Study Immediate and Consolidation Settlement of Shallow Foundations

In the present study, laboratory model tests and numerical analysis are carried out to study the immediate, and consolidation settlement of shallow foundations rested on clayey soil. The purpose is to evaluate the immediate and consolidation settlement of different cases and compares them with the calculated values using theoretical equations; the numerical analysis is utilized by the Plaxis-3D program for developing the finite element model, whereas the soft soil model was used for simulation. It was studied the effect of three parameters on the behavior of the foundation for immediate and consolidation settlement, these parameters are soil cohesion, the pressure applied on the foundation, and layer thickness. The obtained results indicated that the simulation using the soft soil model underestimates the immediate settlement by about 30 % and gives excellent results for predicting consolidation settlement. The total settlement of shallow raft foundation rested on a clay layer of depth three times raft width to one time was increased by about 66 %. The consolidation settlement is much higher than the immediate in clayey soils, however, the average of immediate to consolidation settlement is equal to 0.3 % for pressure 20 kPa, and increases with rising applied pressure until it reaches 1.2 %. The numerical analysis revealed a lower value than the calculated using the theoretical equation for immediate settlement, while for consolidation settlement, the results are close except for the soft clay condition c_u = 20 kPa.