soil liquefaction evaluation 3

[Kope]

i have to do a study about soil liquefaction, and within that work I need to use the so called chinese criteria. is there someone who actually used these criteria. As a matter of fact my question is What could be the mmeaning of "liquid limit". I guess that's a common term, frequently used in geotechnical language, but till now i didn't find its meaning. Thanks for your patience.

kope

 

[Qshake]

The liquid limit is defined by ASTM D-4318 as the moisture content at which a groove closure of 13 mm (1/2&quot occurs at 25 blows.

Perhaps a more useful relationship is:

PI=LL-PL

Where PI is the Plasticity Index, LL is the liquid limit, and PL is the Plastic limit.

Values of LL vary from 25 to 100 typically but can be larger.

Back to liquefaction, the following factors affect liquefaction characteristics and may be found in Prakash's Soil Dynamics:

Grain size distribution of sand
density of deposit (initial relative density, Dr)
vibration characteristics
location of drainage and dimensions of deposit
magnitude and nature of superimposed loads
method of soil formation
period under sustained load
previous strain history
entrapped air

 

[KAM_imported]

Since liquid limit is a term usually associated with silts, clays, or sand-silt, sand-clay mixtures, which are usually somewhat liquefaction resistant (since cohesive fines help stick the soil particles together, and thereby prevent liquefaction) the term "liquid limit" in this context may mean something else. I agree with QSHAKE about the "normal" definition of this term, however. Liquefaction is normally a problem in saturated, loose sands, but can be a problem with non--plastic silts as well.

 

[Kope]

The so-called Chinese criteria, as defined by Seed and Idriss (1982), stipulate that liquefaction can only occur if all three of the following conditions are met:

(1) The clay content (particles smaller than 5micro) is less than 15 percent, by weight.
(2) The liquid limit is less than 35% percent.
(3) The natural moisture content is less than 0.9 times the liquid limit.

Now, as you can see, I don't think that the liquid limit, in this context, has a diferent meaning than the one specified by qshake. It is refered strictly as a geotechnical soil property, not as an ad-hoc term defined especially within liquefaction susceptibility. Although, kam's asummption was not bad at all; liquid limit in terms of liquefaction could be a matter of common sense, regards liquefiable soils. The liquefaction potential is well-binded by the meaning of LL.

Thanks a lot!! both of you for your time and answers.