Seismic displacement of geosynthetic-reinforced slopes subject to cracks

Abstract

The kinematical approach of limit analysis associated with pseudo static assumption is employed to evaluate the displacement of geosynthetically reinforced soil slopes subject to cracks. According to existing literature, the seismic displacements for soil slopes have been calculated with the effect of possible cracking being neglected, such cracking is likely to emerge due to an earthquake with even moderately large motion. In this paper, a new technique is proposed to estimate the horizontal displacement of the slope toe for geosynthetically reinforced slopes resulting from a given earthquake postulating a rough estimation of real time crack propagation. The effect of crack formation as part of the failure process during the earthquake on the horizontal displacement of the slope toe is specifically tackled. The seismic displacement is estimated by incorporating a stepwise yield acceleration corresponding to postulated crack propagation. Rotational failure mechanisms accounting for either intact reinforced slopes that can show cracks or reinforced slopes with pre-existing cracks are considered. Two types of reinforcement layouts are employed here; uniformly distributed reinforcement along the slope height and linearly increasing distribution (i.e. the spacing between layers decreases linearly with depth). An example illustrating the procedure for a given earthquake is presented. Results show that the horizontal displacement of the slope toe calculated using the stepwise yield acceleration for both uniform distribution of reinforcement and for linearly increasing distribution can provide a reasonable estimation of the slope displacement. Furthermore, in terms of the slope displacement, linearly increasing distribution yields better results than the uniform layout.