A Consolidated Earth Pressure Model for Geotechnical Stability Design of Embedded Cantilever Walls-Paper

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The paper presents the WYDIWYG (“What You Design Is What You Get”) consolidated earth pressure model for determining embedment depths of propped and free cantilever retaining walls. It addresses weaknesses in conventional methods, which can treat pressures below the limit equilibrium depth as extra disturbing loads, making calculated loads vary with embedment and producing inconsistent stability assessments.<br /><br />The model uses limiting earth pressures and establishes a fixed design-load reference at the limit equilibrium depth. Pressures developing below that depth are treated as net stabilizing resistance. Design proceeds in stages: determine the limit equilibrium depth, calculate additional embedment to meet the required factor of safety, and—for free cantilever walls—adjust the final embedment to satisfy both rotational and horizontal force equilibrium. This framework also clarifies how geotechnical reduction factors apply under AS 5100.3, including where stress reversal occurs.<br /><br />A 5 m excavation example compares the model with four established industry methods under long-term effective-stress and transient undrained conditions. WYDIWYG produces consistent stability factors across the scenarios and, in the study’s example, can reduce required embedment by up to 15% compared with traditional approaches without compromising safety or standards compliance. It also remains applicable across the tested undrained-strength range, where some comparison methods fail or give unreliable results.<br /><br />The authors conclude that the model offers a rational, economical, and automatable approach to wall embedment design. By satisfying both force and moment equilibrium, it can also provide convergent wall loads for structural design. Although developed around AS 5100.3, its principles may be applicable under other design standards and to other laterally loaded cantilever structures.

Keywords

WYDIWYG

earth pressure model

embedment depth

retaining walls

propped cantilever

free cantilever

limit equilibrium

stability factor

AS 5100.3

geotechnical design