黄土路基边坡降雨响应的试验研究

为了研究降雨入渗对黄土路基边坡孔隙水压力（吸力）、含水量、变形等的影响，选取甘肃平-定高速公路上某段9 m高的填方路基边坡进行了4场人工降雨模拟试验并持续现场监测一个月。监测结果表明：人工降雨模拟引起浅层土体（1m以上）吸力明显下降和含水量增大，致使土体有效应力减小，抗剪强度降低；另外雨水冲刷引起坡面冲沟发育，导致雨水入渗增大和土体强度的进一步衰减。压实度最小的坡脚处降雨引起的湿陷变形最大。在持续降雨的条件下，湿陷变形的发展会导致坡底的沉陷，最后发展为滑坍破坏。从减少雨水入渗，减小土体的强度损失以及控制湿陷变形等方面综合考虑，提高黄土路基边坡的压实度对防止降雨导致的边坡失稳具有重要意义。

Experimental research on response of a loess subgrade slope to artificial rainfall

To study the influence of rainfall infiltration on suction, water content and deformation of loess subgrade slopes, artificial rainfall simulation tests were conducted for four times on a 9 m high loess filled subgrade slope of Pingliang-Dingxi Expressway in Gansu Province, China, and the total in-situ monitoring continued for a month. Monitored results show that rainfall infiltration leads to obvious increase in soil moisture and decrease in soil suction within the top 1m soil layer, which results in a reduction of effective stress and shear strength. Meanwhile, the development of gullies on slope surface results in larger infiltration of rainfall and as a result a further decrease in shear strength. The maximum rain-induced collapse deformation occurred at the toe of the slope where the compaction degree is the lowest, which may lead to a local subsidence and trigger a slide slope failure in the condition of continuance rainfall. In consideration of controlling collapse deformation, reducing rainfall infiltration and the loss of shear strength of soil, it seems quite important to increase compaction degree of loess subgrade slopes.