scholarly journals Bearing Capacity Analysis and Zoning of Kathmandu for Shallow Foundations

2018 ◽  
Vol 4 ◽  
pp. 111-117
Author(s):  
Ram Krishna Danai ◽  
Indra Prasad Acharya
Keyword(s):  
Bearing Capacity ◽  
Numerical Models ◽  
Failure Criteria ◽  
Unit Weight ◽  
Soil Parameters ◽  
Primary Concern ◽  
Borehole Data ◽  
Element Analysis ◽  
Theoretical Approaches ◽  
Coulomb Failure

The bearing capacity of foundation is the primary concern in the field of geotechnical engineering. In this study numerical models are developed for each of the secondary borehole data collected around Kathmandu valley. Finite element analysis (i.e. PLAXIS 2D) is carried out using Mohr-coulomb failure criteria to represent two dimensional soil models. Foundation is aimed to model as square footing and prescribed settlement of 10% of footing width is provided to obtain corresponding bearing capacity. In plaxis, effective stress is considered as an ultimate bearing capacity. Drained behavior with axisymmetical models have been considered for soil model in plaxis software. Various soil parameters like C (Cohesion), γ (unit weight), Φ (Frictional angle), ν (Poison ratio), E (Elasticity) for each 1.5m and 3m depths have been considered in models and in theoretical approaches.

Reliability analysis of static liquefaction of loose sand using the random finite element method

2015 ◽  
Vol 32 (7) ◽  
pp. 2100-2119 ◽  
Author(s):  
Ali Johari ◽  
Jaber Rezvani Pour ◽  
Akbar Javadi
Keyword(s):  
Finite Element ◽  
Pressure Ratio ◽  
Monotonic Loading ◽  
Unit Weight ◽  
Soil Parameters ◽  
Loose Sand ◽  
Element Analysis ◽  
Content Type ◽  
Static Liquefaction ◽  
Random Finite Element

Purpose – Liquefaction of soils is defined as significant reduction in shear strength and stiffness due to increase in pore water pressure. This phenomenon can occur in static (monotonic) or dynamic loading patterns. However, in each pattern, the inherent variability of the soil parameters indicates that this problem is of a probabilistic nature rather than being deterministic. The purpose of this paper is to present a method, based on random finite element method, for reliability assessment of static liquefaction of saturated loose sand under monotonic loading. Design/methodology/approach – The random finite element analysis is used for reliability assessment of static liquefaction of saturated loose sand under monotonic loading. The soil behavior is modeled by an elasto-plastic effective stress constitutive model. Independent soil parameters including saturated unit weight, peak friction angle and initial plastic shear modulus are selected as stochastic parameters which are modeled using a truncated normal probability density function (pdf). Findings – The probability of liquefaction is assessed by pdf of modified pore pressure ratio at each depth. For this purpose pore pressure ratio is modified for monotonic loading of soil. It is shown that the saturated unit weight is the most effective parameter, within the selected stochastic parameters, influencing the static soil liquefaction. Originality/value – This research focuses on the reliability analysis of static liquefaction potential of sandy soils. Three independent soil parameters including saturated unit weight, peak friction angle and initial plastic shear modulus are considered as stochastic input parameters. A computer model, coded in MATLAB, is developed for the random finite element analysis. For modeling of the soil behavior, a specific elasto-plastic effective stress constitutive model (UBCSAND) was used.

scholarly journals Bearing Capacity of Ring Foundations on Sand Overlying Clay

2020 ◽  
Vol 10 (13) ◽  
pp. 4675
Author(s):  
Chaowei Yang ◽  
Zhiren Zhu ◽  
Yao Xiao
Keyword(s):  
Bearing Capacity ◽  
Friction Angle ◽  
Failure Criteria ◽  
Unit Weight ◽  
Sand Layer ◽  
Collapse Mechanisms ◽  
Internal Radius ◽  
Vertical Bearing ◽  
Vertical Bearing Capacity ◽  
Ring Foundations

The vertical bearing capacity of rough ring foundations resting on a sand layer overlying clay soil is computed in this study by using finite element limit analysis (FELA). The sands and clays are assumed as elastoplastic models, obeying Mohr–Coulomb and Tresca failure criteria, respectively. Based on the FELA results, design charts are provided for evaluating the ultimate bearing capacity of ring foundations, which is related to the undrained shear strength of the clay, the thickness, the internal friction angle, the unit weight of the sand layer, and the ratio of the internal radius to the external radius of the footing. A certain thickness, beyond which the clay layer has a negligible effect on the bearing capacity, is determined. The collapse mechanisms are also examined and discussed.

