机制砂级配及含量对压实膨胀土干缩裂隙演化规律

Influence of Machine Made Sand Gradation and Content on the Evolution of Dry Shrinkage Cracks in Compacted Expansive Soil

为研究砂含量以及级配对压实膨胀土干缩开裂的影响,以勉县滑坡点膨胀土为研究对象,制备了五种机制砂含量和四种机制砂级配的压实膨胀土试样,开展一系列压实土样干燥试验。利用图像处理技术并结合分形理论,对表面干缩裂隙的发育过程及最终状态的裂隙网络几何参数进行了量化分析。研究结果表明:表面裂隙面积的增加,前期表现为裂隙长度的增加,后期表现为裂隙宽度的增加;砂级配相同,随着砂含量从0%增加到40%,最终的表面裂隙率呈现依次降低的趋势,分别为13.18%,11.39%,10.47%,8.91%,7.68%;砂含量(40%)相同,随砂级配从[0.15 mm,0.3 mm)增加到[1.18 mm,2.36 mm),表面裂隙率依次减小,分别为7.68%,7.66%,4.38%,3.75%;裂隙分形维数的变化规律与表面裂隙率相同。

The paper aims to deal with the influence of sand content and gradation on dry shrinkage cracking of compacted expansive soil.The expansive soil of a landslide in Mianxian County was taken to prepare compacted expansive soil samples with five kinds of machine made sand content and four kinds of machine made sand gradation,on which a series of drying tests were carried out.Using image processing technology and fractal theory,the development process of surface dry shrinkage fractures and the geometric parameters of the final fracture network were quantitatively analyzed.The results show that the increase of the surface crack area exhibits an increase in crack length in the early stage and an increase in crack width in the later stage.With the same sand gradation,as the sand content increases from 0%to 40%,the final surface crack rate decreases gradually,being 13.18%,11.39%,10.47%,8.91%and 7.68%respectively.The sand content(40%)is the same.With the increase of sand gradation from[0.15 mm,0.3 mm)to[1.18 mm,2.36 mm),the surface crack rate decreases in turn,which is 7.68%,7.66%,4.38%and 3.75%respectively.The variation of the fractal dimension of the crack is the same as that of the surface crack rate.