Performance and stability of short piles in cracked desiccated soil

Many solar farms use solar panels supported by pile foundations. The required load capacities are small, but often design leads to a requirement for long piles because of reactive soil concerns. This situation is partly a consequence of limited evidence on the performance of piles in reactive soils, particularly when desiccation cracks are present. There is ambiguity regarding the influence of swelling and shrinkage on the strength of soil and its effect on soil-structure interaction that lead to practical challenges and disagreements in the design of short piles for solar farm foundations where economy favours pile termination within the active zone. While it is certain that cracks reduce the capacity, improved understanding in quantifying crack depth and the changes in soil stiffness and strength would reduce uncertainties required for cost effective design of foundations for solar farms in arid regions of Australia where expansive clays are encountered. A series of laboratory experiments have been performed using small scale model piles in expansive clays and sand-bentonite mixtures to understand the behaviour of piles under cycles of wetting and drying in the presence of cracks. These are to complement a full-scale test program underway in Adelaide. The load-displacement responses are compared with finite element simulations to quantify pile performance. Finite element simulations on scaled piles were performed to study performance variation in saturated and partially saturated conditions and results are presented.