Experimental research on disintegration of the Heifangtai loess

To study the disintegration characteristics and mechanisms of loess, this paper examines the Malan loess of Heifangtai by using the self-developed disintegration instrument. A series of disintegration experiments with undisturbed loess are conducted. Six probable impact factors of disintegration are selected, including pore diameter, sample size, initial moisture content, water temperature, pH value and salinity. The experiments are carried out by using the variable-controlling approach, the whole process of disintegration is recorded, the curve of disintegration is drawn, and each corresponding disintegration velocity is calculated. Finally, the correlation between the disintegration velocity and the impact factors is obtained by fitting the experimental data. The experiment results also show that the disintegration procedure of the loess can be divided into three stages, including the water absorption stage, softening stage and collapsing stage. The duration of the first two stages is very short, and disintegration is weak at this time because it occurs mainly in the third stage. According to these curve of disintegration, it is found that the disintegration velocity is positively correlated with the pore diameter and water temperature but is negatively correlated with the sample size and initial moisture content, and the corresponding value of R2 are 0.897 3, 0.854 4, 0.950.3 and 0.970.9 When the initial moisture content is under 10%, the disintegration velocity changes in small ranges, when the initial moisture content is between 10% and 20%, the disintegration velocity decreases sharply with increasing moisture content, and when the initial moisture content is greater than 20% and gets close to saturation, the disintegration velocity is gradually close to a stable value. When pH is between 5. 5 and 6.5 or 9.5 and 10.5, the disintegration velocity is high. The effect degree of salinity is small. In addition, the disintegration is related to soil structure, grain size composition, cement, and so on.