The typical loess on high slopes along the BaoLan High-speed Rail, China, was selected as the research object. The influence of the freeze-thaw cycle and dry-wet alternation on the shear-strength parameters of the uns...The typical loess on high slopes along the BaoLan High-speed Rail, China, was selected as the research object. The influence of the freeze-thaw cycle and dry-wet alternation on the shear-strength parameters of the unsaturated loess was investigated by laboratory experimental methods. Moreover, the temperature field, seepage field, and stability of slopes with different gradients were simulated under the effect of the freeze-thaw cycle and dry-wet alternation by using the geotechnical analysis software Geo-Studio. The research results showed(1) when the freeze-thaw cycle was repeated on the slope, with the frozen depth increasing, the melted depth did the same; besides, the closed loop of isotherms formed on the slope;(2) under the action of dry-wet circulation, the negative pore-water pressure and volumetric water content showed an upward tendency. However, owing to the different slope gradients, rainfall infiltration was not the same. As time went by, the differences of the negative pore-water pressure and volumetric water content between the slopes of different gradients continued to increase;(3) with the freeze-thaw cycle and dry-wet alternation increasing, the slope-safety factor decreased. Especially in the early period, the slope-safety factor changed remarkably. For slopes undergoing freeze-thaw action, the slope-safety factor was negatively correlated with the gradient. However, with regard to slopes undergoing dry-wet alternation, the result became more complex because the slope-safety factor was related to both seepage strength and slope grade. Accordingly, further research is needed to study the effect of seepage strength and slope grade on the stability of loess slopes.展开更多
为探明凉山干热河谷典型坡耕地土壤入渗性能的动态变化特征及其影响因素,选用微型圆盘入渗仪(mini disk infiltrometer)探究不同地表处理和不同时段(5、8、10月)的土壤入渗特征.研究结果表明:坡耕地连续休闲处理的土壤属性和入渗性能动...为探明凉山干热河谷典型坡耕地土壤入渗性能的动态变化特征及其影响因素,选用微型圆盘入渗仪(mini disk infiltrometer)探究不同地表处理和不同时段(5、8、10月)的土壤入渗特征.研究结果表明:坡耕地连续休闲处理的土壤属性和入渗性能动态变化不大,而5月份雨季初期的翻耕扰动是导致土壤属性突变和导水率急剧增加的主要原因,翻耕后的土壤属性和入渗性能至8月可恢复至连续休闲对照的水平;坡耕地种植玉米可显著降低土壤容重和增加团聚体水稳性,从而提升土壤入渗性能;土壤累积入渗量可以用入渗时间的二次多项式方程进行模拟,在Kostiakov、Philip和Green-Ampt 3种常用入渗过程模型中,GreenAmpt模型用于模拟坡耕地土壤水分入渗过程的效果最优.研究结果可为凉山干热河谷地区的坡耕地水分管理及土壤保持措施布设提供依据.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 51769013)
文摘The typical loess on high slopes along the BaoLan High-speed Rail, China, was selected as the research object. The influence of the freeze-thaw cycle and dry-wet alternation on the shear-strength parameters of the unsaturated loess was investigated by laboratory experimental methods. Moreover, the temperature field, seepage field, and stability of slopes with different gradients were simulated under the effect of the freeze-thaw cycle and dry-wet alternation by using the geotechnical analysis software Geo-Studio. The research results showed(1) when the freeze-thaw cycle was repeated on the slope, with the frozen depth increasing, the melted depth did the same; besides, the closed loop of isotherms formed on the slope;(2) under the action of dry-wet circulation, the negative pore-water pressure and volumetric water content showed an upward tendency. However, owing to the different slope gradients, rainfall infiltration was not the same. As time went by, the differences of the negative pore-water pressure and volumetric water content between the slopes of different gradients continued to increase;(3) with the freeze-thaw cycle and dry-wet alternation increasing, the slope-safety factor decreased. Especially in the early period, the slope-safety factor changed remarkably. For slopes undergoing freeze-thaw action, the slope-safety factor was negatively correlated with the gradient. However, with regard to slopes undergoing dry-wet alternation, the result became more complex because the slope-safety factor was related to both seepage strength and slope grade. Accordingly, further research is needed to study the effect of seepage strength and slope grade on the stability of loess slopes.
文摘为探明凉山干热河谷典型坡耕地土壤入渗性能的动态变化特征及其影响因素,选用微型圆盘入渗仪(mini disk infiltrometer)探究不同地表处理和不同时段(5、8、10月)的土壤入渗特征.研究结果表明:坡耕地连续休闲处理的土壤属性和入渗性能动态变化不大,而5月份雨季初期的翻耕扰动是导致土壤属性突变和导水率急剧增加的主要原因,翻耕后的土壤属性和入渗性能至8月可恢复至连续休闲对照的水平;坡耕地种植玉米可显著降低土壤容重和增加团聚体水稳性,从而提升土壤入渗性能;土壤累积入渗量可以用入渗时间的二次多项式方程进行模拟,在Kostiakov、Philip和Green-Ampt 3种常用入渗过程模型中,GreenAmpt模型用于模拟坡耕地土壤水分入渗过程的效果最优.研究结果可为凉山干热河谷地区的坡耕地水分管理及土壤保持措施布设提供依据.
