NONLINEAR SOIL-STRUCTURE INTERACTION

Abstract

The shallow foundation may be subjected to eccentric-inclined load. For designing and proportioning such type of foundations, the main criteria to be considered are bearing capacity, settlement, tilt, and horizontal. displacement. Since soil behavior is usually nonlinear, the nonlinear constitutive laws are commonly employed. For this, the material parameters depend upon the state of stress. To encounter this, an incremental approach is often used, which requires a separate solution process for each increment of load. In the analysis of footing subjected to centrally inclined load in clay soil, several theories and model and field test results have been conducted. The bearing capacity, load settlement characteristics, non-dimensional factors for bearing capacity have also been produced by earlier investigators. In the present investigation, analysis and study the behavior of strip footing, resting on the surface of uniform clay in an undrained state subjected to centrally-inclined load with the finite element analysis has been carried out by using incremental theory of plasticity. The yield criteria which is employed is Von Mises Criteria. Pressure versus vertical settlement curves for strip footing (B = 2.0 m), resting on various type of clays have been obtained for values of load inclination i = 00, 5°, 15°, 20°, 25°, and 30°. All the pressure-settlement characteristics display an initial linear elastic behavior followed by in-elastic behavior till failure during which large settlements occur for every successive pressure increment. It has been found that the values of ultimate bearing capacity decrease with the decrease of consistency of clay from hard to very soft. As the inclination of load increases, the values of ultimate bearing capacity and failure load decrease. This reduction of ultimate bearing capacity is significant in the high consistency range of clay Similar to the pressure-vertical settlement characteristics, the change of average horizontal displacement is less at low-pressure but as the pressure increases and approaches the failure, the horizontal displacements increase rapidly. It can be seen also that as the inclination of load increases, the horizontal displacements at the failure also increase. The bearing capacity factor, N, value, decreases with increasing of load inclination. The N. values from finite element analysis have been compared with experimental results of Saran and Agrawal (1986), and this values are somewhat on the higher side for i > 100, and on the lower side when I < 10°..