtual particles” contributing to the particle summations. (2) The numerical oscillation in SPH simulation can be mitigated effectively by artificial viscosity with the suggested parameter values. (3) The tension cracking treatment, artificial viscosity and artificial stress work well in removing the tensile instability problem in SPH method. In addition, the nearest neighboring particle searching (NNPS) algorithm, spacing ratio, smoothing length and time step influence the efficiency and accuracy of SPH method significantly. It is shown that SPH method with suggested parameters values can produce a very good result compared with the experimental result.

      PubDate: 2017-09-02T09:26:44Z
  • Prediction of fracture trajectory in anisotropic rocks using modified
           maximum tangential stress criterion
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Ehsan Mohtarami, Alireza Baghbanan, Hamid Hashemolhosseini
      A new criterion to predict crack propagation trajectory in anisotropic rocks with incorporating the concept of T-stress in formulating stress field near the crack tip was developed. The developed criterion along with enrichment functions and interaction integral in the extended finite element method (XFEM) framework made a sophisticated tool in modeling fracturing process in anisotropic media. Numerical results indicated that stress intensity factors considerably depend on orientation of anisotropy axes and ratio of the elastic modulus. The proposed formulation for anisotropic media provides a more accurate prediction of crack propagation trajectory compared with conventional methods, especially in mixed mode conditions.
      Graphical abstract image

      PubDate: 2017-09-02T09:26:44Z
  • Reliability evaluation of slope considering geological uncertainty and
           inherent variability of soil parameters
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Zhi-Ping Deng, Dian-Qing Li, Xiao-Hui Qi, Zi-Jun Cao, Kok-Kwang Phoon
      Geological uncertainty is often ignored in slope reliability analysis, even though the inherent variability of soil parameters is considered. This paper aims to propose a method for slope reliability analysis by considering both the inherent variability of soil parameters and geological uncertainty. A coupled Markov chain (CMC) model is used to simulate the geological uncertainty. An implementation procedure for slope reliability considering the aforementioned two types of uncertainty is provided. A slope reliability problem is analyzed to validate the proposed method with the borehole data from Perth, Australia. Different borehole layout schemes are designed to reflect the effect of both number and location of boreholes on slope reliability. Moreover, which type of uncertainty mentioned above has a greater impact on slope reliability is explored. The results indicate that the proposed method can effectively evaluate the slope reliability considering these two types of uncertainty. If only the inherent variability is considered, the accuracy of reliability analysis mainly depends on the used geological profiles. Borehole layout scheme has a significant effect on slope reliability. Both probability of failure ( P f ) and mean of factor of safety (FS) of slope do not monotonously vary with an increasing number of boreholes. The boreholes designed in the critical influence zone can provide more information to improve the accuracy of slope reliability. The coefficients of variation (COVs) of shear strength parameters and the discrepancy among the means of shear strengths for different soils play different and major role between the two types of uncertainty in the reliability analysis of soil slope.

      PubDate: 2017-09-02T09:26:44Z
  • A study on how to couple thermo-hydro-mechanical behaviour of unsaturated
           soils: Physical equations, numerical implementation and examples
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Ayman A. Abed, Wojciech T. Sołowski
      This paper describes a thermo-hydro-mechanical framework suitable for modelling the behaviour of unsaturated soils. In particular, this paper focuses on bentonite clay subjected to a thermo-hydro-mechanical load, as in the case of nuclear waste engineering barriers. The paper gives a theoretical derivation of the full set of coupled balance equations governing the material behaviour as well as an extended physical interpretation. Finally, a finite element discretisation of the equations and number of simulations verifying their implementation into a custom finite element code is provided. Some aspects of the formulation are also validated against experimental data.

