Analysis of Interfering Circular Footings on Reinforced Soil by Physical and Numerical Approaches Considering Strain-Dependent Stiffness
Publication: International Journal of Geomechanics
Volume 17, Issue 11
Abstract
This paper numerically examines the bearing capacity, settlement, and failure kinematics of two closely spaced circular footings on reinforced soil. A number of large-scale tests are performed to identify the influence of the tilt of interfering footings on their ultimate bearing capacity and settlement, and these experimental results are used to verify the numerical model. Because the mobilization of shear strength in soil and tensile resistance in the geogrid depend to a large extent on the strain level (especially in small strains), a nonlinear elastic-plastic constitutive model in conjunction with a nonassociated flow rule is proposed. In addition, the model accounts for the dependency of the friction and dilation angles on the strain level in the plastic domain. The constitutive parameters are calibrated for the triaxial loading test, whereas the numerical model for the closely spaced footings is verified with reference to the large-scale test results. Thereafter, the ultimate bearing capacity and settlement of interfering circular footings on reinforced soil are studied for different configurations, and the critical size and position of reinforcements that maximize the bearing capacity are characterized. Results show that the ultimate bearing capacity increases up to a maximum of 40 and 90% by the use of one and two layers of geogrid, respectively. Beyond the bearing capacity, the settlement of adjacent circular footings increases up to 45% (compared with a single footing with the same safety factor). Finally, the influence of reinforcing soil on failure kinematics and soil deformation pattern is investigated.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The first writer is sponsored through a scholarship from the Alexander von Humboldt Foundation, Bonn, Germany. This support is gratefully acknowledged.
References
Adams, M., and Collin, J. (1997). “Large model spread footing load tests on geosynthetic reinforced soil foundations.” J. Geotech. Geoenviron. Eng., 66–72.
Allen, T. M., Bathurst, R. J., Holtz, R. D., Walters, D. L., and Lee, W. F. (2003). “A new working stress method for prediction of reinforcement loads in geosynthetic walls.” Can. Geotech. J., 40(5), 976–994.
Borja, R., Tamagnini, C., and Amorosi, A. (1997). “Coupling plasticity and energy-conserving elasticity models for clays.” J. Geotech. Geoenviron. Eng., 948–957.
Boushehrian, J. H., and Hataf, N. (2003). “Experimental and numerical investigation of the bearing capacity of model circular and ring footings on reinforced sand.” Geotext. Geomembr., 23(2), 144–173.
Das, B. M., and Larbi-Cherif, S. (1983). “Bearing capacity of two closely spaced shallow foundations on sand.” Soils Found., 23(1), 1–7.
De Beer, E. E. (1970). “Experimental determination of the shape factors and the bearing capacity factors of sand.” Géotechnique, 20(4), 387–411.
Detert, O., Lavasan, A. A., and Schimmel, L. (2016) “Relevant properties for reinforcing products based on latest research and field measurements.” Proc., 3rd Pan-American Conf. on Geosynthetics, Minerva-Technology, Resources and Information, Jupiter, FL, 1268–1278.
Duncan, J., and Chang, C. (1970). “Nonlinear analysis of stress and strain in soils.” J. Soil Mech. and Found. Div., 96(SM5), 1629–1653.
Einav, I., and Puzrin, A. (2004). “Pressure dependent elasticity and energy conservation in elastoplastic models for soils.” J. Geotech. Geoenviron. Eng., 81–92.
FLAC3D [Computer software]. Itasca Consulting Group, Minneapolis.
Frydman, S., and Burd, H. (1997). “ Numerical studies of bearing capacity factor Nγ.” J. Geotech. Geoenviron. Eng., 20–29.
Ghazavi, M., and Lavasan A. A. (2007). “Influence of interference on bearing capacity of strip footing on reinforced sand.” Proc., 5th Int. Symp. on Earth Reinforcement, Vol. 1, Taylor & Francis, London, 431–436.
Ghazavi, M., and Lavasan, A. A. (2008). “Interference effect of shallow foundations constructed on sand reinforced with geosynthetics.” Geotext. Geomembr., 26(5), 404–415.
Houlsby, G. T. (1985). “The use of a variable shear modulus in elastic-plastic models for clays.” Comput. Geotech., 1(1), 3–13.
Houlsby, G. T., Amorosi, A., and Rojas, E. (2005). “Elastic moduli of soil dependent on pressure: A hyperelastic formulation.” Géotechnique, 55(5), 383–392.
Itasca Consulting Group. (2001). FLAC3D 2.1 user’s manual, Itasca Consulting Group, Minneapolis.
Iwan, W. D. (1967). “On a class of models for the yielding behavior of continuous and composite systems.” J. Appl. Mech., 34(3), 612–617.
Jardine, R. J. (1992). “Some observations on the kinematic nature of soil stiffness.” Soils Found., 32(2), 111–124.
Jeremic, B., and Sture, S. (1997). “Implicit integrations in elasto-plastic geotechnics.” Mech. Cohes.-Frict. Mater., 2(2), 165–183.
Jewell, R. A. (1986). Soil reinforcement with geotextiles, CRIA, London.
