Improving the Reliability of Pile Drivability Studies by Explicitly Simulating Ground Disturbance-PPT Presentation

PPT Presentation

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The presentation proposes a modelling approach to improve pile drivability predictions by explicitly simulating how pile installation disturbs the surrounding ground. Conventional wave-equation analyses represent soil resistance with simplified elements, while current methods often account for installation and time-dependent effects using empirical coefficients. These effects are difficult to predict because they involve interacting mechanisms, including excess pore pressure, changes in soil structure, stress relaxation, and soil–pile interface behaviour.<br /><br />The proposed method couples stress-wave analysis with independent axisymmetric finite-element models attached to ground nodes along the pile. During each simulated hammer blow, information is exchanged between pile and ground nodes to estimate ground stiffness and resistance. After the blow, the finite-element models are updated to reflect the ground displacement and interface slip that occurred. This framework creates an opportunity to represent installation effects and subsequent changes in ground response using soil constitutive models, rather than relying solely on empirical adjustments.<br /><br />A demonstration using a conventional continuum model shows that soil softening can affect predicted shaft resistance and the number of hammer blows required for installation. The approach may ultimately make parameter estimation more closely tied to laboratory testing and established soil mechanics.<br /><br />Further work is needed to develop constitutive models that capture installation and ageing mechanisms, represent the two-dimensional strain path around a pile, and account for waiting periods and pore-pressure dissipation. The authors also identify the need to verify that static finite-element simulations adequately reproduce disturbance caused by dynamic loading, determine suitable ground-model dimensions, and ensure the models remain reliable at large deformations.

Keywords

pile drivability

wave-equation analysis

finite-element model

soil disturbance

installation effects

excess pore pressure

soil softening

shaft resistance

stress-wave analysis

pile driving