降雨诱发黄土高填方支挡边坡失稳机理研究

近些年，由于机场建设、公路铁路等地面交通网以及城镇化的建设在黄土丘陵地区开展越来越频繁，形成大量的黄土填方高陡边坡，虽然这些地区的年降雨量较小，但是降雨已经是诱发黄土滑坡的主要因素，通过对研究区黄土高填方边坡进行原位渗流实验和裂缝存在条件下暂态非饱和渗流以及饱和黄土力学特性进行分析的基础上，对降雨诱发黄土高填方支挡边坡失稳机理研究，研究表明：（1）3d后的原位渗流中实验试坑中心的最大入渗深度为1.30m，湿润锋最大深度位于入渗最大深度以下0.20m，但降雨条件下，裂缝的存在是黄土边坡发生浅层滑动的重要因素；（2）当围压小于300kPa时，饱和土体的轴向应变增长到20%左右时，达到稳定状态，在静力驱动剪应力大于稳态抗剪强度的条件下则会使高填方坡体的局部发生流滑破坏；（3）总体来说黄土高填方支挡边坡变形破坏的形成机制为：推移式蠕滑-支挡结构失效-累进性滑移剪断-牵引式溃滑。

RAINFALL INDUCED INSTABILITY MECHANISM OF HIGH EMBANK-MENT RETAINING LOESS SLOPE

In recent years, the constructions of airport, highway and railway transportation network and urbanization in the loess hilly areas have been carried out more and more frequent. They have formed a large quantities of high loess embankment slope. Although the annual rainfall of these areas is semiarid, rainfall is the main factor for the failure of loess slopes. This paper analyses the in-situ seepage experiment and the transient unsaturated seepage under the conditions considering the fractures and the mechanical properties of saturated loess. It examines the failure mechanism of high fill retaining loess slope. The results show the following. (1) The maximum infiltration depth of the test pit center is 1.30m after 3 days in the in situ seepage experiment. The maximum depth of the wetting front is 0.20m below the maximum infiltration depth. (2) When the confining pressure is less than 300kPa, the axial strain of the saturated soil increases to about 20%, and reaches the steady state. Under the condition that static driving shearing stress is larger than the steady shear strength, the local flowslide failure of the high fill slope can occur. (3) In general, the formation mechanism of deformation and failure of the retaining high embankment slopes is as follows:push creeping-retaining structural failure-progressive slip shear-traction collapse.