Research For Soil-water Characteristic Curve Of Unsaturated Reticulate Red Clay

Abstract:Reticulate red clay is the most common construction soil Dongting Lake area,and is wildly Distributed in our country. Currently, domestic research for unsaturated soil-water characteristic curve is still far behind the level of foreign, and research for unsaturated Reticulate red clay is minimal. Matric suction Have a significant impact on The shear Strength of unsaturated Reticulate red clay.This study Focus on how to solve problems encountered in engineering practice in the Dongting Lake region and this research has very important theoretical significance. Through theoretical,and experimental two parts, This study measured the soil water characteristic curves of reticulate red clay and studied the trends of the reticulate red clay suction during the wet and dry conditions change, the results research are the following:(l)Firstly, use the suction of NaCl liquor in the determination of equilibrium time. The filter paper is domestic double circle brand NO.202-type ashless filter paper. Filter paper calibration curve obtained general equation and the moisture content measured at the inflection point of the filter paper calibration curve. This experiment can NOt only provide the necessary reference data to the follow-up experiments to study unsaturated soil,and also reveal the relationship between total suction and moisture content of domestic double circle brand NO.202-type ashless filter paper.This work has a guiding significance to future research.:Using filter paper can measure a widely range of matric suction, and can meet the accuracy requirements very well. However, the experimental results will be affected by the operator is relatively large. When display the calibration results of the domestic double ring card NO.202ashless filter paper in the semi-logarithmic coordinates, the calibration curve is bilinear line with the inflection point.The inflection point occurs at about36%of moisture content. When the moisture content is small, suction rate of change with moisture content less; and when the moisture content exceeds the value inflection point, this rate will be significantly increased.(2)When use filter paper method to measure the suction, the growth rate of moisture content is the fastest at the beginning in the first day; the growth rate will be significantly reduced after until the moisture content is basically stable. The results of this experiment showed that4d can be used as an equilibrium time in the after experiments, this experiment provides a theoretical basis for the experimental program.The Moisture content of upper filter paper is always higher than the lower filter paper.(3) After finishing the experiment of calibrating filter paper curve,measured the textured unsaturated clay humidification curve and dehumidification curve.Calculated from the mathematical model of soil water characteristic curve. The results showed that:unsaturated textured clay humidification curve and dehumidification curve basically can be divided into three sections.In the high suction force region and low suction force region,the rate of suction changing is quickly, and relatively the middle region is flat. When the moisture content of the unsaturated soil is identified, the desorption process curve is always higher than the corresponding total suction humidification process curve. While his phenomenon reflected On SWCC, dehumidifying curve is always higher than the humidifying curve.(4) By study and compare the unsaturated textured red clay desorption process curve with humidification process curve, determine the parameter values of soil water characteristic curve model.