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

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.