New Model for Predicting the Bearing Capacity of Large Strip Foundations on Soil under Combined Loading
Publication: International Journal of Geomechanics
Volume 22, Issue 5
Abstract
The bearing capacity of large strip foundations under combined loading is an important issue in geotechnical engineering, which is related to the design and stability analysis of foundations such as gravity dams, retaining walls, and ground anchorages of bridges. Herein, a new model for predicting the bearing capacity of large strip foundations under combined loading was proposed. First, a series of numerical simulation analyses of a large strip foundation resting on the surface of the soil were conducted to investigate the shape of the failure envelope in the V–M–H (vertical load, overturning moment, and horizontal load) loading space, and an improved form of failure equation was proposed. Second, the main factors influencing Vmax (the vertical ultimate bearing capacity) and the shape of the failure envelope were determined. Last, an applicable empirical equation of the failure envelope in the V–M–H loading space was presented. The results show that the deflection angle of the ellipse (θ), which is considered as a certain constant by previous studies, varies with the vertical load (V); the width of the foundation (B), the depth of the foundation (D), the cohesion of the soil (c), and the internal friction angle of the soil (φ) are the main factors influencing Vmax and the shape of the failure envelope; only parameters B, D, c, φ, and γ are needed to determine, in a unique way, the empirical equation of the failure envelope in the V–M–H loading space. The proposed model provides a convenient means of calculating the bearing capacity of large strip foundations on soil under combined loading.
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Acknowledgments
The work reported in this paper is financially supported by the Traffic Science, Technology and Education Project of Yunnan Province (2017) No. 33; the Youth Innovation Promotion Association CAS (No. 2021325); and the National Natural Science Foundation of China (No. 51779250).
Notation
The following symbols are used in this paper:
- a
- length of the semiaxis of the ellipse corresponding to the M-axis;
- B
- width of the foundation;
- b
- length of the semiaxis of the ellipse corresponding to the H-axis;
- bγ, bc, bq
- foundation bottom inclination factors;
- c
- cohesion of soil;
- D
- depth of the foundation;
- dγ, dc, dq
- foundation depth factors;
- e
- load eccentricity;
- gγ, gc, gq
- ground inclination factors;
- H
- horizontal load;
- h
- height of the foundation;
- iγ, ic, iq
- load inclination factors;
- li, mi, ni
- fitting coefficients of failure equations;
- lij, mij, nij
- fitting coefficients;
- M
- overturning moment;
- Nγ, Nc, Nq
- bearing capacity factors that depend mainly on the internal friction angle of soil;
- pu
- ultimate bearing capacity of the foundation per unit area with respect to the vertical component of the load;
- Q
- resultant applied load;
- Qmax
- ultimate resultant applied load;
- q
- overburden pressure on both sides of the foundation;
- sγ, sc, sq
- foundation shape factors;
- th, tm
- factors controlling the values of H and M at a certain V;
- V
- vertical load;
- Vmax
- ultimate bearing capacity of the foundation when only vertical load is applied;
- vmax
- ultimate bearing capacity of the foundation per unit area when only vertical load is applied;
- α
- load inclination;
- β1
- initial slope of the curve in the V–H loading plane;
- β2, β3
- factors controlling the position and value of the maximum point in the V–H loading plane;
- γ
- effective unit weight of soil;
- ξ1
- initial slope of the curve in the V–M loading plane;
- ξ2, ξ3
- factors controlling the position and value of the maximum point in the V–M loading plane;
- η
- factor controlling the deflection angle of the ellipse;
- θ
- deflection angle of the ellipse; and
- φ
- internal friction angle of soil.
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Published In
International Journal of Geomechanics
Volume 22 • Issue 5 • May 2022
Copyright
© 2022 American Society of Civil Engineers.
History
Received: Sep 4, 2021
Accepted: Jan 15, 2022
Published online: Mar 15, 2022
Published in print: May 1, 2022
Discussion open until: Aug 15, 2022
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