Effect of spatial correlation of cone tip resistance on the bearing capacity of piles

The cone tip resistance (q_c) from cone penetration tests (CPTs) is widely used to determine the bearing capacity of piles. Although it is widely known that soil properties are spatially correlated, the spatial correlation of q_c is not considered in the current methods for predicting the bearing capacity of piles. In this paper, a probabilistic approach is presented for predicting the bearing capacity of driven piles in clay by considering the spatial correlation between q_csVn (the spatial average of q_c of the bottom soil layer within the pile length) and q_cbV (the spatial average of q_c over an interval near the pile base). Parametric studies are conducted to evaluate the effect of the spatial correlation between q_csVn and q_cbV on the bearing capacity of piles. The results indicate that it is important to consider the spatial correlation between q_csVn and q_cbV in the probabilistic prediction of the bearing capacities of piles. Ignoring the spatial correlation between qcsVn and qcbV will underestimate the probability of failure and lead to unsafe design. Finally, 14 field test piles are analyzed with the presented approach to demonstrate the probabilistic prediction of the bearing capacity of piles by considering the spatial correlation of the CPT data.