Abstract: Based on the upper bound limit analysis theorem, the three-dimensional seismic stability of inhomogeneous soil slopes is investigated using the pseudo-dynamic approach, and the explicit expression of the factor of safety is obtained by the gravity increase method (GIM). In addition, the genetic algorithm is used for optimization and the results are verified by comparing with other published data. Parametric studies are performed to investigate the effect of relevant parameters on the stability of slopes. The results indicate that for the slope with the given height, the increase of width-to-height ratio and slope angle, and the decrease of internal friction angle and inhomogeneous coefficient will lead to the reduction of factor of safety. The pseudo-static method yields a larger result compared with the pseudo-dynamic method, and the difference between the results of the two approaches increases with the increases of the horizontal seismic coefficient and the effective internal friction angle, but decreases with the increase of the slope angle. The increasing of the soil amplification factor can lead to a significant decrease in the factor of safety of slope, while changes in the period and velocity of the shear wave have little effect on the stability of slopes. The trace of the slip surface is greatly influenced by the horizontal seismic coefficient, but less affected by the inhomogeneous coefficient.

Key words: inhomogeneous slope, three-dimensional stability, limit analysis, pseudo-dynamic method, seismic effect