      PubDate: 2017-09-02T09:26:44Z
  • Multi-directional modeling for prediction of fabric anisotropy in sand
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Hadi Dashti, Seyed Amirodin Sadrnejad, Navid Ganjian
      Anisotropy in the onset of liquefaction and post liquefaction under cyclic loading condition causes the change in response behavior of the soil. The proposed model operates within the integration of sliding/opening/closing framework of 17 predefined planes as local deformation. This leads to the use of better stress/strain multilaminate histories with many directional effects on soil behavior specifically internal mechanism during pre and post-liquefaction. The ability of multilaminate model for fabric anisotropy has been proven by comparison with the experimental results under drain and undrained conditions and monotonic and cyclic loading. The effects of induced anisotropy was also investigated.
      Graphical abstract image

      PubDate: 2017-09-02T09:26:44Z
  • Bearing capacity of ring footings on cohesionless soil under eccentric
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Omid Sargazi, Ehsan Seyedi Hosseininia
      This paper presents a study on the bearing capacity of eccentrically-loaded rough ring footings resting over cohesionless soil. To this aim, a series of 3D numerical simulations were performed using the finite difference method. In order to consider the effect of load eccentricity, reduction factor method is applied. In this method, the ratio of an eccentrically-loaded bearing capacity to the bearing capacity of the same footing under vertical load is defined. Comparison between the results of the numerical simulations with those of analytical solutions and experimental data indicates good agreement. A mathematical expression is also introduced for eccentrically-loaded ring footings.

      PubDate: 2017-09-02T09:26:44Z
  • Critical-state-based Mohr-Coulomb plasticity model for sands
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Sang Inn Woo, Hoyoung Seo, Joonyoung Kim
      This paper presents a refined Mohr-Coulomb model for sands based on the critical state theory. The refined model adjusts a dilatancy angle based on the state parameter with respect to the critical state line. Furthermore, a friction angle is decomposed into the critical state friction angle and a portion of the dilatancy angle to capture the peak phenomenon of dilative sands. The elemental simulations of the drained and undrained triaxial compression tests on Toyoura sand using the refined model showed much better performance than the conventional Mohr-Coulomb model.

      PubDate: 2017-09-02T09:26:44Z
  • Time-dependent tunnel deformations in homogeneous and heterogeneous weak
           rock formations
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Atsushi Sainoki, Shingo Tabata, Hani S. Mitri, Daisuke Fukuda, Jun-ichi Kodama
      To investigate long-term, time-dependent tunnel deformations, this study employs a non-linear rheological model capable of considering the tertiary creep behaviour of the rock mass (Okubo and Fukui, 2006). A model parametric study is undertaken with a 3D numerical model encompassing a tunnel. The results show that the tunnel walls start to deform at an accelerating rate after a lapse of ten years. The results offer an explanation to previously reported tunnel instability cases. A 3D numerical model encompassing weak rock formation obliquely intersecting with the tunnel is then constructed. The analysis yields asymmetric wall deformation pattern, suggesting the need for optimizing rock supports.

      PubDate: 2017-09-02T09:26:44Z
  • Seepage simulation using pipe network flow model in a discrete element
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Y. Wang, Q. Dong, Y. Chen
      The pipe network flow model can simulate the seepage process with DEM conveniently because of its simple algorithm. However, whether it can recover the correct seepage process has not been verified. In this paper, the equation to update the fluid pressure is rebuilt according to the flow conservation. Through the steady seepage simulation, this algorithm is verified to be able to recover Darcy’s law, and the equation to calibrate the aperture according to macro permeability is derived. Furthermore, the modified algorithm is used to simulate the unsteady seepage process, and the results show good agreement with the analytical solutions.

      PubDate: 2017-09-02T09:26:44Z
  • A simple method to describe three-dimensional anisotropic failure of soils
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Yu Tian, Yang-Ping Yao
      In order to describe the anisotropic failure of soils caused by the internal fabric, isotropic failure criterion should be generalized to be anisotropic. This paper achieves the generalization by introducing a simple method, called anisotropic transformed stress method, which apparently differs from the common way. Physical interpretation of this method are analyzed further. Using this method, many existing isotropic criteria can become anisotropic in the same way, and will be expressed by a unified formula finally. To verify this method, anisotropic Unified Strength Criterion is used to predict the peak strength of anisotropic soils in different loading conditions.

