Quasi-statischer Ansatz der seismischen Anregung von Böschungen mit nicht-linearer Wellenausbreitung

Quasi-static approach for stability analysis of slopes under seismic excitation using non-linear wave propagation

For the simplified stability analysis of slopes under seismic loading pseudo-static methods are used in some cases. In the limit equilibrium analysis the inertial force is considered to be static by the use of seismic coefficients, which relate the horizontal mass acceleration to the earth acceleration. In this paper such coefficients are derived on the physical basis of non-linear wave propagation within the slope. Recent design requirements of earth structures or slopes for seismic events within recurrence period of 2500 years lead for some projects by the employment of the simplified pseudo-static methods to overall factors of safety less than one. For the example of a slope within a brown coal open cut mining and filling area the derivation of the seismic coefficient is demonstrated and with FEM calculations for the non-linear dynamic case it is shown that states of equilibrium exist below the global factor of safety equal one. The design therefore has to take into account in such cases the acceptance criteria for deformations based on the serviceability and vulnerability of the nearby infrastructure affected by the permanent deformations of the slope.