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ENGINEERING (1201 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: 17)
AAPG Bulletin     Hybrid Journal   (Followers: 7)
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: 247)
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: 8)
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: 26)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
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: 22)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 26)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 29)
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: 38)
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: 31)
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: 17)
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: 16)
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   (Followers: 1)
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)
Asia-Pacific Journal of Science and Technology     Open Access  
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: 5)
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: 32)
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   (Followers: 1)
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: 10)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 24)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 43)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 8)
Case Studies in Thermal Engineering     Open Access   (Followers: 4)
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: 7)
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: 22)
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: 4)
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: 265)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 188)
Composites Part B : Engineering     Hybrid Journal   (Followers: 278)
Composites Science and Technology     Hybrid Journal   (Followers: 182)
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: 7)
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: 7)
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   (Followers: 1)
CTheory     Open Access  

        1 2 3 4 5 6 7 | Last

Journal Cover Computers and Geotechnics
  [SJR: 2.033]   [H-I: 58]   [10 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0266-352X
   Published by Elsevier Homepage  [3048 journals]
  • Analysis of pile foundations using natural element method with disturbed
           state concept
    • Abstract: Publication date: Available online 14 November 2017
      Source:Computers and Geotechnics
      Author(s): Emad Ghazavi Baghini, Mohammad Mohsen Toufigh, Vahid Toufigh
      The mesh-free method is a numerical technique that typically uses higher-order approximate functions. The mesh-free method exhibits higher accuracy for problems of large deformation compared to the traditional finite element method. In this paper, a computational model was undertaken using a mesh-free technique called the natural element method. Furthermore, the disturbed state concept was used to evaluate the response of piles, including their softening behaviour under axial uplift loading. The results of two field tests were considered to justify the accuracy of the proposed method. The results showed a strong correlation between the proposed numerical method and field tests.

      PubDate: 2017-11-16T11:52:51Z
  • Joint back analysis of the creep deformation and wetting deformation
           parameters of soil used in the Guanyinyan composite dam
    • Abstract: Publication date: Available online 10 November 2017
      Source:Computers and Geotechnics
      Author(s): Yufeng Jia, Bin Xu, Shichun Chi, Biao Xiang, Dai Xiao, Yang Zhou
      The inserted junction in the composite dam of the Guanyinyan hydropower station, with a height of 75 m, is the weak point of the dam structure. During the first impoundment, cracks appear on the junction crest of the earth-rockfill dam, which primarily results from the uncontrollable deformations of the dam. The deformations of earth-rockfill dams generally include static, rheological and wetting deformations. Therefore, the deformation parameters, which include the constitutive model, rheological and wetting parameters, are the key issues for controlling dam deformation. In this paper, parameters of the E-B model (constitutive model), creep deformation model and wetting model of the earth-rockfill materials were jointly back-analyzed using a parallel mutation particle swarm optimization method, according to the displacements that were monitored on the dam body. The back-analysis results showed that the non-uniform settlement induced by creep deformation and wetting deformation of the dam soil ultimately caused the cracks on the crest. More than 83% of the displacement that is generated by creep deformation is predicted to be released within three years after impoundment, and the total settlement on the crest ten years after construction is predicted to remain at less than 1% of the dam height.

      PubDate: 2017-11-16T11:52:51Z
  • Deformation and stability investigations in 3-D of an excavated rock slope
           in a hydroelectric power station in China
    • Abstract: Publication date: Available online 8 November 2017
      Source:Computers and Geotechnics
      Author(s): Menglong Dong, P.H.S.W. Kulatilake, Faming Zhang
      A three-dimensional numerical model was built incorporating stratigraphy, geological structures and mechanical properties of rock masses and discontinuities to perform stress, deformation and stability analyses for an excavated slope in China using the 3DEC software. Based on this model, numerical modeling was conducted to study the effect of boundary conditions, lateral stress ratio, and rock mass and fault parameter variability and uncertainty on the deformation and stability of the excavated rock slope. Displacement comparisons were made between the field monitoring values and numerical simulations. In the 3DEC modeling, both the stress and zero displacement boundary conditions were used to represent the lateral boundaries of the slope. Because the lateral boundaries were placed not far enough from the faults, the stress boundary conditions provided realistic results compared to the zero displacement boundary conditions. The best comparison with the field monitoring values were obtained when k0max is in the range 1–1.5 and k0min = 0.7. The best comparison between the numerical results and the monitoring data were obtained when the rock mass and fault property values were reduced by about 30% from the average material property values. The modeling approaches given in this paper should be useful in performing realistic three-dimensional stress, deformation and stability analysis of rock slopes.

