To investigate the presence of pressure melting during the compression of frozen gravel soil

we conducted unconfined compression tests and resistance tests on gravel soil samples with varying water (ice) contents and freezing temperatures. The unfrozen water content in saturated gravel soil samples was quantified using nuclear magnetic resonance (NMR) spectroscopy. The results indicate that: (1) During compression

the resistance of gravel soil initially decreased rapidly

subsequently slowing down

with only the dry sample ex-hibiting an increase in resistance post-peak stress. (2) In the rapid reduction stage

the resistance reduction rate of dry samples was lower compared to saturated frozen samples. Specifically

the resistance reduction rate of −4 ℃ saturated samples was 26.8%

which was fourfold that of dry samples at the same temperature. (3) As the freezing temperature decreased

the rate of resistance reduction initially increased and subsequently decreased during the rapid reduction stage. (4) Upon temperature reduction

the relative contents of both free water and capillary water underwent rapid declines

whereas the relative content of adsorbed water initially increased marginally before gradually decreasing. Analysis reveals that the compression of frozen gravel soil elicits a pressure melting effect

resulting in an increase in unfrozen water content within the high-stress regions of the sample during loading. This meltwater subsequently migrates through the unfrozen water film into the pore spaces of low-stress areas

where it re-freezes

altering the pore structure. Notably

the pressure melt-ing effect is most pronounced within the temperature range of －2 ℃ to －4 ℃.