Coupling Analysis On Seepage And Stress Fields In Unsaturated Soil In Response To Rainfall Infiltration

With in-depth understanding of engineering and geological calamity occurred frequently,the theory of unsaturated soil have been increasing attention.How to describe the interactionbetween the soil skeleton and the the fluid of seepge fieldhas always been a difficult point.Therefore,study of the coupled mathematical model of the seepage field and the stress fieldand the problem with a free boundary has scientific value and practicability.The classic Green-Ampt infiltration model has a strong applicability, while there is noconditions of landform included.The rainfall infiltration modelⅠis established by takinginto account different surface slope infiltration ,where the perpendicular direction haveinfiltration,and based on the composition of rainfall. There may be some time infiltrationafter the end of rainfall .Then,the modelⅡis based on this point and the Green-Amptinfiltration model,with taken pressure potential into account. This paper argues that theimpact of rainfall on seepage is mainly reflected in the impact on the flow velocity.The normally basic differential equation of seepage field and stress equation onunsaturated zone are derived from the Reynolds transport theorem,which is a typical theoremof fluid and is proofed by some simple mathematical analysis knowledge in the paper.The passage redefined the permeability coefficient function according to the relevanttheory of continuum mechanics, with considered stress accumulation and water history. Thetwo-field coupled equations in rainfall is based on the redefined function and the secondrainfall infiltration model.Wetting front divides the original area into staturated zone and unstaturated zone. Butwith the rain water infiltration, wetting front position has been changing.If that is coupledequations wetting front of a border, so as to form a free boundary problem. Such problemsare given a variational form, which lay a theoretical foundation on a calculation procedurefor the preparation of the follow-up.