Lateral Stress Effects on CPT Liquefaction Resistance Correlations

The liquefaction potential of sand is increasingly evaluated using correlations between cone penetration test (CPT) tip resistance and cyclic resistance. These CPT liquefaction correlations have generally been assumed to be independent of the coefficient of lateral earth pressure at rest K0, because an increase in K0 is expected to increase both CPT tip resistance and cyclic resistance. In this paper, a procedure is developed that quantifies the effect of K0 on CPT liquefaction correlations for uncemented clean sand by considering separately the effects of K0 on CPT tip resistance and on cyclic resistance. It is shown that CPT liquefaction correlations appear to be reasonably independent of K0 for normalized tip resistances qc1 less than about 12 MPa. However, when K0 exceeds about 1.2 times its normally consolidated value (i.e., K0,NC), neglecting the effects of K0 on the CPT liquefaction correlations can be significantly unconservative for qc1 values greater than about 12 MPa. The proposed procedure may be of practical significance when evaluating ground improvement techniques that derive some of their observed benefit from increases in the in-situ lateral stresses.