      PubDate: 2017-11-16T11:52:51Z
  • Seismic analysis of rigid walls retaining a cross-anisotropic elastic soil
           layer over bedrock
    • Abstract: Publication date: Available online 8 November 2017
      Source:Computers and Geotechnics
      Author(s): Niki D. Beskou, George A. Papagiannopoulos, Athanasios P. Chassiakos
      The dynamic response of rigid walls retaining a cross-anisotropic elastic soil layer over bedrock to seismic horizontal excitation is determined analytically under conditions of plane strain. The problem of a pair of rigid walls is solved first and the one with a single wall is obtained as a special case for a large separation distance between those walls. Assuming time harmonic motion, expansion of the unknown displacements in Fourier sine and cosine series along the horizontal direction, reduces the system of the two partial differential equations of motion in the frequency domain into a system of two ordinary differential equations, which is easily solved analytically. Thus, one can obtain closed form expressions for the seismic soil pressure, the distance from the base of the point of application of the resultant seismic pressure and the base shear force and bending moment. The above cross-anisotropic solution is first verified by comparing it for the special case of isotropy against existing isotropic solutions. Afterwards parametric studies are conducted in order to assess the effect of cross-anisotropy on the seismic response of the wall-soil system.

      PubDate: 2017-11-16T11:52:51Z
  • Simulation of rock dynamic failure using discontinuous numerical approach
    • Abstract: Publication date: Available online 8 November 2017
      Source:Computers and Geotechnics
      Author(s): Xiu-Li Zhang, Yu-Yong Jiao, Jiang-Feng Ma
      In this paper, an improved DDA method proposed by the authors is used to simulate the rock failure process under dynamic loading, and several SHPB tests on Brazilian discs with different angle pre-cracks are conducted for verification. The simulated main crack paths of different specimens agree well with the observations in the SHPB tests. In addition, the perforation process of a hard projectile into rock is also simulated, and some heavily discontinuous phenomena in impact failure are captured. It shows that the improved DDA method is able to simulate the failure behavior of rock under dynamic loading.

      PubDate: 2017-11-16T11:52:51Z
  • Development of coupled numerical model for simulation of multiphase soil
    • Abstract: Publication date: Available online 8 November 2017
      Source:Computers and Geotechnics
      Author(s): K. Edip, V. Sesov, C. Butenweg, J. Bojadjieva
      In this paper, a coupled multiphase model considering both non-linearities of water retention curves and solid state modeling is proposed. The solid displacements and the pressures of both water and air phases are unknowns of the proposed model. The finite element method is used to solve the governing differential equations. The proposed method is demonstrated through simulation of seepage test and partially consolidation problem. Then, implementation of the model is done by using hypoplasticity for the solid phase and analyzing the fully saturated triaxial experiments. In integration of the constitutive law error controlling is improved and comparisons done accordingly. In this work, the advantages and limitations of the numerical model are discussed.

