Deflection Mechanism and Stress Analysis of Large Steel Structure Derrick in Mine

The issue of large steel structure derrick in mine of freeze sinking on deep alluvium suffering from deflection and security enhancement is studied using the auxiliary shaft derrick of Dingji Coal Mine as a model system. First, the study analyses the mechanisms of uneven settling of the foundations in frost-thawed soil, the experimental results show that the bearing capacity and compression modulus of the soil mass decrease after freeze thawing. Since the soil texture and artificial freeze temperature field are uneven, resulting in uneven settlement of the foundation soil of the derrick footing and causing the deflection of the derrick. Secondly, the analysis of finite-element numerical values indicates that in the event of uneven settling, the greatest tensile stress in the derrick structure of Dingji auxiliary shaft increased by 39.83% and the largest pressure stress increased by 33.33%. These stresses have seriously affected the security enhancement of the derrick and ground stabilisation and deviation rectification of the derrick is urgently required.