Dr. Arindam Dey Presentations/2021/Dey...05-01-2021 Short Course, NIT Warangal 17 •Modelling...

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Dr. Arindam Dey Associate Professor Geotechnical Engineering Division Department of Civil Engineering IIT Guwahati Short Course Finite Element Analysis of Static and Dynamic Soil-structure Interaction of Geosystems Department of Civil Engineering, NIT Warangal

Transcript of Dr. Arindam Dey Presentations/2021/Dey...05-01-2021 Short Course, NIT Warangal 17 •Modelling...

  • Dr. Arindam DeyAssociate Professor

    Geotechnical Engineering Division

    Department of Civil Engineering

    IIT Guwahati

    Short Course

    Finite Element Analysis of Static and Dynamic

    Soil-structure Interaction of Geosystems

    Department of Civil Engineering, NIT Warangal

  • Introduction• Growing habitation and urbanization on hilly terrains

    • Foundations on or near the edges of slopes

    Examples of such practice

    Buildings or roads constructed in hilly regions

    Electric transmission towers built on mountain slopes

    Foundations for bridge abutments

    • Foundations on slope or near the slope

    Reduction in ultimate bearing capacity

    Incomplete formation of passive zone

    Lack of resistance of outward lateral movement

    05-01-2021 Short Course, NIT Warangal 2

  • Foundations on Horizontal Ground

    • Hosseini (2014)

    Carried out experimental and numerical investigation

    Bearing capacity estimation of square footing

    Comparison of results with conventional theories

    • Khan et al. (2006), Cerato and Lutenegger (2006) and Nareeman (2012)

    Carried out experimental investigation

    Increased bearing capacity of square footing

    Increase of footing width

    • Cerato and Lutenegger (2007)

    Carried out Experimental investigation

    Enhanced bearing capacity of square footing

    Significant effect of relative density of soil

    • Khan et al. (2006), Pusadkar et al. (2013), Lavasan and Ghazavi (2014)

    Inteference effect of square footing

    Bearing capacity increased

    Interfering footing than isolated footing

    • Asaduzzaman and Iftiarul (2014), Dhatrak and Farukh (2014), Belal and Ahmed (2015)

    Reinforcing soil bed

    Enhanced bearing capacity

    05-01-2021 Short Course, NIT Warangal 3

  • Foundations on Sloping Ground

    • Shields et al. (1977), Bauer et al. (1981), Kumar and Ilampurthy(2009), Castelli and Lentini (2012), Keskin and Laman (2013)

    Strip footing on dry cohesionless sandy slope

    Ultimate bearing capacity and bearing capacity factor

    Effecting various parameter (Setback distance, relative density, slope angle, load inclination)

    • Castelli and Lentini (2012)

    Square footing on cohesionless sandy slope

    Bearing capacity and bearing capacity factor

    • Azzam and Farouk (2010)

    Skirted strip footing resting on the crest of sandy slope

    Ultimate bearing capacity

    • Clark et al. (1988)

    Field test with anchored inclined footing

    Overall response

    • Alamshahi and Hataf (2009), Yoo (2001)

    Geosynthetic inclusion

    Enhanced bearing capacity of strip footing by altering the reinforcing parameter

    05-01-2021 Short Course, NIT Warangal 4

  • Codal Provisions

    • IS-1904 (1986)

    Provided various design guidelines

    The construction of shallow footing resting on slope face

    • AASHTO (2012)

    Provide various design charts

    Shallow footings resting on or near the sandy or clayey slope

    05-01-2021 Short Course, NIT Warangal 5

    0.5u cq qq cN BN

  • Bearing Capacity of Square Footing Resting on Crest of c-φ Slope

    05-01-2021 Short Course, NIT Warangal 6

  • Numerical Finite Element Modelling

    05-01-2021 Short Course, NIT Warangal

    • PLAXIS 3D

    Three-dimensional analysis

    Deformation

    Stability

    Ground water flow in geotechnical engineering

    Equipped with features

    Various aspects of complex geotechnical structures

    • PLAXIS 3D Analysis

    Geometry

    Two types of model geometry

    Horizontal ground surface or footing below horizontal ground surface

    Footing on slope crest or on the slope face

    The dimensions of the models

    “0.1q” significant stress contour

    Not to be intersected by the side and bottom edges of the model

    The outermost significant stress isobar

    Effect of the applied load

    Considered to be negligible

    7

  • Numerical Finite Element Modelling Boundary Conditions

    Vertical edges of the model

    Horizontal fixity

    Slope of the model

    No fixity

    Bottom edge

    Both vertical and horizontal fixities

    Assumed to be non-yielding

    This boundary condition

    “Standard fixity”