      PubDate: 2017-11-08T14:19:46Z
  • Stability of NATM tunnel faces in soft surrounding rocks
    • Abstract: Publication date: Available online 4 November 2017
      Source:Computers and Geotechnics
      Author(s): Zhiqiang Zhang, Xiaoquan Shi, Bo Wang, Huayun Li
      NATM (new Austrian tunneling method) tunnel construction is unable to proceed under instable states of working face, so the stability of working face has been regarded as a key scientific issue. In this paper, a horizontal slice method based on the limit equilibrium analysis theory is employed to establish a model for the tunnel face stability. This model can overcome the shortcomings of the intersections between the slices and the bolts. In particular, an equivalent pressure coefficient is proposed to analyze the reinforcement of tunnel face bolts. Furthermore, based on the model, the influence of soil parameters and reinforcing strength of tunnel face bolt on the limit support forces are investigated. Moreover, based on the limit analysis upper bound theorem, the tunnel face failure model is also established, and the factors such as the soil parameters, the length and support force for unsupported section, tunnel depth and reinforcing strength of tunnel face bolt, are studied in order to investigate the limit support forces for tunnel faces. It is found that the tunnel face bolts can effectively increase the shearing strength of the front core soil. However, the strength of surrounding rocks cannot be enhanced too much because such an enhancement is not economical and effective. Finally, based on the comparison analysis, it is demonstrated that the variation trends of support force with the above relevant factors are almost the same in the proposed stability models, indicating the promising and wide applications of the proposed method.

      PubDate: 2017-11-08T14:19:46Z
  • Finite element modelling of fracture propagation in saturated media using
           quasi-zero-thickness interface elements
    • Abstract: Publication date: Available online 4 November 2017
      Source:Computers and Geotechnics
      Author(s): Ignasi de-Pouplana, Eugenio Oñate
      A new computational technique for the simulation of 2D and 3D fracture propagation processes in saturated porous media is presented. A non-local damage model is conveniently used in conjunction with interface elements to predict the degradation pattern of the domain and insert new fractures followed by remeshing. FIC-stabilized elements of equal order interpolation in the displacement and the pore pressure have been successfully used under complex conditions near the undrained-incompressible limit. A bilinear cohesive fracture model describes the mechanical behaviour of the joints. A formulation derived from the cubic law models the fluid flow through the crack. Examples in 2D and 3D, using 3-noded triangles and 4-noded tetrahedra respectively, are presented to illustrate the accuracy and robustness of the proposed methodology.

      PubDate: 2017-11-08T14:19:46Z
  • Stability and airtightness of a deep anhydrite cavern group used as an
           underground storage space: A case study
    • Abstract: Publication date: Available online 2 November 2017
      Source:Computers and Geotechnics
      Author(s): Han-xun Wang, Bin Zhang, Dong Fu, Abisai Ndeunjema
      This paper studies the usability of a deep mined-out anhydrite mine located in Anhui, China. The physical and mechanical parameters of the anhydrite intact rock and rock mass were determined through laboratory analysis and field investigation, and the stability of the cavern group was analyzed using the element safety factor method (ESFM) proposed in this paper. Moreover, the permeabilities of the anhydrite intact rock and rock mass were estimated based on laboratory and field tests. The results demonstrated that the stability and airtightness of the anhydrite cavern group are suitable for underground storage.

      PubDate: 2017-11-08T14:19:46Z
  • Finite element limit analysis of ultimate lateral pressure of XCC pile in
           undrained clay
    • Abstract: Publication date: Available online 2 November 2017
      Source:Computers and Geotechnics
      Author(s): Hang Zhou, Hanlong Liu, Lehua Wang, Gangqiang Kong
      X-section Cast in place Concrete (XCC) pile is a non-cylindrical pile that the cross section not obeying plane rotationally symmetric. In this case, the geometry of cross section as well as the lateral load direction may have influence on the ultimate lateral pressure of XCC pile. This paper presents rigorous upper and lower bound solutions for the ultimate lateral pressure of X-section Cast in place Concrete (XCC) pile in clay through two dimensional plane strain finite element limit analysis (FELA). The geometric effect, lateral load direction and the adhesion factor at the pile-soil interface are selected for parametric study. Subsequently, an empirical closed-form equation of the ultimate lateral pressure factor is proposed for predicting the lateral force acting on a XCC pile in undrained clay. It is found that the XCC pile with relatively small ratio of b/a has larger ultimate lateral pressure than the conventional circular pile under the condition of the same area of cross section.

