钙、铝离子滤层结构对分散性土的改性试验研究

Experimental study on the modification of dispersive soil by calcium and aluminum ion filter layer structure

分散性土抗冲蚀能力很低,在水利工程中使用时易发生管涌破坏或淋蚀破坏,引发大坝防渗安全问题。本文针对黏土心墙坝的工程特性,提出了一种在心墙上游坝体内增设钙、铝离子滤层结构改性分散性土的方法,从而改善分散性土的易冲蚀性。通过针孔试验、碎块试验分别研究了石灰、氯化铝、氯化钙作为滤层结构对分散性土的改性效果及随时间的变化规律。结果表明,石灰滤层结构改性分散性土的效果与石灰水渗入土样后的时间有关,在1~5d可将土样改性为过渡性土,7d后可将土样改性为非分散性土;氯化钙滤层结构可将土样由分散性改性为非分散性,改性效果良好;而氯化铝滤层结构改性效果不佳。

Dispersed soil has a low erosion resistance and is prone to piping damage or erosion damage when used in water conservancy projects,leading to dam seepage prevention safety issues.According to the engineering characteristics of clay core dams,this paper proposes a method of adding calcium and aluminum ion filter layers to the core dam to modify the dispersed soil,thereby improving the erodibility of the dispersed soil.The effects of lime,aluminum chloride,and calcium chloride as filter layer structures on the modification of dispersive soils were investigated using pinhole tests and fragment tests,with a focus on studying how these effects changed over time.The results revealed that the effectiveness of lime filter layer structure in modifying dispersive soils was dependent on the time of lime water infiltration into the soil sample.It transitioned the soil into transitional soil within 1~5 days and non-dispersive soil after 7 days.The calcium chloride filter layer structure successfully transformed the dispersive soil into non-dispersive soil,demonstrating good modification performance.However,the modification effect of the aluminum chloride filter layer structure was found to be unsatisfactory.