    Meshing

    Finite element calculation

    Discretized into smaller finite number of tetrahedral elements

    10-noded tetrahedral elements

    Five basic meshing schemes

    Very coarse, coarse, medium, fine, and very fine

    User-defined refinements

    Special conditions

    Mesh should be sufficiently fine

    Accurate numerical results

    Avoid very fine mesh

    Excessive time

    Convergence study05-01-2021 Short Course, NIT Warangal 8

  • Numerical Finite Element Modelling

    • Geometry

    ‘0.1 q’ stress isobar

    • Boundary condition

    Standard fixities

    • Meshing

    10-node

    Tetrahedrons

    • Location

    Footings

    Various setback distance

    Embedment depth

    05-01-2021 Short Course, NIT Warangal 9

  • Development of Numerical Model

    • Material

    Soil (Keskin and Laman 2013)

    M-C model

    Associated flow rule

    Footing (Boushehrian and Hataf 2002)

    M20 concrete

    Linear elastic model

    Rinter = 1 (Nasr 2014)

    Newton-Cotes integration

    • The failure mechanism generated beneath the footing

    Resting on horizontal ground

    Postulated by Terzaghi (1943)

    Assumption that the base of the footing is rough

    05-01-2021 Short Course, NIT Warangal 10

    Unit weight (γ)

    (kN/m3)

    Modulus of elasticity E

    (GPa)Poisson's ratio (ν)

    25 22 0.15

  • Results and Discussions• Validation study

    Castelli and Lentini (2012)

    Same soil properties

    Domain size

    B = 0.08 m (square)

    b = 0.12 m

    • Convergence study

    Fine mesh

    Significant match

    Numerical

    Experimental outcomes

    05-01-2021 Short Course, NIT Warangal 11

  • Results and Discussions

    05-01-2021 Short Course, NIT Warangal 12

    • Convergence study

    Various slope angles

    Embedment depth

    Fine mesh

    Opted for analysis

    • Parametric investigation

    Variation of c

    Bearing capacity increased

    Shear strength increases

    Increase of c

    Variation of φ

    Bearing capacity increased

    Confinement increases

    Increase of φ

  • Results and Discussions

    05-01-2021 Short Course, NIT Warangal 13

    • Variation of unit weight (γ)

    Insignificant effect

    On ultimate bearing capacity (qu)

    • Variation of width of footing (B)

    Significant effect

    Bearing capacity (qu) increased

    Increasing B

    Larger soil domain

    Support the incumbent load

  • Results and Discussions

    05-01-2021 Short Course, NIT Warangal 14

    • Variation of slope angle (β)

    Ultimate bearing capacity decreased (qu)

    Smaller zone of passive resistance

    Increase of β

    • Variation of Embedment depth (Df)

    Ultimate bearing capacity increased (qu)

    Higher confinement effect

    Restricting the soil movement

  • Results and Discussions

    • Failure mechanism

    Setback ratio (b/B) = 0

    • Formation of passive zone

    One-directional

    Curtailed by the slope

    Dominant free deformation

    • Setback ratio increases

    Influencing effect of the slope

    Gradually diminishes

    • Setback ratio (b/B)critical = 4

    Footing behaves

    Resting on horizontal ground

    05-01-2021 Short Course, NIT Warangal 15

    Acharyya R, Dey A (2017) Finite element investigation of the bearing capacity of

    square footings resting on sloping ground. INAE Letters 2(3): 97-105.

    Acharyya R, Dey A, Kumar B (2018) Finite element and ANN-based prediction ofbearing capacity of square footing resting on the crest of c-φ soil slope. InternationalJournal of Geotechnical Engineering DOI: 10.1080/19386362.2018.1435022.

