高水位软弱地层条件下大直径钢顶管稳定性.

The instability of the pipe jacking has threatened the safe construction of the project seriously during the jacking process. The research was based on the Shiyanbei sewage diversion steel pipe jacking project, which was undertaken by the Fourth Engineering Co., Ltd. of China Communications Second Highway Bureau. Based on the buckling theory of thin-walled cylindrical shells, the stress, buckling mode and buckling load was analyzed by changing the influencing factors such as slenderness ratio, diameter-thickness ratio and buried depth. The research results show that the stability of steel pipe jacking decreases with the increase of slenderness ratio (the ratio about the length of the jacking pipe to the outer diameter of the pipe). When the slenderness ratio <30 (short jacking pipe), local buckling failure is prone to occur. However when the slenderness ratio >30 (long jacking pipe), the overall instability failure is prone to occur. Under distributed confining pressure, the buckling mode of steel pipe jacking is dominated by local buckling, and its stability decreases with the increase of the diameter-to-thickness ratio. The actual stability coefficient is determined by the pressure around the pipe and the elliptical deformation, which varies with the buried depth. Based on the above analysis results, an empirical formula was proposed about the stability coefficient of large-diameter steel pipe jacking. It has been verified by engineering examples and has good guiding significance. [ABSTRACT FROM AUTHOR]