      PubDate: 2017-09-02T09:26:44Z
  • Ultimate lateral resistance of tripod pile foundation in clay
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Zihao Zhao, George Kouretzis, Scott Sloan, Yufeng Gao
      In this paper we investigate the effect of pile group geometry and loading direction on the ultimate lateral soil resistance developing on a tripod foundation, using numerical and analytical upper bound methods. Two distinct kinematic mechanisms are established, corresponding to different failure modes associated with wide and narrow pile spacing. A comparison of tripod group performance against other common pile group layouts suggests that the former results in optimal efficiency for cases when the direction of the lateral load is unknown, such as the foundation of offshore structures subjected to wind, wave and ocean current loads.

      PubDate: 2017-09-02T09:26:44Z
  • Axisymmetric consolidation of saturated multi-layered soils with
           anisotropic permeability due to well pumping
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Zheng Li, Zhen-Dong Cui
      Axisymmetric consolidation of multi-layered soils induced by groundwater extraction from a dewatering well is studied with consideration of the anisotropic permeability and the well length. Laplace-Hankel transforms are utilized to solve the governing equations. The analytical layer-element method is used to build relationships between displacements, stresses, excess pore pressure and seepage velocity in the transformed domain. The real solutions can be obtained by the inversion of Laplace-Hankel transforms. A series of parametric studies, especially the length of a dewatering well and the combined effect of pumping and recharging, are conducted to analyze the consolidation behaviors of layered soils.

      PubDate: 2017-09-02T09:26:44Z
  • Discontinuous deformation analysis of super section tunnel surrounding
           rock stability based on joint distribution simulation
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): Peng He, Shu-cai Li, Li-ping Li, Qian-qing Zhang, Fei Xu, Yun-juan Chen
      Based on binocular stereo photography measurement technology, the actual distribution information of joints and fractures in the tunnel face were obtained via image processing and feature extraction, and the preliminary evaluation of surrounding rock stability of Laohushan tunnel was conducted according to surrounding rock classification method. Since all available surrounding rock classification approaches didn’t consider the influences of the size effect of tunnel excavation span and unfavorable geologic bodies such as weak-fracture zones, an improved discontinuous deformation analysis (DDARF) method was adopted to conduct a numerical simulation of the deformation and fracture processes of the surrounding rock. Using the traveling wave method, triangle DDA blocks were automatically generated in the calculation zone, and the block boundaries were divided into real joints and virtual joints. Based on the real joint information obtained via aforementioned photographic measurement, the real joints in the tunnel face were dynamically modified, in order to achieve the simulation of joint distribution. The results revealed that the fracture evolution regularity, deformation failure mechanism, and block dropping phenomenon that the DDARF joint simulation model calculated are in good agreement with actual conditions, while those obtained based on conventional models present differences from field situation. Additionally, focusing on the localised rockfall phenomenon of Laohushan tunnel, the crack extension rate was introduced to conduct a quantitative comparison of the rock crack evolution process with or without anchor supporting. The research results offer practical guidance for field construction and anchorage support scheme optimization.

      PubDate: 2017-09-02T09:26:44Z
  • A numerical study on cracking processes in limestone by the b-value
           analysis of acoustic emissions
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Qi Zhang, Xiao-Ping Zhang
      To better investigate the cracking processes under uniaxial compression, a numerical approach using bonded-particle model (BPM) was adopted to simulate the loading processes and AE events of limestone. To validate the model, a physical experiment with acoustic emission (AE) monitoring was performed. It revealed that the AE parameters in the BPM including crack number and AE event were generally comparable with the AE count and AE hit in the experiments. The b-value of AE does not accurately evaluate the degree of damage in rocks. But it can indicate the different states of damage during cracking processes.

