Dr. Arindam Dey Presentations/2021/Dey...05-01-2021 Short Course, NIT Warangal 17 •Modelling...
Transcript of Dr. Arindam Dey Presentations/2021/Dey...05-01-2021 Short Course, NIT Warangal 17 •Modelling...
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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
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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
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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
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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
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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
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Bearing Capacity of Square Footing Resting on Crest of c-φ Slope
05-01-2021 Short Course, NIT Warangal 6
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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
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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
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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
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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
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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
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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
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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
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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
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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.
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Bearing Capacity of Strip Footing Located on Crest of c-φ Slope
05-01-2021 Short Course, NIT Warangal 16
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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
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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
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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.
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Interaction Mechanism of Strip Footings Resting on a Horizontal Ground
05-01-2021 Short Course, NIT Warangal 20
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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
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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
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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
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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
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Results and Interpretations
• Total displacement and vertical stress distribution
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Results and Interpretations
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Results and Interpretations
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Results and Interpretations
• Incremental deviatoric strain
05-01-2021 Short Course, NIT Warangal 28
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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
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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
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Results and Interpretations
05-01-2021 Short Course, NIT Warangal 31
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Response of Interfering Footings Located on Crest and Face of Slope
05-01-2021 Short Course, NIT Warangal 32
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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
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Interfering Foundations on Slopes
05-01-2021 Short Course, NIT Warangal 34
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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
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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
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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
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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
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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°
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Results and Discussion
• Setback distance (b)
Bearing capacity
Increased
Increasing
Setback distance
05-01-2021 Short Course, NIT Warangal 40
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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)
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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
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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
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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
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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
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Mechanism of a Footing on a Slope Face
• Plaxis 2D output
05-01-2021 Short Course, NIT Warangal 46
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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
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Interaction Mechanism of Footings on Slope Face
05-01-2021 Short Course, NIT Warangal 48
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Interaction Mechanisms of Footings on Slope Face
05-01-2021 Short Course, NIT Warangal 49
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Interaction Mechanisms of Footings on Slope Face
05-01-2021 Short Course, NIT Warangal 50
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Interaction Mechanisms of Footings on Slope Face
05-01-2021 Short Course, NIT Warangal 51
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Interaction Mechanism of Footings on a Slope Face
05-01-2021 Short Course, NIT Warangal 52
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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
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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
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Interaction Mechanism of Footings on a Slope Face
05-01-2021 Short Course, NIT Warangal 55
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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
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Interaction Mechanisms of Footings on Slope Face
• Displacement iso-surfaces
05-01-2021 Short Course, NIT Warangal 57
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Interaction Mechanisms of Footings on Slope Face
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Application of Artificial Neural Networks in Predicting Bearing Capacity of
Foundations on Slopes
05-01-2021 Short Course, NIT Warangal 59
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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
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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
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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
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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
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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
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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
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Results and Discussions
• Sensitivity analysis
Garson’s algorithm (1991)
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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
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Results and Discussions• Predicting Expression (Goh 1994; Das and Basudhar 2006; Das and Basudhar 2008)
(Square footing on slope)
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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
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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
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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
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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
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Acknowledgment
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Dr. Rana Acharyya
Assistant Professor
Dehradun Institute of Technology
Uttarakhand
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Further Interaction
http://www.iitg.ac.in/arindam.dey/homepage/index.html
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https://www.researchgate.net/profile/Arindam_Dey11
http://www.iitg.ac.in/arindam.dey/homepage/index.htmlhttps://www.researchgate.net/profile/Arindam_Dey11
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Thank You for Patient Hearing