Comparing bearing capacity factor Nγ of finite element method with analytical methods for sandy soils

Shallow strip footings are essential to carry loads from structures. Load bearing capacity factors can be calculated both by the field tests (plate load test) and numerically. Bearing capacity factors are the main parameters that affect the bearing capacity of any foundations. Nγ, one of these factors, have significant impact. Increase in internal frictional angle (ϕ), causes enhance the Nγ value. However, after ϕ value reaches 30°, dramatic increase is observed. This make the bearing capacity values complicated. In this study, strip foundation on surface resting on sandy soils were designed with a Geostudio 2012 software. Various foundation width (1, 1.25, 1.5, 1.75 and 2 m) and internal friction angle (29°, 31°, 33°, 35°, 37°, 39°, and 41°) was selected. Bearing capacity values were calculated with both numerical (software) and analytical methods. After, Nγ values of analytical methods were compared to results obtained from software. Results indicate that, Biarez 1961 has the average Nγ values while Terzaghi (1943) and Michalowski (1997) have the maximum. Nγ value obtained from numerical analysis (finite element method) increased with an increase in foundation width also. Values from finite element method is average of other analytical methods when B = 1.25 m, while Nγ values of numerical methods are the biggest when B = 2 m.