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[探讨]用不排水强度参数分析基坑开挖 [复制链接]

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离线geofem

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只看该作者 12楼 发表于: 2007-08-24
这是相同模型,采用mc本构,处理前后的位移场。 -jJhiaJ$<  
PS:未处理模型网格稍有不同,但网格大小密度基本一直。
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mano 鲜花 +1 - 2007-08-24
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离线geofem

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只看该作者 13楼 发表于: 2007-08-24
至于有什么理论依据,拿不上台面,没有理论支持,经验不多,这里就不误导人了,呵呵。
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离线daniellb1023

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只看该作者 14楼 发表于: 2007-08-24
To mano / geofem: \>S.nW  
thanks for your good explainations $R}C(k ;?  
. 4PVg?  
however, i still got some questions to consult you all as my knowledge is poor. 8 o}5QOW  
O ?T~>|  
1. you are saying "固结不排水“ means "consolidation under undrain condition"(am i right?) , does it mean, if i am runing a case using PLAXIS, i need to run the consoildation while the soil parameter is in undrain condition? or depends ? <l1/lm<#  
.!~ysy  
2. May I know how to define in the PLAXIS software that effective stress /total stress method to be used? I mean how the software know effective stress is supposed to used in the analysis.  From the option when you select the soil type is "undrain/drain"? or from the soil parameter you key in? or from other place? SL uQv?R}9  
 _ %mm  
3. For normal / typical soil. what are the possion ratios (typ.)  for Soft Clay, Hard Clay, Marina Clay, Peaty Clay, Loose Sand & Dense Sand ?  Seems like this ratio may effect the basal heave, it may necessary to get it correct. at least to know the typical value, because this ratio normally will not provided in Soil Report. Mzg'$]N  
;,-)Z|W  
Thanks
离线mano

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只看该作者 15楼 发表于: 2007-08-24
Thank you for your example! 'q9Ejig  
I wonder how did you deal with the mesh? ])pX)(a  
e77s?WxbK  
引用第12楼geofem于2007-08-24 17:01发表的  : 6Hc25NuQZ  
这是相同模型,采用mc本构,处理前后的位移场。 ~(m6dPm$}m  
PS:未处理模型网格稍有不同,但网格大小密度基本一直。
离线mano

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只看该作者 16楼 发表于: 2007-08-24
Question 1): "固结不排水",    normally, it means that soil consolidated with drained condition and shear under undrained condition in triaxial test.  It came out Cu and phi_u or C' and phi'(using Mohr Circle with total stress reducing  pore pressure to get these effective value) ;Xidv9c  
                  J!rZs kd  
                  When u use PLAXIS, firstly of all, which type of soil you use(sand or clay, I have explained that in the previous post)? and which type of analysis you will use(short term analysis or long term analysis).  In the undrained condition, there are three options in PLAXIS. gKU*@`6G  
=L$RY2S"  
Question 2) Total stress analysis: typically for undrained condition. In PLAXIS, you should use choose"undrained condition" and material type should be"non-porous" or "drained", and poisson ration should be 0.45-0.49.  The detailed information, please take a look the MANUAL. Cyv_(Oh?dv  
Zfu" 8fX  
Question 3) the poisson's ratio value: it depends on the saturated degree and soil type. For saturated clay (normal consolidation,medium clay), it may be 0.49. For medium sand, it may be 0.33. The specified poisson's ratio, please check some textbook or references. xT9+l1_  
!oV'  
Suggestion: reading the textbook: <Soil Strength and Slope Stability> GmGq69]J*  
                          by J. Michael Duncan, Stephen G. Wright, Stephen G. Wright, Stephen G. Wright <.7W:s,f=  
                          They talked about some conception very cleayly, such as :undrained and drained condition, total stress analysis  and effective stress analysis  and so on jP @t!=  
:?%_JM5U  
Hope some help!
[ 此贴被mano在2007-08-24 17:52重新编辑 ]
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geofem 鲜花 +1 - 2007-08-24
离线benjackxu

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只看该作者 17楼 发表于: 2007-08-24
引用第15楼mano于2007-08-24 17:18发表的  : :S7yM8 b`  
Thank you for your example! 1J *wW# e  
I wonder how did you deal with the mesh?
"/XS3s v"s  
kk5i{.?[  
g9"_BG  
同问,咋处理的?对基坑比较感兴趣,除搞过边坡和堆石坝外,还没接触过别的呢。
离线geofem

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只看该作者 18楼 发表于: 2007-08-25
The secrete is the interface!
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离线mano

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只看该作者 19楼 发表于: 2007-08-25
Thanks, the interface element is always used when you model soil, concrete or steel. That is looks pretty important for excavation!  Actually, the interface element is used for all interface between soil and concrete or steel.
[ 此贴被mano在2007-08-25 11:01重新编辑 ]
离线daniellb1023

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只看该作者 20楼 发表于: 2007-08-25
引用第13楼geofem于2007-08-24 17:03发表的  : KJ)&(Yx  
至于有什么理论依据,拿不上台面,没有理论支持,经验不多,这里就不误导人了,呵呵。
C|J1x4sb@  
G!;[If :<e  
从你的2张图片上面看,(如果scale诗一样的话)明显basal heave变小了。请问你是怎么做到的,如果在plaxis上面要做到像你这样的情况要如何作处理(mc本购)?  虽然你说明了,这个是你的经验处理,没有理论支持,不过我感觉这样比较适合实际情况,所以很有兴趣知道你是怎么做到的。谢谢。
离线daniellb1023

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只看该作者 21楼 发表于: 2007-08-25
to mano: \veL5  
Xt84Evo  
may i know your QQ number? I want to consult you something step by step. i cannot fully understand what to do from your post. G]1pGA;  
UVJ(iNK"  
thanks a lot.
离线mano

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只看该作者 22楼 发表于: 2007-08-25
I am sorry, I can not use QQ in my office.  6{X>9hD  
8w[EyVHA  
You can read one fundmental book about soil mechanics. You may understand more! 3raA^d3!?  
[9_ (+E[}  
If u have any question, please send me message.  I will try to help you out!
离线daniellb1023

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只看该作者 23楼 发表于: 2007-08-25
actually , my question is not more about the soil parameter but how to apply it correctly into PLAXIS software. Pm(:M:a  
GPLt<K!<#  
by the way, the latest version has Duncan-Chang model or not? ,D2_Z]  
B~z g"  
thanks
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