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Heave analysis of shallow foundations founded in swelling clayey soil at N’Gaous city in Algeria

Abdelaziz Khennouf
Abdelaziz Khennouf
 y 
Mohamed Baheddi
Mohamed Baheddi
   | 07 jul 2020
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Article Category: Original Study
Publicado en línea: 07 jul 2020
Páginas: 210 - 221
Recibido: 09 sept 2019
Aceptado: 14 may 2020
DOI: https://doi.org/10.2478/sgem-2019-0051
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© 2019 Abdelaziz Khennouf et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Figure 1

Example of damage of swelling soil in N’Gaous city.
Example of damage of swelling soil in N’Gaous city.

Figure 2

Free swelling strain versus elapsed time.
Free swelling strain versus elapsed time.

Figure 3

Swelling strain versus vertical pressure
Swelling strain versus vertical pressure

Figure 4

Scheme of stresses distributions in the soil below a shallow foundation.
Scheme of stresses distributions in the soil below a shallow foundation.

Figure 5

(a) Initial states of layers, (b) Final states of layers after total heave.
(a) Initial states of layers, (b) Final states of layers after total heave.

Figure 6

Geometry of the model.
Geometry of the model.

Figure 7

Three-dimensional mesh of the numerical model.
Three-dimensional mesh of the numerical model.

Figure 8

Comparison of heave results Ssw for square footing obtained from numerical and analytical prediction.
Comparison of heave results Ssw for square footing obtained from numerical and analytical prediction.

Figure 9

Contours and vectors heaving of square footing for σ0=100 kPa.
Contours and vectors heaving of square footing for σ0=100 kPa.

Figure 10

Comparison between numerical and analytical results of heave evolutions throughout the soil depth. Case of square footing of width B=1m and σ0=0 to 500 kPa.
Comparison between numerical and analytical results of heave evolutions throughout the soil depth. Case of square footing of width B=1m and σ0=0 to 500 kPa.

Figure 11

Variation of vertical swelling strain ɛsw after swelling for square footing with H/B ratio and σ0=0 to 500 kPa.
Variation of vertical swelling strain ɛsw after swelling for square footing with H/B ratio and σ0=0 to 500 kPa.

Figure 12

Comparison between numerical and analytical results of square footing heave Ssw with D/B ratio for σ0= 100 kPa.
Comparison between numerical and analytical results of square footing heave Ssw with D/B ratio for σ0= 100 kPa.

Figure 13

Variation of square footing heave Ssw of width B=1m with soil stiffness Esoil for σ0=0 to 500 kPa.
Variation of square footing heave Ssw of width B=1m with soil stiffness Esoil for σ0=0 to 500 kPa.

Figure 14

Contours heaving of square footing of width B=1m and σ0=300 kPa with Esoil variation: (a) Esoil=5 MPa, (b) Esoil=10 MPa, (c) Esoil=15 MPa, (d) Esoil=20 MPa.
Contours heaving of square footing of width B=1m and σ0=300 kPa with Esoil variation: (a) Esoil=5 MPa, (b) Esoil=10 MPa, (c) Esoil=15 MPa, (d) Esoil=20 MPa.

Soils parameters used in the numerical study.

ParametersValue
Unit weight, γ (kN/m3)20
Elastic Modulus, E (MPa)10
Poisson's ratio, ν0.35
Cohesion, C (kPa)100
Friction angle, φ (°)25
Dilatancy angle, ψ (°)0

Geotechnical characteristics of soil samples.

Soil propertiesValue
Sampling depth2.3–2.5 m
Liquid limit, LL (%)72.28
Plastic limit, PL (%)29.20
Plasticity Index, PI (%)43.08
Natural dry unit weight, γd (kN/m3)17.5
Natural wet unit weight, γh (kN/m3)20.0
Specific Gravity, Gs2.74
Natural water content, Wn (%)14.1
Natural degree of saturation, Sr (%)80.82
Initial void ratio, e00.478
Compression Index, Cc0.15
Swelling Index, Cs0.054
Preconsolidation pressure, Pc (kPa)190
Cohesion, after saturation C (kPa)100
Friction angle, after saturation φ (°)25
Grain size distribution71
Clay (%)24.5
Silt (%)4.5
Sand (%)98.90
C80 μm (%)71
C2 μm (%)

Heave prediction analytical and numerical of rectangular and circular footing with D/B ratio for σ0= 100 kPa.

D/BSsw (mm) Rectangular footingSsw (mm) Circular footing
Present studyDepartment of armyNelson And MillerPresent studyDepartment of armyNelson And Miller
0125.2125.7121.3125.1135.4130.6
0.5116.1108.6104.8114.3116.8112.7
1.0100.493.690.299.3100.797.1
1.588.580.477.587.486.683.5

Heave prediction for each type of isolated shallow foundations from numerical and analytical analysis.

Foundation TypeFoundation Heave Ssw (mm)Applied Loads σ0(kPa)
0100200300400500
RectangleB = 1 m, L = 2 mCalculated
  Nelson and Miller167.5121.398.982.4268.9957.48
  Department of army173.7125.79102.5685.4771.5459.61
  Numerical158125.2108.996.183.771.2
CircleD = 1.8 mCalculated
  Nelson and Miller167.5130.6110.996.284.173.6
  Department of army173.7135.48115.0899.887.2276.39
  Numerical157.2125.1108.694.580.566.3
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