EXPERIMENTAL EVALUATION OF THE INFLUENCE OF THE LEVEL OF THE GROUND WATER TABLE ON THE BEARING CAPACITY OF CIRCULAR FOOTINGS

In this study, a bearing capacity device is designed and fabricated to determine the load-settlement behavior of three circular footing models resting above the ground water table. Capillary rise in the studied well graded sand is measured and the level of the water table is controlled at the desired heights during each bearing capacity test. Moreover, shear strength parameters and soil water retention curve of the soil are also determined. Experimental results show that using the conventional equations available in the literature of foundation engineering to determine the bearing capacity of footings built above the ground water table can be highly conservative. Moreover, despite the conventional theories, lowering of the ground water table can result in a decrease in the bearing capacity of shallow foundations. Therefore, utilizing the in situ experiments such as cone penetration test performed while the ground water table is at its highest level can lead to a quite non-conservative estimation of the bearing capacity of footings. In addition, an empirical relationship is proposed to simulate the bearing capacity factor, N-gamma, of circular footings based on the experimental results.