Influences of spatial variability of hydrothermal properties on the freezing process in artificial ground freezing technique

Artificial ground freezing (AGF) has been extensively applied in underground engineering construction as a popular ground-support technique. In recent decades, a series of investigations on AGF have been conducted through analytical, experimental and numerical methods. However, as critical parameters in AGF, the inherent spatial variabilities of hydrothermal properties of soils have been merely considered in previous studies. Therefore, this work aims to explore the influences of spatial variability of the hydrothermal properties (i.e., thermal conductivity and permeability) on AGF by stochastic finite element method combined with Monte Carlo simulation (MCS). Two-dimensional lognormal random fields are generated to account for the spatial variability of hydrothermal properties. The closure time is adopted as an indicator to evaluate the impact of uncertainty in hydrothermal properties on the freezing efficiency of AGF. In addition, the effect of MCS number on the statistics of the closure time in AGF is determined. Results demonstrate that spatial variability of the hydrothermal properties considerably affects the estimation of closure time. This study reveals the importance of random analysis in coping with the variation in hydrothermal properties and provides references for the design and construction of AGF.