模拟降雨条件下寒旱地区边坡土体位移及土压力特征

摘要

The displacement and earth pressure characteristics of the vegetated slope and the bare slope in a cold and arid region under rainfall condition are explored to quantitatively analyze and evaluate the slope protection effects of plants.The self-built test area is located in Qinghai University of Xining Basin.Through in-situ rainfall simulation to the bare slope and the slope vegetated with Caragana Korshinskii.kom,the earth pressure values of the two slope surfaces are analyzed.Changes in the displacement in both the horizontal and vertical directions are analyzed as well.The stability of two kinds of slopes in the test area is evaluated.The results show that as to the slope vegetated with C.Korshinskii before and after the rainfall simulation in layer a (below slope surface 0 ～ 20 cm) and layer b (below slope surface 20 ～ 40 cm),the increase rates of soil moisture are reduced by 32.03 ％ and 13.63 ％ compared with the bare slope,which indicates that the plant stems and leaves play an important role in rainfall interception.After the rainfall simulation,the average earth pressures of the two slopes are slightly higher than that before the rainfall simulation,the average earth pressure of the bare slope is 0.125 kPa higher than that before rainfall and the average earth pressure of the slope vegetated with C.Korshinskii is 0.129 kPa higher than that before rainfall.The surface deformations in both the horizontal and the vertical directions of the bare slope before and after rainfall are 0.196 cm and 0.158 cm,respectively,and the slope vegetated with C.Korshinskii before and after rainfall are 0.031 cm and 0.027 cm,respectively.The results also show that the plants can significantly reduce the deformation of slope surface and improve the stability of the slope surface.The results of this test have theoretical and practical significance in preventing the occurrence of geological disasters,such as soil and water loss and shallow landslide in the test area.%为深入研究降雨条件下寒旱地区植物边坡与裸坡浅层位移及土压力特征,定量评价植物护坡效应,以位于西宁盆地的青海大学自建试验区为例,通过对柠条锦鸡儿边坡与裸坡开展原位模拟降雨试验,系统分析两种边坡浅层土体的土压力值及其水平、垂直方向上位移量变化规律;在此基础上评价这两种类型边坡的稳定性.得到以下主要结论:降雨前后,柠条锦鸡儿边坡a层(边坡表层以下0 ～ 20 cm)、b层(边坡表层以下(20 ～40 cm)土体含水率增加幅度均较裸坡降低32.03％、13.63％,反映出模拟降雨过程中植物茎叶起到降雨截流作用;降雨后两种边坡平均土压力值均较降雨前略高,其中裸坡增加0.125 kPa,柠条锦鸡儿边坡增加0.129 kPa.降雨前后柠条锦鸡儿边坡在水平、垂直方向的平均位移量分别为0.031,0.027 cm,裸坡坡面的分别为0.196,0.158 cm,说明柠条锦鸡儿根系在一定程度上起到有效抑制坡面土体变形效果,达到了提高边坡稳定性的作用.