Model test on the development of thermal regime and frost heave of a gravelly soil under seepage during artificial freezing

Abstract

In order to investigate the development of thermal regime and frost heave of a gravelly soil under seepage during artificial freezing, a large-scale model test system was designed. The typical gravelly soil in Beijing obtained from a construction site was taken as the study object. Artificial freezing tests were carried out on the soil layer under different seepage velocities. The test results indicated that the greater was the seepage velocity, the longer the closure time of frozen wall was needed, while the frozen wall would not intersect when the seepage velocity was too large. Lagged frost heave was observed after the thermal balance was reached. The frost heave of soil layer increased with the increase in the distance from the freezing pipes. Within the frozen range, frost heave increased with the increase in seepage velocity. Under seepage, the soil layer would turn into a soil of weak frost heave according to the Chinese code, while it was classified as non-frost heave under the hydrostatic condition. The model test showed that when the artificial ground freezing is used in the gravelly soil layer under seepage, the influence of seepage on thermal regime should be sufficiently considered, and considerable frost heave of soil layer might be expected.