Energy method for stability of steel jacking pipes during construction in uniform soil

As a trenchless technology, the jacking pipe has been used in more and more underground pipe line projects. The steel jacking pipe may have overall bucking by improper jacking force during construction. Pipe structure will fail by the instability. To deal with this problem, several effects such as constraint of surrounding soil, fraction between soil and pipe and initial bending of pipe are considered. The analytical solution of critical jacking force is deduced by the energy method. The laws for coefficients of stability development are discussed in the aspects of initial bending, coefficient of subgrade reaction of surrounding soil and fraction stress between soil and pipe. The overall stability coefficients decrease with the increasing slenderness for initial bending jacking pipe. The axis line deviation significantly reduces the overall stability. On the other hand, the constraint of surrounding soil strengthens the overall stability. The fraction stress between soil and pipe has little influence on the overall stability and can be ignored. The laws for the overall stability of steel jacking pipes in uniform soil are very different from those for the ordinary steel structural members. The analytical solution of critical jacking force can be used for the design of steel jacking pipes.