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Over the past few years, a new foundation called composite piled raft (i.e., raft with composite pile) foundation has been introduced by engineers and researchers. In this type of foundation, flexible materials are used for the formation of short piles which can provide strength in the case of soft soil, whereas relatively stiff/rigid materials are used for forming long piles which are used for settlement reduction purposes. Sometimes, cushion layers are also used beneath the raft to redistribute the stresses of surrounding piles. As the concept of this type of composite foundation is new, very limited research is available to understand the behaviour of this foundation. Therefore, the major aim of this paper is to study the behaviour of rafts with composite piles through finite element modelling. In order to utilize the finite element modelling, ABAQUS 3D finite element software is used for the analysis. In this study, the raft and long piles are made of concrete materials and short piles are made of cement fly ash and gravel (CFG) materials. Various pile arrangements are investigated under vertical loading to assess the optimum pile configuration of composite piles. Settlement pattern and axial stress distribution along the short pile and long pile are also investigated. From the results of the numerical analysis, it is observed that maximum axial stresses are generated at a depth of 0.25-0.3 times the length of the pile and the axial stresses generated along the long pile are smaller as compared to the short pile in the case when cushion layer is not used beneath the raft. The overall performance of the composite piled raft foundation is found to be comparatively better than the conventional piled raft foundation.

Keywords: Composite piled raft, finite element, CFG, settlement, axial stress

Priyangi Sharma, Chandigarh University; Kaustubh Sinha, Chandigarh University; Anurag Sharma, Chandigarh University; Nishant Chaudhary, Chandigarh University; Vinay Kumar Chatwal, Chandigarh University; Plaban Deb, Chandigarh University

International Conference Proceedings