To daniellb1023
NOzAk%s3I Suggestion:
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LA:L W2 1) Read through the PLAXIS Manual, it explains a lot too!
'r/+z a:2 A@:h\< 2)Try to read some books about soil strength or soil mechanics including undrained and drained condition discussion.
)uG7 DR c ;RL<83: 1。plaxis 里面的plastic point 应该就是你说塑性点。我想问，这些点是不是就是接近fail的点？如果run construction sequence的时候，如果不能运行下去，出现错误，是不是说明是这些点fail了？那么请问应该怎么做才可以让你的程序继续运行。或者应该做些什么improvement 工作？ 谢谢。
$C&y-Hnar U;PGBoe When you run the program, what's the error you meet?
)\xDo<@ 06)B< 1)Numerical error: Check your geometry and some soil parameters (it may be obvious wrong)
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T 2)Interplation error and accurancy: you can increase the tolerate error, desired steps and so on. Check the Manual!
[.ya&E)x #Qi r%\*V 2。你的帖子里面说，如果是undrain conditioin的soil,从塑性和弹性来说，你建议用effective stress的方法来算。不过一般undrain condition的土都是clay / clayey soil.那么按经验+理论来说，不是一般都作total stress analysis的吗？这样不就是有矛盾之处了吗？
yX`5x^w Vw 2 b&&3u8 Total stress analysis for undrained condition is traditional thinking. But when you program, the result is not good. So far many software use effective stress analysis to deal with this issue(Please check out Manual, it explain that very clear)
\Uz7ar#, 6!QY)H^j9, You may read my previous posts. For undrained condition, there are three options in PLAXIS:
F=T} ;b 9i^dQV.U= A) analysis in terms of effective stresses (undrained material with E', v',
/Soc,PjZ c', phi' and psi').
^/ "[jq3F is the " undrained material" you mentioned is "clay " or also "silt"? because sand should always be drained, unless in special case. if yes. you suggest to use effective stress analysis for clay/silt?
te<lCD6 (by the way, psi is the value for what? and normally what is the value for typ. soil? )
\ytF@"7 obRYU|T V?yTJJ21X B) analysis in terms of effective stresses with undrained strength
a;GuFnfn, parameters (undrained material with E', v', but with c_u, phi=0)
xAZ-_ }'tW Xyz w.%4c compare the parameter between A)&B). seems like only c/c' & phi is different. may i know how to determine what one i should use. I mean how to apply it based on the real case.
W UN|,P`b )qbjX{GZ7 C) analysis in terms of total stresses (material is drained and dry, or non
V"A*k^} porous, E_u, v_u, c_u and phi = 0)
u lA|| ?QbxC,& i i can understand why to use this parameter for non-porous material. However, if the material is "drained" , which mean is "sand" or "dry silt/clay". in this case, it is suitable to use total stress analysis? or use effective is better. as the relationship/effert between water and soil in this case may not so.....closed.
2kXa *_ qLLJg actually , i have seen your this post. and understand that Plaxis can model the soil parameter/properties in such kind of way. However, i have some quaries also, some of questions have listed above. and additional question is: 1. based on my memory. there is a reference book/notes saying/suggesting that if the soil the clay, better to use undrain condition and use total stress analysis (because it is more realitic). am i right? or i misunderstood the reference notes? and if i input effective stress parameters. is "gama dry " = "gama wet - water density" ? thanks.
R&v V! d :gwM$2 vv 3。在 plaxis运行中，如果你想对改土进行total stress analysis，是不是就是把这个土的parameter都输入undrain的？gama wet 约=gama dry， 输入c/phi? 如果你要对改土进行effective stress analysis,就输入drain的condition? 输入c', phi', gama wet>> gama dry?
ktEdbALK 3RbPc8($Y A),B),C) can answer this question two!
G (Ky7S Z h?D>Dfeg% yes. but may i double check with you something.
z\kiYQ6kA 1. is about the soil density. which i also wrote in question 2.
/Wx({N'h$ U8||) + In MC model, it can not consider soil relative density (Dr).
{ S$]I)tV @ ,9cpaL3 2. from your answer of question2 c). for undrain material, if the material because drain due to some reason (ie: long term effect). you still suggested to input undrain parameters for this soil? or need to change it to drain parameter?
u#Z#NP ~F0 ]cKxYX)J If it is long term analysis, it should be drained condition, use drained parameters.
[ 此贴被mano在2007-09-02 07:58重新编辑 ]
