富水盾构隧道地表固结沉降及控制措施研究

Study on Ground Surface Consolidation Settlement and Control Measures of Water Rich Shield Tunnel

依托某城市富水盾构隧道,通过数值模拟,研究地表沉降控制措施,结果表明:富水地层中地表固结沉降占比较高,计算需考虑渗流。考虑渗流下,结构受力变形有不同程度提高;隧道四周剪切塑性区增大。围岩孔压在拱腰聚集,开挖后地下水指向内空,管片注浆后,地下水沿衬砌背后向下渗流;盾尾注浆会改善盾壳受力及不均匀性。考虑渗流,管片变形及弯矩由拱顶、拱底向拱底(变形)和拱顶(弯矩)转移;增大注浆圈为较实用措施。

Relying on an urban water rich shield tunnel,by numerical simulation,we studied the control measures of surface settlement.The result shows that the surface consolidation settlement accounts for a high proportion in the water-rich stratum,and seepage flow should be considered when calculating.The deformation and force are all increased to different degrees considering the seepage,and the shear plastic zone around the tunnel increases.The pore pressure of surrounding rock aggregates at the waist of the arch,the groundwater points to the inner space after excavation.After the segment grouting,the groundwater seepage downward along the back of the lining.Grouting at shield tail can improve the stress and nonuniformity of shield shell.After considering seepage,the deformation and bending moment of segment transfer from vault and arch bottom to arch bottom(deformation)and vault(bending moment).Increasing grouting circle is a practical measure.