  • Bearing Capacity of Strip Footing Located on Crest of c-φ Slope

    05-01-2021 Short Course, NIT Warangal 16

  • Numerical Modelling

    05-01-2021 Short Course, NIT Warangal 17

    • Modelling

    Plaxis 2D

    • Meshing

    15-node

    Triangular element

    • Geometry and boundary condition

    • Material model (Soil and Footing)

    Same as considered

    Square footing on slope

  • Results and Discussions

    05-01-2021 Short Course, NIT Warangal 18

    0 1 2 3 4 5 6 7 8 9 10 110

    20

    40

    60

    80

    100

    120

    140

    qu/

    Hs

    Setback ratio (b/B)

    c = 10 kPa

    c = 30 kPa

    c = 50 kPa

    , B = 2m, D

    f/B = 0

    0 2 4 6 8 10

    8

    16

    32

    64

    128

    ckPa = , D

    f/B = 0, B = 2 m

    Setback ratio (b/B)

    qu/

    Hs

  • Results and Discussions

    • Failure mechanism

    Various setback distances

    b = 6B (B = width of footing)

    Behaves footing on horizontal surface

    05-01-2021 Short Course, NIT Warangal 19

    Acharyya R, Dey A (2018) Assessment of bearing capacity for strip

    footing located near sloping surface considering ANN-model.

    Neural Computing and Applications DOI: 10.1007/s00521-018-

    3661-4.

  • Interaction Mechanism of Strip Footings Resting on a Horizontal Ground

    05-01-2021 Short Course, NIT Warangal 20

  • Interfering Foundations on Horizontal Ground

    • Stuart (1962) is the first

    Given the concept of interference of shallow footings

    Efficiency factors were added in

    The ultimate bearing capacity expression given by Terzaghi (1943)

    To show the effect of interference

    On Terzaghi’s bearing capacity factors

    • Saran and Agarwal (1973)

    Laboratory investigation done

    For two dimensional and three dimensional cases

    Bearing capacity factor and settlement characteristics

    Results are matched

    Stuart (1962)

    Bearing capacity decreased

    For increasing of spacing of footing

    05-01-2021 Short Course, NIT Warangal 21

  • Interfering Foundations on Horizontal Ground

    • Das and Larbi Cherif (1983)

    Experimental Investigation

    Ultimate bearing capacity of closely spaced strip footings

    Obtained values compared

    Stuart (1962)

    Bearing capacity decreased

    For increasing of spacing of footing

    • Kumar and Kouzer (2007)

    upper bound limit analysis in conjunction with finite elements

    linear computer programming

    Results given

    In terms of ‘Efficiency factor’ (ξ )

    When two footings having no gap

    The magnitude of ξ is 2.0

    05-01-2021 Short Course, NIT Warangal 22

  • Interfering Foundations on Horizontal Ground

    • For the validation

    The experimental studies done by Das and Larbi Cherif (1983)

    Two different numerical models have been developed

    One model was formed for strip footing resting on surface of horizontal ground

    Other model was made for footing resting on horizontal ground with embedment depth

    Dry sand having relative density of (Dr) of 54%

    Dry density of 15.88 kN/m3

    And angle of internal friction (φ) of 38°

    medium mesh has been used to discretize the model

    05-01-2021 Short Course, NIT Warangal 23

  • Results and Interpretations

    • Numerical simulations

    Conducted for varying spacing of the footings,

    Ranging from 1B to 10B,

    Where B is the width of an individual footing

    The interaction reduces

    The increase in spacing between the footings,

    Non-overlapping displacement and stress contours

    05-01-2021 Short Course, NIT Warangal 24

  • Results and Interpretations

    • Total displacement and vertical stress distribution

    05-01-2021 Short Course, NIT Warangal 25

  • Results and Interpretations

    05-01-2021 Short Course, NIT Warangal 26

  • Results and Interpretations

    05-01-2021 Short Course, NIT Warangal 27

  • Results and Interpretations

    • Incremental deviatoric strain

    05-01-2021 Short Course, NIT Warangal 28

  • Results and Interpretations

    • Footings spaced

    Distance of 6B can be

    Considered to have mutual influences

    On their stress and settlement characteristics

    Termed as closely-spaced interfering footings.

