Effect of Foundation Embedment Depth on Contact Stress Distribution and Differential Settlement

Abstract

The increase of the embedded depth of the foundations increased the bearing capacity of soils, because the surrounding soil of the footing confined the stressed soil under the footing. For the same reason, the embedded depth of the foundations may affect the distribution of the contact stresses and settlement under footings. Usually, the researchers studied the contact stress analytically or practically without any depth of embedment. This may affect the resulted distribution of the contact stresses and the corresponding differential settlement. Therefore, the study of this effect is needed to be qualified. Two types of soils were studied, sandy and clayey soils. The elastic perfect plastic, Mohr-Coulomb, model was adopted to represent the soils. This model is the simplified non-linear model that is producing a fair distribution for the contact stress. It is investigated that, the contact stress distribution is affected by the embedded depth of the footings. The contact stresses under footing center were increased with the increase of the embedded depth, and the edge stresses were decreased. Distributions of the contact stresses under footing in sandy or clayey soils are concentrated near footing edges. The resultant of this concentration near edges increases the resulted maximum bending moment at footing. The maximum settlement and the differential settlement are decreased with the increase of the embedded depth. Sandy and clayey soils result approximately the same distribution of contact stresses for different embedment depths except the zero depth, which is not realistic. Therefore, to enhance the future studies of the contact stresses distribution under reinforced or non-reinforced soils, uniform applied loads besides the footing should be applied. In addition, the most of settlement calculation methods that widely used by practical engineers weren’t consider the embedment depth of footings, which affect the results as shown in this paper, and it needed to be further improved.