Experimental Research of Matrix Suction of the Unsaturated Red Clay

Matric suction has great impact on the strength of soil. Some physico-mechanical indexes, such as the water content, dry density of soil, have close relationship with the matric suction. The experiments were conducted in the laboratory to study the relationship between the matric suction, the water content and dry density of unsaturated red clay. The filter paper method was used to get the soil-water characteristic curve of the unsaturated red clay. The results show that: water content has great impact on matrix suction. The soil-water characteristic curve can be divided into three stages. In low water content area, matrix suction decreases rapidly with the increase of water content. Then, the rate of change slows down after the inflection point. Matrix suction increases obviously with the increase of dry density under the condition of low water content, but the impact disappears under high water content. So the matrix suction is affected by dry density and water content.