EQ Engineering

Question 1

When/where does liquefaction occur?

Answer 1

In LOOSE, SATURATED sands during RAPIDLY APPLIED LOAD like ground shaking
Uniformly graded and/or rounded soils are more susceptible to liquefaction
Not enough time for water to dissipate so particles can’t move closer together –> reduces contact stress b/w particles which softens soils

Question 2

How is liquefaction calculated?

Answer 2

CRR/CSR > 1.1
Less than 1.1 is liquefiable
CRR: standardized to M7.5 and multiplied by magnitude scaling factor
CSR: avg shear stress/effective initial overburden stress

N160 > 30 is not considered liquefiable*
qc1n > 150 is not considered liquefiable*