Use of Finite Element Analysis for the Estimate of Freezing & Maintenance Phase of Indirect & Direct Artificial Ground Freezing of Proposed Frozen Silt Mat, an Alternative of Timber Mat

The use of heavy cranes has increased with the impact of modernized modular construction, which in turn has led to heavier modules, with weights often measured in hundreds of tons. As a result, the criticality of such lifts depends primarily upon the ground support health. The traditional approach is to make use of timber/steel mats for ground stability. The use of frozen silt (water and silt frozen mixture) as an alternative to this or to reduce the number of layers of timber mats is a novel technology that is explored in this work. For projects where this technology could be applicable, heavy construction companies will be able to avoid extensive ground preparation and reclamation by adopting this approach. The mechanical properties of frozen silt are comparable to timber mats (Coastal Douglas-fir), but are dependent upon the temperature constraint. This contribution encompasses the use of artificial ground freezing for the preparation of frozen silt matting for ground support. The required mat surface temperature is considered as ?10 °C, based on the competitive mechanical properties for its practical use. The freezing process is investigated using Finite Element Analysis (FEA). Simulation is performed to obtain the bottom-up estimate of ground freezing using indirect freezing (brine chillers) and direct freezing (liquid nitrogen) for both the freezing phase and maintenance phase. The simulation is executed under three ambient temperatures (10 °C, 5 °C and 0 °C) in order to make it realistic. The results from these simulations can establish a baseline for cost estimation for the alternative crane matting solution in the form of frozen silt mat.