A study on pullout behavior of plate anchor in reinforced soft clay

Anchor foundation systems are widely used to withstand uplift or pullout loads. Structures like tall buildings, transmission towers, jetty structures etc. experience such loads which can hinder the stability of the structure. Plate anchors develop resistance from the imposed soil weight and the shear stress along the failure surfaces formed during pullout, as the plate experiences the pullout load. Thus, the pullout load is resisted. The paper studies the pullout behavior of plate anchor using extensive laboratory model tests. The effect of different sizes of plate anchors, their embedment and different position of reinforcement on the pullout behavior have been studied. Different non-dimensional parameters have been used to represent the pullout behavior and the improvement in pullout capacity. Further, this study aims to identify the enhancement of pullout capacity over unreinforced soil due to the inclusion of reinforcement. For this, a parametric study has been carried out by conducting pullout tests with model square, rectangular and strip anchors embedded in unreinforced and reinforced soil made up of artificially prepared compacted Kaolin as clay bed. The outcomes have been presented in different non-dimensional form, such as: embedment ratio (H/B), relative depth of reinforcement (H/H), size of plate (L/B), and relative ultimate displacement (Su/B), and the influence of different parameters has been studied. Breakout factors for anchors of different sizes have been obtained from the ultimate pullout loads for both reinforced and unreinforced soil. Pullout capacity of plate anchors gets increased due to geotextile reinforcement in the embedded soil irrespective of depth of embedment of anchors. Considering all the parameters used in the present study such increase is about 47 to 63% in cases of square and rectangular anchors compared to 36% in strip anchor. Further, the position of geotextile also significantly influences the pullout behavior of anchor. Maximum increase in pullout load is achieved for reinforcement nearer to the plate.