Analysis Of Long-Distance Curve Pipe Jacking Technology

In allusion to prevalent and advanced long-distance jacking construction technics used at present, choice of pipe material, caculate way of jacking force and some key constrction technics such as reducing friction through injecting slurry, setting of relay well, ventilation, measuring are analysed.The analysis of curve jacking force mechanism is emphasized. By setting up mechanical model, the relationship of curve radius, jacking force and effect factors such as pipe diameter, length of pipe section, thickness of wooden piece, elasticity of material and the difference of jack displacement is investigated. Two instances whether pull stress emerges on pipe section are discussed. When pull stress emerge on pipe section, two forced states of pipe section and fetch of pipe are analysed.The research indicates that when the pull stress emerges on pipe section curve radius lies on the difference of jack displacement, while it is a little influenced by jacking force. The max press stress on fetch of pipe is sensitive to the change of difference of jack displacement, and the change of difference of jack displacement has little influence on jacking force. On the other hand, when curve radius is constant, the pull stress on pipe section is greatly affected by jacking force. And at this time, in order to avoid crack, the max jacking force must be controlled. When pipe is pressed on the whole section, the allowable difference of jack displacement is small, less than one millimeter currently. And at the same time, the least allowable curve radius is quite great.In the last part of this paper, the deduction is validated by a project example.