Load-Settlement Prediction of Footings on Steep Slopes

The use of spread footings on slopes is a common practice in the design of bridge foundations. Footings are generally constructed in the slope or at its crest to minimize the bridge length, thereby minimizing costs. However, the analytical methods that are frequently used to predict the ultimate bearing capacity of shallow spread footings on slopes yield a wide range of solutions. As a result, allowable foundation bearing capacities are selected conservatively leading to the design of spread footings which are larger and more costly than necessary. There has been an increased effort in recent years to evaluate and improve techniques for predicting the deformation and ultimate bearing capacity of shallow spread footings located on or near slopes. Research efforts currently underway include detailed centrifuge tests on scaled physical models and advanced numerical techniques used in conjunction with sophisticated elasto-plastic constitutive models. For the work reported here, scaled centrifuge models are used to obtain maximum bearing pressures of prototype shallow spread footings located near sand slopes. These results are compared with classical bearing capacity solutions and numerical predictions obtained with finite element discretizations and a proper constitutive model.