EXPERIMENTAL EVALUATION OF PULLOUT ANALYSES FOR PLANAR REINFORCEMENTS

This paper presents results of laboratory pullout experiments with planar soil reinforcements that are used to evaluate the proposed shear-lag analyses described in a companion paper. Measurements of tensile stress distributions were obtained for thin steel and nylon 6/6 sheet inclusions embedded in dense Ticino sand. The steel reinforcement is relatively inextensible, with linear stress distribution and load-elongation behavior. The interface friction is well defined from repeatable measurements of the peak pullout resistance. In contrast, the response of the extensible nylon 6.6 reinforcements is highly nonlinear with a pronounced postpeak reduction in pullout resistance. The interface friction can be interpreted reliably from the residual pullout resistance, although these data are affected by stick-slip behavior in tests performed at low displacement rates. The measured data are in good agreement with shear-lag predictions of nonlinear load distributions throughout the test and illustrate very clearly the postpeak ''snap-through'' mechanism described by the analysis. Further experimental measurements are required to evaluate other aspects of the analyses such as stress concentrations at the sliding front.