###### Abstract  
This paper presents an experimental study on the pullout resistance of a newly improved reinforcement. The applied reinforcement was a smooth steel strip reinforcement with transverse members used to improve the pullout-resistance problems of the smooth steel strip reinforcement. The pullout and bearing resistance of the improved reinforcement were evaluated using results of large-scale pullout tests. The evaluation result confirmed that the bearing resistance of the improved reinforcement was about 33-66% of the total pullout resistance, and it had an evenly distributed friction and bearing resistance. The bearing bond coefficient, considering the interference effect, gradually converged when normal stress was higher than a certain value. This result confirmed that the increment of interference effect is caused by the increment of the transverse member and normal stress. In the pullout-resistance evaluation of the improved reinforcement, a number of transverse members can be predicted using the relationship between bearing-resistance stress and the bearing bond coefficient due to normal stress, which can be applied as a reasonable prediction method. reinforced earth wall; inextensible reinforcement; large-scale pullout test; pullout resistance; interference; bearing bond coefficient 23 February 2021 16 March 2021 19 March 2021  
caused by bearing resistance, and the rigidity of transverse members has a significant effect on bearing resistance [9; 10]. That is, the deformation of transverse members can adversely affect the stability of reinforced earth walls. Therefore, if steel strip reinforcement friction resistance that has a primary pullout resistance can be added to the transverse members in the resistant zone, the problem of the existing steel grid is improved. This reinforcement can be the improved type considering the anchor retaining effect because the number of transverse members can be selectively applied in resistant zones. In the early stages of the introduction of the reinforced earth wall in Korea, smooth steel strip reinforcement was mostly used, and ribbed steel strip reinforcement was then applied to increase friction resistance between reinforcement and backfill material. However, the reduction in durability due to the corrosion of the steel reinforcement led to a rapid decrease in its application. The use of the geogrid-reinforced earth wall has greatly increased since the late 1990s [11], and about 6.5 million m\({}^{2}\) of geogrid was applied to reinforced earth walls in 2005 [12]. A large effective site is required due to Korea's mountainous topographical feature. Therefore, the number of cases of the application of reinforced earth walls that have a wall height of 10-15 m is increasing to support heavier surcharge load. For this reason, reinforced earth walls need reinforcement to improve soil strength. The application of backfill materials has material criteria to increase the pullout resistance of the geogrid and prevent damage due to compaction. The maximal particle size of backfill soil should be less than 19 mm [12]. However, weathered granite soil, which is more than 19 mm, is sometimes applied to backfill material because it is difficult to obtain fine soil due to the field conditions. Furthermore, strength-reduction factors considering the extensibility of the geogrid that is excessively applied in a reinforced earth wall needs to be in sufficient control for wall displacement. Therefore, it is necessary to study inextensible reinforcements since most corrosion problems are solved by developing and applying an anticorrosion technique. In addition, the application of inextensible reinforcement that has considerable pullout resistance has increased. In this study, inextensible reinforcement is improved, which resolves the problem of the existing smooth strip reinforcement. The form of the improved reinforcement is smooth steel strip reinforcement with transverse members.