Nonlinear settlement prediction theory for CEP piles considering the effect of the consolidated body

A key construction feature of the Consolidated Expanded-Plate (CEP) pile is that the plate section is formed within a pre-consolidated soil mass, thereby eliminating the risk of borehole collapse associated with conventional squeezed branch piles. However, existing settlement prediction models for uniform-diameter and squeezed-branch piles generally neglect the influence of the consolidated body, leading to significant errors in settlement prediction. Accordingly, a nonlinear settlement prediction theory for CEP piles is developed based on the load-transfer method. The proposed model explicitly incorporates the shaft resistance contributions of both the consolidated transition section and the plate section, and is solved using a displacement-based iterative algorithm implemented in MATLAB. An orthogonal experimental design and sensitivity analysis are conducted to quantify the contributions of pile diameter, plate diameter, and six empirical parameters to the ultimate settlement, while investigating their effects on the load-settlement response. The results indicate that the plate diameter is the dominant factor governing the ultimate pile-head settlement, with a contribution rate of 45.68%. The consolidation amplification factors for the friction angle, cohesion, and elastic/shear modulus rank next, each contributing approximately 9–15%, whereas the remaining parameters have a combined contribution of less than 10%. Comparisons with field static load test results demonstrate excellent agreement between the predicted and measured responses. Under high loading levels, the average prediction error for pile axial force remains below 5%, while the maximum relative errors for plate resistance and pile tip resistance are less than 7%. The proposed method provides a reliable analytical framework for predicting the settlement behaviour of CEP piles and offers a practical basis for calibrating parameters and optimising design under similar geological conditions.