Influence of Aggregate Filled Geocell Reinforcement on the Uplift Capacity of Anchor Plate

Abstract

An anchor is a type of foundation system which is generally used to resist vertical uplift or horizontal pullout forces with the support of surrounding soil in which anchor is embedded. The uplift capacity of plate anchors depends on many factors such as density of soil, embedment depth, the size and shape of anchor etc.If the pulling load to be resisted is large, then we have to increase either the size of the anchor plate or the depth of embedment or both, resulting increase in the size of the excavation area and depth of excavation. This not only leads to increase in size of the foundation area and cost of excavation, but also arises the problem of excavation below the existing water table and compacting fill material below water table at great depths. In such condition we have to find an alternate cost effective method so as to improve the uplift capacity of a shallow anchor. In the present study, the uplift behavior of horizontal square anchor plate embedded in sand with and without geocell reinforcement has been investigated. Gravel sized material is used to fill in the cells of the geocell so as to improve the grid interlocking. The pullout resistance of plate anchors was investigated using a laboratory small scale modal experiment. Rope and pulley arrangement was used to conduct test on plate anchors. To investigate effect of the width of geocell mattress on the anchor uplift capacity, geocell mattress having width diameter ratios (b/B) of 2,3,4 were considered and the studies were conducted on anchor plates having size 60mm embedded at embedment ratio (L/B) = 4. The test results indicate that inclusion of geocell increases the uplift capacity of anchor plate in the order of 1.33,1.44 and 1.67 times than that of unreinforced case for each increment in the width ratio of geocell mattresses i.e., (b/B) of 2,3,4 respectively. However, with the addition of aggregates in the cells of the geocell mattresses significantly improves the performance of the plate anchors both in terms of increased uplift capacity and sustained deformations. The increase in the uplift capacity of the plate anchor with the addition of aggregates in the cells of geocell mattresses is in order of 2.56, 3.11 and 3.67 times than that of unreinforced case for each increment in the width ratio of geocell mattresses i.e., (b/B) of 2,3,4 respectively.