重塑饱和黄土长期渗流劣化机制及其渗透性分析

为研究重塑饱和黄土在长期渗流条件下的劣化机制，以杨凌Q3黄土为研究对象，用pH=4的稀乙酸溶液作为渗透液加速劣化，通过长时间的常规渗透试验和不同围压下的三轴渗透试验，测量了渗透系数随时间的变化过程，分析了渗透系数随时间的变化规律，探讨了重塑饱和黄土在长期渗流条件下的劣化机制。结果表明：渗透系数随着渗透时间持续减小，与时间符合幂函数关系；渗透系数是反映黄土劣化最敏感的参数；最小孔隙比面的孔隙比决定了渗透系数的大小；最小孔隙比面的孔隙比与初始孔隙比的比值可以用来描述黄土长期渗流的劣化程度，其比值定义为黄土长期渗流劣化率；结合黄土的非线性渗透模型提出了在一定围压下三轴渗透试验渗透系数与黄土长期渗流劣化率的关系式，进而推导出黄土长期渗流劣化率随时间的变化关系式。

Degradation mechanism of long-term seepage and permeability analysis of remolded saturated loess

In order to study the degradation mechanism of the remolded saturated loess under long-term seepage, dilute acetic acid of pH=4 was used as percolation fluid so as to accelerate the deterioration. After a series of long-term conventional percolation tests and triaxial percolation tests under different confining pressures were conducted using Yangling Q3 loess as samples, the permeability coefficient was measured; and the relation between the permeability coefficient and time was analyzed; then the degradation mechanism of the remolded saturated loess under long-term seepage was studied. The results show that the permeability coefficient decreases with time; and the relationship between permeability coefficient and time meets power function. The permeability coefficient is the most sensitive parameter reflecting the degradation degree of the loess, which is determined by void ratio in the minimum void ratio surface. Loess seepage rate of deterioration is defined by the ratio of void ratio in the minimum void ratio surface and initial void ratio, to describe the degradation degree of the remolded saturated loess in long-term seepage. At last, the relationship between loess seepage rate of deterioration and permeability coefficient is proposed based on the nonlinear permeability model of loess, as well as the relationship between loess seepage rate of deterioration and the percolation time is derived.