Multiple layers of geogrids for strength enhancement in a soft Ugandan clayey soil

Abstract

Rapid urban development has resulted in increased land pressure, including areas with weak foundation soils such as soft clays. These soils often require improvement, using techniques like geogrid reinforcement, in order to increase their bearing capacity and reduce their settlement tendencies. Although geogrid reinforcement has been widely accepted, there is limited research to support its application in soft clays. This study investigated the performance of multiple layers of geogrid reinforcement in enhancement of the bearing capacity of a soft Ugandan clayey soil. Experiments were conducted to investigate the number (N) and the spacing (h) of consecutive geogrid layers that could yield the maximum bearing capacity improvement (BCI). Thus, h and N were the variables, while the width (b) and the depth of embedment (u) of the geogrids were kept constant. Loading tests were conducted under three conditions to determine the percentage strength improvement in terms of BCI: (i) without geogrid reinforcement, (ii) varied h with constant b, u and N, and (iii) varied N with constant b, h and u. The load-settlement characteristic generated from the tests yielded optimum h and N of 50 mm and 3 respectively. The BCI achieved was found to be up to 219%.