Load–Settlement Response and Bearing Capacity of a Surface Footing Located Over a Conduit Buried Within a Soil Slope
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VIEW THE REPLYPublication: International Journal of Geomechanics
Volume 20, Issue 10
Abstract
Engineers often face challenges when designing foundations that are located over buried structures. This paper presents a laboratory model test investigation of the load–settlement response and the bearing capacity of a surface footing located over a conduit, buried within a soil slope. An attempt is made to explain the effect of the crest distance of the footing, burial depth, and diameter of the conduit on the load-carrying ability of the footing based on its failure mechanism. The test results show that the burial depth of the conduit is the most important parameter that affects the settlement and bearing capacity of the surface footing. To avoid any detrimental effect on the load-carrying ability of the footing, the depth of the crown of the buried conduit needs to be at least three times the width of the footing. The graphical illustrations and the developed correlations, presented in this paper, can be used by practicing engineers to ensure the stability of the footing.
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Acknowledgments
This research was funded by The Higher Education Commission, Government of the Islamic Republic of Pakistan (Project ID: G1003978). The authors also acknowledge the assistance provided by Muhammad Aamir in conducting the regression and sensitivity analysis.
Notation
The following symbols are used in this paper:
- Bc
- outer diameter of the conduit (mm);
- Bc1
- outer diameter (80 mm) of conduit (mm);
- Bc2
- outer diameter (160 mm) conduit (mm);
- BCR
- bearing capacity ratio (dimensionless);
- Cc
- coefficient of curvature (dimensionless);
- Cu
- coefficient of uniformity (dimensionless);
- c
- cohesion (kPa);
- Dr
- relative density (%);
- D10
- effective grain size (mm);
- D30
- grain size corresponding to 30% finer by weight (mm);
- D60
- grain size corresponding to 60% finer by weight (mm);
- E
- Young's modulus of the conduit material (MPa);
- e
- Euler's number (dimensionless);
- e/B
- crest distance of the edge of the footing from the slope edge (dimensionless);
- emax
- maximum void ratio (dimensionless);
- emin
- minimum void ratio (dimensionless);
- Gs
- specific gravity of soil (dimensionless);
- i
- angle of the soil slope (degrees);
- q
- applied surface pressure (kPa);
- qu
- ultimate bearing capacity of the surface footing without the buried conduit (kPa);
- qu,pipe
- ultimate bearing capacity of the surface footing with the buried conduit (kPa);
- (R2)
- coefficient of determination (dimensionless);
- RCR
- relative contribution ratio (dimensionless);
- ril
- radius of the logarithmic spiral OP at pole angle θl (mm);
- ris
- radius of the logarithmic spiral OR at pole angle θs (mm);
- rol
- initial radius of the logarithmic spiral OP (mm);
- ros
- initial radius of the logarithmic spiral OR (mm);
- s/B
- settlement of the surface footing (%);
- Xl
- base dimension of the elastic wedge MNO on the level ground side (mm);
- Xs
- base dimension of the elastic wedge MNO on the slope side (mm);
- z/B
- depth of the crown of the buried conduit from the soil surface (dimensionless);
- γdmax
- maximum dry unit weight (kN/m3);
- γdmin
- minimum dry unit weight (kN/m3);
- θl
- pole angle of the logarithmic spiral on the level ground side (degrees);
- θs
- pole angle of the logarithmic spiral on the slope side (degrees);
- ν
- Poisson's ratio of the conduit material (dimensionless);
- ϕ
- friction angle (degrees);
- ωl
- internal angle of MNO on the level ground side (degrees); and
- ωs
- internal angle of MNO on the slope side (degrees).
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© 2020 American Society of Civil Engineers.
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Received: Dec 19, 2019
Accepted: May 27, 2020
Published online: Jul 28, 2020
Published in print: Oct 1, 2020
Discussion open until: Dec 28, 2020
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