Liquefaction Analysis
Liquefaction Analysis
(OP)
Fine Grained and Coarse Grained soil.
How is the current liquefaction analysis interpreted?
If you have a fine grained soil (50%+ passing #200) with a PI < 12, and Wc greater than 85% LL than it will behave like a sand, and is therefore liquefiable. Got it.
But if you have a clayey sand (or silty sand with say, passing #200 = 45%, is it then considered a sand, or sand-like, and therefore liquefiable. What if the 45 percent is montmorillinite, it will NOT liquefy.
Will a sand liquefy with 45 % montmorillinite? I don't think so.
BUT,
Can you run a PI on sand if it all passes the #40 sieve? Why not, but then how would you classify it on the Cassgrande Chart when it only references CL, CH, Ml, MH, etc.? Maybe classify it as a clayey sand, plastic fines?? sounds a bit crazy.
Any help?
How is the current liquefaction analysis interpreted?
If you have a fine grained soil (50%+ passing #200) with a PI < 12, and Wc greater than 85% LL than it will behave like a sand, and is therefore liquefiable. Got it.
But if you have a clayey sand (or silty sand with say, passing #200 = 45%, is it then considered a sand, or sand-like, and therefore liquefiable. What if the 45 percent is montmorillinite, it will NOT liquefy.
Will a sand liquefy with 45 % montmorillinite? I don't think so.
BUT,
Can you run a PI on sand if it all passes the #40 sieve? Why not, but then how would you classify it on the Cassgrande Chart when it only references CL, CH, Ml, MH, etc.? Maybe classify it as a clayey sand, plastic fines?? sounds a bit crazy.
Any help?
RE: Liquefaction Analysis
http://ussdams.com/proceedings/2014Proc/29-38.pdf
RE: Liquefaction Analysis
Their conclusion is interesting: "...As a result of the different purposes and
terminologies used, it is important to recognize that soils that are susceptible to
liquefaction are not equivalent to sand-like soils, and soils that are not susceptible to
liquefaction are also not equivalent to clay-like soils..."
"...Before using these liquefaction susceptibility methods (the ones presented in the document) it is important to understand
whether the soil is coarse-controlled or fines-controlled. When the coarse-grained
particles control the behavior (coarse-controlled), the liquefaction susceptibility methods
are not applicable and traditional liquefaction evaluation procedures should be used. On
the other hand, when the fines content controls the behavior (fines-controlled), the
liquefaction susceptibility criteria are applicable..."
RE: Liquefaction Analysis
RE: Liquefaction Analysis
Failure modes: There is also as mentioned the traditional pore water pressure increase until liquefaction occurs, and then soil mobility and other strength losses, to make it more complex. The PI is a good indicator if all soil passes the #40. Question, how would you classify a clayey fine to medium sand with a PI of 15, can it be a medium plasticity clayey fine to medium sand?
RE: Liquefaction Analysis