Empirical modeling of pore size distribution for rock materials with its impact on pore water freezing

Abstract

The phase transition of pore water in porous rock is closely related to the pore size distribution (PSD) based on thermodynamic equilibrium, and the ice formation is further affected by the internal hydraulic pressure and external confinement. This study quantitively assesses the risk of frost damage for rocks with/without surrounding pressures through a thermodynamic approach. First, an empirical PSD model is established and compared with experimental results, which is further adopted to calculate water saturation and ice volume under different humidity and temperature conditions. Then the depression of freezing point is discussed under undrained condition by dividing these rocks into three typical groups in terms of porosity and strength. Moreover, confinement by the high surrounding stress is considered for underground structures to study its influence on the ice formation process. Finally, correlation is found between the lowest bearable temperature and the expression of the porosity and strength of rocks, enabling a convenient assessment of frost damage risk for the rocks.