Research On The Methods Of Design And Calculation Of Approach Slap In Highway

Along with the quick development of the economy, the mileage of our national highways is increasing fast in recent years. However, there are some common faults in these constructed highways, of which the bumping at the bridge head is universal and typical. The bumping at the bridge head is caused by the consolidation settlement and the secondary consolidation settlement of the fill-back soil at bridge abutments and the settlement of the foundation of bridge approaches. When the vehicle cross fast the transition segment ,they will bump violently.There are many ways to deal with the bridge head bump ,but set the approach slap is undoubtedly the most common way. Setting approach slap is easy and useful. The purpose of that is to disperse the mutational difference of elevation of the faulted slabs in the joining place of the abutment bank to the bridging slab's two ends, so as to develop the traffic condition. However, there is no clear prescription of the disposal of the approach slap. In the practice we have no special design of the approach slap , and the theoretical thereunder is not so reasonable. For example, when calculate the length of the approach slap, we adopt the permission differential change slap and settlement, without considering the height of road embankment filling , the form of abutment and the properties of the filling sort, so sometimes it is hard to eliminate the bridge head bump completely because of the disjoint, rupture or overshort of the approach slap, influencing the use of the road and bridge. So we should make deep research of the approach slap design in the step.On the basis of detail analyzing the cause and influence factors of the approach slap design, this paper which utilize the flexible ground beam theory and finite element numerical calculation method to calculate the ground reaction,internal force (shear force ,bending moment) and bending deflection, in each condition of disjoint and undisjoint of the approach slap near the abutment end, with the different ground module and length of the approach slap, achieves some valuable conclusions. What's more, the calculation product will benefit for the project to make the reasonable size of the approach slap, so as to eliminate the hidden trouble of the bridge head bump.