堆积碎石土斜坡浅表入渗的空间分布与变异性研究
Spatial distribution and variability of infiltration characteristics for shallow slope of gravel soil
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摘要: 为探究强降雨下堆积体斜坡入渗参数的空间分布与空间变异性,通过筛分试验及双环入渗试验分别对堆积体斜坡试验点不同粒径区间碎石质量分数、碎石土渗透系数、饱和渗透系数、不同深度碎石土含水率进行测量,对数据进行普通Kriging插值统计分析,运用交叉检验选定合理理论模型与参数,获得其空间分布与变异性特征。研究结果表明:测试区碎石土入渗符合Kostiakov模型;不同粒径区间碎石质量分数采用高斯半变异函数理论模型空间插值精度最高,碎石土渗透系数和不同深度碎石土含水率采用球状半变异函数理论模型空间插值精度最高;粒径大于10 mm碎石主要分布于坡顶与坡腰区域且使该区域碎石土渗透系数的空间变异性相对较大,细小碎石(粒径2~10 mm)则聚积在坡脚位置,碎石土渗透系数速率沿坡面由上至下呈逐渐减少的空间分布趋势;浅土层(0~15 cm)坡腰含水率比坡顶、坡脚要高,而深土层(15~25 cm)坡脚含水率比坡顶、坡腰要高,且随深度增加缓慢上升。研究结果可作为碎石土滑坡降雨致滑的理论参考依据。Abstract: For accurate analysis of the spatial distribution and spatial variability of infiltration characteristics of aggregate gravel soil, the self-made double ring infiltration apparatus and gravel screening instrument have been used for testing gravel mass fraction of different particle size on slope , the permeability coefficient of gravel soil and different depth of gravel soil moisture content. Software is used for spatial interpolation of the discrete test data through the Kriging interpolation method. The cross tests are used to select a reasonable theoretical model, and the precise interpolation results are obtained. The results show that Kostiakov formula is used to simulate the infiltration process of gravel soil. The highest spatial interpolation precision about the gravel in different particle size sections is Gaussian semi-variable function theoretical model, and spherical model for the permeability coefficient of gravel soil and the moisture content of gravel soil at different depths. The gravels with particle size larger than 10 mm are mainly distributed in the top and middle slope regions, and the regional spatial variability of infiltration rate is relatively large. The small gravels (size of 2~10 mm) accumulate in the slope foot. The permeability coefficient of gravel soil along slope from top to bottom has a gradually decreasing spatial distribution trend. The moisture content at the slope waist is higher than that at the slope top and toe in shallow soil (0~15 cm), but that at the slope toe is higher than that at the slope top and toe in deep soil layer (15~25 cm). The water content of slope increases slowly with the increasing depth. The research results lay a theoretical foundation for the establishment of the prediction model for gravel soil.