Prediction and Analysis of Formation and Development Characteristics of Frozen Soil Wall: A Case Study on the Chengjiao East Ventilation Shaft Repair

Abstract

Due to their advantages, artificial ground freezing methods are widely used in deep shaft construction and repair with the continuous exploitation of coal and other mineral resources. The boundary convection due to ventilation conditions will affect the formation and development of this frozen soil wall, which needs to be studied systematically. Thus, in this study, a numerical calculation model of a freezing temperature field was established based on the actual conditions of the east ventilation shaft in the Chengjiao coal mine during repair by the freezing method, and the temperature and thickness laws of the frozen soil wall and the shaft wall were studied by changing the influencing parameters. The results indicated that the thickness of the outside position gradually exceeded that of the inside position of the frozen soil wall due to the ventilation effect, and the difference between these two parameters was approximately 0.2~0.3 m, while the temperature difference was no more than 1 °C. The frozen soil wall did not complete a cross-loop within 180 d under ventilation conditions when the freezing tube pitch exceeded a certain threshold, which was about 2.3~2.5 m for this ventilation shaft. The soil moisture content played an important role in the initial freezing under ventilation conditions in the full combination calculation. This paper provides theoretical support for studying the application of the artificial ground freezing method for shaft construction and repair under ventilation conditions.