    Beyond this spacing

    The interaction effects of the footings cease to exist

    The footings can be considered as isolated footings

    05-01-2021 Short Course, NIT Warangal 29

    S/B = 1 S/B = 1.5

    S/B = 2 S/B = 3

    S/B = 4 S/B = 5

    S/B = 6 S/B = 10

  • Results and Interpretations

    05-01-2021 Short Course, NIT Warangal 30

    S/B = 1 S/B = 1.5

    S/B = 2 S/B = 3

    S/B = 4 S/B = 5

    S/B = 6 S/B = 10

  • Results and Interpretations

    05-01-2021 Short Course, NIT Warangal 31

  • Response of Interfering Footings Located on Crest and Face of Slope

    05-01-2021 Short Course, NIT Warangal 32

  • Interfering Foundations on Slopes

    • Interference on sloping ground

    No documentation observed

    • From practical point of view

    The mechanism of a single footing

    Not represent the mechanism of building footings

    Due to the presence of various types of multiple footings within a small region

    • Common in hilly regions

    Find most of the houses

    Resting either on the slope face or on the slope crest

    Most of these inhabitations

    Comprises of buildings resting on shallow footing

    05-01-2021 Short Course, NIT Warangal 33

  • Interfering Foundations on Slopes

    05-01-2021 Short Course, NIT Warangal 34

  • Mechanism of Footings Located on a Slope Crest

    • Investigate the basic mechanism

    The interaction effect of strip footing

    Resting on or near the slope

    Basic difference of mechanisms of interaction

    For strip footings resting on horizontal surface

    And strip footings resting on or near the slope

    A sloping model of homogeneous dense sandy soil,

    developed in PLAXIS 2D

    05-01-2021 Short Course, NIT Warangal 35

  • Mechanism of Footings Located on a Slope Crest

    05-01-2021 Short Course, NIT Warangal 36

    • Footings are kept over the crest of the slope

    Nominal setback distance and spacing,

    Mass movement of the soil occurs towards the slope face

    Lack of passive resistance from the slope boundary

    • This behaviour is different in comparison

    Footings resting on horizontal ground with a nominal spacing

    The total displacement was downwards

    Rather than one directional

  • Development of Numerical Model

    • Geometry

    ‘0.1q’ stress isobar

    Not intersected by boundaries of domain

    • Boundary condition

    Standard fixities

    05-01-2021 Short Course, NIT Warangal 37

    • Meshing

    10-node

    Tetrahedrons

    Fine mesh

    Used in analysis

  • Development of Numerical Model

    • Material

    Soil (Nader and Hataf 2014)

    Associated flow rule

    (Drescher and Detournay1993)

    Footing

    M20 concrete

    Interface

    Rough

    Rinter = 1

    05-01-2021 Short Course, NIT Warangal 38

    Soil typesCohesion

    (c) (kPa)

    Angle of

    internal

    friction

    (φ)°

    Unit

    weight (γ)

    (kN/m3)

    Modulus

    of

    elasticity

    (E) (kPa)

    Poisson's

    ratio (ν)

    Soil-A 10 40

    8000 0.3Soil-B 30 30 17

    Soil-C 80 10

    Unit weight (γ)

    (kN/m3)

    Modulus of elasticity E

    (GPa)

    Poisson's ratio

    (ν)

    25 22 0.15

    • Validation

    Das and Larbi-Cherif (1983)

    Experimental Investigation

    Geometrical and geotechnical properties

    Same taken

    Numerical analysis

    Dry sand having relative density of (Dr) of 54%,

    Dry density of 15.88 kN/m3

    Angle of internal friction (φ) of 38°

    Fine mesh

    Used to discretize the model

  • Results and Discussion

    • Variation of Spacing

    Bearing capacity

    Increased

    up to S/B = 1.5

    Decreased

    Up to S/B = 3

    Isolated strip footing

    Resting on crest of slope

    Slope angle increased

    Bearing capacity

    Decreased

    05-01-2021 Short Course, NIT Warangal 39

    0 2 4 6 8 10

    1500

    2000

    2500

    3000

    3500

    4000

    4500

    s/B

    qu (

    kP

    a)

    b/B = 2, Soil-A

    ß=10°

    ß=20°

    ß=30°

    ß=40°

  • Results and Discussion

    • Setback distance (b)

