The effects of shaking history on CPT based liquefaction triggering correlations for clean saturated sand are examined using cone penetration resistance and cyclic strength data pairs from dynamic centrifuge model tests. Three model tests on a 9-m radius centrifuge examine liquefaction responses of level profiles of saturated Ottawa F-65 sand subjected to multiple (17 to 29) shaking events that produced successive changes in density and model response characteristics. Inverse analysis of data from dense accelerometer arrays are used to define time series of cyclic stress ratios and shear strains throughout the profile. Cyclic resistance ratios against triggering of ~100% excess pore pressure ratio in 15 equivalent uniform cycles are computed at multiple depths based on weighting of the cyclic stress ratio time series up to the time of triggering. Cone penetration tests performed at select times during each model test are used to define the variation in cone tip resistances with depth and shaking history. The resulting data pairs, with normalized cone tip resistances ranging from 20 to 340 and cyclic resistance ratios ranging from 0.1 to 2.0, show that both quantities progressively increase as a result of recurrent liquefaction events, and generally follow the trends predicted by case history based liquefaction triggering correlations. Three 1-m radius centrifuge tests of similar configurations produced consistent results. Implications for the interpretation of case histories and engineering practice are discussed.

The effect of shaking history on cone penetration resistance, cyclic resistance ratio, and their correlation to each other for saturated sand is examined using centrifuge model tests. Prior laboratory and centrifuge modeling studies have shown strain history can have a strong effect on the cyclic strength of sand, but data describing how these effects track with cone penetration resistance are lacking. The effects of shaking history on cone penetration resistance and cyclic strength are investigated using centrifuge models of saturated Ottawa sand on a 1-m radius centrifuge with a 6-mm diameter cone penetrometer. The centrifuge models are subjected to a series of shaking events at progressively increasing amplitudes until liquefaction is triggered. This motion is repeated until the sand no longer liquefies. Cone penetration tests are performed before any shaking, after liquefaction is triggered, and after liquefaction no longer occurs. Inverse analyses of accelerometer array data are used to compute profiles of dynamic shear stresses and strains. The results are used to examine the effects of prior strain history on cone penetration resistance, cyclic resistance ratio, and their correlation to each other. The centrifuge test results are also compared with a case history-based liquefaction triggering correlation.