Abstract: Under the effect of eccentric jacking force caused by lifting jack, the lifting phenomenon of box culvert occurs. By adopting the Winkler foundation model, the analytical solution of the vertical attitude variation of box culvert is derived theoretically. And then the mechanism and variation regulars of lifting phenomenon of box culvert under eccentric jacking force are explored based on field measurement analysis. The research results show that: (1) The imbalance torque caused by the different action elevation of jacking force and the combined force of thrust resistance is the core cause for the lifting phenomenon. (2) The main construction measures to mitigate lifting phenomenon include reducing the jacking force or the earth pressure of soil ahead of pipe jacking machine, increasing the stiffness of the upper row of pipe roof, reducing local friction on the upper face of box culvert, flushing and unloading soil from the bottom of the box culvert, etc.〖KG-*3〗, in which the measure of reducing jacking force or the earth pressure of soil ahead of pipe jacking machine is the most effective. 

Key words: soft soil stratum, piperoof box culvert, vertical attitude, eccentric jacking force, box culvert jacking, mechanism of lifting phenomenon