Abstract: 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.

Key words: remolded saturated loess, percolation test, permeability, deterioration rate of long-term loess seepage