Evaluation of Oblique Pullout Capacity of Inextensible Reinforcement using Non-linear Pasternak Model

Abstract

The internal stability of reinforced soil structures majorly depends on the pullout capacity of the reinforcement.Failure of these structures occurs along a slip surface, intersect the reinforcement with some angle, causes an oblique pull to the reinforcement. In this study, an attempt is made to find the pullout capacity of inextensible reinforcement subjected to end oblique pullout force. Soil subgrade is represented as non-linear Pasternak model which makes it more realistic approach for the analysis of oblique pullout capacity. The response of non-linear Pasternak model is similar to the Mohr-Coulomb failure criteria. Equilibrium equations for the deformed shape of the reinforcement and stress conditions are applied. An iterative finite difference scheme is employed for obtaining the solution for the governing differential equations. Parametric study indicates that the pullout capacity of reinforcement is highly affected by interface friction angle and obliquity of pullout force.

The present work is also involved with the parametric and case study of reinforced soil wall. Parametric study is carried out using AASHTO simplified method. Stability of wall increases with increase of angle of internal friction of soil and length of reinforcement. A case study is considered to study the behaviour of a 3.6m high MSE wall reinforced with geogrid reinforcement. Reinforcement spacing is 0.6m. A limit analysis has been carried out using LimitState-GEO (which used discontinuity layout optimization DLO) to study the performance of a full scale wall. The maximum reinforcement tension at each level was computed and results are compared with the same obtained by measurement, AASHTO simplified method and finite element analysis.