Fractal prediction method for SWCCs (soil-water characteristic curves) under deformation condition

Abstract

The invention discloses a calculation method for predicating SWCCs (soil-water characteristic curves) under the deformation condition on the basis of the fractal theory. According to the method, fractal dimension D and air entry value after deformation are determined by utilizing the SWCC under the condition of initial void ratio e0 as a reference state, so that the SWCC under the condition of any void ratio e after deformation is predicated. On the basis of the fractal theory, a relation of water content and fractal dimension is obtained by the aid of a void diameter distribution density function, so that a fractal model is derived out. On the basis of the fractal model, the SWCCs under different initial void ratios are mainly controlled by the air entry value, and the fractal dimension is almost unchanged. A fractal dimension calculation method based on SWCC test data is proposed on the basis of the fractal theory, and a predication method of the air entry value under different initial void ratios is established. The test indicates that the SWCCs predicated with the method are better matched with actually measured values. The fractal prediction method has great significance in the aspects of hydraulic-mechanical coupling analysis of unsaturated soil, soil mass seepage characteristic research under the deformation condition and the like.

Description

technical field [0001] The invention relates to the technical field of researching unsaturated soil water-force coupling and soil seepage characteristics under deformation conditions, and more specifically relates to a fractal prediction method for soil-water characteristic curves under deformation conditions. Background technique [0002] Soil is widely distributed in nature, and most of the soil in nature is in an unsaturated state. With the development of society and the progress of science and technology, the study of unsaturated soil has become the research focus of the academic field of rock and soil mechanics. The study of unsaturated soil will inevitably come into contact with the soil-water characteristic curve. The soil-water characteristic curve is an important basis for the theoretical study of unsaturated soil mechanics. The soil-water characteristic curve plays an important role in the study of the theoretical and mechanical properties of unsaturated soil. occ...

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Problems solved by technology

[0006] 1. Direct measurement methods based on experiments: such as "Sandy Soil-Water Characteristic Curve Test Device and Test Method", "Multifunctional Soil-Water Characteristic Curve Tester", "Unsaturated Coarse Granular Soil-Water Characteristic Curve and Test device for permeability coefficient", "Automatic measurement system for high-precision soil-water characteristic curve", "A double-layer pressure plate instrument for measuring soil-water characteristic curve", "Method for obtaining Van Genchten model parameters of soil moisture characteristic curve" , "Testing device for soil-water characteristic curve with double air intake value of coarse-grained soil", "A soil-water characteristic curve test device with measurable volume change", the method proposed by this type of patent can only measure a certain void ratio The soil-water characteristic curve under the condition of 100% cannot achieve the purpose of predicting the soil-water characteristic curve under other void ratio conditions

If you want to know the soil-water characteristic curve under the condition of specific void ratio, you must pass the test method, which will consume more time and manpower

[0007] 2. Indirect measurement methods based on formulas or models: such as: 1. "A Simulation Method for Soil Moisture Characteristic Curve Based on Multifractal", this invention is based on multifractal method, fully considers the influence of soil structure on the simulation of moisture characteristic curve, and improves The simulation accuracy of soil moisture is improved, but the calculation model and calculation process are relatively complicated, and the soil-water characteristic curve under any void ratio cannot be predicted, and the invention belongs to the field of agricultural technology

②. "A Correction Method for the Unsaturated Soil-Water Characteristic Curve Tested Based on the Axis Translation Technology", this invention provides a method for improving the accuracy of the axis translation technology in testing the unsaturated soil-water characteristic curve, so that The test results are closer to the real results, but this method fails to achieve the purpose of predicting the soil-water characteristic curve

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