强度折减法在超大直径顶管群抗浮稳定分析中的应用

为评价和指导超大直径顶管群的设计,将强度折减法应用于水下顶管群的抗浮稳定分析。利用单管和六管并行两种方案,研究了适合水下顶管抗浮稳定分析的失稳判据。并通过调整群管间距,研究管间距对群管抗浮稳定安全系数的影响。结果表明:将强度折减法用于顶管群的抗浮稳定分析是可行的。综合运用地表位移突变性及塑性区贯通性作为失稳判据较为合理,而数值计算收敛性因受多种因素影响不适合作为失稳判据。群管间净距小于顶管外径时,会导致群管抗浮安全系数偏小,相邻顶管间的土体易出现塑性区贯通。

Application of Strength Reduction Method to the Anti-floating Stability Analysis of Super Large Diameter Pipe-jacking Cluster

In order to evaluate and guide the design of the super large diameter pipe-jacking cluster, the strength reduction method was applied to analyze the anti-floating stability of the underwater pipe-jacking cluster. Two cases with single pipe and six-pipe were analyzed by using strength reduction method to find the suitable instability criterion for the anti-floating stability of the underwater pipe-jacking. The influence of the pipe spacing on the anti-floating stability safety factor was also studied. The results show that it is feasible to apply the strength reduction method in the anti-floating stability analysis of the underwater pipe-jacking cluster. The criteria based on the abruptness of the displacement at the surface and the connectivity of the plastic zone should be jointly used in the analysis of the anti-floating stability of the pipe-jacking. The convergence of the numerical computation is controlled by a number of factors. So it is not suitable for evaluating the anti-floating stability of pipe-jacking. If the pipe spacing smaller than outer diameter of pipe-jacking, the anti-floating stability safety factor will be small and the plastic zone easily occur in the soil between two adjacent pipe jacking.