合肥轨道交通沿线新老黏土特性比较分析

Comparative Analysis of Characteristics of New and Old Clay along Hefei Rail Transit

合肥轨道交通1~5号线浅埋暗挖隧道穿越地层黏土主要是全新世黏土和晚更新世黏土,根据形成年代的早晚可以称之为新黏土和老黏土,两种黏土的工程特性存在差异,主要表现为老黏土具有膨胀性而新黏土不具有膨胀性,为了更深入地了解造成两种黏土特性差异的原因,依据合肥轨道交通沿线勘查资料,统计了两种黏土的物理力学参数,并对两种黏土的物理力学参数特征进行了比较分析,得到了两种黏土特性存在差异的初步结论;分别对两种黏土的物理力学参数进行了相关性分析;从微观角度揭示了新、老黏土结构的特点和差异,解释了两种黏土的微观结构对其工程性质的影响。得出结论:合肥地区新、老黏土在亲水性、压缩性和抗剪强度等物理指标上存在明显差异,以及新、老黏土微观结构不同,是造成两种黏土工程特性差异性的原因。

The clay of the strata along shallow-buried tunnels of Hefei Rail Transit Line 1-5 mainly consists of Holocene clay and Late Pleistocene clay,which can be called neo-clay and old clay respectively according to their formation age.The engineering characteristics of the two kinds of clay are different mainly in that the neo-clay is expansive while the old clay is not.In order to better understand the causes for the differences between the two clays,the physical and mechanical parameters of these two kinds of clays were analyzed on the basis of data from the geological examination along Hefei Rail Transit Line 1-5,and preliminary conclusions of the differences between the two kinds of clay were made.Besides,the correlation between the physical and mechanical parameters of the two kinds of clay was explored.This paper also studied the characteristics of both clay and their existing variances through the lens of microscope,explained the influence of microstructure of the two kinds of clay on their engineering properties.It concluded that the obvious differences in physical indexes such as hydrophily,compressibility and shear strength between neo-clay and old clay in Hefei area,and the differences of their variant microstructures led to their different soil engineering characteristics.