强降雨致洪因素下渗流对高速公路路基稳定性的影响

Influence of Seepage on the Stability of Expressway Subgrade Under Heavy Rainfall-Induced Flood Conditions

近年来由于全球变暖的影响,极端降雨事件频发.洪水灾害多由暴雨引起,极端降雨一旦诱发洪水,会增大灾害的破坏力,严重威胁高速公路路基稳定性.采用有限元分析的方法,分析不同降雨强度、强降雨致洪作用下路基模型的渗流场、位移分布规律和安全系数的变化规律,探究降雨入渗、洪水渗流作用对高速公路路基边坡稳定性的影响.得出结论:①高速公路路基安全系数随降雨时长和强度的增加而降低,降雨强度越大,延长降雨时间对路基边坡安全系数的影响越大,路基的安全性能折损越严重,失稳风险越大.②高速公路路基的安全系数随着强降雨诱发的洪水高度的增加而降低,洪水水位越高,行洪时间的延长对路基边坡安全系数的影响越大,路基的安全系数折损越严重,失稳风险增加.③对比洪水对自然状态下的路基进行渗流,强降雨致洪条件下路基更容易失稳.与洪水直接对自然状态下公路路基渗流相比,若洪水作用前路基经历72h强降雨(20mm/h)作用,4、6、8m高洪水分别导致安全系数降低15.368%、21.438%、13.928%.

In recent years,global warming has amplified occurrences of extreme rainfall and related water disasters.Heavy rains frequently trigger floods,escalating the destructive potential of the disaster and posing a severe threat to highway subgrade stability.This study utilizes the finite element analysis method to investigate how varying rainfall intensities affect highway subgrade stability.Additionally,it innovatively assesses the impact of extreme rainfall-induced floods on the subgrade.Through an analysis of seepage fields,displacement distributions,and safety factor variations in roadbed models subjected to different rainfall intensities and flood levels,the study delves into how rainfall infiltration and flood seepage affect the stability of highway roadbed slopes.The findings suggest that the safety factor of the highway subgrade diminishes with increased rainfall duration and intensity.Greater rainfall intensity exacerbates the impact of prolonged duration on the safety factor of the subgrade slope,intensifying the safety performance loss and escalating instability risks.The safety factor of the highway subgrade diminishes with increasing flood height caused by extreme rainfall.Higher flood levels intensify the impact of prolonged flood seepage on the safety factor,leading to greater safety factor losses and increased instability risks.Under the combined influence of rainfall and flood,the potential for highway subgrade instability is higher.In comparison to natural seepage of the highway subgrade,if the subgrade experiences 72 hours of rainstorm infiltration before the flood,the 4 m,6 m,and 8 m high floods will cause the safety factor to decrease by 15.368%,21.438%,and 13.928%.