黏性土在不同温度下干缩裂缝的发展规律及形态学定量分析

Developing law and morphological analysis of shrinkage cracks of clayey soil under different temperatures

通过试验,研究了黏性土干缩裂缝的发生和发展与温度之间的关系,运用计算机图像处理和编程技术,对不同温度下形成的黏性土干缩裂缝的表面结构特征进行了描述和定量分析。结果表明:土样裂缝的发生和发展过程基本上分三个阶段,在裂缝出现时,土样失水率有上升趋势;温度对黏性土表面裂缝节点个数、裂缝长度、裂缝条数、块区个数、块区的最可几面积、裂缝率和裂隙网络的分维数等参数有重要影响;块区面积分布函数的峰值随温度的升高而减小。

An experimental program was undertaken to investigate the effect of temperature on the shrinkage cracks of clayey soil. In this investigation, three groups of clayey soil samples were prepared and dried in oven at 30℃, 40℃ and 50℃. The forming and developing process of shrinkage cracks were observed at any time. Computer image processing techniques and programming were applied to quantify and describe the structure and geometric characteristics of surface cracks under different temperatures. It was shown that the structure parameters of surface cracks, such as the intersections of cracks network, length of cracks, number of crack segments, number of aggregates and the porosities （crack area in percentage of the image） and so on, were significantly influenced by temperature. Measurement of the fractal dimension of crack patterns using box counting indicated that the values of fractal dimension of the clay soil samples increased with the increase of temperature, and a larger value of fractal dimension indicated a more irregular and complex cracks structure. In addition, it was observed that cracking took place at three stages and the rate-of-loss of water increased when shrinkage cracks appeared on the surface of soil samples.