Settlement Prediction of Nodular Diaphragm Walls Using the Load-Transfer Approach

Abstract This study proposes a load-transfer-based analytical method for predicting the compressive settlement of nodular diaphragm walls (NDWs), an advanced deep foundation system incorporating enlarged intermediate and bottom nodular sections to significantly enhance shaft friction and end-bearing capacity. The NDW is discretized into regular wall segments, middle nodular units, and bottom nodular units. Bilinear load-transfer functions are employed for shaft shear resistance (including nodular surface contributions) and compressive resistance beneath the middle nodule, while a hyperbolic model governs base resistance. To address the rectangular cross section, an equivalent elliptical shear field model is developed to rationally determine the peripheral shear stiffness. Stiffness parameters for nodular and base resistances are derived from elastic continuum solutions, with rigid-body displacement correction factors refined through numerical calibration. A displacement-compatibility iterative algorithm is formulated and implemented in a computational program to solve the complete nonlinear load–settlement response, explicitly accounting for layered soil conditions, self-weight effects, and nodular enhancement mechanisms. The proposed method is evaluated through comparisons with three-dimensional finite-element simulations established from published field load test data and a published physical model test. The comparisons demonstrate reasonable agreement in terms of load–settlement response, load-sharing ratios, and skin friction mobilization. The results confirm that the presented approach delivers accurate, practical, and theoretically sound predictions of NDW settlement in layered soils, providing a valuable engineering tool to support the design and wider adoption of this innovative foundation technology.