My understanding is that there are two different processes. There are some
chemical reactions involved in the deep cement mixing so the water content
reduced and the strength of the soil increased not just be consolidation.
This is a process which is difficult to be modelled by consolidation
theories.
CJ
-----Original Message-----
From: DR. A.H.C. CHAN [mailto:[log in to unmask]]
Sent: Tuesday, April 27, 1999 12:13 AM
To: [log in to unmask]
Cc: Chen Limin
Subject: Re:
...> Dear Sir/Madam:
...>
Dear Limin,
...> I have a question to ask,they are as the followings.
...>
This is an interesting question.
...> I am now using a FEM program based on Biot
consolidation theory to do
...> a two dimensional calculation for my dissertation. I
try to assess the
...> consolidation rate of soft clay ground improved by deep
mixing method
...> which final displacements are not same as the nature
ground. But I am
...> comfused by one question: How can I determine the
ground improved by
...> deep mixing method consolidate faster or slower than
the nature
...> ground.
By using deep mixing, the ground should be stiffer and
consolidation
should be faster. But on the other hand, the permeability
would be
reduced, the consolidation should be slower. On balance, the
amount
of settlement should be reduced but the consolidation should
take
longer.
...> Since the displacementand excess pore water pressure
are
...> interactive based on Biot consolidation theory.
There is no difference with Terzaghi consolidation except
the Biot
alpha factor.
...> Is the conception of
...> the "degree of consolidation"(defined by excess pore
water pressure)
...> still useful? In two dimensinal consolidation
analysis,can I compare
...> the rate of consolidation by average consolidation
degree defined by
...> the nodal vertical displacement which is just under the
loading and
...> in the middle?
...>
If you want to use "degree of consolidation", you should
consider all
nodes affected. Since the distribution of excess pore water
pressure
is not uniform, it would NOT have a linear relationship with
the
settlement at the ground level.
...> I will appreciate you if you kindly give me some
advices.
...>
I hope this is useful.
...> Best regards!
...>
...> L. Chen
...>
...>
...>
regards,
Andrew
...> ______________________________________________________
...> Get Your Private, Free Email at http://www.hotmail.com
...>
--
If a failure has to come in one's life, it'd better if it
comes early.
Dr. Andrew H.C. Chan: [log in to unmask] or
[log in to unmask]
Reader, School of Civil Engrg, Univ of Birmingham B15 2TT UK
Tel: +44(0)121 414 5100 Fax: +44(0)121 414 3675 Room 118B
http://www.bham.ac.uk/CivEng/pg/soils/chan/chan01.htm
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