      PubDate: 2017-08-02T12:33:35Z
  • The role of observations in the inverse analysis of landslide propagation
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Michele Calvello, Sabatino Cuomo, Pooyan Ghasemi
      Model calibration is usually based on trial-and-error procedures that, in turn, rely on expert judgment or previously acquired experiences for similar phenomena. Efficient and reliable procedures for model calibration of the propagation stage of landslides are still needed. This paper addresses this issue by proposing an inverse analysis procedure and applying it to the case history of a short run-out landslide triggered by a rising perched water table after a heavy rainfall. It focuses on the key role played by the field observations used to set up the inverse analysis, and evaluating the reliability of the numerical simulations. It also investigates the effect of different types of optimization parameters on the inverse analysis results, referring to a mixed-phase model or to a two-phase model for the propagating soil. Several sets of observations are used; all of them refer to the soil deposit thickness at the end of propagation, but differ in both location and number of the adopted values. The numerical analysis of the case history is performed through the academic “GeoFlow_SPH” model, and model calibration by inverse analysis is conducted using the “UCODE” software. The results obtained are discussed with the aim to provide practical criteria to identify the minimum amount of information required for a satisfactory model calibration.

      PubDate: 2017-08-02T12:33:35Z
  • Numerical investigations of the fracture geometry and fluid distribution
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Wan Cheng, Guosheng Jiang, Hong Tian, Qi Zhu
      Hydraulic fracturing is an important technique used for developing shale gas reservoirs. Compared with multistage consecutive fracturing, multistage alternative fracturing is a more challenging technique due to the current limitations of downhole tools. This paper simulates multistage fracturing and compares the fracture geometries and fluid distributions of consecutive and alternative fracturing. It is found that simultaneous propagation of multiple fractures results in their unequal stimulations. Some perforations do not contribute to well production because their fractures are restrained. Alternative fracturing tends to create more uniform length fractures and thus achieves a greater stimulated reservoir volume than that of consecutive fracturing.

      PubDate: 2017-08-02T12:33:35Z
  • Determination of microscopic parameters of quartz sand through tri-axial
           test using the discrete element method
    • Abstract: Publication date: December 2017
      Source:Computers and Geotechnics, Volume 92
      Author(s): Kuang Cheng, Yin Wang, Qing Yang, Yanbao Mo, Ying Guo
      A calibration procedure, in which coupled effects of microscopic parameters are considered, is proposed to determine the values of the microscopic parameters in the Discrete Element Method (DEM) for Fujian quartz sand. Laboratory tri-axial tests are conducted to be compared with the DEM simulations and the effects of end restraint in the laboratory tests are eliminated through a digital image measurement system. Sensitivities of the macroscopic behaviour of the specimen to the microscopic parameters are analyzed through DEM simulations. Four coupled effects of the microscopic parameters on the macroscopic behaviour are investigated through a graphic method and then considered in the calibration procedure.

      PubDate: 2017-08-02T12:33:35Z
  • Microscopic interpretation of one-dimensional compressibility of granular
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): Chaomin Shen, Sihong Liu, Yishu Wang
      The one-dimensional compressibility of granular materials is investigated analytically in the framework of micromechanics and simulated using the discrete element method. The results show that the oedometric modulus can be expressed in terms of the material properties of particles and fabric-related variables. By relating the coordination number to different quantities, two forms of the compression curve equations are discussed.

      PubDate: 2017-08-02T12:33:35Z
  • Predicting bending failure of CDM columns under embankment loading
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): Jin-chun Chai, Sailesh Shrestha, Takenori Hino, Takemasa Uchikoshi
      The mechanism of bending failure and the magnitude of the bending moment in a column formed by cement deep mixing (CDM) under an embankment load were investigated by a series of three-dimensional (3D) finite element analyses. Based on the numerical results, a design method to consider the bending failure of the CDM column has been established. The usefulness of the proposed methods was verified using the results of two centrifuge model tests of the embankments on the CDM column improved soft model ground model reported in the literature, and the columns had tensile cracks or showed complete failure.

