In this paper a numerical method is presented for assessing the ultimate bearing capacity of footing on layered subsoil subjected to inclined load. In the proposed method, the nonlinear behavior of interaction of footing and subsoil is taken account by using the Coulomb friction contact model. And the Mohr-coulomb elasto-plastic constitutive model with associated flow rule is used to represent nonlinear and inelastic characteristics of soils. Moreover, a series of model loading tests on sand overlain by rubble are carried out to verify the reliability of the numerical methods. Based on the numerical and experimental investigation, an empirical correlation coefficient of inclination of load is developed and the improved formulas for evaluating ultimate bearing capacity of layered subsoil under inclined loads are presented.
The stability of foundations under inclined loads is a fundamental problem in geotechnical engineering. The effect of combined load is a particularly important factor in marine and offshore engineering where foundations are usually subjected to vertical and horizontal loads as well as moments (e.g. jacking up rigs and gravity based platform). Typically, the vertical force is resulted from the weight of the superstructure while the horizontal load and moment are induced by wind and wave forces or earthquake inertia force.
For homogeneous soils, the inclination of the load can be taken into consideration through a certain empirical correction on vertical bearing capacity of foundation. Up to now, most of the bearing capacity theories for a vertical load are derived using the superposition principle introduced by Terzaghi (1943), which assumes that contributions from the cohesion, the surcharge and the unit weight can be summed independently. At present, the bearing capacity theories of Meyerhof (1951&1953), Hanse (1970) and Vesić (1975) are wildly adopted in various national design standards.
