天然沉积亚砂土固结特性研究

大量室内外试验研究清楚表明亚砂土在粒度分布、强度特性、压缩性和塑性图等方面与一般粘性土完全不同,因此室内固结试验所得到的天然沉积亚砂土的固结系数与一般粘性土固结系数基本相同是明显不合理的。基于竖向排水体饱和土地基固结理论解答,提出了考虑地基排水井加固区下卧层修正沉降数据反演地基固结特性的计算方法。比较了室内实验数据与相关现场反演计算参数,得出了反演分析固结系数相对高出室内固结试验结果2个数量级。运用这一结果,预测路堤中线下地基固结沉降历时曲线与实测沉降曲线很好吻合。

On the Characteristics of Consolidation of Natural Deposits of Sandy Loam

Extensive field and laboratory tests were performed on the natural deposits of sandy loams to demonstrate the very difference in the behavior from clayey soils in the grain size distributions,strength characteristics and plasticity chart,etc.It is a significant error that the sandy loams have almost the same magnitude of coefficient of consolidation measured in the laboratory as that of clayey soils.Based on the theoretical solution to vertical drain consolidation,an approach of the back-analysis to evaluate the field consolidation behavior is proposed,in which the consolidation affected by underlying stratum below the subsoil improved with prefabricated vertical drains is modified.Then,a comparison is made between coefficient of consolidation measured in the laboratory and corresponding back-calculated field values of the parameters,and from which the coefficient of consolidation for the sandy loams derived from the back-calculated approach is about 2 magnitude greater than that measured in the laboratory.The back-calculated results are further used to predict the settlement versus time curves under the embankment centerline which matches those measured in the field fairly well.