论文题目（1）：Coupled thermal–hydraulic modeling of artificial ground freezing with uncertainties in pipe inclination and thermal conductivity
作者：Yong Liu (刘勇)*, Kai-Qi Li (李凯奇), Dian-Qing Li (李典庆), Xiao-Song Tang (唐晓松) & Shi-Xiang Gu (顾世详)
杂志：Acta Geotechnica
DOI: 10.1007/s11440-021-01221-w
APA引用格式： Liu, Y., Li, K. Q., Li, D. Q., Tang, X. S., & Gu, S. X. (2021). Coupled thermal–hydraulic modeling of artificial ground freezing with uncertainties in pipe inclination and thermal conductivity. Acta Geotechnica, DOI: 10.1007/s11440-021-01221-w.
摘要：
Artificial ground freezing (AGF) has been widely used as a temporary soil stabilization and waterproofing technique in geotechnical practices (e.g., tunnel construction). Many sources of uncertainty exist during AGF. Firstly, groundwater seepage flow can adversely affect the freezing efficacy. Secondly, freeze pipe inclination inevitably occurs during installation, which is likely to yield an unfrozen path and elevate construction risk. Thirdly, as a key soil parameter, the spatial variability in thermal conductivity can also affect the freezing process. In this work, a unit cell model of freeze pipes is established by a coupled thermo-hydraulic finite element method to examine the effects of these sources of uncertainty. The pipe inclination is considered in the unit cell model by prescribing various values of freeze pipe spacing. The thermal conductivity of soil solid is simulated as a three-dimensional lognormal random field to account for the spatial variability of soil. Results are tabulated to evaluate the additional freezing time required in the AGF system due to the existence of these uncertainties. The findings are capable of determining a reasonable range of freeze pipe spacings and the corresponding critical seepage velocity, and can offer practitioners a rule of thumb for estimating freeze pipe spacing.
论文题目（2）：A generalized model for effective thermal conductivity of soils considering porosity and mineral composition
作者：Kai-Qi Li (李凯奇), Dian-Qing Li (李典庆), Dar-Hao Chen (陈达豪), Shi-Xiang Gu (顾世详) & Yong Liu (刘勇)*
杂志：Acta Geotechnica
DOI: 10.1007/s11440-021-01282-x
APA引用格式：Li, K. Q., Li, D. Q., Chen, D. H., Gu, S. X., & Liu, Y. (2021). A generalized model for effective thermal conductivity of soils considering porosity and mineral composition. Acta Geotechnica, DOI: 10.1007/s11440-021-01282-x.
摘要：
Soils have a variety of mineral compositions. Although a number of thermal conductivity models have been developed for soils, few quantitatively investigated the effect of mineral composition. In this study, the finite element method was employed to estimate the thermal conductivity of dry porous soils (kdry) considering the impact of mineral composition and porosity. A generalized model is proposed to predict kdry. The proposed model involves two steps. First, a modified form of Johansen’s model to evaluate the thermal conductivity of soil solid (ks) was established. The modified form considers a large number of soil samples where the soil composition varies and an empirical formula is obtained. Second, kdry is observed parabolically decreasing with porosity. Based on the relationship between kdry and porosity, a generalized model to predict the thermal conductivity of dry soil is proposed, and the empirical parameters for various types of soils are also determined for the sake of engineering applications. The performance of the proposed model is validated by comparing the predicted results with experimental data. A working illustration is exemplified for application of the generalized model.
