Development of the K-stiffness method for geosynthetic reinforced soil walls constructed with c-φ soils

In this paper the K-stiffness method is extended to the case of c-phi soils using data obtained from a total of nine new case studiesa- six from Japan and three from the USA. A common feature in this new data set is that the walls were all constructed with a vertical face using backfill soils with a range of fines content. The walls varied widely with respect to facing type. This new data set together with previously published data for vertical walls is now used to isolate the effect of soil cohesion on reinforcement loads within the framework of the original K-stiffness method. The new data set is used to calibrate a modified K-stiffness method equation that includes a cohesion influence factor. The modified K-stiffness method is demonstrated to quantitatively improve the estimate of the magnitude and distribution of reinforcement loads for internal stability design of vertical-faced geosynthetic reinforced soil walls with c-phi soil backfills when compared to the current American Association of State Highway and Transportation Officials simplified method.