Degree of artificial freezing analyses under high seepage condition.

• Governing equations for thermal-hydro-salt-mechanical (THSM) coupling model are presented. • The THSM coupling model is used to analyze the artificial freezing process in the sand-marine clay layers under seepage flow conditions. • The average degree of artificial freezing at a given time is proposed to qualitatively analyze the effects of the artificial freezing. In this paper, the general governing equations for thermal-hydro-salt-mechanical (THSM) coupling consider the effects of adsorption salt on the surface of soil particles, the mushy zone at the phase-change interface, molecular diffusion and crystal growth, the compressibility of liquid and solid matrices, nonlinear high-salinity groundwater, non-convective flux and thermal permeability. The THSM coupling is used to analyze the artificial freezing process around freeze pipe installed in the sand-marine clay layers under seepage flow conditions. The good agreement between the calculations of the theoretical model and experiment models in the literature. Parametric studies were conducted to investigate the effects of seepage velocity and freeze pipe installation patterns on the effectiveness of artificial freezing which was evaluated using a new definition called the degree of artificial freezing. The average degree of artificial freezing DF at a given time is proposed to qualitatively analyze the effects of the artificial freezing. The lower the flow velocities of groundwater and the spacing of the freeze pipes, the more quickly the formation of the freeze curtain reaches DF =100 %. The freeze curtain with DF =100 % can be earlier formed in the sand layer with freeze pipes installed in rectangular pattern than those installed in triangular pattern. [ABSTRACT FROM AUTHOR]