      PubDate: 2017-11-08T14:19:46Z
  • Settlement and load transfer mechanism of a pile group adjacent to a deep
           excavation in soft clay
    • Abstract: Publication date: Available online 2 November 2017
      Source:Computers and Geotechnics
      Author(s): M. Shakeel, Charles W.W. Ng
      Three-dimensional coupled consolidation analysis is conducted to gain insight into the response of a 2×2 floating pile group adjacent to deep excavation in soft clay. By using a validated finite element model, the influence of the excavation depth, pile length, pile group location from excavation, the supporting system stiffness, soil state and permeability, and working load are systematically studied. The analysis revealed that the maximum settlement occurs when the pile group is founded at the excavation level and at a distance of 0.75-times the excavation depth, although the induced bending moment is minimum. In contrast to pile group settlement, tilting is maximum when it gets closer to the wall and minimum at a distance of 0.75-times the excavation depth. It is also observed that the influence of system stiffness is more pronounced for the flexible wall and when the pile group is located at the excavation level. Applied working load influences pile group settlement but has relatively minor effects on pile group tilting. Excess negative pore water pressures are generated in the soil elements due to excavation. Pile group experiences progressive long term settlement with the dissipation of excess negative pore water pressure.

      PubDate: 2017-11-08T14:19:46Z
  • Grain breakage criteria for discrete element models of sand crushing under
           one-dimensional compression
    • Abstract: Publication date: Available online 2 November 2017
      Source:Computers and Geotechnics
      Author(s): Wenbo Zheng, Dwayne D. Tannant
      Frac sand consisting of quartz grains is widely used in hydraulic fracturing of tight shales to prop fractures open. However, the sand can be crushed by high compressive stress acting on the fractures and this reduces the fracture conductivity. In practice, a one-dimensional compression test is widely used to evaluate the crushing resistance of frac sand. This paper presents the results of discrete element modelling of sand crushing calibrated with laboratory data from one-dimensional compression tests. Three criteria for grain breakage that incorporate grain-size dependent particle strength and failure under shearing/tensile conditions were implemented and evaluated in PFC2D. An innovative aspect is linking the breakage of a clustered particle under multiple contacts in PFC2D to grain breakage criteria to examine the applicability of these breakage criteria in grain crushing. A macro-scale calibration demonstrates how incorporation of particle breakage algorithms can allow the PFC2D model to capture the change in particle size distribution as well as the non-linear stress-strain response of sand under high compressive stresses. The calibrated grain breakage criterion was used to study the crushing behaviour and permeability evolution of a mesh 20/40 Jordan frac sand.

      PubDate: 2017-11-08T14:19:46Z
  • Numerical study of crack propagation in an indented rock specimen
    • Abstract: Publication date: Available online 2 November 2017
      Source:Computers and Geotechnics
      Author(s): Jie Liu, Jun Wang, Wen Wan
      Indentations were simulated to investigate the stress evolution characteristics of the indentation process using the discrete element method (DEM). The maximum principle stress and the shear stress were recorded by applying measurement circle logic. The results indicate that an increase in indentation force contributes to the concentration of shear and tensile stresses at the crack tips. The indentation force decreases because of the crack propagation, which is accompanied by stress dissipation at the crack tips. In addition, tensile and shear-tensile cracks, propagating in different modes, have been observed. The results show that the shear-tensile cracks are responsible for chip formation.

