为探明经地层预加固后的大直径盾构工程地层变形机制，以佛山市季华路西延线盾构工程堤坝保护为背景，开展经地层预加固后的浅埋大直径盾构穿越大堤的三维数值仿真分析，探究不同地层加固方案对地层的变形控制效果。结果表明： 1）隧道上方土体预加固有效控制了盾构掘进引起的土体变形，地层加固后最大使地表最大沉降值降低约50%； 2）旋喷桩加固深度以加固到隧道底部为最优，但加固到拱顶、拱腰、拱底3种不同加固深度对地层变形控制效果相近，可基于经济高效等原则合理选择； 3）沿掘进方向的不同加固长度对已处于加固区域土体的变形影响较小，根据穿越长度布置旋喷桩加固区域即可。
To explore the ground deformation mechanism after prereinforcement
induced by overlargediameter shield tunneling, a case
study is conducted on a shield tunneling in Jihua west road extension line
crossing underneath a dam. Threedimensional numerical
simulation is conducted to examine the ground settlement control effect by
various ground reinforcement schemes. Findings are as follows: (1) The soil
deformation is effectively controlled by prereinforcing the soil above the
shield tunnel, and the maximum surface settlement decreases by approximately
50% after the ground reinforcement. (2) The optimal reinforcement depth is
reinforcing to the bottom of the tunnel by jet grouting piles. However, the
three different reinforcement depths to the arch, the arch waist, and the arch
bottom have similar control effects on the ground deformation, which can be
rationally selected based on the principle of economy and efficiency. (3) The
different reinforcement lengths along the shield advancing direction affect the
deformation of reinforced area, thus, the reinforcement area can only be
determined according to the crossing length.