      PubDate: 2017-08-02T12:33:35Z
  • Discrete element modeling of crushable sands considering realistic
           particle shape effect
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): Ru Fu, Xinli Hu, Bo Zhou
      This study proposed a novel approach for generating crushable agglomerates with realistic particle shapes in discrete element modeling (DEM). The morphologies of sand particles were obtained by X-ray micro-computed tomography scanning and image processing. Based on the particle surface reconstructed by spherical harmonic analysis, the crushable agglomerates with realistic particle shapes can be generated in DEM simulations. The results of single particle crushing tests showed that particle shapes significantly influence the fracture patterns and crushing strengths of sand particles. Furthermore, two one-dimensional compression tests were conducted to investigate the particle shape effect on micro- and macro-mechanical behaviors of crushable sands.

      PubDate: 2017-08-02T12:33:35Z
  • Calculation of head difference at two sides of a cut-off barrier during
           excavation dewatering
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): Shui-Long Shen, Yong-Xia Wu, Anil Misra
      This paper proposed a series of simple equations to calculate the head difference at the two sides of waterproof curtain. The barrier effect of waterproof curtain is considered from two situations with respect to without barrier case: (i) groundwater head difference below the barrier and (ii) groundwater head difference by convergence into the opening. The solution for the first situation can be derived from hydraulic analyses and the second situation can be obtained using a numerical analysis. The final groundwater head difference is the sum of these two situation according to the superposition principal. In the proposed equations, the head difference is expressed as a function of the inserted depth of the barrier into confined aquifer, the ratio of the hydraulic conductivity of the aquifer, the thickness of the aquifer, and hydraulic gradient under normal conditions. Finally, the proposed equation was applied to a field case to verify the validity of the proposed approach. Compared with the field data, the results show that the proposed method is reasonable.

      PubDate: 2017-08-02T12:33:35Z
  • Reliability analysis of seismic bearing capacity of strip footing by
           stochastic slip lines method
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): A. Johari, S.M. Hosseini, A. Keshavarz
      In this research, the reliability analysis of seismic ultimate bearing capacity of strip footing is assessed with implementing slip lines method coupled with random field theory. The probability density functions of seismic and static bearing capacities which are log-normal and nearly normal distribution respectively are compared to each other. The predicted Probability Density Function (PDF) of the seismic bearing capacity by slip line method is verified, with those of the Terzaghi equation and Monte Carlo simulation (MCs). For uncertainties analysis by Terzaghi equation the Nc , Nq and Nγ are assessed stochastically.

      PubDate: 2017-08-02T12:33:35Z
  • Thermal and settlement analyses under a riverbank over permafrost
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): Hu Zhang, Jianming Zhang, Enliang Wang, Ze Zhang, Wei Cao, Panfeng Zhou
      Thermal regime evolution and settlement behavior of a riverbank over ice-rich permafrost in 20years were estimated by numerical simulation and layerwise summation calculation. The results show that the permafrost under the riverbank will undergo a thawing process at a dramatically rate under the conditions of practical geology and construction structure, which is responsible for a remarkable settlement. The cases on different conditions of concrete hydration, backfilled soil temperature, seepage and mean annual ground temperature were also discussed, suggesting that these factors have the capability in improving the riverbank performance, among them seepage may be of the most importance.

      PubDate: 2017-07-23T13:10:48Z
  • Modeling hydraulic fracture propagation using cohesive zone model equipped
           with frictional contact capability
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): Y. Li, J.G. Deng, W. Liu, Y. Feng
      We present a new pore pressure cohesive element for modeling the propagation of hydraulically induced fracture. The Park-Paulino-Roesler cohesive zone model has been employed to characterize the fracturing behavior. Coulomb’s frictional contact model has been incorporated into the element to model the possible shear reactivation of pre-existing natural fractures. The developed element has been validated through a series of single-element tests and an available analytical solution. Furthermore, intersection behaviors between the hydraulic fracture and the natural fracture under various conditions have been predicted using the present element, which shows good agreement with experimental results.

