廊坊沉降区深层黏性土压缩指数相关性分析

Correlation Analysis of Compression Index of Deep Clayey Soil in the Settlement Area of Langfang City

深层黏性土的压缩指数对于地面沉降估算具有重要意义,目前通过固结试验获得压缩指数,其具有耗时长和超高压加载的缺点。在廊坊沉降区获取深层黏性土原状试样的基础上,通过土工试验获得物理力学指标,进而对物理指标与压缩指数的相关性进行分析,得到如下结论:(1)该区埋深100 m以下的黏性土物理力学指标的变异系数较小,说明数据的离散程度较小,能够进行统计分析;(2)通过回归分析建立了液限、天然含水率、天然孔隙比、塑性指数与压缩指数的线性关系,并能够预测压缩指数的最大值、中间值和最小值;(3)利用天然含水率、天然孔隙比预测压缩指数的频数服从正态分布,采用天然孔隙比预测压缩指数较为准确。

The compression index of a deep clayey soil is of great significance for the evaluation of land subsidence,but the compression index obtained through consolidation tests has the disadvantages of time consuming and ultra-high pressure loading.On the basis of obtaining undisturbed samples of deep clay in the settlement area of Langfang,the physical and mechanical indexes were obtained by geotechnical tests.Then the correlations between physical index and compression index are analyzed,and the following conclusions are obtained:(1)the variation coefficients of physical and mechanical indexes of clayey soils are small when the buried depth exceeds 100 m,which shows that the data is less discrete and can be analyzed statistically;(2)the linear relations between liquid limit,natural water content,natural void ratio,plasticity index and compression index are established by regression analysis,which can predict the maximum,median and minimum value of the compression index;(3)the frequency of predicted compression index obeys normal distribution by using natural void ratio and natural water content,and it is more accurate to predict compression index by natural void ratio.