| Bumping at bridgehead is one of common problem which is difficult to be solved in express way construction especially on soft foundation. When the problem is serious, it not only can be result in traveling uncomfortable, but also make the vehicle lose control that bring on traffic accident. Using Bidirectional geogrid to reinforce bridgehead embankment is new method of accounting for bumping at bridge head. At present, there is few researches on this method. Some engineering examples prove it is useful, but being short of theory. Via setting up FEM model research on using bidirectional geogrid to reinforce bridgehead foundation is done in this paper, further more, the result is compared with the experimental data carried both in laboratory and in field. The distributing rules of settlement after completion and stress of reinforced soil behind abutment are analyzed in detail. Some conclusions mentioned bellow are obtained.(1) Using bidirectional geogrid to reinforce bridgehead embankment with one end of it fixed on abutment can reduce the settlement of embankment behind abutment, which leads a smooth transition of the settlement between abutment and embankment. So the bumping at bridge-head may be controlled.(2)Placing multilayer geogrid in bridgehead embankment can decrease the settlement of soil at the reinforcement layer. The more the reinforcement layers are, the more decrement of settlement at embankment surface appears.(3)Bidirectional geogrid can make the stress in the reinforced embankment distribute evenly at a larger area, which makes the settlement of a reinforced embankment after completion of reduced, and makes the settlement after completion become more symmetrical. It is in favor of extending pavement life and controlling of bumping at bridgehead.(4) When using bidirectional geogrid to reinforce bridgehead embankment to control the bumping at bridgehead, the space between the geogrid layers had better to be 50-60 cm. |
