“三背”主要指桥涵台背、挡墙背、路基范围内的结构物台背,原因就是“三背”位置的填筑质量控制不好,导致其沉降超过一定的限度造成。因此,“三背”位置的沉降控制做好了,跳车问题也就根除了。对“三背”填筑施工的质量控制进行了阐述。 “Three backs ” Mainly refers to the back of the bridge culverts, retaining the back of the wall, the back of the structure within the roadbed, the reason is that the quality control of filling the “three backs” position is not good, causing the settlement to exceed a certain limit . Therefore, the settlement control of the “three backs” position is well done and the problem of jumping off is eliminated. The quality control of “Three Backs” construction is described.