      PubDate: 2017-07-23T13:10:48Z
  • A general semi-analytical solution for consolidation around an expanded
           cylindrical and spherical cavity in modified Cam Clay
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): Hang Zhou, Hanlong Liu, Yahui Zha, Feng Yin
      This paper presents a general semi-analytical solution for undrained cylindrical and spherical cavity expansion in Modified Cam Clay (MCC) and subsequent consolidation. The undrained cylindrical and spherical cavity expansion response in MCC model is obtained through the similarity solution technique. Then, the subsequent consolidation process around the cavity is governed by the classical partial differential equation for consolidation. Finite Difference Method (FDM) is selected for solving the consolidation equation numerically. The proposed semi-analytical solution is validated by comparing the prediction of the dissipations of the pore pressure with Randolph’s closed-form solution for elastic-perfectly plastic soil. Parametric study shows that G 0/p 0′, R and M have significant influence on the cavity wall excess pore pressure dissipation curve, while it is not sensitive to the value of ν′. It is also found that the negative pore pressure generates around the expanded cylindrical and spherical cavity wall during the consolidation process when R >5 for typical Boston blue clay. The developed solution has potential applications in geotechnical problems, such as the pile foundation, in-situ test, tunnel construction, compaction grouting, and so forth.

      PubDate: 2017-07-23T13:10:48Z
  • Influences of strain rate and soil remoulding on initial break-out
           resistance of deepwater on-bottom pipelines
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): Bithin Ghorai, Santiram Chatterjee
      Large deformation finite element analyses have been conducted to study the initial break-out resistance of on-bottom pipelines. Soil model that takes strain rate and soil remoulding into consideration was implemented. Results from detailed parametric study are presented in terms of failure envelopes in vertical-horizontal load space. The maximum vertical and horizontal resistance responses normalized by an equivalent shear strength incorporating the rate and softening parameters lead to a narrow band of values. Obtained results are generalized and fitted to simple equations. The proposed methodology predicts undrained break-out resistance with maximum error limited to 10% for wide range of parameters.

      PubDate: 2017-07-23T13:10:48Z
  • Constitutive model for soft rocks considering structural healing and decay
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): Mamoru Kikumoto, Vu Pham Quang Nguyen, Hideaki Yasuhara, Kiyoshi Kishida
      The behavior of soft rock depends on the contact area between mineral particles and the tensile strength of the interparticle cementation, which are usually referred to as structures. We investigated the effects of structural decay and healing on the behavior of soft rock through monotonic and slide-hold-slide triaxial tests under the drained condition with constant effective confining pressure. We developed a constitutive model for soft rocks incorporating structural healing and decay in the context of the extended critical state theory. The model was validated via laboratory tests and captured the behavior of soft rock, including the healing and decay phenomena.

      PubDate: 2017-07-23T13:10:48Z
  • Integration of creep into a modified hardening soil model for
           time-dependent analysis of a high rockfill dam
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): Pornthap Pramthawee, Pornkasem Jongpradist, Raksiri Sukkarak
      This paper proposes an approach to extend a modified hardening soil model into the time-dependent analysis of high rockfill dams. The key feature of the extended model is the integration of a creep model and the double yield surface elasto-plastic model, via modifying the hardening functions. The integrated model is validated by a laboratory multistage creep test. Results from three-dimensional analyses including the without creep and with creep considerations of the Nam Ngum 2dam have been compared with the in-situ measurements. The prediction of dam deformation can be significantly enhanced by the proposed model.

      PubDate: 2017-07-23T13:10:48Z
  • Numerical modelling of the effect of curing time on the creep behaviour of
           a chemically stabilised soft soil
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): Paulo J. Venda Oliveira, António A.S. Correia, Luís J.L. Lemos
      This work studies the effect of the curing time on the creep behaviour of a stabilised soft soil, using volumetric and deviatoric creep laws associated with constitutive models. Results of unconfined compressive strength tests for several curing times are used to define the time evolution of the mechanical and creep properties. The models/creep laws are validated by oedometer and triaxial creep tests, for 28 and 90days of curing. The long-term behaviour of an embankment built on a soft soil reinforced with deep mixing columns shows that the effect of curing time decreases the settlement and increases the improvement factor.

