液态CO2地层冻结温度场演化的原位试验与数值模拟OA

In artificial ground freezing(AGF),traditional low-temperature refrigerants encounter challenges in meeting the construction demands of complex strata.This is primarily attributed to their relatively low freezing efficiency and high energy consumption.To address these issues,this paper presents a novel freezing technology based on liquid CO2.This technology enables efficient heat transfer and rapid freezing of the strata through three closed-loop circulation systems.Through a combination of in-situ experiments and numerical simulations,a systematic investigation is conducted on the evolution law of the temperature field and the reinforcement effectiveness of liquid CO2 freezing.The experimental results demonstrate that the cooling rate of this technology is four times that of traditional brine freezing.After just one day of freezing,the ground temperature can be reduced to-30℃.After 36 days of freezing,the thickness of the frozen wall reaches 3.06 m,with an average temperature of-23.9℃,and the expansion rate is 33.6 mm/d.All of these parameters are significantly superior to those of the traditional brine freezing method.By establishing a coupled hydro-thermal model,the mechanism of frozen will growth and closure is revealed.The simulation results indicate that the intersection of the frozen wall occurs after five days of freezing.Leveraging the efficient release of latent heat during phase change and the effective transfer of cooling capacity,the liquid CO₂technology not only enhances the freezing efficiency but also substantially reduces the construction cost,thereby holding great promise for engineering applications.