In this study, a nonlinear model is presented for analysis of damage-cracking behavior in arch dams during strong earthquakes using different seismic input mechanisms. The nonlinear system includes a plastic-damage model for cyclic loading of concrete considering strain softening and a contact boundary model of contraction joint opening. Two different earthquake input mechanisms are used for comparison, including massless foundation input model and viscous-spring boundary model considering radiation damping due to infinite canyon. The results demonstrate that effects of seismic input mechanism and radiation damping on nonlinear response and damage-cracking of the dam are significant. Compared with the results of using massless foundation input model, the damage-cracking region and contraction joint opening are substantially reduced when using viscous-spring boundary model to take into account radiation damping. However, if the damping ratio of the dam is artificially increased to about 10%–15% for massless foundation input model, the joint opening and damage-cracking of the dam are comparable to the results obtained from the viscous-spring boundary model.
The present paper generalizes the method for solving the derivatives of symmetric isotropic tensor-valued functions proposed by Dui and Chen （2004） to a subclass of nonsymmetric tensor functions satisfying the commutative condition. This subclass of tensor functions is more general than those investigated by the existing methods. In the case of three distinct eigenvalues, the commutativity makes it possible to introduce two scalar functions, which will be used to construct the general nonsymmetric tensor functions and their derivatives. In the cases of repeated eigenvalues, the results are acquired by taking limits.
Rock rebound relaxation deformation,or even rock burst,caused by the excavation of dam base and abutment or high rock slope affects their stability and results in the fall of mechanical properties of the rock.So an inverse analysis method was proposed in this paper to establish the time-dependent model of deformation modulus caused by excavation rebound.The basic principle is based on the combination of observed data of the excavation rebound deformation of dam abutment or rock slope,and the calculated rebound deformation by FEM under ground stress at the corresponding time in the excavation process.The norm of the residuals of observed data and calculated data are taken as the objective function.Accordingly,the time-dependent model of bedrock deformation modulus can be established.The method displays its significance in the design of excavation,construction and operation management of dam base and high slope.
