Numerical Study of the Effect of Verification Core Hole on the Point Bearing Capacity of Drilled Shafts

Abstract

This paper presents a numerical investigation of the effect of a verification core hole on the point bearing capacity of drilled shafts installed in clay shales. The verification core extracted at the shaft tip may reduce the point bearing capacity of drilled shafts as a result of degradation of clay shales and imperfect core hole infill. Finite-element analyses were conducted using the Mohr-Coulomb model with total stress material parameters estimated from laboratory tests. A series of load-displacement curves was calculated for 1 cycle of air drying and wetting; different drying durations and different core hole conditions were considered; and the point bearing capacity was determined at 3 and 5% shaft diameter displacements. The numerical analyses indicate that the point bearing capacity of drilled shafts with a verification core hole does not decrease for most cases, and the maximum reduction merely reaches 5%. Recommendations are made to reduce the effect of the verification core extracted at the shaft bottom during construction.