Taking into account moisture migration and heat change during the soil freezing process, as well as the influence of absolute porosity reduction on seepage during the freezing process, we construct a numerical model of hydrothermal coupling using laws of conservation of energy and mass. The model is verified by the results of large-scale laboratory tests. By applying the numerical calculation model to the formation of artificial shaft freezing temperature fields under the action of large-flow groundwater, we conclude that groundwater with flow rates of less than 5 m/d will not have a significant impact on the artificial freezing temperature field. The maximum flow rates that can be handled by single-row freezing pipes and double-row freezing pipes are 10 m/d and 20 m/d, respectively, during the process of freezing shaft sinking. By analyzing the variation of groundwater flow rate during freezing process, we find that the groundwater flow velocity can reach 5–7 times the initial flow velocity near the closure moment of the frozen wall. Finally, in light of the action characteristics of groundwater on the freezing temperature field, we make suggestions for optimal pipe and row spacing in freezing pipe arrangement.

To investigate the mechanical properties of frozen saline soil, the deep calcareous clay in the Huanghuai mining area was chosen as the research object, and an orthogonal test was carried out to study the true triaxial mechanical properties of frozen saline calcareous clay under the influence of multiple factors. The stress–strain characteristics, strength, and influence trend of salted frozen calcareous clay with different salt content, stress paths, and water content, and the relationships among the above-mentioned factors, were investigated. The analysis of the test results by an orthogonal test revealed the order of importance of the factors that influenced strength. The primary and secondary order of influence σ₁ is as follows: confining pressure σ₃, water content ω, temperature T, medium principal stress coefficient b, and salt content φ. Under the influence of multiple factors, the strength of frozen soil in the real state is not the result of single factors with independent influences that are then simply superimposed. Instead, the complex interactions of various factors affect strength. The stress path significantly influences the stress–strain relationship of frozen calcareous clay. As the coefficient of the intermediate principal stress b increases, its influence on the strength of salted frozen calcareous clay diminishes, and the optimal principal stress coefficient b = 0.33 maximizes the strength of the specimen. The influence of the moisture content on the strength of the sample is negatively correlated. The effect of different moisture contents on the deformation and failure characteristics of unsaturated saline calcareous clay is not significantly different, and this difference does not exceed 5%.

The uses of inorganic metal oxide as ultraviolet (UV) absorbers have potential to increase the production of UV protection and can also overcome the disadvantages of organic molecules. In this article, we report an effective technique to fabricating polyvinyl chloride (PVC) films with well UV shielding efficiency. Surface modification of zinc oxide (ZnO) nanoparticles (NPs) with different silane coupling-agents were achieved, and through solution casting technique dispersed within the PVC matrix. Infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and UV spectrophotometer were applied to study the structures, dispersions, and optical properties. The results showed that the functionalized ZnO NPs could be well dispersed in PVC and endow the polymer composite films with significantly improved anti-UV capability. The facile processing and obtained properties of PVC composites have shown potential for low cost and environmentally sustainable applications in the UV protection field.

Aiming at the complicated engineering conditions of the auxiliary shaft repair in the Banji coal mine, it was proposed to seal the water around the shaft lining by differential control freezing technology using double rows of holes. The outer row of holes is completely frozen, and the inner row of holes is local differential frozen according to the degree of destruction of the shaft lining. The local differential freezing pipe was successfully developed according to engineering requirements. Numeral simulations were used to predict the development of the freezing temperature field; the results showed that the inward expansion range of the frozen wall formed by the inner row freezing holes was effectively limited and the temperature drop rate of the shaft lining was significantly reduced after the local differential freezing technique was adopted. The on‐site monitoring data showed that the temperature of the limited freezing layer was about 5°C higher than that of the conventional freezing layer. During the drainage work and the construction of the new shaft lining, the thickness and average temperature of the frozen wall remained stable, indicating that the implementation of the local differential freezing technology achieved the expected results. Further analysis showed that when the temperature of the limited freezing part of freezing pipes in the inner row was controlled within the range of −15 to −10°C, not only could the frozen wall reach the design thickness and strength but the frost heaving pressure on the existing shaft lining could be effectively eliminated.