吹填土地基在真空预压插板期间的沉降计算

吹填土地基是滨海新区围海造陆的主要地基形式，由于在吹填土层的增加，改变了原来地基的应力状态，使原天然地基在吹填土有效重力作用下产生附加荷载，而吹填土为欠固结土，所以吹填土地基在真空预压插板过程中会产生固结沉降。故本文提出吹填土地基真空预压产生的沉降是由插板期间发生的固结沉降和真空预压期间发生的固结沉降两部分组成。现场监测表明吹填土地基在真空预压插板期的沉降占总沉降的30％－50％，但在目前的设计计算中未能考虑。本文通过分析吹填土地基各土层的受力状态，提出插板期间各土层的沉降量计算方法，计算结果与现场试验结果比较吻合，从而完善了真空预压软基加固沉降计算方法。本文同时深入研究了真空预压各施工时段固结度的计算方法

Settlement calculation for vacuum preloading during installing PVDs

Large consolidation settlement will take place during strengthen the soft soil foundation with the vacuum preloading technique. The total settlement consists of the settlement during PVD installation and that during later vacuum loading. There have been several methods for estimating the settlement developed during vacuum preloading. But the displacement during PVD installation has not been suitably considered by the current design method. A procedure to calculate the settlement during PVD installation is put forward in this paper based on the analysis on the loading characteristics of the soil layers of the improved soil foundation. The calculated results have been compared with the observed data in the field and found they agree with each other very well. The degree of consolidation is also discussed in this paper.