SPT and CPT Testing for Evaluating Lateral Loading of Deep Foundations

Current design software (FloridaPier, Com624P) requires p-y curves to estimate the foundation lateral load resistance. Input parameters used to develop these curves can be obtained from in situ standard penetration test (SPT) and cone penetration test (CPT)] correlations. This paper presents an evaluation of predictions using input soil parameters from SPT and CPT correlations versus field measured values. A lateral load test database consisting of 24 SPT and 6 CPT data sets was developed. The comparisons showed that four different SPT correlations for ? coupled with three different k-values all produce similar R-values. (R-value = measured∕predicted × 100%). Therefore, little difference exists between the SPT correlation combinations, albeit the estimated k value has a greater effect on predicted deformation. Similar combinations of CPT correlations also show little effect among the commonly used correlations. SPT predictions are quite conservative at low load levels (R-values ≈ 53%) and remain conservative (R-values ≈ 87%) at high load levels. Also, the scatter (standard deviation) is high (≈40%). CPT evaluations gave unconservative predictions (R-values ≈ 105 to 154%). In addition, the scatter (standard deviation) is high (≈34 to 74%).