Effect of Utilization of Geosynthetic on Reducing the Required Thickness of Subbase Layer of a Two Layered Soil

Authors: R. Ziaie Moayed, M. Nazari

Abstract:

This paper tries to study the effect of geosynthetic inclusion on the improvement of the load-settlement characters of two layered soil. In addition, the effect of geogrid and geotextile in reduction of the required thickness of subbase layer in unpaved roads is studied. Considering the vast application of bearing ratio tests in road construction projects, this test is used in present investigation. Bearing ratio tests were performed on two layered soil including a granular soil layer at the top (as the subbase layer) and a weak clayey soil placed at the bottom (as the subgrade layer). These tests were performed for different conditions including unreinforced and reinforced by geogrid and geotextile and three thicknesses for top layer soil (subbase layer). In the reinforced condition the reinforcing element was placed on the interface of the top granular layer and the beneath clayey layer to study the separation effect of geosynthetics. In all tests the soils (both granular and clayey soil layers) were compacted according to optimum water content. At the end, the diagrams were plotted and were compared with each other. Furthermore, a comparison between geogrids and geotextiles behaviors on two layer soil is done in this paper. The results show an increase in compression strength of reinforced specimen in comparison with unreinforced soil sample. The effect of geosynthetic inclusion reduces by increasing the subbase thickness. In addition it was found that geogrids have more desirable behavior rather than geotextiles due to interlocking with the subbase layer aggregates.

Keywords: Bearing ratio, Subgrade, Subbase, Sand layer thickness, Geosynthetic.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1063417

References:

