An incrementation-adaptive multi-transmitting boundary for seismic fracture analysis of concrete gravity dams

This study presents a numerical framework and methodology that features a nonlinear extended finite element formulation for earthquake fracture analysis of dam-reservoir-sediment-foundation coupled systems and an adaptive time incrementation multi-transmitting boundary for modeling seismic wave propagation in both infinite reservoir and foundation domains. To improve the convergence rate during the iterative solution of the highly nonlinear dynamic equilibrium equation, the original Multi-Transmitting Formula (MTF) is modified and coupled to the automatic incrementation time-stepping scheme through the introduction of a fictitious time scale in conjunction with an interpolation scheme that links the fictitious time scale to the real time scale. Meanwhile, the dynamic crack initiation and propagation in the body of the dam is represented by the extended finite element method including the effects of branching and intersecting cracks. As an application of the proposed formulation, the seismic cracking behavior of a representative concrete gravity dam system is analyzed.