    Bearing capacity

    Increased

    Increasing

    Setback distance

    05-01-2021 Short Course, NIT Warangal 40

  • Results and Discussion

    • Variation of Footing Width (B)

    Bearing capacity

    Increased

    Larger soil domain

    Support the incumbent load

    05-01-2021 Short Course, NIT Warangal 41

    • Variation soil type

    Soil-A

    S/B = 3

    Soil-B

    S/B = 3

    Soil-C

    S/B = 2

    Bearing capacity

    Increased

    Increasing angle of internal friction (φ)

  • Results and Discussion• Failure mechanism

    (b/B) = 3

    β = 30°

    Soil-A

    (S/B) critical = 3

    Isolated strip footing

    05-01-2021 Short Course, NIT Warangal 42

    Acharyya R, Dey A (2018) Assessment of bearing

    capacity of interfering strip footings located near

    sloping surface considering Ann-technique. Journal

    of Mountain Science 15(12): 2766–2780

  • Mechanism of a Footing on a Slope Face

    • The mechanism for a strip footing located in a slope

    Plane strain approach taken for

    Assessment of mechanism

    Through PLAXIS 2D

    A 60 m high hill slope with sloping angle of 30°

    A 2 m wide strip footing has been considered

    Located on the hill-slope having

    A minimum embedment depth of 1 m from the slope face

    A homogeneous medium dense sandy soil

    To make the hill slope and

    A vertical failure load given over the footing

    The numerical investigation

    Natural hill-slopes will not be a purely sandy medium

    And will comprise of other soil constituents as well

    However, to keep the problem simple for understanding

    The pre-failure and failure mechanisms of the footing and the slope

    The simulation has been carried out

    Considering only homogeneous cohesionless medium.

    05-01-2021 Short Course, NIT Warangal 43

  • Mechanism of a Footing on a Slope Face

    • A 55m high hill slope

    Modelled in the PLAXIS 2D

    Represent a typical field slope geometry

    The failure displacement

    Given to the strip footing

    As 20% of the footing width (B)

    05-01-2021 Short Course, NIT Warangal 44

  • Mechanism of a Footing on a Slope Face

    • While evaluating the stress and deformation mechanisms

    The shallow strip footing resting on slope face

    Observed that at failure load

    The footing exhibits rotation

    Initially, it has been believed

    Such rotation is bound to be exhibited due to

    The outward movement of the soil mass owing to the lack of passive resistance

    From the slope face

    Illustrates the mechanism developed

    Terms of the incremental displacement, incremental deviatoric strain and soil displacement vectors

    It can be easily deducted that the soil displacement

    Beneath the footing has occurred predominantly

    Towards the slope face, resulting in the tilting of the footing

    It was supposedly assumed that such tilting of footing should not occur

    For a footing resting on horizontal ground in a symmetric numerical model and subjected to a symmetric loading

    05-01-2021 Short Course, NIT Warangal 45

  • Mechanism of a Footing on a Slope Face

    • Plaxis 2D output

    05-01-2021 Short Course, NIT Warangal 46

  • Interaction Mechanism of Footings on a Slope Face

    • 2D simulation

    • The degree of interaction

    Quantified by the overlap of the 0.1Bdisplacement contour

    Termed as ‘significant displacement contour

    Produced by the adjacent footings

    Highlights the significant displacement contour

    Produced by the loading of the benchmark footing

    The region bounded by the significant displacement contour

    Susceptible to substantial movement upon loading of the footing

    Any other footing present in this region,

    Simultaneously loaded till failure

    Result in further drastic movement of the soil in the bounded region

    05-01-2021 Short Course, NIT Warangal 47

  • Interaction Mechanism of Footings on Slope Face

    05-01-2021 Short Course, NIT Warangal 48

  • Interaction Mechanisms of Footings on Slope Face

    05-01-2021 Short Course, NIT Warangal 49

  • Interaction Mechanisms of Footings on Slope Face

    05-01-2021 Short Course, NIT Warangal 50

  • Interaction Mechanisms of Footings on Slope Face

    05-01-2021 Short Course, NIT Warangal 51

  • Interaction Mechanism of Footings on a Slope Face

    05-01-2021 Short Course, NIT Warangal 52

  • Interaction Mechanism of Footings on a Slope Face

    • Numerical simulation of the interference effects of footings

    Resting on horizontal ground has been carried out

    And validated against the existing theories.