Axial compressive capacity of helical piles from field tests and numerical study

2013 ◽  
Vol 50 (12) ◽  
pp. 1191-1203 ◽  
Author(s):  
Zeyad H. Elsherbiny ◽  
M. Hesham El Naggar
Keyword(s):  
Bearing Capacity ◽  
Load Transfer ◽  
Numerical Study ◽  
Numerical Models ◽  
Field Tests ◽  
Reduction Factor ◽  
Full Scale ◽  
Cohesionless Soil ◽  
Soil Parameters ◽  
Helical Piles

The compressive capacity of helical piles in sand and clay is investigated by means of field testing and numerical modeling. The numerical models are conducted using the computer program ABAQUS and are calibrated and verified using full-scale load testing data. The calibration was accomplished by using reasonable assumptions regarding soil–pile interaction and soil parameters reported from the literature. The model was verified by comparing its predictions with observed load–displacement curves obtained from full-scale pile load tests. The verified numerical model was used to perform a parametric study considering different pile configurations and soil parameters to evaluate the compressive capacity and load-transfer mechanism of helical piles. The compressive capacity obtained from the numerical models is compared with that obtained from existing theoretical methods for calculating the capacity. It is found that the predictions of theoretical equations for piles in cohesionless soil vary largely depending on the choice of bearing capacity factors and proper failure criteria. The interaction of closely spaced helices on the capacity of a helical pile is also evaluated. A bearing capacity reduction factor, R, and helix efficiency factor, EH, are proposed to evaluate the compressive capacity of helical piles in cohesionless soil considering an industry-acceptable ultimate load criterion corresponding to settlement equal to 5% of helix diameter, D.

scholarly journals Prediction of Ultimate Bearing Capacity of Shallow Foundations on Cohesionless Soils: A Gaussian Process Regression Approach

2021 ◽  
Vol 11 (21) ◽  
pp. 10317
Author(s):  
Mahmood Ahmad ◽  
Feezan Ahmad ◽  
Piotr Wróblewski ◽  
Ramez A. Al-Mansob ◽  
Piotr Olczak ◽  
...  
Keyword(s):  
Gaussian Process ◽  
Bearing Capacity ◽  
Gaussian Process Regression ◽  
Ultimate Bearing Capacity ◽  
Shallow Foundations ◽  
Cohesionless Soil ◽  
Unit Weight ◽  
Cohesionless Soils ◽  
Computing Technique ◽  
Theoretical Approaches

This study examines the potential of the soft computing technique—namely, Gaussian process regression (GPR), to predict the ultimate bearing capacity (UBC) of cohesionless soils beneath shallow foundations. The inputs of the model are width of footing (B), depth of footing (D), footing geometry (L/B), unit weight of sand (γ), and internal friction angle (ϕ). The results of the present model were compared with those obtained by two theoretical approaches reported in the literature. The statistical evaluation of results shows that the presently applied paradigm is better than the theoretical approaches and is competing well for the prediction of UBC (qu). This study shows that the developed GPR is a robust model for the qu prediction of shallow foundations on cohesionless soil. Sensitivity analysis was also carried out to determine the effect of each input parameter.

scholarly journals The research of dynamic impacts on the hydraulic structure foundation base, transformed in the process of accident recovery

2018 ◽  
Vol 251 ◽  
pp. 04040
Author(s):  
Zaven Ter-Martirosyan ◽  
Ivan Luzin
Keyword(s):  
Field Experiments ◽  
Dynamic Properties ◽  
Soil Parameters ◽  
Experimental Site ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Foundation Base ◽  
Dynamic Impacts ◽  
Scale Experiment ◽  
Selection Of

The article presents the results of a comprehensive research of the dynamic impacts on a modified base. The modified base was obtained as a result of compensatory injection at the experimental site for the accident recovery at the hydraulic engineering structure. The complex study of the dynamic impacts includes special laboratory tests to determine the soil parameters, the finite element analysis of the experimental site, taking into account the dynamic properties, the selection of the necessary equipment for field experiments based on the numerical solution results, a full-scale experiment with the measurement of the foundation sediments of the experimental site.

scholarly journals Influence of the groundwater level on the bearing capacity of shallow foundations on the rock mass

2021 ◽  
Author(s):  
Ana Alencar ◽  
Rubén Galindo ◽  
Svetlana Melentijevic
Keyword(s):  
Rock Mass ◽  
Bearing Capacity ◽  
Groundwater Level ◽  
Sensitivity Study ◽  
Shallow Foundations ◽  
Unit Weight ◽  
Geological Strength Index ◽  
Strength Index ◽  
Mass Type

AbstractThe presence of the groundwater level (GWL) at the rock mass may significantly affect the mechanical behavior, and consequently the bearing capacity. The water particularly modifies two aspects that influence the bearing capacity: the submerged unit weight and the overall geotechnical quality of the rock mass, because water circulation tends to clean and open the joints. This paper is a study of the influence groundwater level has on the ultimate bearing capacity of shallow foundations on the rock mass. The calculations were developed using the finite difference method. The numerical results included three possible locations of groundwater level: at the foundation level, at a depth equal to a quarter of the footing width from the foundation level, and inexistent location. The analysis was based on a sensitivity study with four parameters: foundation width, rock mass type (mi), uniaxial compressive strength, and geological strength index. Included in the analysis was the influence of the self-weight of the material on the bearing capacity and the critical depth where the GWL no longer affected the bearing capacity. Finally, a simple approximation of the solution estimated in this study is suggested for practical purposes.

