Research on evolution characteristics of early-age temperature-stress field of inner lining at deep frozen shaft

In order to study scientific problem of early thermal stress of inner lining at deep frozen shaft under thermo-mechanical coupling, the thermo-mechanical coupling numerical simulation method with many boundary conditions such as internal heat, external cold source, friction constraints, upward shaft load and formation lateral pressure were proposed based on heat conduction and axial symmetry thermal stress theory. The evolution characteristics of temperature-stress field was obtained. The high-risk area of early-age thermal cracking was identified. The optimized direction of many measures of reducing early-age thermal cracking were proposed. The results as follows：①the results of temperature and strain of inner lining by numerical model are consistent with field measurement. ②Temperature in the center of inner lining is far higher than inner and outer edge due to the hydration exothermic and this easy to cause temperature cracking.③The strain value of inner lining is positive at early period of concrete poured, and center to inner edge value is higher than outer edge. Shrinkage strain emerged from center to outer edge and its value is -6×10 -5 at the later period. ④Pressure stress is stored in the inner lining at early period of concrete poured, and center value is higher than inner and outer edge. The tensile stress of inner lining at outer edge is 2.2 MPa with temperature decline.