RAINFALL INFILTRATION TEST AND ANALYSIS OF LOESS SLOPE UNDER DIFFERENT RAINFALL INTENSITIES
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摘要: 黄土边坡的失稳问题是岩土工程中迫切需要解决的工程难题之一。首先,选取陕北黄土边坡为研究对象,开展4种雨强条件下的野外人工模拟降雨试验,通过测试边坡两侧开挖隔离槽并埋设隔离布从而改进测试边坡两侧的边界条件,实测不同雨强条件下边坡浸水深度以及土体含水率变化;然后分析不同雨强条件下降雨入渗过程和边坡应力变化特征,并比较不同雨强条件下入渗规律之间的差异。试验结果表明,不同雨强条件下的黄土边坡入渗深度均呈现坡脚最深、坡顶次之、坡中最浅的规律,入渗速率则是坡顶最快,其次是坡脚,最后是坡中;且随着深度的增加,雨水入渗能力逐渐减弱。随着雨强的增大,同一埋深处测点的体积含水率及土压力变化幅值变大,且含水率及土压力突变时间相应缩短,边坡的冲刷效果愈加明显。最后基于Geo-studio软件进行渗流分析,验证了现场试验结果的正确性,明晰了雨强对黄土边坡降雨入渗的影响。Abstract: The instability of loess slope is one of the engineering problems that urgently need to be solved in geotechnical engineering. Firstly, the loess slope in Northern Shaanxi is selected as the research object. Four field simulated rainfall experiments under the condition of rain intensity are carried out. The boundary conditions of the slope are improved by digging the isolation groove on both sides of the slope. The changes of the depth of the water immersion and the soil moisture content of the soil under different rainfall intensity conditions are measured. Then, we analyze the rainfall infiltration process and slope stress variation characteristics under different rain intensity conditions, and compare the differences between different infiltration laws under different rain intensity conditions. The test results show that the rule is as follows. The deepest infiltration is at slope toe. The second is at slope crest. The last is at slope middle surface. The infiltration rate is the fastest at slope crest, followed by the slope toe, and the last at the middle slope. The rainfall infiltration capacity gradually weakens as the depth increases. The volumetric water content and earth pressure change amplitude of the measuring point at the same buried depth become larger with the increase of rain intensity. The time is shortened for the abrupt change of water content and soil pressure. The effect of the scour is more obvious. Finally, the seepage analysis based on Geo-studio software verifies the correctness of the field test results and clarifies the influence of rain intensity on rainfall infiltration of loess slope.
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表 1 实验黄土物理性质
Table 1. Physical properties of loess
干重度
γd/kN·m-3天然含水率
w/%孔隙比
e渗透系数
k/10-6m·s-1塑性指数
Ip13.20 3.50 1.02 5.72 10.01 表 2 黄土土-水特征曲线参数
Table 2. Soil-water characteristic curve parameters of loess
模型参数 Van Genuchten a 12.92 n 1.68 m 0.38 R2 0.956 饱和含水率θs/% 46.2 残余含水率θr/% 2.7 表 3 渗透系数函数属性
Table 3. Properties of the osmotic coefficient function
土体性质 粉质黏土 饱和渗透系数/m·s-1 5.72e-006 孔隙比 1.02 进气值/kPa 17.3 残余含水率θr/% 2.7 渗透系数估计方法 Van Genuchten -
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