干湿循环下改良膨胀土抗剪强度及裂隙发育特征研究

Study on Shear Strength and Fracture Development Characteristics of Improved Expansive Soil Under Dry-wet Cycle

为探究石灰改良膨胀土在干湿循环作用下裂隙发育规律及抗剪强度特征,设计并开展了室内干湿循环试验,对5%石灰掺量的改良膨胀土进行不同干湿循环次数下的直剪试验,然后采用MATLAB及PCAS图像处理技术对干湿循环后的土样裂隙进行定量分析。结果表明:随着干湿循环次数的增加,改良膨胀土黏聚力和内摩擦角逐渐减小,其中黏聚力呈指数下降,随着循环次数达到一定数量后趋于稳定值,内摩擦角随循环次数的增加下降较小。土样裂隙随干湿循环的进行而不断发展,且在前三次循环时发展较为明显,裂隙率在前三次共增加了6.38%,灰度均值在前三次共下降了23.67,土样裂隙的发展与上一次循环时具有较高相似性,裂隙沿着上一次的方向进行扩展延伸发育。

In order to explore the fracture development law and shear strength characteristics of lime improved expansive soil under dry-wet cycle,an indoor dry-wet cycle test was designed and carried out.The direct shear tests of improved expansive soil with 5%lime content under different dry-wet cycles were carried out,then,MATLAB and PCAS image processing technology were used to quantitatively analyze the cracks of soil samples after dry-wet cycles.The results show that with the increase of the number of dry-wet cycles,the cohesion and internal friction angle of the improved expansive soil gradually decrease,and the cohesion decreases exponentially.As the number of cycles reaches a certain number,it tends to be stable,and the internal friction angle decreases slightly with the increase of the number of cycles.The fracture of the soil sample develops continuously with the dry-wet cycle,and the development is more obvious in the first three cycles.The fracture rate increased by 6.38%in the first three times,and the gray mean decreased by 23.67 in the first three times.The development of the soil sample fracture has a high similarity with the last cycle,and the fracture extends along the direction of the last time.