The optimized design and construction of the opposite-direction crossing for HDD pipeline

The Jing River crossing project is the biggest pipe diameter and long-distance directional HDD opposite-direction pipeline crossing engineering in China. The crossed strata mainly contain cobble layer, silt sand layer and silt clay layer. The combination crossing program of "heavy excavation of deep foundation pit to lay pipe+long-distance raming cannula+HDD oppositedirectional crossing" was adopted for ϕ1219 pipe crossing design. And also, many kinds of innovated construction technologies such as the optimization of reamer's combination, modification of the mud property and application of pipe pusher to tow back the pipeline were used in this crossing project. Lots of difficulties were solved successfully in traversing the pebble layer of riverbank, the aiguille blocking or clasping in the highly hard-plastic silty clay layer and the pipe locking in the towback. All of those were useful to similar pipe diameter directional drilling crossing project.