Pullout Resistance Factors for Inextensible MSE Reinforcements Embedded in Sandy Backfill

This paper presents results from a laboratory program of 402 pullout tests of inextensible reinforcements used for Mechanically Stabilized Earth (MSE) walls. Results focus on evaluation of pullout resistance factors for ribbed steel strip and welded steel grid reinforcement embedded in sandy backfill that marginally met AASHTO requirements for select granular fill. This project used Texas Tech University’s large-scale MSE Test Box with dimensions of 12 feet x 12 feet x 4 feet and an applied overburden capacity of 40 feet of backfill. This test box facilitates pullout testing at a scale not unlike typical field construction. The research design evaluated pullout resistance factors for both ribbed strip and welded grid reinforcements for a variety of independent variables including overburden pressure, reinforcement length, level of compaction, grid wire size, and grid geometry including both transverse and longitudinal wire spacing. Appropriate statistical analyses were used to interpr