复合地基褥垫层厚度的设计方法研究

Research on the Design Method of Composite Foundation Cushion Thickness

从褥垫层受力和变形的角度出发,提出了一种求解复合地基褥垫层厚度的设计方法。首先,在前人工作的基础上,提出了临界桩土应力比、桩顶应力临界扩散厚度计算公式,由计算公式可以看出桩土临界应力比是置换率和扩散厚度的函数,与荷载水平无关。其次,垫层厚度等于桩顶应力扩散厚度与桩顶刺入量之和,分别给出了桩顶应力扩散厚度与桩顶刺入量的设计方法,桩顶刺入量是荷载水平的函数,荷载越大,刺入量越大,进而求解了垫层厚度。最后,将本文方法计算结果与复合地基载荷试验结果比对,结果比较接近,从而验证了本文计算方法的合理性。

From the prospection of cushion stress and deformation,this paper raises a calculation method of composite foundation cushion thickness. To begin with,the dissertation put forward a calculation formula,which is related to the critical stress ratio of pile and soil as well as the critical thickness of stress diffusion above the pile. From this formula,it can be concluded that the critical stress ratio of pile and soil is a function of replacement rate and the thickness of stress diffusion,however,it has no relation to load level. Furthermore,cushion thickness is equal to the sum of the thickness of stress diffusion above the pile and pile tip penetration. In this paper the calculation method of these two are presented respectively,pile tip penetration is a function of load level,which is the greater,the more pile tip penetrate is. Eventually,by comparing with the load test of composite foundation,the result of calculation method is agreed well.