Simulation of Early Age Concrete Thermal Stress of Composite Wall in Cut-Cover Subway Station

Strongly restrained by the retaining structures, the stress status of lining structure is complicated and cracks and seepage occur frequently. The FEM method is used to simulate the process and general trend of concrete hydration heat of lining wall. Further considering the concrete strength development, the early stage thermal stress of lining wall is analyzed as well as the influencing factors, including the maintenance conditions and lining wall thickness. Compressive stress generates and increases gradually with the temperature rising, then develops into a tensile stress as the temperature drops gradually. The maintenance conditions and lining wall thickness have a significant impact on thermal stress, which increases when the thickness increases and the maintenance conditions are bad. Good maintenance conditions can delay the generation of tensile stress, which is conducive to the stress creep and concrete strength increasing and can reduce the risk of thermal cracking at an early age.