Seismic evaluation of helical soil-nailed walls using shaking table testing

Abstract

The effects of the nail arrangement and nail inclination on the dynamic performance of helical soil-nailed walls (HSNWs) were evaluated using a series of shaking table tests. The results showed that although a uniform increase in the nail length along the wall height significantly improved the seismic performance of the HSNWs, this improvement could also be achieved to some extent by increasing the length of the nails locally in the lower and upper halves of walls reinforced with horizontal and inclined nails, respectively. The use of inclined nails instead of horizontal ones was an efficient solution for reducing the lateral displacement, the acceleration amplification and increasing the fundamental frequency of HSNWs. The effectiveness of this solution was reduced with the use of shorter nails in the upper half of a wall and eventually minimized by reducing the length of the nails across the wall height. The nails located in the lower half of the wall were identified as having the greatest effect on the seismic performance of HSNWs when horizontal nails were used. The opposite occurred when inclined nails were used. A parabolic failure surface with a specific inflection point was observed to be the potential failure surface of the HSNW. The dimensions of the potential failure surface increased with an increase in the length and inclination of nails. Also, a combination of overturning and base sliding was identified as the predominant deformation mode in HSNWs, although the base sliding mode faded with an increase in the nail inclination.