Bearing Capacity Factor of Circular Footings on Two-layered Clay Soils
Geotechnical engineers often deal with layered foundation soils. In this case, the soil bearing capacity assessment using the conventional bearing capacity theory based on the upper layer properties introduces significant inaccuracies if the top layer thickness is comparable to the rigid footing width placed on the soil surface. Under undrained conditions the cohesion increases almost linearly with depth. A few theoretical studies have been proposed in the literature in order to incorporate the cohesion variation with depth in the computation of the ultimate bearing capacity of the strip and circular footings. Rigorous solutions to the problem of circular footings resting on layered clays with linear increase of cohesion do not appear to exist. In this paper, numerical computations using FLAC code are carried out to assess the vertical bearing capacity beneath rough rigid circular footing resting on two-layered clays of both homogeneous and linearly increasing shear strength profiles. The bearing capacity calculation results which depend on the top layer thickness, the two-layered clays strength ratio and the cohesion increase rates with depth are presented in both tables and graphs, and compared with previously published results available in the literature. The critical depth for circular footing is found significantly less than for strip footing.
Full Text: PDF
Button, S. J. “The bearing capacity of footings on a two-layer cohesive subsoil.” In: Proceeding of the 3rd International Conference on Soil Mechanics and Foundation Engineering, Zurich (1953): 332–335.
Meyerhof, G. G., and A. M. Hanna. “Ultimate Bearing Capacity of Foundations on Layered Soils under Inclined Load.” Canadian Geotechnical Journal 15, no. 4 (November 1, 1978): 565–572. doi:10.1139/t78-060.
Merifield, R. S., S. W. Sloan, and H. S. Yu. “Rigorous Plasticity Solutions for the Bearing Capacity of Two-Layered Clays.” Géotechnique 49, no. 4 (August 1999): 471–490. doi:10.1680/geot.19184.108.40.2061.
Gupta, Arushi, Rakesh Kumar Dutta, Rajnish Shrivastava, and Vishwas Nandkishor Khatri. “Ultimate Bearing Capacity of Square/Rectangular Footing on Layered Soil.” Indian Geotechnical Journal 47, no. 3 (March 29, 2017): 303–313. doi:10.1007/s40098-017-0233-y.
Chi, Chao-Ming, and Zheng-Shan Lin. “The Bearing Capacity Evaluations of a Spread Footing on Single Thick Stratum or Two-Layered Cohesive Soils.” Journal of Marine Science and Engineering 8, no. 11 (October 29, 2020): 853. doi:10.3390/jmse8110853.
Rao, Pingping, Ying Liu, and Jifei Cui. “Bearing Capacity of Strip Footings on Two-Layered Clay under Combined Loading.” Computers and Geotechnics 69 (September 2015): 210–218. doi:10.1016/j.compgeo.2015.05.018.
Salimi Eshkevari, Seyednima, Andrew J. Abbo, and George Kouretzis. “Bearing Capacity of Strip Footings on Sand over Clay.” Canadian Geotechnical Journal 56, no. 5 (May 2019): 699–709. doi:10.1139/cgj-2017-0489.
Das P. P. and V. N. Khatri. ‘‘Bearing Capacity Estimation of Shallow Foundations on Layered Sand Strata Using Finite Elements Analysis.’’ Conf. Construction in Geotechnical Engineering, Editors: Latha Gali, Madhavi, Pallepati, Raghuveer Rao (2020): 1-13.
Karkush, Mahdi O, and Ala N. Aljorany. “Numerical Evaluation of Foundation of Digester Tank of Sewage Treatment Plant.” Civil Engineering Journal 5, no. 5 (May 22, 2019): 996–1006. doi:10.28991/cej-2019-03091306.
Bishop, A. W. “The Strength of Soils as Engineering Materials.” Géotechnique 16, no. 2 (June 1966): 91–130. doi:10.1680/geot.19220.127.116.11.
Davis, E. H., and J. R. Booker. “The Effect of Increasing Strength with Depth on the Bearing Capacity of Clays.” Géotechnique 23, no. 4 (December 1973): 551–563. doi:10.1680/geot.1918.104.22.1681.
Reddy, A. Siva, Anil K. Singh, and Suresh S. Karnik. “Bearing Capacity of Clays Whose Cohesion Increases Linearly with Depth.” Journal of Geotechnical Engineering 117, no. 2 (February 1991): 348–353. doi:10.1061/(asce)0733-9410(1991)117:2(348).
Khatri, Vishwas N., and Jyant Kumar. “Bearing Capacity Factor Nc Under Φ=0 Condition for Piles in Clays.” International Journal for Numerical and Analytical Methods in Geomechanics 33, no. 9 (November 25, 2008): 1203–1225. doi:10.1002/nag.763.
Itasca. “Fast Lagrangian Analysis of Continua.” Minneapolis: ITASCA Consulting Group, Inc. (2018).
Benmebarek, S., S. Benmoussa, L. Belounar, and N. Benmebarek. “Bearing Capacity of Shallow Foundation on Two Clay Layers by Numerical Approach.” Geotechnical and Geological Engineering 30, no. 4 (April 18, 2012): 907–923. doi:10.1007/s10706-012-9513-6.
Merifield, R. S., and V. Q. Nguyen. “Two- and Three-Dimensional Bearing-Capacity Solutions for Footings on Two-Layered Clays.” Geomechanics and Geoengineering 1, no. 2 (August 31, 2006): 151–162. doi:10.1080/17486020600632637.
Houlsby, G. T., and C. M. Martin. “Undrained Bearing Capacity Factors for Conical Footings on Clay.” Géotechnique 53, no. 5 (June 2003): 513–520. doi:10.1680/geot.2003.53.5.513.
Yun, Gijae, and M Fraser Bransby. “The Horizontal-Moment Capacity of Embedded Foundations in Undrained Soil.” Canadian Geotechnical Journal 44, no. 4 (April 1, 2007): 409–424. doi:10.1139/t06-126.
Shiau, J. S., R. S. Merifield, A. V. Lyamin, and S. W. Sloan. “Undrained Stability of Footings on Slopes.” International Journal of Geomechanics 11, no. 5 (October 2011): 381–390. doi:10.1061/(asce)gm.1943-5622.0000092.
Salgado, R., A. V. Lyamin, S. W. Sloan, and H. S. Yu. “Two- and Three-Dimensional Bearing Capacity of Foundations in Clay.” Géotechnique 54, no. 5 (June 2004): 297–306. doi:10.1680/geot.2004.54.5.297.
Kusakabe, Osamu, Hiroyuki Suzuki, and Akio Nakase. “An Upper Bound Calculation on Bearing Capacity of a Circular Footing on a Non-Homogeneous Clay.” Soils and Foundations 26, no. 3 (September 1986): 143–148. doi:10.3208/sandf1972.26.3_143.
- There are currently no refbacks.
Copyright (c) 2021 Samir BENMOUSSA
This work is licensed under a Creative Commons Attribution 4.0 International License.