Through the analysis we found that the effect will become more obviously with the increase of thickness or width of superstratum and the decrease of the coefficient of foundation bed ; ( 3 ) anisotropy and nonlinear elastic f . e . m . model has been established and the effect of stress dispersion in compound two - layer foundation was analyzed on the base of the model . from the analysis we can conclude that the coefficient of subsidiary stress dispersion will amplify with the increase of thickness or width or stiffness of back - up coat ; ( 4 ) the formula which can be used in conventional calculation has been deduced for calculating the coefficient of subsidiary stress dispersion and it also has been affirmed to be reasonable through the checking calculation ; the whole theory of compound two - layer foundation has been brought forward in this paper and it ' ll enrich the theory of composite foundation 针对以上问题本文做了以下一些工作并得到若干结论： ( 1 )提出了“复合双层地基”的概念，并通过工程实例证明此概念的提出有其合理性和必要性； ( 2 )用弹性地基梁理论证实了复合双层地基确有应力扩散效应，且扩散效应随上覆硬层厚度、刚度的增加而增大，随下卧层基床系数的增大而减小； ( 3 )建立了非线弹性、各向异性有限元模型，并以此为基础分析了复合双层地基的应力扩散效应，得到附加应力系数随加固层厚度、宽度、刚度的增加而增大的结论； ( 4 )推导了可用于常规计算的复合双层地基应力扩散系数公式，并代入工程实例进行了验证。