[1] Guido, V.A., Chang, D.K., Sweeney, M.A., 1985. Bearing capacity of shallow foundations reinforced with geogrids and geotextiles. Proceedings of the Second Canadian Symposium on Geotextiles and Geomembranes, Edmonton, Alberta, pp. 71-77.
[2] Guido, V.A., Sweeny, M.A., 1987. Plate loading tests on geogridreinforced earth slabs. Proceedings of the Geosynthetic '87 Conference, New Orleans, pp. 216-225.
[3] Khing, K.H., Das, B.M., Yen, S.C., Puri, V.K., Cook, E.E., 1992. Interference e!ect of two closely-spaced strip foundations on geogridreinforced sand. Geotechnical and Geological Engineering 10, 257}271.
[4] Khing, K.H., Das, B.M., Puri, V.K., Cook, E.E., Yen, S.C., 1993. The bearing-capacity of a strip foundation on geogrid-reinforced sand. Geotextiles and Geomembranes 12, 351}361.
[5] Omar, M.T., Das, B.M., Puri, V.K., Yen, S.C., 1993a. Ultimate bearing capacity of shallow foundations on sand with geogrid-reinforced. Canadian Geotechnical Journal 30, 545-549.
[6] Omar, M.T., Das, B.M., Yen, S.C., Puri, V.K., Cook, E.E., 1993b. Ultimate bearing capacity of rectangular foundations on geogridreinforced sand. Geotechnical Testing Journal 16, 246-252
[7] Yeo, B., Yen, S.C., Puri, V.K., Das, B.M., Wright, M.A., 1993. A laboratory investigation into the settlement of a foundation on geogridreinforced sand due to cyclic load. Geotechnical and Geological Engineering 11, 1-14.
[8] Das, B.M., Omar, M.T., 1994. The effects of foundation width on model tests for the bearing capacity of sand with geogrid reinforcement. Geotechnical and Geological Engineering 12, 133-141.
[9] Huang, C.C., Menq, F.Y., 1997. Deep-footing and wide-slab e!ects in reinforced sandy ground. Journal of Geotechnical and geoenvironmental Engineering, ASCE 123 (1), 30-36.
[10] Kurian, N.P., Beena, K.S., Kumar, R.K., 1997. Settlement of reinforced sand in foundations. Journal of Geotechnical and Geoenvironmental Engineering, ASCE 123 (9), 818-827.
[11] Gabr, M.A., Dodson, R., Collin, J.G., 1998. A study of stress distribution in geogrid-reinforced sand. Proceedings of Geosynthetics in Foundation Reinforcement and Erosion Control Systems, ASCE Geotechnical Special Publication, Vol. 76, pp. 62-76.
[12] Wayne, M.H., Han, J., Akins, K., 1998. The design of geosynthetic reinforced foundations. Proceedings of Geosynthetics in Foundation and Erosion Control Systems, ASCE Geotechnical Special Publication, vol. 76, pp. 1-18.
[13] British Rail Research, 1998. Supporting roll-Geogrids provide a solution to railway track ballast problems on soft and variable subgrades. Ground Engineering 31 (3), 24-27.
[14] Tensar International, 1995. Tensar geogrid reinforced sub-bases-Case studies. New Wellington Street, Blackburn BR2 4PJ, England.
[15] Bender, D.A., Barenberg, E.J., 1978. Design and behaviour of soilfabric- aggregate systems. Transportation Research Record 671, 64-75. Washington, DC.
[16] Chan, F., Barksdale, R.D., Brown, S.F., 1989. Aggregate base reinforcement of surfaced pavements. Geotextiles and Geomembranes 8 (3), 165-189.
[17] Gobel, C.H., Weisemann, U.C., Kirschner, R.A., 1994. Effectiveness of a reinforcing geogrid in a railway subbase under dynamic loads. Geotextiles and Geomembranes 13 (1), 91-99.
[18] Miura, N., Sakai, A., Taesiri, Y., Yamanouchi, T., Yasuhara, K., 1990. Polymer grid reinforced pavement on soft clay grounds. Geotextiles and Geomembranes 9 (2), 99-123.
[19] Moghaddas-Nejad, F., Small, J.C., 1996. Effect of geogrid reinforcement in model track tests on pavements. Journal of Transportation Engineering 122 (6), 468-474.
[20] Perkins, S.W., 1999. Mechanical response of geosynthetic reinforced flexible pavements. Geosynthetics International 6 (5), 347-382.
[21] Alawaji H.A., 2001. Settlement and bearing capacity of geogridreinforced sand over collapsible soil. Geotextiles and Geomembranes 19 (2001) 75-88
[22] Bergado D.T., Youwai S., Hai C.N., Voottipruex P., 2001. Interaction of nonwoven needle-punched geotextiles under axisymmetric loading conditions. Geotextiles and Geomembranes 19 (2001) 299-328
[23] Duncan, E.W., Attoh-Okine, N.O., 2007. Effect of geogrid in granular base strength - An experimental investigation. Construction and Building Materials 22 (2008) 2180-2184
[24] Haas, R., Walls, J., Carroll, R.G., 1988. Geogrid reinforcement of granular bases in flexible pavements. Transportation Research Record 1188, 19-27. Washington, DC.
[25] Kazimierowicz-Frankowska, K., 2007. Influence of geosynthetic reinforcement on the load-settlement characteristics of two-layer subgrade. Geotextiles Geomembranes 25 (6), 366-376.
[26] Hufenus, R., Rueegger, R., Banjac, R., Mayor, P., Springman, S.M., Bronnimann, R., 2006. Full-scale field tests on geosynthetic reinforced unpaved roads on soft subgrade. Geotextiles and Geomembranes 24 (1), 21-37.
[27] AASHTO T 180, 2009. Standard Method of Test for Moisture-Density Relations of Soils Using a 4.54-kg (10-lb) Rammer and a 457-mm (18- in.) Drop. American Association of State Highway and Transportation Officials.
[28] AASHTO M 147, 1965. Standard Specification for Materials for Aggregate and Soil-Aggregate Subbase, Base, and Surface Courses. American Association of State Highway and Transportation Officials.
[29] ASTMD1883, 2005. ASTM Standard Test Method for Bearing Ratio of Laboratory- Compacted Soils. ASTM, Philadelphia.