Three dimensional finite difference analysis of soil-nailed walls under static conditions

Abstract

Soil nailing has been extensively used as an efficient method for improving stability of slopes. There are many different approaches including limit equilibrium methods to understand soil-nailed wall behaviour under static loading conditions. Having three construction stages involved in soil nailing construction (excavation, nail installation and face stabilization), in the framework of a numerical approach, the present study aimed to evaluate the earth pressure distribution during and after excavation. Research parameters affecting soil-nail wall behaviour were also investigated. Employing the finite difference method a three dimensional model has been developed in the proper finite difference code. The soil behaviour was predicted through an Elastic-Perfectly-Plastic constitutive model utilizing Mohr-Coulomb failure criterion. The developed numerical model simulated soil medium and nail inclusions as well as shotcrete facing interaction behaviour. A comprehensive study was conducted to examine effects of different crucial factors such as nail inclination, nail length, length pattern, slope inclination and nail bars arrangement on the performance of soil-nailed structures. The results showed an increase in nail inclination improves soil shear strength to an optimum condition whereas more increase in nail inclination would decrease its reinforcing effect. Nail length and nail length patterns both contribute to improve wall stability.