[关键词]

[摘要]

为探究降雨条件下边坡坡度与坡体材料对临水岸坡失稳的影响，考虑不同边坡坡度和坡体材料2个变量，开展5组降雨条件下临水岸坡失稳模型试验，观察不同时刻岸坡变形特点并采用孔隙水压力计和土压力计监测坡体不同位置的孔隙水压力和土压力变化。试验结果表明：降雨对坡体表层结构稳定性影响显著，表层结构在降雨作用下迅速饱和，抗剪强度大幅降低，稳定性劣化，而内部结构因为水体较难渗入，影响较小；边坡坡度对边坡稳定影响较大，坡度越大降雨下渗越深入，下滑力增大，向下渗透力更强，对边坡稳定不利，即影响性坡度60°＞45°＞30°；坡体材料直接影响边坡稳定，不同材料的坡体渗透性能不同，当坡体含砂率为40%时渗透性能最好，坡体在5 min产生破坏且孔隙水压力响应较快，其发生失稳的概率更高；而坡体为纯黏土时渗透性最差，未产生明显破坏且坡内孔隙水压力响应较慢，降雨对边坡稳定性的影响有限。

[Key word]

[Abstract]

Bank slope instability is a common geological hazard,which extremely threatens people′s property and life in China.Rainfall is an important cause of bank slope instability,and the slope angle and the slope material directly control the stability of the bank slope.Therefore,it is meaningful to study the influence of slope angle and slope material on bank slope stability under rainfall conditions. To explore the influence of slope angle and slope material on the instability of water banks under heavy rainfall,5 model tests were carried out by taking different slope angles,slope materials and the deformation characteristics of bank slope were observed at different times.The change of pore water pressure and earth pressure in different positions of the slope were monitored by a pore water pressure gauge and earth pressure gauge. By comparing the failure process of 5 model tests at different times,the results showed that heavy rainfall had a significant effect on the stability of the slope surface structure.Under the action of rainfall,the surface structure rapidly saturated,the shear strength was greatly reduced and the stability deteriorates.However,the internal structure was less affected because the water was difficult to penetrate.At 60° slope angle,there were obvious cracks in the bank slope after 10 minutes of rainfall,and the cracks became larger as the rainfall time increased.After 2 hours of rainfall,the slope angle changed from 60° to 47°,and there were many obvious cracks on the surface of the bank slope.When the slope angle was 30° and 45°,there was no obvious damage on the bank slopes.The change in bank slope with different slope materials was also significantly different.There was little obvious damage to the clay slope during the whole test.When the sand content was 20%,the bank slope had erosion damage after 40 minutes of rainfall,and as the rainfall time increased,the damage gradually increased,Eventually,a collapse occurred on the surface of the bank slope when the sand content was 40%,and it was also noted that the bank slope had obvious cracks after 5 minutes of rainfall.About 70 minutes,there was a scour groove in the middle of the bank slope,which gradually widened with the increase of rainfall time. Under the rainfall,the bank slope became heavier and the sliding force increased.Moreover,with the increase of the water content of the bank slope,the shear strength decreased sharply,then induced bank slope instability.The slope angle had a great influence on bank stability.The bigger the slope angle,the deeper the rain seep,and the sliding force and infiltration force become stronger,which was not conducive to the stability of the bank slope,the influence was 60°＞45°＞30°,respectively.The slope material affected the bank slope stability directly,and different materials had different permeability.When the sand content was 40%,the permeability was best,and bank slope was damaged at 5 minutes and the response of pore water pressure was fast,the instability probability was higher with the worst permeability.When the bank slope was pure clay,and no damage obviously,and the response of pore water pressure was slow,the impact of rainfall on bank slope stability was low relatively.

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