The Application Research Of Transformation In Masonry Arch Bridges Reinforcing And Widening Based On Bolt-Shotcrete Concrete

Masonry arch bridges are the first and often used bridge structure type in our country, which occupies important position in in the early bridge history of China. However, because of a long construction time, the bridges aging, deformation, cracks, breakage are serious, and the original design load standards can not meet the requirements of present traffic. So the reinforcement and widening of the arch bridges are needed to restore or improve their load power to extend the bridges life. It can not only retain the old bridges, but also meet the present and future transport needs, which has an important economic and social significance.And the bolt-shotcrete reinforcement method is commonly used in reinforcing masonry arch bridge. Take the Ian-river bridge as an engineering example, the systematic study on application technology of the reinforcement and widening in highway masonry arch bridges is carried out in this paper. The main contents are as follow:(1) The basic principles of reform, the main technical contents and processes, and the problom of technical means of widening and reconstruction of the bridge widening should be pay attention to in highway masonry arch bridges are reviewed.(2) The strength, deformation and other performance features of bolt-shotcrete concrete are systematically summarized to provide a basis of correct spraying concrete and mix proportion design. The construction technology of jet concrete, and the characteristics and the processes of dry spray and wet spray are introduced, so that the construction technology of properly shooting concrete provide the foundation.(3) The mechanical characteristics of the bridges, the basic principles of shotcrete reinforcement in masonry arch bridges and the mechanical characteristics of composite structures after strengthening are analysed, which provide a theoretical foundation to the arch bridge.(4) The checking method of bearing capacity and allowable stress of bolt-shotcrete reinforced masonry arch bridge which considered the weak layer between the new and old concrete layer are proposed based on the current reinforcement checking method of masonry arch bridge. And it also provides future references to the arch bridges calculation.(5) Using the bolt-shotcrete concrete to reinforce main arch ring is proposed, which is a new reinforcing and widening methodology of masonry arch bridge realized by increasing outward cantilevered deck through the bridge panel.