      PubDate: 2017-11-08T14:19:46Z
  • Numerical evaluation of reinforced slopes with various
           backfill-reinforcement-drainage systems subject to rainfall infiltration
    • Abstract: Publication date: Available online 2 November 2017
      Source:Computers and Geotechnics
      Author(s): Kuo-Hsin Yang, Joseph Ng'ang'a Thuo, Vo Duyen Anh Huynh, Thanh Son Nguyen, Fernando Henrique Martins Portelinha
      This paper presents a numerical study investigating the hydraulic response and stability of geosynthetic-reinforced soil slopes subject to rainfall. A series of numerical simulations of unsaturated slopes with various backfill–reinforcement–drainage systems subject to rainfall infiltration was performed by comprehensively considering the combined effect of backfill (i.e., sand, silt, and silty clay), reinforcement type (i.e., geogrid or nonwoven geotextile), and rainfall intensity (350 and 500 mm/day). The backfills were modeled using three soil–water characteristic curves (SWCCs) representing the general suction range associated with sand, silt, and clay. The influence of sand cushions in improving the stability of reinforced clay slopes was also assessed. The numerical results reveal that the loss of matric suction and development of a capillary barrier effect within clay backfills could have adverse impacts on both the global and local stabilities of the reinforced clay slopes. The contribution of matric suction in enhancing slope stability was initially high for reinforced clay slopes; however, the global stability of the reinforced clay slope substantially decreased due to the loss of matric suction as the rainfall infiltration proceeded. The local instability of the geotextile-reinforced clay slope occurred due to the capillary barrier effect at the geotextile–clay interface. The reinforced marginal soil slopes cannot effectively drain the infiltrating water under torrential rainfall. Free drainage conditions may not be assumed for these slopes if the drainage is not properly considered. Both the global and local factors of safety (FS) of the reinforced sand slope were minimally influenced by the loss of matric suction induced by rainfall infiltration. The required reinforcement tensile strengths for the reinforced silt and clay slopes to maintain FS = 1.3 were, respectively, approximately 3 and 4 times larger than that for reinforced sand slopes. Numerical results also indicated that the inclusion of sand cushions, which provide both strength and drainage functions, can effectively enhance the slope stability. An optimal sand cushion thickness of 15 cm (replacing 20% of marginal backfill with sand) was determined in this study.

      PubDate: 2017-11-08T14:19:46Z
  • A fully coupled three-dimensional hydro-mechanical finite discrete element
           approach with real porous seepage for simulating 3D hydraulic fracturing
    • Abstract: Publication date: Available online 2 November 2017
      Source:Computers and Geotechnics
      Author(s): Chengzeng Yan, Yu-Yong Jiao, Hong Zheng
      A fully coupled 3D hydro-mechanical model with real porous seepage is presented for simulating hydraulic fracturing. In this model, fluid flow in a fracture is expressed by 2D fracture seepage in the broken joint elements based on the Cubic law, while fluid flow in the rock matrix is represented by 3D porous seepage in the tetrahedral elements based on Darcy's law. Several problems that have closed-form solutions and a 3D fracturing problem are given to verify the model. The simulation results show that the model can capture crack initiation and propagation, and the fluid pressure evolution during hydraulic fracturing.

      PubDate: 2017-11-08T14:19:46Z
  • Novel discrete element modeling coupled with finite element method for
           investigating ballasted railway track dynamics
    • Abstract: Publication date: Available online 2 November 2017
      Source:Computers and Geotechnics
      Author(s): Daisuke Nishiura, Hirotaka Sakai, Akira Aikawa, Satori Tsuzuki, Hide Sakaguchi
      A quadruple discrete element method (QDEM) was developed for viscoelastic multi-body dynamics. The sleeper motion modeled using QDEM was coupled with the rail motion modeled using a finite element method (FEM). The traffic impact response of a ballast particle and a sleeper was analyzed. The three-dimensional spatial distribution of ballast particle displacement was clearly revealed. Moreover, the ballast layer absorbed the low frequency vibration of the sleeper more effectively than its high frequency vibration. This study suggests that the proposed QDEM-FEM can provide greater insight into the impact response of ballasted railway tracks.

      PubDate: 2017-11-08T14:19:46Z
  • 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
  • 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
  • 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
  • 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
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