DOI: 10.3724/SP.J.1249.2018.01070

Journal of Shenzhen University Science and Engineering (深圳大学学报理工版) 2018/35:1 PP.70-77

Transient flow in unsaturated soil under the constant air pressure

In order to discover seepage characters of unsaturated soil under air pressure, we establish a partial differential equation for the pore water pressure dissipation of triaxial specimens in terms of Darcy's law, the empirical formula between permeability coefficient and saturation or matrix suction. Then, we give the solution method for the partial differential equation based on differential principle. After the Wykeham Farrance (WF) unsaturated soil triaxial experiment system is employed, we perform the drying process under matric suction based on the axis-translation technique. Combined with the parameters obtained from the experiment, we solve the higher order nonlinear partial differential equations, and simulate the unsaturated process by finite element method (FEM) at the same time. The results are in a good agreement with the experimental data, the analysis solution and the FEM results. It shows that the established partial differential equation can depict the dissipation process of the unsaturated soil under the effect of air pressure. This study illustrates physical essence of the axis translation technique and may improve the existing experiment theory in unsaturated soil mechanics.

Key words:soil mechanics,unsaturated soil,constant suction,axis-translation,transient flow,differential principle

ReleaseDate:2018-03-20 15:26:55

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