酸蚀作用下黄土高原红黏土物理及力学性质劣化规律试验研究

Experimental Study on the Deterioration Effects of Acid on Mechanical Properties of Red Clay in the Loess Plateau

为探讨酸蚀作用下陕甘黄土高原第三纪红黏土的抗剪强度、膨胀率和渗透率等工程性质劣化机理,开展了常温常压下室内红黏土酸溶液浸泡模拟实验,对比分析酸蚀作用前后红黏土物理及力学性质的变化特征。结果显示:随着土体干密度和酸性水溶液pH值的增大,重塑红黏土的黏聚力和内摩擦角均表现为增大的趋势;重塑红黏土的无荷载膨胀率随着其干密度的增大而升高,但随溶液pH值的增大却降低;重塑红黏土的渗透率与干密度表现为显著的负指数相关性;在低干密度区间,重塑红黏土的渗透率随干密度的增大而显著降低;在高干密度区间,重塑红黏土的渗透率随干密度的增大而缓慢降低;相同干密度下,重塑红黏土的渗透率随酸性水溶液pH值的增大而减小。红黏土矿物与酸性水溶液发生的水岩化学作用是红黏土物理及力学性质劣化的主要控制机理。

In order to investigate the deterioration effects of acid solution on mechanical property of Tertiary red clay in Qingyang area,northern China,characteristics of shear strength,swelling and permeability of remolded red clay immrsed in acide solution were studyed in this paper.It is found out that cohesion and internal friction angle of remolded red clay increased as the increasing of dry density of soil mass and the pH value of acid solu⁃tion.Swelling effect of the remolded red clay was found to be time-sensitive and can be classified as rapid swell⁃ing stage,slow swelling stage,and stable stage.Unloaded swelling rate of the remolded red clay increased with the increase of soil dry density,whereas it decreased with the increase of solution pH value.Variable water-head permeability testing results show that the permeability of remolded red clay exponentially decreased with the in⁃crease of dry density.It is also found that as dry density increasing,the permeability of remolded red clay showed a rapid decreasing trend in lower soil dry density range and a slow decreasing trend in higher soil dry density range.Furtermore,Under the condition of identical soil dry density,the permeability of remolded red clay demon⁃strated a decreasing trend as solution pH increasing.The permeability of red clay can be effectively reduced through increasing the compaction degree of roadbed.Our study reveals that the water-rock chemical interaction between red clay and acidic aqueous solution is the main controlling mechanism of mechanical deterioration of red clay.