亚洲一区欧美在线,日韩欧美视频免费观看,色戒的三场床戏分别是在几段,欧美日韩国产在线人成

Aiming to investigate the evolution characteristics of soil desiccation cracks with multiple dry—wet cycles, laboratory tests were carried out to quantitatively analyze the geometric and morphological characteristics of cracks. It indicated that the soil was cracked at the same position during each dry—wet cycle, and behaved a similar crack closure law. The crack ratio was decreased slowly before moisture content was increased to 12%, and decreased rapidly when moisture content reached 18%, while it was remained stable when moisture content was between 12% and 18%. Both the crack length density and connectivity index were decreased quickly after got a critical moisture content, which was reduced with the increase of dry—wet cycles, respectively, and kept constant before that. However, the initial cracking law was greatly affected by the first dry—wet cycle. Since the second cycle, the acceleration of crack ratio was decreased when the moisture content was changed from 30% to 20%, and about 90% of the crack was developed before moisture content reduced to 30%, and the connectivity index was increased at a constant speed when moisture content was larger than 14%. When the dry—wet cycles were increased, it can be concluded that: the crack morphology and length were kept stable;the cracking moisture content was reduced and the connectivity of crack network was enhanced, but there were no obvious differences;the average crack width and stable crack ratio were decreased gradually, and the average width tended to be the same, which weakened the crack preferential. The research result has practical guiding for cracked soil irrigation.