英语翻译

英语翻译
1)Proper drainage is essential in road building,because if the foundation became soggy,the heavy road would sick into it.And if the water were to freeze in the ground,it would expand and crack the road.To protect the highway from such damage,drainpipes called culverts are laid across the roadbed wherever a strong flow of water is expected.the roadbed itself is shaped so that the middle of the finished road would be higher than the sides.Then water and melting snow will easily drain off its surface into the drainpipes or ditches.The roadbed is given a final grading(smoothing) and is now ready to receive the road itself.
2)A bridge has always offered man the satisfaction of successfully conquering an obstruction,be it a primitive bridge of the ancients or a modern bridge of immense gracefuk in view,balanced in distribution of mass,harmonious in proportion,orderly in lines,integral with the environment.
3)In ancient times,bridges often crossed rivers at right angles,had humps in the middle,had no discrete footpaths,and were invariably built of stone and timber using the arch form of construction.The subsequent evolution of bridge engineering is the result of improvement of structural form as permitted by gradually improved understanding of structural analysis and design,coupled with improved construction materials and methods of fabrication and erection.
4)Scientific knowledge about materials and structural behavior has expanded tremendously,and computing techniques are now widely available to manipulate complex theories very quickly.Engineers have virtually revolutionized bridge design and construction methods in the past decade.these advances apply to short-,medium-,and long-span bridges.
5)Common elements of the substructure are abutments (usually at the bridge ends)and piers(between the abutments).Piers and abutments often rest on separately constructed foundations such as concrete spread footings or groups of bearing piles; these foundations such as concrete spread footings or groups of bearing piles; these foundations are part of the substructure.Occasionally a bridge substructure comprises a series of pile bents in which the piles extend above the waterline and are topped by a pile cap that,in return,supports the major structural elements of the superstructure.