Earthquake Geotechnical Engineering

A: That's the most common mistake — mixing total and effective stress or quietly dropping rd because it looks close to 1. The difference matters because liquefaction triggering hinges on σv/σ'v blowing up in saturated profiles, and COMAH reviewers will check the arithmetic. Using σv = 144 kPa, σ'v = 64 kPa gives the higher ratio that drives CSR to about 0.29.

A: That's the most common mistake — importing drained intuition into an undrained cyclic problem. The difference matters because during shaking the sand can't dissipate pressure fast enough, effective stress collapses, and you get cyclic mobility right when loads peak. Saying drainage saves you during the event won't survive a regulator's challenge.

A: That's the most common mistake — reaching for a chemical attack mechanism because the environment sounds aggressive. The difference matters because stone columns fail mechanically under earthquake cycling; aggregate breaks down and the column softens. Chlorides are a steel problem, not a crushed rock one, and an inspector will call that out fast.

A: That's the most common mistake — blaming axial capacity when the geometry screams kinematic demand. The difference matters because lateral spreading imposes bending from soil movement, not from the structure. If you mislabel it, the mitigation and the audit trail both fall apart.