Seismic Performance Of Geogrid Embankment

The embankment stability is brought out because of many mountains and frequent earthquakes in our country and the seismic stability of the embankment engineering is looming larger with the embankment being built in highly seismic regions when the strategy of developing the West is implemented. The seismic hazard investigation of Wenchuan earthquake shows that none of the embankment engineering of Dujiangyan-Wenchuan road is broken, some embankment slopes collapse and only local deformation of the embankment slopes with geogrid reinforcement is discovered. The geogrid can effectively obstruct the transfer of seismic forces and strengthen the seismic stiffness, intensity and stability of the embankment. The successful application of geogrid is hopeful to lessen some common embankment hazards in highly seismic regions and improve the earthquake-resistance capability of highways. There is no specification in current codes of highway and railway aseismatic design and little research has been conducted on the aseismatic effect and reinforcing effect of geogrid at home and abroad. The aseismatic design theory of geogrid in the thesis makes sense for the embankment aseismatic design in highly seismic regions in the context of imperfect and unmature aseismatic analysis methods and insufficient accumulation of field test data.The research contents and findings are as follows:(1) The seismic hazard investigation of the embankment engineering in Wenchuang earthquake shows the seismic hazard has the following characteristics: the embankments are damaged more or less, some embankments without geogrid collapse and only local deformation is discovered for embankments with geogrids.(2) The conclusion is drawn that the subgrade engineering designed with the pseudo-static method are basically stable in earthquakes whose magnitude is less than the design magnitude according to the pseudo-static analysis based on the practical deformation characteristics of embankment engineering in Wenchuan earthquake.(3) It can be seen from the numerical simulations of embankments with geogrids in the upper part, in the middle and in the bottom that the geogrids in different positions of embankments can improve the earthquake-resistance capability of embankments in different degrees. The strengthening effect of geogrids placed in the upper part is greater than those placed in the middle and in the bottom and therefore the geogrid design can be optimized according to the conclusions above.(4) The geogrids in the middle and in the bottom of the embankment are canceled and more geogrids are placed in the upper part in the optimum design of YA'AN-HUGU speedway. The earthquake-resistance capability of the optimized embankment is improved than that of the original embankment and about 30% of the geogrids can be saved according to the dynamic analysis of the optimized embankment.