Analysis Of The Interaction Between The Foundation In Soft Slab And The Surrounding Weak Soil

Pile foundation and continuous wall foundation are widely used in coastal regions, where the character of local soil is always very weak. With the development of design method and the advancement of constructing technology, many new types of pile and continuous wall are applied, like the thin-wall hollow pile and the multi-function continuous wall, which can be used not only as temporary fencing structure, but also as permanent loading structures. The interactional mechanics characteristic between such kind of complex underground structures is difficult to realize. Unfortunately, few systemic researches have been engaged on this topic, and there are few references can be consulted up till now.At present, numerical analysis is widely used in such complex structure-soil interaction questions. It is effective to apply 3D nonlinear finite element in practical projects after setting up the numerical models for them. Due to the difference of material characters and mechanics performance between concrete structures and soils, it is necessary to pay great attention to model the interface element, simulate the soil behavior and the optimization of the finite elements to satisfy the numerical precision and the compatibility relation of the whole project.Several classical methods of interface element, soil behaviors and structure characters are presented in this paper. The author made great effort on the modeling of the interface element and the underground structure element, while considering the soil obey the Mohr-Columnb yielding principle, modified the existing beam element for solid rectangle pile and applies this element into thin-wall hollow pile, proposes a kind of board element. Some examples are presented in the paper to test these new concepts and corresponding formulas. The calculation results also prove that the standard solid element is not appropriate for modeling these complex underground structures. All these efforts intend to obtain a convenient numerical method for analyzing the interaction between complex foundations and soft soil.The test on horizontal bearing capacity of thin-wall hollow pile is analyzed in the paper, which has been carried by Shanghai investigation and design institute. The calculation results conform to the testing results. So, the analysis methods presented in the paper are validated by the results from field test.In the end, these methods are used to analyze the continuous wall foundation of the outlet-gate in east Punan, Shanghai and find its internal force under typical load. The final conclusions are retional.