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 本文在总结已有的结构与土相互作用问题中的接触面单元形式、土的本构关系以及结构的数值模拟方法的基础上，对满足摩尔库仑屈服条件的土体材料用常规的薄层单元模拟进行了更加深入的验证，在已有实心矩形截面桩与土相互作用描述模式的基础上推导了薄壁筒桩用梁模拟时与土相互作用分析模式，和考虑与土相互作用时用板单元模拟地下连续墙的分析方法。
As result of above , soil character ' s variation can be measured by structure , especially by mini - scale structure , under circumstance of normal temperature , normal pressure and slowly groundwater variation , and so mini - scale structure is platform and main location for water - soil interaction taking place and developing , also the carrier of their effect . the water - soil interaction can be analyzed by the soil mini - scale structure , from this the mathematical model on the variation of mini - scale structure and the deformation forecast model can be established . it is manifested by tests and researches that there is the variation of soil structure caused by water - soil interaction , moreover , which can be recognized and showed by some tests . it can conform the existence of the structure variation by water - soil interactio 由理论分析提出，域市常温、常压、缓慢的地下水变异环境下的土体性质的可变性将由结构一尤其是细观结构来度量，进而提出细观结构是水土作用发生与发展的“平台”和主要场所、是水土作用效果表现的载体，水土相互作用分析可通过土细观结构这个桥梁来进行，由此建立了细观结构变异数学模型以及变形的预测模型；试验研究表明水土作用引起土的结构变异是存在的，而且结构变异可以被认识，并可以通过一定的测试手段来显现。
