Numerical analyses of pile raft foundation subjected to water table fluctuations

This research studies the behavior of pile raft foundation immersed in multi-layer soil and the effect of rising and lowering of the groundwater table from a case implemented in the ground was analyzed numerically by the computer program (PLAXIS 3D), the foundation is constructed in a multi-layer soil with Raft dimensions 30m x 36m and 90 piles of 26m in length and 1m in diameter. Spacing between piles is 3.6 meters based on multi-story building and a stress of 241 kN/m2. The soil was simulated as a material of the type (Mohr-Coulomb). In comparison, the concrete was simulated as a material (Liner elastic), and the foundation and pile of the program were implemented with the exact, realistic dimensions to hold the same load, change the groundwater level, and take it to the level of 1.1m and 2.2m. One pile has been loaded and compared to the field pile load test results to check the validity of the PLAXIS 3D program. The study also examined how the diameter of piles, length, and raft thickness impact the strength of the pile raft when the groundwater level changes. The results found that the settlement is lower when the groundwater level is 1.1m. The results also found that the effect of the diameter of the pile is small, while the effect of length is more significant. In addition, the impact of the thickness of the raft foundation is almost insignificant.