Analysis Method Of The Interaction Between Superstructure, Pile Foundation And Subgrade And Its Application On The Deviation Rectifying Of Building

The deviation of building is a usual engineering incident of soft subgrade. It is caused by the leaning of foundation that is the result of the uneven deformation of subgrade. Because of the lack of theory and the limitation of construction and monitoring technic, many well-known constructions in the history have not been rectified up to now. A representative case is the leaning tower of Pisa. Some of them had collapsed. The springing up of deviation rectifying technic of building is a result of the development of the theory of soil mechanics and the improvement in foundation treatment, construction machinery and monitoring technic. Another cause is that there are so many leaning building today. By far, many deviation-rectifying measures are just resting on the experience of engineers. Little improvement has been done on the theory. This makes the work much arbitrary.Many engineering practices have proved that foundation settlement rests with not only external load but also mainly the stiffness of subgrade, foundation and superstructure. The much more accuracy analysis method is to take the three parts into account at the same time. This method is called interaction analysis method. The interaction analysis between superstructure, foundation and subgrade needs the three keeping continuity on the contact surface. Because of the diversified structural models of superstructure and foundation and the longing odds stiffness of the three parts, it is sophisticated to do so. It is more complicated to find the deviation causation of building than normal foundation design analysis. Say nothing of deviation rectifying. Superstructure, foundation and subgrade interact with each other and are in an indivisibility system. The effect of deviation rectifying is greatly influenced by the stiffness of superstructure and foundation. New theory needs to be established for this rising subject. This dissertation is about the interaction analysis method between superstructure, pile foundation and subgrade. It deals mainly with the incline analysis and deviation rectifying method of a high building resting on thick and soft soil.The major content of this dissertation is as follows:(1) It uses nonlinear finite element method to take the three parts of building into account. A reduced integration element is developed to avoid volumetric locking when the material behavior is (almost) incompressible. The constitutive model of soil is an extension of the Modified Cambridge Clay Model. The extension version can depict the different yield character of soil under tension and compression. And it uses porous elastic model toexpress the relation of stress and strain before plasticity. Finite deformation formulation is used to describe the deformation of material.(2) It probes into with the influence of ultimate capacity of single pile that is poured by different construction technics. Because the contact performance of soil and piles lies mainly on the construction technics. The range of variation of ultimate capacity of single pile is great. A contact interaction model is developed to simulate the interaction between pile and soil. The contact model can simulate easily the closing, opening and slipping between two surfaces. It uses the contact model to study the affecting "factor of ultimate capacity of single pile poured by the construction technics.(3) The derivation of the stiffness development of superstructure and multilevel superstructure is given out; this derivation process can be used to simulate the construction process of building. The substructuring method is used to take the stiffness of superstructure into account in interaction analysis of foundation.(4) Infinite element is developed to consider the effect of far field, and the vicinity field of foundation it uses finite element. Finite elements and infinite elements must satisfy deformation continuity at joined position. An engineering example is analyzed using the interaction method developed in this dissertation. The deformation of soil and piles is sim...