Stochastic Damage Model for Concrete Structure of High-Speed Railway Tunnel Substrate

Based on the principles of thermodynamics and energy dissipation, and focused on the “tension to compression” repeated stress characteristics of high-speed railway tunnel substrate concrete structure, a double scalar damage variable was defined. By introducing a hardening function and revising the elastoplastic Helmholtz free energy, a stochastic damage constitutive model for concrete structure of high-speed railway tunnel substrate was established. In the effective stress space, the damage evolution law of damage variable was derived according to the orthogonal rule of plastic mechanics. Combined with the probability density evolution equation theory, the three-step numerical framework, i.e., “elastic predictor-plastic corrector-damage corrector” was provided, and a secondary development program was developed to achieve the numerical calculation of the proposed constitutive model. Uniaxial tension and uniaxial compression numerical tests of concrete were conducted, the results were compared with laboratory tests, through which, the accuracy and applicability of the proposed model were verified. Moreover, the proposed model can also reflect stress-strain relationship of concrete in the mean sense, and simulate its discrete range in the probabilistic sense. By applying it, the nonlinear and stochastic characteristics of concrete mechanical behavior can be comprehensively reflected and can also be used to calculate the damage evolution law and damage fatigue life of tunnel substrate concrete structure. © 2017, Editorial Department of China Railway Science. All right reserved.