干湿循环作用下膨胀土裂隙演化规律及其对抗剪强度影响

Crack Evolution Rules of Expansive Soil and the Effect on the Shear Strength under the Action of Dry-wet Circulation

运用计算机图像处理软件对干湿循环作用下膨胀土表面裂隙的特征进行了表征,分析了膨胀土表面裂隙的演化规律,并结合直剪强度试验结果,探讨了表面裂隙形态的力学效应。结果表明:裂隙的节点个数、条数、总长度、区块个数、裂隙率和分形维数随土样干湿循环次数的增加而增加,而裂隙的平均长度、区块平均面积却相应的减小;第1次循环后,裂隙参数变化幅度最大,并干湿循环次数的增大逐渐趋于稳定。随着膨胀土表面裂隙网络裂隙率和分形维数的增大,粘聚力呈单调减小。而内摩擦角与裂隙网络分形维数和裂隙率的相关性较低。膨胀土抗剪强度随裂隙表面分形维数以及裂隙率的变化规律与抗剪强度随干湿循环次数的变化规律一致。

The computer image processing software is used to represent the characteristics of the fracture surface of expansive soil under dry-wet cycles,analyses the evolution rules of expansive soil surface crack,and combined with the test results of direct shear strength,mechanical effects of surface crack morphology is discussed. The results showed that： the fracture node number,article number,total length,number of blocks,crack rate and the fractal dimension increases with the increase of the dry-wet cycles,and the average length of crack,the average block area is decreased accordingly; After the first cycle,the fracture parameter variation is the largest,and the increase of dry-wet cycles gradually stabilized. With the increase of expansive soil surface crack network and fractal dimension,the cohesive force is monotone decreasing. And the correlation of internal friction Angle with the fracture network of fractal dimension and crack rate is low. The change rules of expansive soil shear strength with crack surface fractal dimension and the crack rate is the same as the shear strength with the dry-wet cycles.