Influence of arrangement of freezing tubes on the ground freezing process with flowing groundwater

Ground freezing process, while now of the groundwater takes place is analysed in the paper. The considered process precedes drilling of the shafts. In particular, problem of arrangement of freezing tubes is discussed in the paper to obtain uniform frozen layer. It was demonstrated(8), that the flow of the groundwater can seriously influence the freezing process, and, if regular arrangement of freezing tubes is used, it can sometimes lead to formation of very unequal frozen layer. The appropriate numerical 2D calculations have been performed and their results are presented. Both the groundwater flow and the temperature field are calculated using FEM. The flow of the groundwater has been assumed to be incompressible. The velocity of the groundwater is then related to the velocity potential by Darcy's law and this potential is described by Laplace equation. The temperature distribution is determined by standard unsteady - state heat conduction equation with convective term in the unfrozen part of the domain and Stefan's boundary condition on the phase change interface. The original technique has been used, because of the unfrozen part of the domain, where the groundwater flows, changes its shape in time.