Computation of vertical bearing capacity factor N c of strip footing by FEM

Abstract

Thispaper presents the computation of vertical bearing capacity factor N c of the smooth and rough strip footings using the finite element algorithm based elasto-viscoplasticstrain method. The soil behaviour is idealized as elastic perfectly plastic satisfying the Mohr Coulomb yield criterion with only non-associated flow rules because it tends to treat the actual behaviour of soil in which value of its frictional angle is always different from that of dilative angle. The bearing resistance is computed using the superposition assumption in Terzaghi classical equation in the way that the surcharge pressure and the unit weight of soil are neglected. Consequently, N c is determined. The comparison of the present solutions with the previous published works including experimental and numerical studies have been presented and discussed. The results reveal in close agreement with the existing published data. In the nutshell, by applying the non-associated soil flow rule representing the real behaviour of soil, the conservation of the superposition assumption is confirmed. Therefore, it could conclude that the results obtaining from these techniques may be confidently applied to a wide range of soil bearing resistance problems. The magnitudes of the factors for a rough footing base provide the same values as the smooth footing for the entire range of soil friction angles (phi).