ANALYSIS OF STABILITY FAILURE FOR PIPELINE DURING LONG DISTANCE PIPE JACKING
长距离顶管管道的失稳分析

When the resistive moment of surrounding soil is less than the torsional moment of eccentric jacking force,stability failure of pipeline occurs and pipes deviates from the designed axes. The reciprocal action between pipes and soil during long-distance linear pipe jacking is analyzed. It is considered that rotational moment arises when pipeline is diagonally loaded. When the maximal soil counterforce of tail pipeline exceeds its bearing capacity,soil fails and pipeline loses stability. The macroscopic model of pipe-soil interaction at failure of pipeline is put forward by assuming that the joints act as hinges. The pipe-soil interaction in the traditional curved pipe jacking is analyzed. The soil counterforce distribution model and load bearing model for the heading and the latter pipelines are set up. By considering displacement for calculating circular earth pressure,the maximal earth counterforce formulas for the heading and the latter pipelines are deduced. The calculation of an example shows that the heading pipeline is apt to lose stability. Finally,several control measures are proposed to avoid failure for long-distance linear and curvilinear pipe jacking construction.