    Interaction effect of the footings, resting on a slope

    Not be according to the conventional theories of interference of footings

    Resting on horizontal ground.

    Based on intensive studies, the interaction effects of footing

    Resting on a hill-slope have been efficiently illustrated

    05-01-2021 Short Course, NIT Warangal 53

  • Interaction Mechanism of Footings on a Slope Face

    • habitations in the hilly terrains

    Most of the urbanization

    Taken place on the hill slopes

    Slope angle within the range of 20° to 40°

    05-01-2021 Short Course, NIT Warangal 54

    As a benchmark problem The response of an

    isolated strip footing investigated;

    This problem is termed as ‘h = 0B’ condition

  • Interaction Mechanism of Footings on a Slope Face

    05-01-2021 Short Course, NIT Warangal 55

  • Interaction Mechanisms of Footings on Slope Face

    • 3D simulation

    • In order to investigate

    • The effect of analysis type on the obtained understanding

    3D simulation has been done by PLAXIS 3D v2015

    To investigate the interference effect of strip footings resting on hill slope

    A 25° hill slope

    Dense sand

    The width of the slope

    such a way that the boundary effect should not come in the analysis

    The height was taken same as taken in 2D analysis

    The length of the footing has been taken as 9 times of the footing width (B)

    The footing should behave like strip footing

    Plain strain condition is maintained

    Failure load imposed over the footing

    05-01-2021 Short Course, NIT Warangal 56

  • Interaction Mechanisms of Footings on Slope Face

    • Displacement iso-surfaces

    05-01-2021 Short Course, NIT Warangal 57

  • Interaction Mechanisms of Footings on Slope Face

    05-01-2021 Short Course, NIT Warangal 58

  • Application of Artificial Neural Networks in Predicting Bearing Capacity of

    Foundations on Slopes

    05-01-2021 Short Course, NIT Warangal 59

  • Overview of ANN

    • Neural networks

    Bio-mimetic data mining structures

    Containing several simple

    Highly interrelated

    Processing elements

    Termed as artificial neurons

    In a complex architecture

    Used to develop correlation maps

    Between the contributory parameters

    Inputs

    The model outcomes

    Outputs

    05-01-2021 Short Course, NIT Warangal 60

    Neural Network

    Learning Algorithm

    Error feedback

    Error

    Desired output

    Input Output

    Change

    parameters to

    reduce error

  • Modelling of ANN

    • Normalization of data

    Input

    Output

    (Rukhaiyar et al. 2017)

    and are before and after normalization magnitude

    and are the maximum and minimum magnitude

    05-01-2021 Short Course, NIT Warangal 61

    min

    max min

    2( )1

    ( )

    a

    n i i

    i

    i i

    P PP

    P P

    a

    iPn

    iP

    max

    iPmin

    iP

    • ANN

    Architecture

    • Network

    Feed-forward cum back-propagation

    • Training function

    Levenberg-Marquardt's

  • Results and Discussions

    • ANN models (Square footing on slope)

    Number of neurons

    Hidden layer

    Varied

    The mean square error (MSE)

    Achieves a minimum (0.0126)

    Ten neurons

    Hidden layer

    7 input nodes

    (c, φ, γ, B, b/B, β and Df/B)

    10 hidden-layer neurons

    A single (1) output node

    (qu)

    The architecture

    7–10–1

    05-01-2021 Short Course, NIT Warangal 62

    2

    1

    1( )

