3、 Technical standard 1. Bridge span: 20m 2. Bridge slope: 0 °, 5 °, 10 °, 15 °, 20 °, 25 °, 30 °, 35 °, 40 °, 45 ° 3. Bridge deck width: 2 × net - 12.0m (used for subgrade width of 28m) 4. Vehicle load: Highway - Class I 5. Design environmental conditions - Class I 6. Internal friction angle of backfill behind abutment δ=35 °, Unit weight τ = 19KN/cubic meter 1. Pier and abutment type The substructure of this set of general drawings adopts column piers. According to the difference of abutment height and construction method, the abutment is designed with pile column abutment and rib abutment, and the foundation design adopts bored pile foundation. The piers are double columns. For the abutment, when the slope is less than 30 °, the double column (double rib) abutment is used; When the slope is greater than or equal to 30 °, three column (or three rib) abutment shall be used. Ribbed abutment can be used when the abutment height is more than 4m; When the height is less than 4m, the pile column platform can be selected.