BEHAVIOR OF PASSIVE PILES IN SOFT CLAY FORMATIONS
Laterally loaded piles’ behavior can be classified depending on how the lateral forces are transmitted to the piles into active or passive loaded piles. Active piles are subjected to direct lateral loads transferred directly from the superstructure to the pile head through the pile caps. On the other hand, passive piles are affected laterally as a result of squeezing and lateral movement of the surrounding soft soils under the effect of the additional vertical stresses). Down drag is defined as the downward settlement of a pile from dragging force exerted by the surrounding soft soil, while the drag load is the load transferred on a pile from negative skin friction. This frictional force reduces the pile structural capacity and decreases its serviceability, and must be considered in pile design. Typical examples of passive piles are deep foundations installed in soft clay and supporting bridges' abutments adjacent to the approach embankments, and piles used to stabilize earth slopes. The effect of lateral loading due to soil movement and squeezing on passive piles may lead to either structural distress of the deep foundations as a result of exceeding their lateral capacity, or serviceability problems as a result of exceeding the lateral displacement tolerable limits. Simulation of such a problem for a published field case study by using a 3D finite element program (Plax is 3D V2020) is investigated to depict the efficiency of using the numerical analysis in predicting the behavior of piles for such cases. The numerical analysis investigates the effect of lateral force on the horizontal soil displacement, lateral pile movement, and the affecting bending moment along the piles’ lengths.
soil-pile interaction, passive pile, deep soft clay, soil movement.