EFFECT OF SALT CONTENT ON DESICCATION CRACKING BEHAVIOR OF SOIL

China is a big country of saline land, especially in the majority of the northern and western regions, the salinization of soil is much serious, which leads to significant deterioration in engineering properties of soil. To study the effect of soil salinity on shrinkage cracking, we prepare NaCl solution of concentration were 0, 1, 2, 3 moLL-1 respectively, then add the solution to soil stir saturated mud made the initial sample, the sample evaporation loss under simulated drought conditions, during the entire drying process measuring the moisture content of the sample timing change and use the camera to record the occurrence and evolution of fractures. The digital image processing system was used to quantitatively characterize the crack pattern, then the surface crack ratio, number of nodes, number of clods and fractal dimension is determined to describe surface cracking extent. The results show that the content of salt in the soil has an important impact on the dry shrinkage cracking process, with the increase of NaCl concentration, evaporation rate trends to decrease, and cracks appeared in the process of drying time delayed gradually, corresponding critical moisture content increases and the critical water content in the corresponding cracking rate increased. In addition, the development degree of fracture surface of specimen become lower with the increase of salt, as well as the crack width, length, fractal dimension, also with increasing salt concentration and decreasing. These phenomena related to the Interaction of salt-clay and the change of the electric double-layer.