Prediction Model of the Bimodal Soil-Water Characteristic Curve with Parameter Independence
In the soil with a dual-porosity structure,there are intra-aggregate pores and inter-aggregate pores,and the soil-water characteristic curve(SWCC)exhibits bimodal characteristics.The existing models of the bimodal SWCC are mostly established by linearly stacking two unimodal SWCC,having too many parameters of no independence.Thus,when they are used to fit experimental data,non-convergence may be caused.In the study,a novel prediction model of the bimodal SWCC was proposed based on the capillary theory.Firstly,by introducing hyperbolic trigonometric functions into a unimodal pore size distribution(PSD)function,the single peak of the unimodal PSD curve was geometrically split into two peaks so that a bimodal PSD function was obtained.Secondly,a bimodal SWCC model was built by accumulatively integrating the newly proposed bimodal PSD function.Finally,physical meanings of the parameters in the new model and their influences on the prediction results were analyzed.It was found that the model has parameters that are independent of each other.This new model was used to predict test data of SWCC of various soils with double-pore structure,achieving a good prediction agreement.
unsaturated soildual-porosity structureSWCCpore size distribution
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