A FINITE ELEMENT STUDY TO INVESTIGATE AN OPTIMAL DESIGN OF GROUP BORED PILES IN CLAYEY SOIL

• Main Author: SHAMINI SOMANATHAN
• Format: text::Thesis
• Language: English
• Published: 2023
• Subjects: OPTIMAL DESIGN; develop viable parametric design; the clayey soil
• Institution: Universiti Tenaga Nasional

The purpose of this study is to validate and develop viable parametric design of group bored piles in clayey soil. The various arrangement of bored piles considering various parameters of applied pressure, pile diameter, pile spacing and pile slope ratio was explored. The design of bored piles in the soil was done in order to avoid excessive consolidation settlement. The bored piles should be properly design before installation so as to prevent unnecessary cost and excessive consolidation settlement of the piles to occur. Numerical simulation offers an interesting solution to investigate the problem and optimize the design of the bored piles in a comprehensive way. For this study, finite element validation on single bored pile exposed to load test in clayey soil was done using PLAXIS software. Parametric assessment was conducted with a goal to develop a viable group design of bored piles in the setting of clayey soil. Several soil models were evaluated in the study namely Mohr-Coulomb (MC), Hardening-Soil (HS) and Softening-Soil (SS) models. Based on the PLAXIS simulation result on load test of the single bored pile in clayey soil, it was realized that the Mohr-Coulomb (MC) soil model in Very Fine mesh has the mesh size of 0.6 m. It best fits the measured data of the load-settlement behaviour of the pile because it has the highest coefficient of determination (R2) value of 0.9840 for the simulated load in comparison to the measured load on the pile. As such, the soil model was applied for the parametric study on the group bored piles. The parametric study on the group bored piles showed that the optimal design of the group bored piles in clayey soil can be established when the bored piles are applied with 50 kPa applied pressure, 1.3 m pile diameter, 3D pile spacing and 1:2 pile slope ratio with reference to the criteria of 25 mm tolerable limit of consolidation settlement. It was further found from the parametric study that the optimal parametric design of the group bored piles best suits clayey soil with a cohesion and an angle of internal friction of 20 kPa and 20° respectively. The significant outcome of the study is that it is important to perform finite element assessment on the group bored piles by considering several pile and soil conditions in order to understand the interaction between the floating group bored piles and the clayey soil under the application of a pressure.