Narrow Results

For the coupled damage problem caused by the surrounding rock of tunnel under high temperature and external load under fire conditions, an elastoplastic damage model is established based on the Mohr–Coulomb (M-C) criterion and the theory of continuous damage mechanics by introducing high temperature and load coupling damage factors. In order to solve the “singularity” problem of the model in the numerical integration process, the fully implicit return mapping algorithm in the principal stress space is deduced by region and including three steps of elastic prediction, plastic correction and damage correction. The finite element solution program of the model is written in C++ language, and uniaxial compression test and tunnel cavern calculation examples are used to verify and analyze the program calculation results. The results show that the difference between the peak intensity calculated by the model and the peak intensity data of the uniaxial test under each temperature is within 5% and the stress–strain curve calculated by the model is consistent with the overall trend of the test curve. The conclusion that damage around the cavity increases with increasing temperature is obtained by the simulation calculation of the cavern, which verifies the accuracy and feasibility of the model and calculation program. The safety and stability evaluation of the surrounding rock of tunnel under the action of fire is provided with a certain theoretical basis by the research content of this paper.

The accuracy of the risk evaluation associated with existing dams as well as the efficient design of future dams is highly dependent on a proper understanding of their behavior due to earthquakes. This paper presents a 3D anisotropic damage model for arch dam under strong earthquakes. The modified effective Mohr–Coulomb criterion is adopted as the failure criteria of the dynamic damage evolution of concrete. From the simulation of the dynamic damage process, some process fields of the dynamic displacement, the dynamic stress, dynamic damage distribution and other necessary information for the safety evaluation are obtained. These results show that the seismic behavior of concrete dams can be satisfactorily predicted. This will provide a reasonable theoretical support on the safety evaluation of the capability for concrete arch dams against earthquake loading.