Study On The Stability Of High Xigeda-Filled Geogrid Embankment

Xigeda is a special rock distributed widely in Xichang and Panzhihua, Sichuan. Nearly one million cubic meters of Xigeda spoil are brought out in the build of Xichang-Panzhihua speedway. It will make considerable economic benefits if the spoil can be utilized effectively in the engineering. The geogrid is a high strength, small ductility, anti-aging geosynthetics. The geogrid placed in filling can improve the stability of embankment and reduce the uneven settlement. Currently, though many study results has been achieved in high-fill geogrid embankment, the corresponding study concerning Xigeda filling are relatively poor. The aim of this thesis is to study the stability of high Xigeda geogrid embankment with centrifugal model test and numerical analysis, to server the design and construction.In the thesis, firstly the theory and method to analyse the stability of reinforced embankment were introduced, and the corresponding achievements were summarized. To study the stability of high Xigeda geogrid embankment, four groups of centrifugal model tests were conducted, including two groups with geogrid and the other two without geogrid. With the results of the deformation and stress of the embankment, the influences of geogrid on the stability of the embankment were analysed.Furthermore, finite element strength reduction method was used to study the influences of the vertical spacing between layers of geogrid and the gradient slope of the embankment on the stability of high Xigeda geogrid embankment. In the computation, elasto-plastic model following Drucker-Prager law was employed for the filling soil. Four-node solid element was used to discretize the embankment, subgrade and geogrid.The results show that the designed embankment with/without geogrid is stable and safe. The distribution of the stress in geogrid embankment is affected by the geogrid observably and the soil in the vicinity of the geogrid is mobilized to withstand the tendency to slip of the embankment. The shearing strength of the soil is mobilized more sufficiently, which may improve the stability of the embankment effectively. Moreover, the axial force of geogrid will increase, as the embankment slope become steeper. Namely, the effects of geogrid become more effective with the increase of the gradient slope of embankment.