      PubDate: 2017-07-23T13:10:48Z
  • Upper bound solution of a laterally loaded rigid monopile in normally
           consolidated clay
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): Jian Yu, Maosong Huang, C.F. Leung, Siyu Li
      A centrifuge test is performed to investigate the ultimate lateral capacity of a free-head rigid monopile foundation in normally consolidated (NC) clay. Based on the test result, an upper-bound velocity field is constructed to illustrate the evolution of the soil resisting mechanisms with the progressive rotation and the effect on reaction forces during loading. Simultaneously finite element analyses are also employed to model the centrifuge test and verify the conclusion of the upper bound analysis. Finally, an empirical expression is presented for predicting the upper-bound collapse loads of monopiles with different eccentricity/length ratios and length/diameter ratios in NC clay.

      PubDate: 2017-07-23T13:10:48Z
  • A Modified Mohr-Coulomb Model to Simulate the Behavior of Pipelines in
           Unsaturated Soils
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): D.J. Robert
      At the present time, it is very common in practice to utilize Mohr-Coulomb model to simulate the soil behaviour in the application of soil-pipeline interaction problems. However, the traditional Mohr-Coulomb model is unable to predict the realistic loading that can apply on buried pipes during large ground deformation. Especially, the linear elastic-perfectly plastic Mohr-Coulomb model is not capable of simulating the unsaturated soil loading which can result larger than anticipated loading due to suction induced additional normal force between the soil particles. A user defined unsaturated modified Mohr-Coulomb model is developed within a generalized effective stress framework considering suction hardening effects to capture the realistic loading induced by unsaturated soil medium. Firstly, the model has been developed considering microscopic and macroscopic suction hardening mechanisms, and was implemented into a commercial finite element program associated with user subroutine written in FORTAN. Then the model was validated through a series of unsaturated triaxial compression tests conducted on the basis of different sand types having various initial conditions. Finally, the model has been applied to simulate the behaviour of pipelines subjected to lateral soil loading in unsaturated soils. The results revealed that the modified Mohr-Coulomb model has reasonable predictions when compared to the load-displacement response of pipes obtained from two large scale testing programs. The developed model can be used to predict the increased strength and stiffness associated with soil suction that increases lateral loads on pipelines, and thus has widespread relevance for simulating the pipeline response in unsaturated soils under externally imposed ground movement.

      PubDate: 2017-07-23T13:10:48Z
  • Study of thermal migration and induced mechanical effects in double U-tube
           energy piles
    • Abstract: Publication date: November 2017
      Source:Computers and Geotechnics, Volume 91
      Author(s): Jin Luo, Haifeng Zhao, Shuqiang Gui, Wei Xiang, Joachim Rohn
      This paper investigates two geothermal energy piles using thermal response tests (TRTs). A set of parameters including pile wall temperature, ground temperature and strain are monitored at four different depths. The thermally induced mechanical behavior of the energy piles are then analyzed based on the monitoring data. The results show the following: (1) The temperature at the pile wall clearly varies throughout the heating and cooling cycle, and the ground temperature distribution shows a delay compared to the TRT stages. (2) The thermally induced mechanical effects are influenced by both the temperature and restraint conditions.

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

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

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

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

      PubDate: 2017-07-09T07:26:59Z
  • Analytical definition of collapse surface in multiaxial space as a
           criterion for flow liquefaction occurrence
    • Abstract: Publication date: October 2017
      Source:Computers and Geotechnics, Volume 90
      Author(s): Alireza Najma, Manouchehr Latifi
      Prediction of flow liquefaction occurrence in multiaxial stress space is presented in this paper. The closed-form relation analytically attained by means of Dafalias-Manzari constitutive equations gives the flow stress ratio as a function of model parameters, state parameter, direction of undrained loading and especially initial condition of consolidation. These proposed flow condition can predict the occurrence of flow liquefaction initiated by any loadings whether the soil is consolidated isotropically or anisotropically. Suggested predictions are compared with the results of triaxial tests performed on Hostun RF sand. The results show that increasing consolidation stress ratio leads to flow stress ratio increase.

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

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

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

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

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

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

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

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

      PubDate: 2017-05-27T08:47:58Z
  • An energy-based interpretation of sand liquefaction due to vertical ground
    • 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
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
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