Soil Water Characteristic Curve Of Unsaturated Soil Based On Filter Paper Method

Unsaturated soils are common soils in engineering construction. It is necessary to clarify the nature and physical parameters of unsaturated soils before carrying out the project. Soil water characteristic curve and unsaturated soil seepage analysis shear .strength body change and other properties are closely linked. Due to the complexity of the nature of unsaturated soils it is very difficult to analyze the changes of soil water characteristics and other properties from the theory. Therefore it is possible to carry out the engineering practice and application value of soil water characteristic curve measurement in unsaturated soil.In this paper the characteristic curves of unsaturated soils were tested by laboratory test and field experiment. In the course of the study the application of unsaturated soil water characteristic curve and filter paper method in measuring the soil water characteristic curve of unsaturated soil is reviewed. The research status theoretical model and test method of soil water characteristic curve are summarized and summarized As well as the research progress of filter paper test theory;Followed by a series of laboratory tests including Whatman No. 42 quantitative filter paper to determine the balance time measured Whatman No. 42 quantitative filter paper total suction and matrix suction rate curve and the use of filter paper test loess silicon Albite montmorillonite fine sand four soil samples of soil water characteristics curve; Finally a three-month matrix suction test was carried out on a slope of Shandong University of Science and Technology. Get the following main findings1. Whatman No.42 Quantitative filter paper After 7 days in a sealed container the moisture content of the filter paper has changed little and tends to be balanced. From the test results can be concluded that the use of 7 days 14 days as a balance of time to test is entirely feasible.2. The total suction of the filter paper has a significant inflection point with the matrix suction rate curve curve.3. The soil water characteristic curves of different soil types have obvious difference and there are typical "S" type curve characteristics;soil particle size the impact of soil water characteristics of the curve has a significant impact;4. Field test With the increase of soil depth the water content of soil gradually increased the measured matrix suction also has a tendency to decrease with increasing depth and the change of suction is related to climatic conditions.