Creep characteristics and time-dependent creep model of tunnel lining structure concrete

Abstract

A creep test of concrete with different moisture contents is conducted using the MTS815.02 test system to investigate the creep damage law of concrete with respect to stress and time. The creep properties of concrete under hydration and the relationship between water content and concrete creep deformation are analyzed. The damage due to hydration and stress is considered comprehensively. The concrete creep characteristics and time-dependent creep model of different water contents are established based on rheological basic components. The Levenberg–Marquardt algorithm is used to fit the test data of concrete with different water contents. Furthermore, the correctness and rationality of the creep model are verified. Under the same stress level, the creep curves of different water contents show different creep stages. As the water content increases, creep changes at the same stress level are prone to stable creep and accelerated creep stages. The damage inside the concrete under high water content is significant, and the concrete is susceptible to creep deformation. The high degree of fit between the test data and the model curve reflects the suitability and feasibility of the established creep model to describe the deformation process of concrete creep with different water contents. The model accurately reflects not only the creep characteristics of the attenuation and stable creep stages but also overcomes the shortcomings of the traditional Nishihara model, which has difficulty in describing the accelerated creep. The deterioration law of creep parameters also reflects the damage degree of concrete under different water content conditions to some extent.