To study the effect of moisture content on mechanical properties of soil subjected to freeze-thaw cycling

a series of triaxial tests were conducted under different confining pressures for samples which were made of silty clay from Qinghai-Tibet Plateau with different original moisture contents and had experienced various freeze-thaw cycles. The results show that the stress-strain curves of samples with different moisture contents tend to be similar after freeze-thaw cycling. The freeze-thaw cycling effect is uncertain because of the level of original moisture content. It is deteriorating for soil with low moisture content

and the deteriorating degree aggravates with the increase of moisture content within a certain range. When the moisture content is increased to a certain value which is generally close to the plastic limit

the effect is strengthening conversely. The water migration inside samples

which are subjected to freeze-thaw cycling in a closed system

leads to the redistribution of moisture content. The higher the original moisture content is

the larger the water migration amount is. The failure strength of soil decreases with the increase of moisture content in a nonlinear law

so the change amplitude of strength in the increase zone of moisture content is different with that of the decrease zone. The failure strength of sample may exhibit different tendencies including increase

decrease or remain unchanged. The mechanical properties of soil subjected to freeze-thaw cycling are affected by the dry density

moisture redistribution and soil structure simultaneously

but the dominant factor is changeable due to different moisture contents and number of freeze-thaw cycles

which makes the freeze-thaw cycling effect on soil diversified correspondingly.