Practical prediction method on thaw deformation of soft clay subject to artificial ground freezing based on elaborate centrifuge modeling experiments

Abstract

Artificial ground freezing (AGF) is a method of paramount importance for underground construction in soft soil area. Compared to the freezing process, the mechanism governing thaw response is much more complicated and harder to specifically control. The prediction of thaw deformation after AGF is of great significance in large-scale perturbation construction underpass existing structures. Currently most field experiments have focused on freezing, but are prohibited to thaw process due to high cost and long-duration, resulting in a lack of well-documented field experimental data to validate empirical or theoretical models from practical points. In this paper, a semi-analytical and semi-empirical practical thaw deformation prediction method was presented, combined with the practical thaw deformation model and a specific designed centrifuge modeling experiment. After the deduction and confirmation of similarity criterion of heat transfer by freezing pipe and heat conduction in surrounding soils from the perspective of temperature field and moisture field, simulation of thaw process under specifically back-deduced geometry and time scaling ratios was evaluated to be reliable through the method of modeling of model in centrifuge. Subsequently, multilayered temperatures and deformations were measured to calculate the actual thawing coefficient, thaw compressibility coefficient and height of thaw deformation domain, serving for practical thaw deformation model computation. Further, the practical thaw deformation model was verified by comparing the calculated thaw settlement with measured value. The relative error of calculation result range between 4.39 ∼ 7.23%, much higher than conventionl empirical model, which proves the applicability of this practical thaw deformation prediction method for AGF. This paper provides valuable practical method combined centrifuge modeling for predicting thaw deformation induced by AGF construction under large scale, extreme conditions in coastal cities, instead of long-term field experiments.