PERFORMANCE OF PILED RAFT IN CLAY

Abstract

The piled raft system is one of the most important systems in the last decades. The purpose of this research is to check the application of piled raft system in stiff clay as well as in soft clay after introducing the available methods for analysis of piled raft system for different case studies. The methodology of analysis is the finite element method using Plaxis 3D software implementing Mohr-Coulomb and Hardening Soil constitutive models. The numerical model has been calibrated using a well monitored “Messeturm” high rise building in Germany supported by Frankfurt over-consolidated clay. A study of the application of piled raft in soft clay compared with traditional piled raft system in view of settlement, differential settlement, piles type and capacity and the engineering value will be discussed. The thesis consists of six chapters: Chapter (1) is an introduction to this research; it discusses the importance, the scope and the main objectives of the research. Chapter (2) is a literature review which briefly summarizes the different methods of analysis piled raft system; also, it presents the previous monitored piled raft systems in different soil conditions. Chapter (3) presents a brief discussion about finite element method and the different constitutive laws to simulate the different elements of the piled raft foundations system. Chapter (4) presents the verification of the numerical modeling using two cases: conceptual simplified case and “Messeturm” high rise building in Frankfurt, Germany. Chapter (5) discusses a characterization of North Delta clay; with a static pile load test in Port Said soft clay. It presents also application of piled raft system compared with the traditional raft on piles for a water treatment tank exist east of Al Tafreah-Port Said.