Quantitative Research on the Relationship between Salinity and Crack Length of Soda Saline-Alkali Soil

摘要

The Songnen Plain in China has a typical type of soda saline-alkali soil that frequently shrinks and cracks under natural conditions, especially during water evaporation. This study aims to study the effects of salt contents on the cracking process of soda saline-alkali soils and to make a quantitative analysis between crack length and some primary salt parameters of soda saline-alkali soils. To achieve the objectives, 57 soil samples with different salinity levels were selected and a laboratory-controlled desiccation cracking test was then conducted. Next, correlation analysis was carried out between extracted crack lengths and salt parameters of all the specimens. The results showed that there are clear linear dependencies between crack length and salinity, Na+, Cl-, and electrical conductivity (EC), and that CO32- is also quite linear with crack length. The fitting results conducted from the verification experiment showed that Na+ content, Cl- content, EC, and total salinity showed high prediction performance (R-20.91 and RPD2.5); that the CO32- content had quite reasonable accuracy (R-2 = 0.78 and RPD = 1.82) but with less stability and poor reliability; that the prediction accuracy for pH, however, was very poor, with R-2 and RPD only 0.42 and 1.06, respectively.