Experimental and modeling investigation of freezing characteristic curve of silty clay using TDR

The soil freezing characteristic curve was investigated using TDR, and the freezing point model was established based on measured temperature-time curve. A modified model was established based on developed relationships between model parameters and total water content ω_total. The freezing degree was defined to describe the freezing process. The freezing point increased hyperbolically with increasing ω_total and decreased linearly with increasing dry density. A critical water content ω_cr was proposed, the growth rate of unfrozen water content gradually decreased with increasing ω_total when ω_total < ω_cr, and it was almost unaffected by ω_total and dry density when ω_total > ω_cr. The three parameters that were related to initial phase transition position, residual unfrozen water content and phase transition intensity in the modified model changed with ω_total rather than fixed constants, thereby overcoming the limitation that unfrozen water content continuously increases with increasing ω_total in the original model, which is suitable and important for changing total water content in multi-field coupling analysis of freezing soil. Comparison between predicted and measured results showed a satisfactory agreement.