TM 5-818-1 / AFM 88-3, Chap. 7
Table 17-6. Criteria for Excluding Need for Detailed Liquefaction Analyses
1. CL, CH, SC, or GC soils.
2. GW or GP soils or materials consisting of cobbles, boulders, uniform rock fill, which have free-draining
boundaries that are large enough to preclude the development of excess pore pressures.
3. SP, SW, or SM soils which have average relative density equal to or greater than 85 percent, provided that
the minimum relative density is not less than 80 percent.
4. ML or SM soils in which the dry density is equal to or greater than 95 percent of the modified Proctor (CE 55)
density.
5. Soils of pre-Holocene age, with natural overconsolidation ratio equal to or greater than 16 and with relative
density greater than 70 percent.
6. Soils located above the highest potential groundwater table.
7. Sands in which the "N" value is greater than three times the depth in feet, or greater than 75; provided that 75
percent of the values meet this criterion, that the minimum "N" value is not less than one times the depth in feet, that there
are no consistent patterns of low values in definable zones or layers, and that the maximum particle size is not greater
than 1 in. Large gravel particles may affect "N" values so that the results of the SPT are not reliable.
8. Soils in which the shear wave velocity is equal to or greater than 2000 fps. Geophysical survey data and site
geology should be reviewed in detail to verify that the possibility of included zones of lowvelocity is precluded.
9. Soils that, in undrained cyclic triaxial tests, under isotropically consolidated, stress-controlled conditions, and
with cyclic stress ratios equal to or greater than 0.45, reach 50 cycles or more with peak-to-peak cyclic strains not greater
than 5 percent; provided that methods of specimen preparation and testing conform to specified guidelines.
Note: The criteria given above do not include a provision for exclusion of soils on the basis of grain-size distribution, and
in general, grain-size distribution alone cannot be used to conclude that soils will not liquefy. Under adverse conditions
nonplastic soils with a very wide range of grain sizes may be subject to liquefaction.
U. S. Army Corps of Engineers
17-17
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