在桥梁施工中，一般都是先作桥台背墙，后安装大梁（空心板梁、T梁等），用具有弹性的物质填塞大梁与背墙间的缝隙，而后作伸缩缝。这种作法的不足之处是：大梁安装时需要运行空间大，增加了安装难度，尤其边孔受桥台背墙的限制，就位困难，另外安装期间大梁极易与背墙发生碰撞 In the construction of the bridge, the first is generally used as the abutment back wall, after the installation of girders (hollow slab, T beam, etc.), with elastic material to fill the gap between the girder and the back wall, and then make expansion joints. The shortcomings of this approach are: the installation of girders need to run a large space, increasing the difficulty of installation, especially the edge of the abutment by the abutment back wall constraints in place, the other during installation of the beam easily collide with the back wall