Temperature Field and Stability Analysis of the Frozen Wall Based on the Actual Position of Freezing Holes

Abstract

Taking the Qingdong Mine as the research object, combined with field measurement data, numerical simulation and theoretical analysis are used to examine the temperature field and stability of the frozen wall in the mine, respectively. The results show that during the active freezing period, under the same freezing time, the average temperature of the effective frozen wall of the fine sand layer is 0.2–1.0 and 0.5–2.5 °C lower than that of the sandy clay layer and clay layer, respectively. The effective frozen wall thickness of the fine sand layer is 0.04–0.17 and 0.17–0.33 m larger than that of the sandy clay layer and clay layer, respectively. The soil cooling between the two circles of freezing holes is the fastest. Due to the deflection of the freezing holes, the interface temperature field is asymmetrical. For deep clay with a depth of 200–250 m, it is most economical and reasonable for the brine temperature in the active freezing period to be −25 and −30 °C. At the designed brine temperature for cooling, during the excavation of the control layer of the topsoil layer (−216 m sandy clay), the side-wall temperature, average temperature, and thickness of the frozen wall meet the design requirements. The ultimate bearing capacity of the frozen wall is 3.20 MPa. When the well is empty for 30 h after excavation, the maximum radial displacement is 26.85 mm, so the frozen wall strength and stability are in a safe state. Overall, the findings of this study can serve as a useful reference for similar freezing projects.