Load Sharing mechanism of Piled-Raft-Foundations

在实践中，深基础是由一组与混凝土筏相连的桩组成的。筏板的作用是将柱荷载均匀地传递给桩。然而，它不与桩分担建筑负荷。而工程师通常设计筏形基础单独承担整个建筑物的荷载。因此，桩基础的设计被认为是高度保守的，实际上是不经济的。桩筏基金会的概念在世界范围内得到越来越多的认可。虽然工程师们认识到筏板对基础荷载的贡献，但在这一领域的研究一直滞后于估计筏板的份额。这是由于桩/土/筏之间的相互作用本质上是复杂的，现场测试充其量是困难的。在文献中，可以找到一些关于桩筏基础荷载-沉降关系的报道。然而，这些报告基于有限的建模，未能认识到一些重要的控制参数和发生在桩筏基础内部的三维应力变形机制的影响。在这个提议中；对桩筏基础进行了试验和数值研究。本文将建立桩筏基础的三维数值模型，并在原型试验装置上进行室内试验。在将数值模型与实验结果和文献数据进行验证后，将使用该模型对控制该地基性能的参数进行检验。本文的研究结果将对高层建筑桩筏基础的施工产生重要的经济影响，同时又不影响其安全性。期望所制定的设计理论、指导方针和建议将被纳入加拿大基础工程手册和美国土木工程师学会实践手册。同样重要的是要注意到，该项目将为高素质人才和科学家提供培训。

In practice, deep foundations are made of a set of piles connected together with a concrete raft. The role of the raft is to transfer the column load to the piles uniformly. It does not however share the building load with the piles. While engineers often design raft foundation alone to carry the entire building load. Accordingly the design of pile foundations is regarded as highly conservative, in fact uneconomical. The concept of Piled-Raft-Foundation has been increasingly receiving recognition around the world. While engineers recognize the contribution of the raft to the foundation loads, research in this field has been lagging to estimate the raft share. This is due to the fact that interaction among the piles/soil/raft is complex in nature and field testing is difficult at best. In the literature, several reports can be found dealing with the load-settlement relationship of piled-raft foundations. Nevertheless, these reports are based on limited modeling, and failed to recognize the effect of some vital governing parameters and the three-dimensional stressdeformation mechanism, which take place within the piled-raft foundation. In this proposal; experimental and numerical investigations on piles-raft foundation will be performed. A three-dimensional numerical model will be developed to simulate the case of piled-raft foundation and laboratory tests will be conducted on prototype experimental set-up. After validating the numerical model with the experimental results and the data available in the literature, the model will be used examine the parameters, believed to govern the performance of this foundation. The results of this study will have significant economic impact on the construction of piled-raft foundations for high-rise buildings without compromising on the safety. It is expecting that the design theories, guidelines and recommendations developed will be incorporated in the Canadian Foundation Engineering manual and American Society of Civil Engineers manual of practice. It is equally important to take note that this project will provide training to the Highly Qualified Personnel and scientists.