Kumar, J., and Bhattacharya, P. (2013). “Bearing capacity of two interfering strip footings from lower bound finite elements limit analysis.” Int. J. Numer. Anal. Methods Geomech., 37(5), 441–452.
Kumar, J., and Ghosh, P. (2007). “Ultimate bearing capacity of two interfering rough strip footings.” Int. J. Geomech., 53–62.
Kumar, J., and Kouzer, K. (2007). “Effect of footing roughness on bearing capacity factor Nγ.” J. Geotech. Geoenviron. Eng., 502–511.
Kumar, A., and Saran, S. (2003). “Closely spaced footings on geogrid-reinforced sand.” J. Geotech. Geoenviron. Eng., 660–664.
Lavasan, A. A., and Ghazavi, M. (2012). “Behavior of closely spaced square and circular footings on reinforced sand.” Soils Found., 52(1), 160–167.
Lee, J., and Salgado, R. (2005). “Estimation of bearing capacity of circular footings on sands based on cone penetration test.” J. Geotech. Geoenviron. Eng., 442–452.
Lopes, P. C., Lopes, M. L., and Lopes, M. C. (2001). “Shear behaviour of geosynthetics in the inclined plane test—Influence of soil particle size and geosynthetic structure. geosynthetics.” Geosynth. Int., 8(4), 327–342.
Mabrouki, A., Benmeddour, D., Frank, R., and Mellas, M. (2010). “Numerical study of the bearing capacity for two interfering strip footings on sands.” Comput. Geotech., 37(4), 431–439.
Mánica, M., Gens, A., Vaunat, J., and Ruiz, D. F. (2016). “A time-dependent anisotropic model for argillaceous rocks. Application to an underground excavation in COX claystone.” Comput. Geotech., 85(May), 341–350.
Mróz, Z., Norris, V. A., and Zienkiewicz, O. C. (1979). “Application of anisotropic elasto-plastic deformation of soils.” Géotechnique, 29(1), 1–34.
Potts, D. M., and Gens, A. (1985). “A critical assessment of methods of correcting for drift from the yield surface in elasto-plastic finite element analysis.” Int. J. Numer. Anal. Methods Geomech., 9(2), 149–159.
Puzrin, A. (2012). Constitutive modelling in geomechanics, Springer, Berlin.
Puzrin, A. M., and Burland, J. B. (1998). “Non-linear model of small-strain behaviour of soils.” Géotechnique, 48(2), 217–233.
Rowe, P. W. (1962). “The stress-dilatancy relation for static equilibrium of an assembly of particles in contact.” Proc. R. Soc. London, Ser. A, 269(1339), 500–527.
Rowe, P. W. (1971). “Theoretical meaning and observed values of deformation parameters for soil.” Proc., Memorial Symp. on Stress-Strain Behaviour of Soils, Foulis and Co., U.K., 143–149.
Ruiken, A. (2013). “The stress-strain behaviour of the composite material geogrid reinforced soil.” Ph.D. thesis, RWTH Aachen Univ., Aachen, Germany (in German).
Schanz, T., and Vermeer, P. A. (1996). “Angles of friction and dilatancy of sand.” Géotechnique, 46(1), 145–151.
Stuart, J. G. (1962). “Interference between foundations with special reference to surface footings in sand.” Géotechnique, 12(1), 15–23.
Sun, W., Chen, Q., and Ostien, J. T. (2014). “Modeling the hydro-mechanical responses of strip and circular punch loadings on water-saturated collapsible geomaterials.” Acta Geotech., 9(5), 903–934.
Taiebat, M., and Kaynia, A. M. (2010). “A practical model for advanced nonlinear analysis of earthquake effects in clay slopes.” Proc., 5th Int. Conf. Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, Missouri Univ. of Science and Technology, Rolla, MO.
Vakili, K., Lavasan, A. A., Schanz, T., and Datcheva, M. (2014). “The influence of the soil constitutive model on the numerical assessment of mechanized tunneling.” Numerical methods in geotechnical engineering, CRC Press, Boca Raton, FL, 889–894.
Yang, K., Zornberg, J., and Bathurst, R. (2010). “Mobilization of reinforcement tension within geosynthetic reinforced soil structures.” Proc., 2010 Earth Retention Conf., 3, ASCE, Reston, VA, 494–501.
Yetimoglu, T., Wu, J., and Saglamer, A. (1994). “Bearing capacity of rectangular footings on geogrid reinforced sand.” J. Geotech. Engrg., 2083–2099.
Zytynski, M., Randolph, M. F., Nova, R., and Wroth, C. P. (1978). “On modelling the unloading-reloading behaviour of soils.” Int. J. Numer. Anal. Methods Geomech., 2(1), 87–93.
Information & Authors
Information
Published In
International Journal of Geomechanics
Volume 17 • Issue 11 • November 2017
Copyright
© 2017 American Society of Civil Engineers.
History
Received: Sep 12, 2016
Accepted: May 9, 2017
Published online: Aug 28, 2017
Published in print: Nov 1, 2017
Discussion open until: Jan 28, 2018
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.