Shallow slope failures induced by rainfall infiltration occur frequently, and the relevant triggering mechanisms have been widely studied.Rainfall-induced landslides are widely recognized to be caused by increases in ...Shallow slope failures induced by rainfall infiltration occur frequently, and the relevant triggering mechanisms have been widely studied.Rainfall-induced landslides are widely recognized to be caused by increases in soil weight, seepage force and pore water pressure or decreases in soil mechanical properties. However, even when all these factors are considered, some landslides still cannot be explained well. The increased pore water pressure in a slope reduces the effective stress of the soil and may trigger slope failure. Similarly, the pore gas pressure in a slope also reduces the effective stress of the soil but has been neglected in previous studies. As the viscosity of air is nearly negligible when compared with that of water, the pore gas pressure spreads faster, and its influence is wider, which is harmful for the stability of the slope. In this paper, the effects of pore gas pressure are considered in a shallow slope stability analysis, and a self-designed experiment is conducted to validate the force transfer mechanism.Numerical simulation results show that the pore gas pressure in the slope increases sharply at different locations under heavy rainfall conditions and that the pore gas pressure causes a rapid decrease in the slope safety factor. Laboratory experimental results show that the pore gas pressure throughout the whole unsaturated zone has the same value, which indicates that the gas pressure could spread quickly to the whole sample.展开更多
Rainfall infiltration on a soil slope is usually an unsaturated seepage process that can be described by a water-air two-phase flow model.The effect of pore air pressure on rainfall infiltration has been widely recogn...Rainfall infiltration on a soil slope is usually an unsaturated seepage process that can be described by a water-air two-phase flow model.The effect of pore air pressure on rainfall infiltration has been widely recognized and validated by means of numerical simulations and laboratory experiments.However,whether a slope can actually seal pore air continues to be debated by researchers.In this study,a water-air two-phase flow model is used to simulate the rainfall infiltration process on a soil slope,and a field experiment is conducted to realistically test the sealing conditions of a slope.According to the numerical simulation,the areas of water and air flow in and out on the slope surface are relatively stable and can be classified as the“inhalation zone”and“overflow zone”,respectively.Intermittent rainfall on the soil slope has an amplifying effect on pore air pressure because rainfall intensity is usually at the millimeter level,and it causes pore air pressure to reach the cm level.A field experiment was performed to determine whether a slope can realistically seal pore air and subsequently verify the regularity of rainfall infiltration.Air pressure sensors were buried in the slope to monitor the pore air pressures during the rainfall process.The monitoring results show that the pore air pressure in the slope changed,which indicates that the slope can seal air.Moreover,the amplification effects of intermittent rainfall on pore air pressure were observed for natural rainfall,which agrees well with the numerical simulation results.展开更多
基金supported by National Key R&D Program of China (Grant No. 2017YFC1501100)the National Natural Science Foundation of China (Grant No. 51279090)Sponsored by Research Fund for Excellent Dissertation of China Three Gorges University
文摘Shallow slope failures induced by rainfall infiltration occur frequently, and the relevant triggering mechanisms have been widely studied.Rainfall-induced landslides are widely recognized to be caused by increases in soil weight, seepage force and pore water pressure or decreases in soil mechanical properties. However, even when all these factors are considered, some landslides still cannot be explained well. The increased pore water pressure in a slope reduces the effective stress of the soil and may trigger slope failure. Similarly, the pore gas pressure in a slope also reduces the effective stress of the soil but has been neglected in previous studies. As the viscosity of air is nearly negligible when compared with that of water, the pore gas pressure spreads faster, and its influence is wider, which is harmful for the stability of the slope. In this paper, the effects of pore gas pressure are considered in a shallow slope stability analysis, and a self-designed experiment is conducted to validate the force transfer mechanism.Numerical simulation results show that the pore gas pressure in the slope increases sharply at different locations under heavy rainfall conditions and that the pore gas pressure causes a rapid decrease in the slope safety factor. Laboratory experimental results show that the pore gas pressure throughout the whole unsaturated zone has the same value, which indicates that the gas pressure could spread quickly to the whole sample.
基金sponsored by The National Natural Science Foundation of China(Grant Nos.51939004 and 51279090)The National Key Research and Development Program of China(2017YFC1501100)the Hubei Key Laboratory of Construction and Management in Hydropower Engineering(2020KSD11).
文摘Rainfall infiltration on a soil slope is usually an unsaturated seepage process that can be described by a water-air two-phase flow model.The effect of pore air pressure on rainfall infiltration has been widely recognized and validated by means of numerical simulations and laboratory experiments.However,whether a slope can actually seal pore air continues to be debated by researchers.In this study,a water-air two-phase flow model is used to simulate the rainfall infiltration process on a soil slope,and a field experiment is conducted to realistically test the sealing conditions of a slope.According to the numerical simulation,the areas of water and air flow in and out on the slope surface are relatively stable and can be classified as the“inhalation zone”and“overflow zone”,respectively.Intermittent rainfall on the soil slope has an amplifying effect on pore air pressure because rainfall intensity is usually at the millimeter level,and it causes pore air pressure to reach the cm level.A field experiment was performed to determine whether a slope can realistically seal pore air and subsequently verify the regularity of rainfall infiltration.Air pressure sensors were buried in the slope to monitor the pore air pressures during the rainfall process.The monitoring results show that the pore air pressure in the slope changed,which indicates that the slope can seal air.Moreover,the amplification effects of intermittent rainfall on pore air pressure were observed for natural rainfall,which agrees well with the numerical simulation results.