关键词: 深厚湿陷性黄土, 现场浸水试验, 暂态饱和区, 沉降变形特征

Abstract: In-situ soaking tests were implemented on undisturbed and remolded soils in the Ili region to study the regularities of soaking infiltration and settlement of Ili loess. Surface settlement and water content were also monitored. The results show that transient saturated zone exists in the soil depending on temporary mechanical equilibrium among pore water pressure, air entry value and pore air pressure of the closed compressed gas. Undisturbed loess presents multistage settlement, which can be described by piecewise function, due to soil structure and stratum structure. On the contrary, there is no obviously multistage settlement for remolded soil due to the structural damage. The wetting front reaches 8.8 m in the 21st day of soaking test. At the same time, the settlement of the remolded soil (S4) is 120 cm, 35% larger than 78 cm of the undisturbed soil (S5). Due to the effect of stress concentration, unsaturated soil below the wetting front does not deform before the saturated soil near the wetting front reaches stable deformation. Therefore, the settlement of S5, less than the calculated value (85 cm) of the dead weight collapsibility volume, is not stable settlement deformation of saturated soil above wetting front. The results provide a basis for the understanding of mechanism of soaking infiltration and calculation of wetting deformation of Ili loess.

Key words: thick collapsible loess, field soaking test, transient saturated zone, settlement regularity