Seismic analysis of underground structures based on damaged plasticity model

The authors give a comprehensive derivation of the concrete damaged plasticity model in ABAQUS, which is based on the damage mechanics and can describe the damaged mechanism of concrete during unloading in postfailure stage through introducing a damaged variable. The constitutive model can consider the stiffness degradation and strain rate under cyclic loading condition which is suitable for the analysis of concrete and other quasi-brittle materials, such as rock, mortar etc. In order to verify the feasibility of applying it to underground structures, a time-history dynamic nonlinearity analysis is achieved for a hydropower station underground structure which mainly considers the influence of different compression stiffness recovery factors and strain rate dependence to the damage of concrete and surrounding rocks. The simulation results indicate that the damage of underground structure is a progressive procedure; the rate dependent effect doesn't immediately occur at the beginning of earthquake but gradually behaves after the understructures have undergone some damage. The results also prove that the damaged plasticity model is dramatically competent for the dynamic nonlinearity study of underground structure during seismic loading especially under strongly seismic loading. The conclusion could be used as a primary guidance to the anti-earthquake design for practical engineering.