这最后的操作叫“拖管”，它使管道就位于河床下面。
This final operation is the"pullback"and installs the line pipe under the river.
深海采矿扬矿管处于海洋环境之中，受海浪、海流以及采矿船拖航的影响，会发生大的偏移。
Deep ocean mining pipe has a large deflective displacement under the wave, currents and dragging by mining vessel in ocean environment.
在水平定向钻穿越管道回拖环节中，容易出现卡管现象，导致穿越失败，造成巨大的经济损失。
Pipe sticking phenomenon appears sometimes during pull-back stage of pipeline crossing with horizontally directional drilling, which results in crossing failure and great economic loss.
应用推荐