Mechanism Study On Geogrid Reinforced Embankment

This study focused on mechanism of geogrid reinforced clayey soil embankment on common earth foundation. It is conducted according to a test road located in TongChuan, North-West China's ShaanXi province. Earth embankment and geogrid reinforced embankment with various slope, various spacing and length of the reinforcements, various heights were calculated by FEM. Each factor's influence on the tensile stress of the geogrids, the stress and displacement distribution in the cross sections of embankments and the response of foundations were analyzed. A centrifuge testing program was undertaken to investigate the distributing of displacement on the embankments' cross sections and to observe the performance of these embankments at failure or the failure trend of these embankments. The responses of foundations were also analyzed. Various slopes and various spacing of the reinforcements were considered in this testing program. And an earth embankment model as a comparison was tested. Construction technology of geogrid reinforced embankment and long term strain of geogrid in the embankment were also researched. The interpretation of FEM analysis and the experimental results provided insight into the performance of reinforced embankment. It is shown that the stiffness and the interior stability of the embankments are increased by reinforcements. The reinforced embankments need evener and stiffer foundations. Research also indicated the slope should be steeper than a critical inclination. Reducing the geogrid space around 1/4-1/3 height of the slope will enhance the stability of the embankment. And unequal length of reinforcements is economical. The bruises of geogrid are decreased if sheep-foot roller is used when lay-down thickness deeper than 30cm. The deformation of geogrid mainly conies of construction. The infiltration of rainwater is disadvantage for the stabilization of geogrid reinforced embankment. Some suggestions are made based on the results of this research and the shortcoming of "Technical Specification for Application of Geosynthetics in Highway", Geogrids should be overlapped on the slope. Much greater importance should be attached to slope protection and drainage system design. If necessary, checking computations of foundation bearing capacity should be done.