ThaiScience  


ENGINEERING JOURNAL CHIANG MAI UNIVERSITY


Volume 27, No. 01, Month APRIL, Year 2020, Pages 198 - 211


Effects of covering ratio and vertical spacing of biaxial geogrid on the compressive strength of reinforced sand

Suraphan Sutjai and Warat Kongkitkul


Abstract Download PDF

In the current design method of a geogrid-reinforced soil structure, only the tensile strength (Tult) is taken into account for stability analysis. In fact, the geogrid is also characterised by covering ratio (CR) (i.e., the ratio of the area covered by geogrid on a plane to the area of that plane). A soil structure reinforced with the geogrids having the same Tult but different CRs would behave differently. In the present study, various prototype biaxial geogrids having different CRs were produced by a 3D printer. The source material was Polyethylene Terephthalate with a Glycol modification (PETG). The strands were arranged in four different patterns such that four different CR values, i.e., 14%, 25%, 50%, and 100%, were achieved. In so doing, the width of each strand was kept constant, while the thickness of each strand was varied so that the geogrids with different CR values had similar rupture tensile strength. A series of triaxial compression tests were performed on uniform air-dried sand specimens, either unreinforced or reinforced with three or six layers of geogrid having the same CR value. The followings were found: i) the peak stress ratio (Rpeak) of sand specimens reinforced with three geogrid layers were controlled by failure of backfill without tensile rupture of reinforcement, while the Rpeak of sand specimens reinforced with six geogrid layers by tensile rupture of reinforcement; ii) increasing in the number of geogrid layers increases the Rpeak; and iii) Rpeak generally increases with an increase in CR until the optimum value, depending on the number of layer, beyond which Rpeak decreases with an increase in CR. An approximate isotropic perfectly plastic solution was used to predict the Rpeak. It was found that Rpeak is well predicted if relevant equivalent angle of friction () is used.


Keywords

None



ENGINEERING JOURNAL CHIANG MAI UNIVERSITY


Published by : Faculty of Engineering Chiang Mai University
Contributions welcome at : http://researchs.eng.cmu.ac.th/?name=journal