卢氏膨胀岩膨胀力特性试验研究

Experimental study on expansion force characteristics of expansive rock in Lushi County,Henan Province

通过对卢氏膨胀岩试样开展物理成分、微观结构和膨胀率等试验,研究了岩样泡水后膨胀力的特性及其变化的微观机理。通过X射线衍射试验发现卢氏膨胀岩的矿物成分中黏土含量约占49.1%,其中伊利石、蒙脱石的相对含量近90%,使其表现为较强的亲水性。基于加压膨胀法,设计了4种不同的初始含水率和4种不同干密度,共16组96个试样的膨胀力测试方案,探究了初始含水率和干密度对卢氏膨胀岩膨胀力的影响规律。通过多因素耦合分析方法,采用幂函数拟合初始含水率,指数函数拟合干密度,并给出了双因素膨胀力的拟合公式。通过电镜试验研究了初始含水率对膨胀力影响的微观机理,结果表明:当初始含水率较低时,黏土颗粒遇水膨胀后出现微小裂隙,导致膨胀力急剧增加;随着初始含水率增加,黏土颗粒的粒径由大变小,粗颗粒崩解,细粒含量增加,出现泥化现象,膨胀力缓慢减小。

By carrying out physical composition,microstructure and expansion rate tests on the expansive rock samples in Lushi County,Henan Province,the characteristics of the expansion force after soaking in water and its microscopic mechanism were studied.Through X-ray diffraction experiment,it was found that the clay content the expansive rock accounted for about 49.1%of the mineral composition,of which the relative content of illite and montmorillonite was nearly 90%,which made it exhibit strong hydrophilicity.We designed 4 different initial moisture contents and 4 different dry densities,a total of 16 groups and 96 samples were tested for the expansion force by the pressure expansion method,and explored the influence of the initial moisture content and dry density on the expansion force.Through the multi-factor coupling analysis method,the power function was used to fit the initial moisture content,the exponential function was used to fit the dry density,and the fitting formula of the two-factor expansion force was given.The microscopic mechanism of the influence of initial moisture content on the change of expansion force was studied through electron microscope experiment.When the initial moisture content was low,tiny cracks appeared due to the clay particles swelled after encountering water,resulting in a sharp increase in the expansion force.As the amount of water increased,the particle size of clay particles would change from large to small,coarse particles would disintegrate and fine particles would increase,during which the phenomenon of argillitization would appear,and the expansion force would slowly decrease.