Analysis of Pullout Tests for Planar Reinforcements in Soil

Abstract

This paper describes a new analysis for predicting the tensile stress distribution and load-elongation response in pullout tests performed on thin, extensible, planar soil reinforcements. The proposed formulation is based on shear-lag approximations and assumes elastic properties of the constituent materials (soil and reinforcement), which are linked through a frictional interface. The analysis identifies four successive phases in the pullout response: (1) initial, linear behavior, characterized by a buildup of interface tractions at the active, loading end of the inclusion; (2) nonlinear load-elongation response associated with the progression of a sliding front from the active end; (3) peak pullout resistance, when the interface friction is fully mobilized at the passive end of the inclusion; (4) postpeak reduction in pullout resistance due to a snap-through mechanism, with coalescence of sliding fronts from the active and passive ends of the inclusion. The principal parameters affecting the load-elongation response during pullout are the relative soil-reinforcement stiffness, inclusion length, and interface friction. The proposed analysis shows important limitations in applying limit equilibrium calculations for interpreting interface friction from pullout tests on extensible reinforcements.