Load Sharing mechanism of Piled-Raft-Foundations

实际上，深基础是由一组桩和一个混凝土筏板连接在一起构成的，筏板的作用是将柱荷载均匀地传递给桩。然而，它并不与桩分担建筑负荷。而工程师往往设计筏板基础单独承担整个建筑物的荷载.桩筏基础的设计被认为是高度保守的，实际上是不经济的，桩筏基础的概念在世界范围内越来越受到重视。尽管工程师们认识到筏板对地基荷载的贡献，但该领域的研究一直滞后于估算筏板份额。这是由于桩/土/筏板的相互作用本质上是复杂的，现场测试是困难的，在文献中，可以找到一些报告处理桩筏基础的荷载-沉降关系。然而，这些报告是基于有限的模型，并没有认识到一些重要的控制参数的影响和三维应力变形机制，这发生在桩筏基础。将建立一个三维数值模型来模拟桩筏基础的情况，并在原型实验装置上进行实验室测试。在利用试验结果和文献资料对数值模型进行验证后，将利用该模型对影响桩筏基础性能的参数进行分析，研究结果将对高层建筑桩筏基础的建设具有重要的经济意义，同时又不影响其安全性。我们期待着这些设计理论、指导方针和建议将被纳入美国基础工程手册和美国土木工程师协会的实践手册。同样重要的是要注意到，该项目将为高素质人员和科学家提供培训。

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 howevershare the building load with the piles. While engineers often design raft foundation alone to carrythe entire building load. Accordingly the design of pile foundations is regarded as highlyconservative, in fact uneconomical.The concept of Piled-Raft-Foundation has been increasingly receiving recognition around theworld. While engineers recognize the contribution of the raft to the foundation loads, research inthis field has been lagging to estimate the raft share. This is due to the fact that interaction amongthe 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 ofpiled-raft foundations. Nevertheless, these reports are based on limited modeling, and failed torecognize the effect of some vital governing parameters and the three-dimensional stressdeformationmechanism, which take place within the piled-raft foundation.In this proposal; experimental and numerical investigations on piles-raft foundation will beperformed. A three-dimensional numerical model will be developed to simulate the case of piled-raftfoundation and laboratory tests will be conducted on prototype experimental set-up. Aftervalidating the numerical model with the experimental results and the data available in theliterature, the model will be used examine the parameters, believed to govern the performance ofthis foundation.The results of this study will have significant economic impact on the construction of piled-raftfoundations for high-rise buildings without compromising on the safety. It is expecting that thedesign theories, guidelines and recommendations developed will be incorporated in the CanadianFoundation 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.