Prediction of ultimate bearing capacity of circular foundation on sand layer of limited thickness using artificial neural network Barada Prasad Sethy, Chittaranjan Patra, Braja M. Das, Khaled Sobhan International Journal of Geotechnical Engineering, 2021 The present study focuses on the development of an Artificial Neural Network (ANN) model equation to estimate the average ultimate load of shallow circular foundation on a sand layer of limited thickness underlain by a rigid rough base subjected to an eccentrically inclined load. The model is developed using the 260 number of data points obtained from extensive laboratory model tests. The input parameters considered are depth of embedment (Df /B) of the foundation, thickness of the sand layer to diameter of foundation ratio (H/B), eccentricity ratio (e/B), and load inclination to friction angle ratio (α/ϕ) to estimate the reduction factor RF as output. The RF is the ratio of the ultimate eccentrically inclined load on a sand layer of limited thickness to the ultimate eccentrically inclined load on a sand layer, which is extending to a great depth. Importance of input parameters, which reflect the output, is studied using Pearson’s correlation and Spearman’s rank correlation. The sensitivity analyses are carried out using Variable Perturbation methods and Weight methods. It has been professing that H/B ratio is the most important input parameter.
Behavior of circular foundation on sand layer of limited thickness subjected to eccentrically inclined load B.P. Sethy, C.R. Patra, B.M. Das, K. Sobhan Soils and Foundations, 2020 A numerical study on the behavior of an eccentrically inclined loaded circular foundation on a sand layer of limited thickness underlain by a rigid rough base is presented. Specific attention is given to simulating the effect of the rigid rough base, load eccentricity (e), load inclination (α) and failure mechanisms in the finite element (FE) analysis assuming axisymmetric conditions. Analyses are performed using two models, namely, (i) an elastic-perfectly plastic Mohr-Coulomb model (MCM) and (ii) an elasto-plastic hyperbolic model called the hardening soil model (HSM) using Plaxis 3D. The results of the numerical modeling indicate that the bearing capacity is modified when the rigid rough base is located at a shallow depth below the base of the foundation and the extent of the failure surface. The results of the FE analysis appear to be in good agreement with those obtained from the tests by Sethy et al. (2019) for all H/B ratios, except for H/B = 0.3. However, the results obtained by the hardening soil model are all close to the results obtained from the laboratory model tests by Sethy et al. (2019). Based on the results of the finite element (FE) analysis and the results of the laboratory model tests by Sethy et al. (2019), the modified ultimate inclined load per unit area is seen to be dependent on the H/B ratio and becomes constant beyond H/B′ ratios (where B′=B-2e) that equal about three.
Bearing Capacity of Circular Foundation on Sand of Limited Thickness under Inclined Loading Khaled Sobhan, Chittaranjan Patra, B. Sethy, Braja M. Das Geotechnical Special Publication, 2020 Laboratory model test results for the ultimate bearing capacity of a circular surface foundation of diameter B supported by a dense sand layer of limited thickness (H) and subjected to inclined loading have been presented. For these tests, the H/B ratio for the sand layer was varied as 0.3, 0.5, 1.0, 2.0, 3.0, and 5.5 (which is considered large depth for sand). The load inclination (α) to the model foundation with respect to the vertical was kept at 0°, 5°, 10°, and 20°. For a given load inclination, the average inclined ultimate load per unit area, qu(H/B, α/ϕ), decreases with the increase in H/B. The ultimate average inclined load per unit area becomes constant [i.e.qu(α/ϕ)] beyond a critical value of (H/B) ≈ (H/B)cr. For the tests (H/B)cr was about 3. Based on the model test results, an empirical nondimensional reduction factor, R, has been developed to estimate the average inclined ultimate load per unit area at a given H/B(≤ 3) from that obtained for the case at larger H/B[i.e.R = qu(H/B, α/ϕ)/qu(α/ϕ) = f (H/B, α/ϕ)].
Ultimate bearing capacity of rectangular foundation on sand under eccentric loading Geotechnical Engineering for Infrastructure and Development Proceedings of the Xvi European Conference on Soil Mechanics and Geotechnical Engineering Ecsmge 2015, 2015