    N

    Simulation ANN

    i

    MSE O ON

    Nd = Number of data

    OSimulation = Numerically simulated values

    OANN = Predicted values of the same entity

  • Results and Discussions

    • ANN architecture

    Training

    Testing

    Validation

    80% of the total data

    used for training

    20% of the total data

    Validation of the ANN architecture

    Training dataset

    Further divided, where

    70% of the data

    Used for actual training

    Remaining 30% of the data

    Used as the testing

    Das and Basudhar 2006

    05-01-2021 Short Course, NIT Warangal 63

  • Results and Discussions

    • Table

    Weight

    Biases

    05-01-2021 Short Course, NIT Warangal 64

    N

    X

    Hidden

    N1

    Hidden

    N2

    Hidden

    N3

    Hidden

    N4

    Hidden

    N5

    Hidden

    N6

    Hidden

    N7

    Hidden

    N8

    Hidden

    N9

    Hidden

    N10

    c (X1) 0.55 -0.67 -0.26 0.84 -0.54 0.95 0.58 -3.58 0.004 -0.12

    φ (X2) -0.56 -0.33 8.43 1.30 -0.64 -7.25 1.27 -5.25 -0.29 -0.91

    γ (X3) 0.32 0.03 0.02 0.16 -0.09 0.03 0.09 -0.75 -0.01 0.04

    B (X4) 0.24 0.11 0.15 0.46 -0.52 -0.06 0.46 4.79 -0.13 -0.13

    b/B (X5) 1.45 0.0008 2.05 0.14 0.07 -1.74 -0.51 2.64 0.02 2.01

    β (X6) -0.38 -0.01 -0.47 -0.04 -0.01 0.51 0.11 -0.67 0.004 -0.46

    Df/B(X7) 1.30 0.57 -0.66 0.72 -0.35 0.66 0.42 6.50 -0.09 -0.05

    N

    Y

    Hidden

    N1

    Hidden

    N2

    Hidden

    N3

    Hidden

    N4

    Hidden

    N5

    Hidden

    N6

    Hidden

    N7

    Hidden

    N8

    Hidden

    N9

    Hidden

    N10

    Output 0.06 -2.16 0.52 1.91 2.01 0.53 0.83 2.32 -3.58 0.97

    Hidden layer biases

    (bhN)

    Output layer biases

    (bO)

    1.16

    -0.61

    -0.48

    -0.66

    -2.16

    1.34

    0.03

    -1.79

    -5.15

    -0.03

    3.03

    Biases

    Hidden-Output weights

    Input-Hidden weights

  • Results and Discussions

    • Sensitivity analysis

    Garson’s algorithm (1991)

    05-01-2021 Short Course, NIT Warangal 65

    10

    71

    1

    XN

    X

    N

    ZN

    Z

    HiddenInput

    Hidden

    (Garson’s algorithm)

    N

    Z

    Hidden

    N1

    Hidden

    N2

    Hidden

    N3

    Hidden

    N4

    Hidden

    N5

    Hidden

    N6

    Hidden

    N7

    Hidden

    N8

    Hidden

    N9

    Hidden

    N10

    c (X1) 0.04 1.45 -0.13 1.61 -1.09 0.50 0.48 -8.31 0.02 -0.12

    φ (X2) -0.04 0.71 4.40 2.49 -1.29 -3.83 1.06 -12.18 1.03 -0.88

    γ (X3) 0.02 -0.07 0.01 0.31 -0.19 0.02 0.08 -1.73 0.02 0.04

    B (X4) 0.02 -0.24 0.08 0.87 -1.04 -0.03 0.38 11.10 0.48 -0.12

    b/B (X5) 0.09 0.0018 1.07 0.26 0.14 -0.92 -0.43 6.13 -0.07 1.94

    β (X6) -0.02 0.03 -0.24 -0.08 -0.01 0.27 0.09 -1.55 0.01 -0.45

    Df/B (X7) 0.08 -1.23 -0.34 1.37 -0.69 0.35 0.35 15.09 0.32 -0.05

    Product of the input-hidden and hidden-output

    connection weights

    Shahin et al. 2002; Das et al. 2012;

    Mishra et al. 2016

    19%

    35%16%

    11%

    7%12%

    c

    φ

    B

    b/B

    β

    Df/B

    Square footing

    Strip footing

    12%8%

    7%

    25%25%

    23%

    c

    φ

    B

    b/B

    S/B

    β

    Interfering strip footing

  • Results and Discussions• Predicting Expression (Goh 1994; Das and Basudhar 2006; Das and Basudhar 2008)

    (Square footing on slope)

