Abstract：Compression tests are conducted on intact loess obtained from Xi¢an and Lanzhou with different water contents. The quantitative comprehensive structural parameter is defined by using porosity ratio of intact and disturbed saturated loess under the same pressure. The effects of moistening water content w and pressure on the structural parameter are investigated. The mechanism of moistening deformation is analyzed using characteristics of the structural parameter change. The study indicates that：(1) the structural parameter decreases and coefficient of moistening collapsibility increases during moistening process under condition of the same pressure，but they scarcely change when moistening water content w is less than the initial moistening water content with structure destruction wf which locates at the turn point and decreases with the increase of pressure. (2) when w is less than wf，water sensitivity of loess is very weak，but it is very strong when w is large than wf. (3) moistening collapsibility is greater under high pressures，and it is weaker under low pressures. The effect of pressure on moistening collapsibility is more obvious at small initial water content than that at large one. (4) moistening deformation decreases with the increase of initial water content w0 under the same w，but its change has no effect on the deformation when w0 is less than wf. (5) the linear relations between and ( ) is almost the same for Xi¢an loess and Lanzhou loess under the condition of different pressures and initial water contents. Namely，structure nearly has identical influence on the growth of moistening deformation under different conditions.
