Four. Sulfate Saline Soil Water And Salt Heat Coupling Effect Test And Theoretical Research

The salt expansion process of soil with Na₂SO₄ is concerned with the complicated interacting course of moisture field, salt field, temperature field, and stress field. The seasonal variety of the air temperature changes the hot condition occurrence of the roadbed, this causes the changing of moisture field, salt field and stress field, that is the key factor to cause the salt expansion. Accurately understanding the mechanism of salt expansion is the demandment of the constructing and development of the saline soil area engineering. In the paper, on the results of the experiment of soil with Na₂SO₄, the author analyzes the law exchanging of the temperature field, moisture field, stress field and salt field along with the sample depth,gives the formulae counting salt expansion rate of soil with Na₂SO₄. Further, posts the mechanism of salt expansion and mutual influence process of the four fields. Formulates the coupling math model of the moisture- salt-heat- stres fields to the soil with Na₂SO₄ during the changing process of the temperature and further research of it's answer. This provides the theories basis of putting forward more valid measure to control the salt expansion.