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    Numerical investigation on the behavior of the gravity waterfront structures under earthquake loading

    , Article Ocean Engineering ; Volume 106 , September , 2015 , Pages 152-160 ; 00298018 (ISSN) Khosrojerdi, M ; Pak, A ; Sharif University of Technology
    Elsevier Ltd  2015
    Abstract
    Abstract Lateral Spreading, which usually occurs as a consequence of liquefaction in gently sloped loose saturated sand layers, is known to be a major source of earthquake-induced damages to structures such as quay walls, bridge piers, pipelines, and highway/railways. Therefore evaluation of the liquefaction potential and using appropriate methods for prediction of the adverse consequences of lateral spreading is of great importance. In this study, numerical modeling has been used to study lateral spreading phenomenon behind rigid waterfront structures. Coupled dynamic field equations of the extended Biot's theory with u-P formulation are used for simulating the phenomenon. A fully coupled... 

    Estimating liquefaction-induced settlement of shallow foundations by numerical approach

    , Article Computers and Geotechnics ; Volume 37, Issue 3 , April , 2010 , Pages 267-279 ; 0266352X (ISSN) Shahir, H ; Pak, A ; Sharif University of Technology
    2010
    Abstract
    Occurrence of liquefaction in saturated sand deposits underlying foundation of structure can cause a wide range of structural damages starting from minor settlement, and ending to general failure due to loss of bearing capacity. If the bearing capacity failure is not the problem, reliable estimation of the liquefaction-induced settlement will be of prime importance in assessment of the overall performance of the structure. Currently, there are few procedures with limited application in practice for estimation of settlement of foundations on liquefied ground. Therefore, development of a general relationship is important from the practical viewpoint. In this paper, the dynamic response of... 

    Interpretation of CPT in unsaturated sands under drained conditions: A numerical study

    , Article International Journal for Numerical and Analytical Methods in Geomechanics ; Volume 45, Issue 18 , 2021 , Pages 2732-2755 ; 03639061 (ISSN) Keshmiri, E ; Ahmadi, M. M ; Sharif University of Technology
    John Wiley and Sons Ltd  2021
    Abstract
    A finite difference-based numerical model simulating the cone penetration process in unsaturated sands is presented. Mohr–Coulomb model (MCM) with simple modifications and Sun model (SM) were implemented to capture the unsaturated sand behaviour. It was shown that the cone tip resistance values resulting from the two models were fairly comparable. Predicted cone tip resistance values in dry, saturated and unsaturated sands using MCM were validated by the results of field and calibration chamber tests. Sensitivity analyses were performed, and the influence of parameters including relative density, mean effective stress and apparent cohesion due to suction on the tip resistance was... 

    Investigation of the influence of permeability coefficient on the numerical modeling of the liquefaction phenomenon

    , Article Scientia Iranica ; Volume 19, Issue 2 , 2012 , Pages 179-187 ; 10263098 (ISSN) Rahmani, A ; Ghasemi Fare, O ; Pak, A ; Sharif University of Technology
    2012
    Abstract
    The soil permeability coefficient plays a key role in the process of numerical simulation of the liquefaction phenomenon. Liquefaction causes a considerable increase in soil permeability, due to the creation of easier paths for water flow. The work presented in this paper tries to investigate the effects of permeability coefficient on the results of numerical modeling of the liquefaction phenomenon. To do this, a fully coupled (u-P) formulation is employed to analyze soil displacements and pore water pressures. Two different versions of a well-calibrated critical state bounding surface plasticity model, which possesses the capability to utilize a single set of material parameters for a wide... 

    Experimental investigation of tertiary oil gravity drainage in fractured porous media

    , Article Special Topics and Reviews in Porous Media ; Volume 1, Issue 2 , 2010 , Pages 179-191 ; 21514798 (ISSN) Rezaveisi, M ; Rostami, B ; Kharrat, R ; Ayatollahi, Sh ; Ghotbi, C ; Sharif University of Technology
    2010
    Abstract
    The amount of residual oil trapped in the matrix of a fractured reservoir after water drive, either natural water drive or water injection, depends on the wettability of the matrix rocks. Gas oil gravity drainage (GOGD) has been proposed as the tertiary oil recovery process for this type of oil reservoir. The current work focuses on experimental investigation of tertiary GOGD in fractured porous media under different types of matrix wettability. Results of a set of experiments performed in artificial porous media composed of sand packs and glass beads of different wettability have been used to check the GOGD rate and the ultimate oil recovery for previously waterflooded models. A novel...