One-dimensional thaw thermo-consolidation model for saturated frozen soil under high temperature and its solution

During the application of artificial ground freezing technique and construction in cold regions, high-temperature hot water is often used to melt the frozen soil manually. For the one-dimensional thawing process of saturated frozen soil under high temperature, a theoretical model describing the process is established and an analytical solution is developed for the model. The model comprises a heat transfer part and a thermo-consolidation part. The former is a heat conduction process of frozen soil with phase change of pore ice considering the unfrozen water effect, while the latter is a thermo-consolidation process of soil in the thawed region under the effects of high temperature, external load and self-weight. The temperature field and the melting interface for the heat transfer part have already been deduced in the existing literatures, which are adopted directly. For the excessive pore water pressure in the thawed region, an analytical solution is developed. By neglecting the thermal expansion of soil grains and water, the proposed model and the developed solution may degenerate to those of the classical one-dimensional thaw consolidation model for frozen soil developed by Morgenstern and Nixon. The analytical solution is then used to analyze the excessive pore water pressure and the settlement for one-dimensional thawing process of frozen soil under high temperature. The results show that the effect of thermal pressure reduces the excessive pore water pressure if the thermo-consolidation intensity factor ε is positive, and this effect increases with the increasing ε. Reducing the thaw consolidation ratio R or increasing the diffusion consolidation ratio F will expand the relative influence zone of the thermal pressure. However, the former leads to a more uniform thermal pressure effect in the thawed region, while the latter generally increases the thermal pressure effect in the thawed region. Increasing the self-weight time factor W_r barely changes the intensity and the relative influence zone of the thermal pressure. The net effect of high temperature is to expand the thawed soil, but it is weaker than the effect of normal consolidation settlement, thus the general effect is still settlement.