粉砂土改良膨胀土的干湿循环特性实验研究

Experimental Study of Cyclic Wetting and Drying on the Properties of Expansive Soil Stabilized by Silty Sand

膨胀土是一种广泛分布且胀缩性明显的特殊土,其裂隙的发育及扩展受到诸多因素的影响.通过30%的粉砂土改良膨胀土进行干湿循环后的直剪实验,采用MATLAB开发的图像处理技术及定量分析裂隙的程序,研究不同含水率的改良土随干湿循环作用的抗剪强度及裂隙的发育规律.研究结果表明:前3次干湿循环作用时,黏聚力下降较迅速,裂隙发育较快,分形维数增长也非常快,说明裂隙网络已初步形成.随后几次干湿循环的作用,黏聚力下降幅度变小,裂隙增长也开始变得缓慢,分形维数曲线也比较平缓,说明新的裂隙在原有裂隙的基础上开始向四周发散,裂缝比较细小.内摩擦角基本不受干湿循环作用的影响,一直保持平稳.

Expansive soil,is a kind of special soil,which is widely distributed and has obvious expansion and contraction.The development and expansion of cracks are affected by many factors.Through the direct shear test of 30%silt improved expansive soil after dry wet cycle,the image processing technology developed by MATLAB and the program of quantitative analysis of cracks are used to study the shear strength and fracture development law of improved soil with different moisture contents under the action of dry wet cycle.The results show that during the first three dry wet cycles,the cohesion decreases rapidly,the fracture develops rapidly,and the fractal dimension increases rapidly,which indicates that the fracture network has been initially formed.After several cycles of drying and wetting,the decreasing range of cohesion becomes smaller,the growth of fracture also becomes slow,and the curve of fractal dimension is relatively gentle,which indicates that the new fracture begins to diverge around on the basis of the original fracture,and the fracture is relatively small.The internal friction angle is not affected by the dry wet cycle and keeps stable.