A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering inGeotechnical and Earth Resources Engineering, School of Engineering and Technology

Thesis (M. Eng.) - Asian Institute of Technology, 2014

An in-depth investigation on design and performance of piled-raft foundation for high rise buildings in Bangkok subsoils was made with an aid of 3D finite element analysis which is meaning to model this complex soil structure interaction problem. The work involved conducting a series of analysis with a purpose of optimization of the design using the case earlier investigated in Amornfa K. (2012){u201F}s dissertation. It was lead that reduction in number of piles and rearrange the pile positions underneath the raft can help improve the settlement profile of the foundation without scarifying safety of the raft. However, the unit effective approach is using variable length of pile corresponding to column load distribution.The analysis of undrained and drained revealed that theraft with pile tips in stiff clay layer would yield higher settlement of the raft in long term than the case of tip in sand layer but magnitude of settlement was still acceptable level. An analysis of the second case of high rise building allows an investigation of effective stiffness of each pile underneath the raft showed that it varied from one location to another. The influence factor of stiffness of piles is governed by the interaction between pile, raft and soil as well as pattern and location of column load