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1、问题：非饱和土的一维固结分析（abaqus在土木工程中的应用page158）9m0I9L5z2O4b$P/Z7r一个2m高的土体，水位线在土体的中央，即1m处，所以土体下半部分饱和，上半部分非饱和。土体的重度=18KN/M3，水的重度为10kN/M3,土的初始孔隙比e0=1，顶部施加一均布荷载为10kpa则其初始地应力如下：&s+U9E'w*T*initialconditions,type=stress,geostatic"w6K#K(t:J,c7v:gnup,-9.789，2，-22.97，1，0.5ndown,-22.97，1
2、，-35.97，0，0.5y=2时的地应力为-9.789是如何得出的？根据单向固结理论，有效应力=总应力-孔隙压应力。在非饱和问题中，ABAQUS采用的是：有效应力=总应力-饱和度*孔隙水压力。又由于ABAQUS对孔压正负号的规定和土力学中一致，而对应力正负号的规定和土力学中刚好相反，故上面公式中的“-”号要改为“+”号。手册中是分饱和，半饱和，以及干燥三部分说的，但是其给出的公式是两个，第一个是把饱和和非饱和结合到一块的，第二个是单存干燥的。手册里地应力平衡和饱和度的计算为：Verticalequilibriuminaporou
3、smediumMostgeotechnicalproblemsbeginfromageostaticstate,whichisasteady-stateequilibriumconfigurationoftheundisturbedsoilorrockbodyundergeostaticloading.Theequilibriumstateusuallyincludesbothhorizontalandverticalstresscomponents.Itisimportanttoestablishtheseinitialcond
4、itionscorrectlysothattheproblembeginsfromanequilibriumstate.Sincesuchproblemsofteninvolvefullyorpartiallysaturatedflow,theinitialvoidratiooftheporousmedium,,theinitialporepressure,,andtheinitialeffectivestressmustallbedefined.Ifthemagnitudeanddirectionofthegravitation
5、alloadingaredefinedbyusingthegravitydistributedloadtype,atotal,ratherthanexcess,porepressuresolutionisused(see“Coupledporefluiddiffusionandstressanalysis,”Section6.7.1).Thisdiscussionisbasedonthetotalporepressureformulation.Thez-axispointsverticallyinthisdiscussion,an
6、datmosphericpressureisneglected.Weassumethattheporefluidisinhydrostaticequilibriumduringthegeostaticproceduresothatwhereistheuser-definedspecificweightoftheporefluid(see“Permeability,”Section22.7.2).(Theporefluidisnotinhydrostaticequilibriumifthereissignificantsteady-
7、stateflowofporefluidthroughtheporousmedium:inthatcaseasteady-statecoupledporefluiddiffusion/stressanalysismustbeperformedtoestablishtheinitialconditionsforanysubsequenttransientcalculations—see“Coupledporefluiddiffusionandstressanalysis,”Section6.7.1.)Ifwealsotaketobe
8、independentofz(whichisusuallythecase,sincethefluidisalmostincompressible),thisequationcanbeintegratedtodefinewhereistheheigh
