OasisLMS

Abstract:  Investigative drilling (ID) represents the practice of measurement while drilling (MWD) in the civil industry in Australia. This study presents a preliminary analysis of the correlations between pile capacities and drilling parameters based on the dynamic testing results of eight piles and their corresponding drilling data collected by ID. The relationships between the original drilling parameters— penetration rate (V_a), feed pressure (P_e), rotation pressure (P_cr), and flush pressure (P_f)— and pile testing outcomes, including shaft resistance, toe resistance, and total bearing capacity (derived from CAPWAP analysis), were examined. Additionally, four derived parameters, including the soil-rock resistance (P_e/V_a), torque reaction ratio (P_cr/P_e), normalized feed pressure (Q_t), and normalized rotation pressure (F_r), were also assessed. Two approaches were employed to process the drilling data: (1) shaft-averaging parameters along the pile length and (2) base-averaging parameters within 1.5D (pile diameter) above and below the pile base, referencing methods for pile capacity estimation using CPT data. Preliminary findings indicated that base-averaged Q_t moderately correlates with the bearing capacity of piles (r = 0.47), while the reciprocal of shaft-averaged penetration rate demonstrates a moderate-to-strong correlation with the bearing capacity (r = 0.63). The effectiveness of CPT-based normalization strategies appears to be variable. While the normalized feed pressure (Q_t) showed promising correlations, the normalized rotation pressure (F_r) produced results that were counterintuitive and require further investigation. Despite the limited pile testing data, this study highlights the potential of using drilling data from investigation boreholes for direct estimation of pile capacity, offering a more efficient and cost-effective approach for early-stage design.

Graduate Researcher Fei Huang

International Conference Proceedings