scholarly journals Application of Artificial Neural Networks for Predicting the Bearing Capacity of Shallow Foundations on Rock Masses

2021 ◽  
Author(s):  
M. A. Millán ◽  
R. Galindo ◽  
A. Alencar
Keyword(s):  
Bearing Capacity ◽  
Analytical Solutions ◽  
Shear Failure ◽  
Numerical Models ◽  
Computational Effort ◽  
Shallow Foundations ◽  
Geological Strength Index ◽  
Rock Masses ◽  
Ann Model ◽  
Artificial Neural

AbstractCalculation of the bearing capacity of shallow foundations on rock masses is usually addressed either using empirical equations, analytical solutions, or numerical models. While the empirical laws are limited to the particular conditions and local geology of the data and the application of analytical solutions is complex and limited by its simplified assumptions, numerical models offer a reliable solution for the task but require more computational effort. This research presents an artificial neural network (ANN) solution to predict the bearing capacity due to general shear failure more simply and straightforwardly, obtained from FLAC numerical calculations based on the Hoek and Brown criterion, reproducing more realistic configurations than those offered by empirical or analytical solutions. The inputs included in the proposed ANN are rock type, uniaxial compressive strength, geological strength index, foundation width, dilatancy, bidimensional or axisymmetric problem, the roughness of the foundation-rock contact, and consideration or not of the self-weight of the rock mass. The predictions from the ANN model are in very good agreement with the numerical results, proving that it can be successfully employed to provide a very accurate assessment of the bearing capacity in a simpler and more accessible way than the existing methods.

A Version of the Failure Criterion Modification for Plane Concrete

2017 ◽  
Vol 755 ◽  
pp. 300-321 ◽  
Author(s):  
Volodymyr I. Korsun ◽  
Yu.Yu. Kalmykov ◽  
S.Yu. Makarenko
Keyword(s):  
Comparative Analysis ◽  
Solid Mechanics ◽  
Concrete Strength ◽  
Failure Criteria ◽  
Analytic Description ◽  
Deformable Solid ◽  
Theoretical Approaches ◽  
Concrete Failure ◽  
Stress States ◽  
Multiaxial Loadings

The paper is about the generally accepted in the deformable solid mechanics principles of constructing limiting surfaces of concrete strength in the principal stress space. The background and theoretical approaches taken by different researchers to describe the functions of deviatoric and meridional curves as the basic elements which determine the surface configuration of concrete strength were analyzed.There was carried out a comparative analysis of different authors’ suggestions on an analytic description of concrete strength for different stress states and a comparison of the developed criteria and the results of short-term tests of plane concrete under multiaxial loadings. Comparing the methods taken for developing the interpolation functions of deviatoric and meridional curves, it was inferred that the application of different approaches to the development of concrete failure criteria is effective. Keeping in mind the results of the comparative analysis of the prerequisites taken to develop the above failure criteria and the requirements of a better approximation of the experimental data, there are made new suggestions to describe concrete strength for the general case of stress state.

Cross-Ply Laminates under Static Three-Point Bending: A Numerical Development Model

2012 ◽  
Vol 498 ◽  
pp. 42-54 ◽  
Author(s):  
S. Benbelaid ◽  
B. Bezzazi ◽  
A. Bezazi
Keyword(s):  
Numerical Model ◽  
Damage Mechanics ◽  
Progressive Failure ◽  
Damage Model ◽  
Continuum Damage Mechanics ◽  
Failure Criteria ◽  
Continuum Damage ◽  
Damage Development ◽  
Element Analysis ◽  
Progressive Failure Analysis

This paper considers damage development mechanisms in cross-ply laminates using an accurate numerical model. Under static three points bending, two modes of damage progression in cross-ply laminates are predominated: transverse cracking and delamination. However, this second mode of damage is not accounted in our numerical model. After a general review of experimental approaches of observed behavior of laminates, the focus is laid on predicting laminate behavior based on continuum damage mechanics. In this study, a continuum damage model based on ply failure criteria is presented, which is initially proposed by Ladevèze. To reveal the effect of different stacking sequence of the laminate; such as thickness and the interior or exterior disposition of the 0° and 90° oriented layers in the laminate, an equivalent damage accumulation which cover all ply failure mechanisms has been predicted. However, the solution algorithm using finite element analysis which implements progressive failure analysis is summarized. The results of the numerical computation have been justified by the previous published experimental observations of the authors.

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