The brittle t-z response of piles under axial loading: Physical models for teaching
The brittle t-z response of piles under axial loading: Physical models for teaching
The load-displacement response of axially-loaded piles is controlled by the axial stiffness of the pile and the shaft friction t-z load transfer behaviour. In many soils, the t-z response softens beyond a peak value, sometimes to as low as 10% of the peak resistance. This behaviour can be critical to the design of offshore piles, particularly in rock. The t-z brittleness causes progressive failure that affects the peak axial capacity of the pile. This paper describes a set of physical models that demonstrate this effect in a simple way, with visual and quantitative demonstrations of the effect of t-z softening and pile axial stiffness on axial capacity. The models use dry spaghetti in three-point bending to provide a linear-elastic brittle-softening t-z response. These pasta t-z elements are loaded in series via 3D-printed model piles with a range of axial stiffness. The response of this physical model can be simulated via classical pile solutions as well as by discrete modelling of the system of springs made up of the pasta t-z elements and the model pile. These physical models provide a visual demonstration of the progressive failure mechanism as well as quantitative results that match theoretical pile t-z response models. Combined with the accompanying teaching materials, these models provide a popular and insightful component of a masters-level course on advanced geotechnical engineering.
Abigail H. Bateman; David White
11th International Conference on Physical Modelling in Geotechnics (ICPMG2026)
Session 1: New facilities, new equipment, and measuring techniques
https://doi.org/10.53243/ICPMG2026-101