Influence of Inclined Bedrock on Undrained Bearing Capacity of Shallow Strip Foundations

Theoretical solutions are available to estimate ultimate undrained bearing capacity of shallow strip footings over saturated soft soil limited by a firm layer, such as bedrock. However, bedrock is often inclined with a dip and a strike. The influence of the bedrock inclination on bearing capacity of shallow foundations is not well understood. In this study, a 2D numerical method incorporated in FLAC 2D software was adopted. The soft soil was modeled as a linearly elastic perfectly plastic material with the Mohr-Coulomb failure criterion under an undrained condition. The footing was considered rigid and the load was applied by a velocity until the failure of the foundation. The influence of the inclined bedrock on the bearing capacity of the shallow strip foundation was investigated by varying the minimum depth-to-width ratio (i.e., the minimum depth of the soft soil to the bedrock/the width of the footing) and the bedrock inclination (assuming the dip perpendicular to the direction of the strip footing). Based on the numerical results, bearing capacity factors were modified with the inclination angle and depth to the bedrock. It is shown that an increase of the inclination angle and/or depth to the bedrock reduced the bearing capacity of the foundation.