Study On Soil-water Characteristics And Its Application In Baiyangdian Area

With the rapid development of social economy,unsaturated soils will often be encountered in practical projects.There are differences in the properties of unsaturated soils and saturated soils,and the physical properties of different regions and soils will be different.Therefore,it is necessary to conduct research on unsaturated soils in specific regions.The difference in shear strength between unsaturated soil and saturated soil is due to the presence of matrix suction in unsaturated soil.Matrix suction is closely related to soil water content,volumetric water content,saturation,etc.Their functional relationship is mainly reflected by the Soil Water Characteristic Curve(SWCC).In this paper,the unsaturated soil in Baiyangdian area is taken as the research object,and the research on its soil and water characteristics is carried out.The main research contents are as follows:The soil water characteristics of unsaturated soil in Baiyangdian area were studied by means of filter paper method by means of the existing instruments and equipment in the laboratory.The soil water characteristic curves of soil samples under different initial dry density were determined.The test results show that the initial dry density and mass moisture content of the soil sample will affect the matrix suction value and total suction value: the larger the initial dry density,the larger the matrix suction value and the total suction value of the soil;the larger the mass moisture content,the soil The smaller the matrix suction value and the total suction value of the body.2.In order to obtain the physical model of soil water characteristic curve suitable for unsaturated soil in Baiyangdian area,this paper selects the physical models commonly used in 8 geotechnical engineering to fit the data measured in this experiment,and adjusts the decision coefficient.The fitting parameters and the fitting curve are compared and analyzed.It is found that the FX3 model,the Gardner model and the package model can achieve a good fitting effect.Through three engineering examples,the influence of matrix suction of soil under different conditions on the anti-overturn stability of the foundation retaining wall is analyzed.Studies have shown that considering the matrix suction can improve the anti-overturning stability coefficient Kt of the foundation pit and reduce the depth D of the retaining wall.In practical engineering,considering the matrix suction and not considering the matrix suction will have different results for the design of the rigid retaining wall of the foundation pit,which will affect the investment of engineering economic cost.