After the pipe is jacked through, the relay ring needs to manually enter the pipe and remove the hydraulic system and jacks therein, and the steel casing can't be taken out anymore, so it can only be discarded.
The pipe jacking construction is the non-excavation construction method, which is a kind of pipe burying construction technology without excavation or less excavation. Pipe jacking construction is in the working pit with the help of jacking equipment to produce the top force, to overcome the friction between the pipeline and the surrounding soil, the pipeline will be designed according to the slope of the top of the soil, and the soil will be transported away. After one section of pipe finishes jacking into the soil layer, the second section of pipe is then lowered to continue jacking. The principle is to push the tool pipe or roadheader from the working pit through the soil layer all the way to the receiving pit for lifting with the help of the main jacking cylinder and the thrusting force between the pipes and the relay. The pipe follows the tool pipe or roadheader and is buried between the two pits. The use of this technology construction, can save a large amount of land acquisition and relocation costs, reduce environmental pollution and road blockage, with significant economic and social benefits.