What is the factor of safety against liquefaction?

FS = CRR7.5 / CSR × MSF, where CSR = 0.65 × (σv/σ'v) × amax/g × rd (stress reduction coefficient), CRR7.5 is the cyclic resistance ratio for Mw 7.5 from (N1)60 correlation, and MSF is the magnitude scaling factor. FS > 1.2 is generally considered non-liquefiable per NCEER (1997) and Youd et al. (2001).

What ground conditions are most susceptible to liquefaction?

Loose, saturated, uniformly graded sandy soils (SP, SM classification per USCS) with (N1)60 < 30 and fines content < 15% are most susceptible. Clays and gravels are generally not susceptible. The water table depth is critical — soils above the water table will not liquefy. ASCE 7 Chapter 11 and ASTM D7928 provide assessment guidance.

Liquefaction Potential Calculator (Seed & Idriss)

Assess soil liquefaction susceptibility using the simplified procedure of Seed & Idriss (1971) with cyclic stress ratio (CSR) and cyclic resistance ratio (CRR) from SPT data.

2D stress state at a point. All stresses in MPa.

σx — Normal Stress X (MPa)

σy — Normal Stress Y (MPa)

τxy — Shear Stress (MPa)

⚙ Mechanical Note: Results are based on standard textbook formulas and ISO/AASHTO references. Always verify critical designs with applicable codes (ISO 898, AASHTO 1993, AISC, Eurocode 3) and a qualified engineer.

How It Works

Assess soil liquefaction susceptibility using the simplified procedure of Seed & Idriss (1971) with cyclic stress ratio (CSR) and cyclic resistance ratio (CRR) from SPT data

Each component has a specific meaning:

Simplified procedure of Seed & Idriss — The simplified procedure of seed & idriss recorded for the patient or scenario being assessed.

Note: Interpret the liquefaction potential result against the clinical thresholds and context described above.

How to Use

Enter the simplified procedure of Seed & Idriss for the patient or scenario you are assessing. Assess soil liquefaction susceptibility using the simplified procedure of Seed & Idriss (1971) with cyclic stress ratio (CSR) and cyclic resistance ratio (CRR) from SPT data. Use the liquefaction potential result to inform your clinical assessment.

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Liquefaction Potential Calculator (Seed & Idriss)

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Frequently Asked Questions

What is the factor of safety against liquefaction?

What ground conditions are most susceptible to liquefaction?