Load Sharing mechanism of Piled-Raft-Foundations

在实践中，深基础是由一组桩和混凝土筏板连接而成，筏板的作用是将柱荷载均匀地传递到桩上。然而，它并不与桩分担建筑荷载。而工程师们经常单独设计筏板基础来承载整个建筑的荷载。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。桩筏基础的概念在世界范围内得到了越来越多的认可。虽然工程师们认识到筏板对地基荷载的贡献，但这一领域的研究一直滞后于估计筏板份额。这是因为桩/土/筏之间的相互作用本质上是复杂的，现场试验是非常困难的。在文献中，可以找到几个关于桩筏基础荷载-沉降关系的报道。然而，这些报道都是基于有限的模型，没有认识到桩筏基础内部一些重要的控制参数和三维应力变形机理的影响。建立了三维数值模型来模拟桩筏基础的情况，并对原型试验台进行了室内试验。在用试验结果和文中提供的数据对数值模型进行验证后，该模型将用于检验控制该基础性能的参数。本研究的结果将在不影响安全性的情况下对高层建筑桩筏基础的施工产生显著的经济影响。预计开发的设计理论、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，该项目将为高素质的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.