Reliability Analysis on Outer Shaft Lining Structure of Freezing Shaft in Deep Alluvium

Double high strength reinforced concrete wall is main support structure for deep surface soil freezing drilling in China. In this study, probability limit state design method is proposed to replace allowable stress design method in order to optimize the reliability design of high strength shaft lining in freezing shaft. Taking 501 m of outer sidewall of Dingji auxiliary well as the research object, the reliability of outer sidewall structure of deep alluvial frozen wellbore was analyzed by ANSYS finite element program. The results show that the reliability index of the coal mine at this depth is 2.98 and there is almost no difference between value of theoretical calculation and finite element simulation analysis. The importance for influence factors of outer shaft wall reliability from the large to the small is freezing pressure, axial compression strength of concrete, thickness-to-radius ratio and reinforcement ratio according to sensitivity analysis in ANSYS software.