    05-01-2021 Short Course, NIT Warangal 66

    1 0.56 0.32 0.24 10.55( ) ( ) ( ) .45( / ) ( )0.38 1.30 / 6( ) 1.1fA c B b B D B

    10 0.12 0.91 0.04 0.13( ) ( ) ( ) ( / )2.01 0.46 0.05 3( ) ( / .) 03fA c B b B D B

    1 1

    1 11 (0. )06

    A A

    A A

    e eB

    e e

    10 10

    10 1010 0 (7 ).9

    A A

    A A

    e eB

    e e

    1 1 2 3 4 5 6 7 8 9 100.61C B B B B B B B B B B 1 1

    1 1

    ( ) ( )C C

    u n C C

    e eq

    e e

    max min min( ) 0.5[( ) 1][( ) ( ) ] ( )u u n u u uq q q q q

    Acharyya R, Dey A, Kumar B (2018) Finite element and ANN-based prediction of bearing capacity of square footing resting on the crest of c-φ soil slope. International Journal of Geotechnical Engineering DOI: 10.1080/19386362.2018.1435022.

    Acharyya R, Dey A (2018) Assessment of bearing capacity for strip footing located near sloping surface considering ANN-model. Neural

    Computing and Applications DOI: 10.1007/s00521-018-3661-4.

    1 1

    ( ) { [ ( )]}h m

    un Sig O N Sig hN iN i

    N is

    qf b w f b w X

    H

  • Typical Design Example using ANN • Design example for square footing resting on crest of a slope

    • The initial step in the assessment of bearing capacity

    Normalize the input and output parameters between 1 to -1

    Equations in previous slide

    The normalized output [(qu)n] magnitude

    -0.307

    The actual magnitude of qu Equation in previous slide

    The ultimate bearing capacity of square footing (qu) for current design problem has been found as 6.1 MPa

    05-01-2021 Short Course, NIT Warangal 67

    Parameters Range

    c (kPa) 0-80

    φ (°) 10-40

    B (m) 0.08-2

    b/B 0-10

    β (°) 10-40

    qu (MPa) 0.25-17.14

    0.5 ( 0.307 1) (17.14 0.25) 0.25 6.1 MPauq

  • Relevant References

    • Acharyya R, Dey A (2017) Finite element investigation of the bearing capacity of square footings resting on sloping ground. INAE Letters 2(3): 97-105.

    • Acharyya R, Dey A, Kumar B (2018) Finite element and ANN-based prediction of bearing capacity of square footing resting on the crest of c-φ soil slope. International Journal of Geotechnical Engineering DOI: 10.1080/19386362.2018.1435022.

    • Acharyya R, Dey A (2018) Assessment of failure mechanism of a strip footing on horizontal ground considering flow rules. Innovative Infrastructure Solution DOI: 10.1007/s41062-018-0150-7.

    • Acharyya R, Dey A (2018) Importance of dilatancy on the evolution of failure mechanism of a strip footing resting on horizontal ground. INAE Letters DOI: 10.1007/s41403-018-0042-3.

    • Acharyya R, Dey A (2018) Assessment of bearing capacity for strip footing located near sloping surface considering ANN-model. Neural Computing and Applications DOI: 10.1007/s00521-018-3661-4.

    • Acharyya R, Dey A (2018) Assessment of bearing capacity of interfering strip footings located near sloping surface considering Ann-technique. Journal of Mountain Science 15(12): 2766–2780.

    • Acharyya R, Dey A (2018) Assessment of bearing capacity and failure mechanism of single and interfering strip footings on sloping ground. International Journal of Geotechnical Engineering. DOI: 10.1080/19386362.2018.1540099

    05-01-2021 Short Course, NIT Warangal 68

  • Acknowledgment

    05-01-2021 Short Course, NIT Warangal 69

    Dr. Rana Acharyya

    Assistant Professor

    Dehradun Institute of Technology

    Uttarakhand

  • Further Interaction

    http://www.iitg.ac.in/arindam.dey/homepage/index.html

    05-01-2021 Short Course, NIT Warangal 70

    https://www.researchgate.net/profile/Arindam_Dey11

    http://www.iitg.ac.in/arindam.dey/homepage/index.htmlhttps://www.researchgate.net/profile/Arindam_Dey11

  • 05-01-2021 Short Course, NIT Warangal 71

    Thank You for Patient Hearing