Research On Key Technology Of Design Of Roadway Under-cross Railway

With the development of urban and rural construction as well as the requirement of the existing railways’ rising speed, it is important to find a better way to communicate the roads across the railways. As a result, a lot of grade crossings of railways and roads, which have a very high accident rate, are needed to be changed into interchange crossings. In the mean time, more and more programming roads are planned to pass through the existing railways. Therefore, the frame bridge is adopted on a large scale as a down through structure. It usually uses the Pipe Jacking Method and has many advantages such as small demolition area is needed, few disturbances to the traffic so that can assure the operation of the railway, lightly and ingeniously structured and easily matching the city architectural style.Although the basic construction method of the frame bridges under existing railways is mature, but with the rapid development of urban and rural economic, the sizes of planning roads become bigger and bigger, the easily construction sites are hard to find, the available construction technologies are more and more difficult to meet the need of urban development. This paper is based on the designing of the overpass project which is under an existing railway in Binhe South Road, Jinan. It concludes the overall design flow of such projects as well as the key techniques, difficulties and solutions.The system design flow of the frame bridge projects with planning road down through existing railway mainly includes aperture setting, structural height and traffic clear height setting, stabilization methods of the route, protections for deep excavation, foundation treatment technologies, drainage pattern and the choose of accessory structures. In this paper, the difficulties in such projects are demonstrates in details especially the stabilization methods of the route, the protections for deep excavation, the foundation treatment technologies and the Pipe Jacking Method. Moreover, it theoretically analyzes the stabilization method of the route. Thus, this paper can give a guidance for the design and construction in these kind of projects.