Influence of the Presence of an Interbedded Weak Clay Layer on Ultimate Bearing Capacity of Sandy Soil Using AFELA and MARS

In this study, the impact of the presence of a compressible clay layer on the ultimate bearing capacity (UBC) of a strip footing supported by a layered soil stratum is evaluated using Adaptive Finite Element Limit Analysis (AFELA). The normalized depth of the compressible layer (H/B), internal friction angle of the sandy soil (ϕ), and undrained shear strength of the clay layer (S_u) were varied as independent parameters over a range of 0.5 to 7, 30° to 45°, and 12 kPa to 192 kPa, respectively, in the computational analysis. The results stipulate that as the clay layer embeds deeper into the soil strata, the bearing capacity ratio (BCR) and the settlement of the footing increase. The location of the compressible layer has the maximum influence on the settlement of the footing, contrary to ϕ, and S_u,  whose influence is found to be relatively minor in the analysis. A data science technique known as the ‘Multivariate Adaptive Regression Spline’ (MARS) has been adopted to develop an empirical equation that represents the relationship between the ultimate bearing capacity (UBC) of a strip footing on a layered soil stratum and the input parameters. The R² value of the empirical equation is found to be 0.9942, indicating a high degree of accuracy in predicting the UBC. Additionally, a sensitivity analysis using MARS is performed to determine the relative importance of each input parameter in affecting the UBC.