Experimental Study on Influencing Factors of Extruded Ice in Sichuan-Tibet Traffic Corridor Region

Extruding ice is a common geological disaster in the Sichuan-Tibet traffic corridor region. Satellite image identification and field investigation show that the extruded ice in the Sichuan-Tibet traffic corridor region is mainly caused by slope-overflow. The effects of topography, permeable layer thickness, aquifer thickness and permeability of the formation of extruded ice are studied by indoor simulation experiments. The experiment shows that extruded ice will form when groundwater is exposed or shallow (generally the groundwater level is lower than the freezing depth in negative temperature conditions. Low-level terrain is more conducive to the accumulation of groundwater and is more likely to form extruded ice. During the formation of extruded ice, the porous water pressure is changed in distinct stages. During the freezing process, the frozen layer gradually closes up. The porous water pressure increases linearly at first, and then the growth rate gradually slows down until the porous water pressure is stable. By increasing the thickness of the permeable layer, the influence of the groundwater level on the formation of extruded ice is studied. This shows that the deeper the groundwater level is, the longer the time of freezing and forming extruded ice is, and the greater the pore water pressure. Therefore, this indirectly proves that the formation of extruded ice is related to the freezing depth. If the depth of groundwater is less than the maximum freezing depth in the region, extruded ice forms easily. The greater the permeability of the aquifer is, the shorter time it takes to form extruded ice, the larger the scale of extruded ice, and the higher the pore water pressure of the groundwater. The greater the thickness of the aquifer, the larger the scale of extruded ice will be. However, the pore water pressure of groundwater will be relatively reduced. Comprehensive experimentation shows that low terrain, shallow groundwater, thick aquifer and good permeability are the favourable conditions for the formation of large-scale extruded ice.