盾构隧道下穿既有铁路路基及框架箱涵地表沉降分析

Analysis on Ground Surface Settlement of Shield Tunnel Underpassing Existing Railway Subgrade and Frame Box Culvert

为研究盾构隧道下穿施工对地表沉降影响,依托武汉地铁3号线区间盾构隧道工程,运用ANSYS有限元软件对盾构隧道在不同埋深条件下下穿路基和箱涵进行模拟,得到了不同埋深盾构隧道下穿施工对既有的路基和箱涵及对应地表沉降扰动规律,将对应的地表沉降与Peck公式预测的地表沉降进行对比分析,总结了盾构下穿施工与Peck公式预测的地表沉降之间异同。结果表明:①随着埋深的增加,盾构隧道下穿施工导致地表沉降减小,沉降槽宽度逐渐增加;②先行线对地表沉降的影响较后行线大;③盾构隧道下穿箱涵施工的地表最大沉降与Peck公式预测值十分接近,而隧道下穿路基的地表最大沉降比Peck公式预测值偏小。

In order to study the influence of shield tunnel underpassing construction on the ground settlement,based on the interval shield tunnel project of Wuhan Metro Line 3,the ANSYS finite element software was used to simulate the shield tunnel underpassing subgrade and box culvert under different buried depth conditions.The disturbance law of the existing subgrade and box culvert and the corresponding surface settlement caused by the shield tunnel underpassing construction with different buried depths is obtained,and the corresponding surface settlement is compared with the surface settlement predicted by Peck formula.The similarities and differences between the shield tunneling underpassing construction and the surface settlement predicted by the Peck formula are summarized.The results show that:①With the increase of buried depth,the shield tunnel underpassing construction leads to the decrease of surface settlement and the width of the settlement tank gradually increases.②The influence of the leading line on the surface settlement is larger than that of the back line.③The maximum surface settlement of the shield tunnel underpassing the box culvert construction is very close to the predicted value of the Peck formula,and the maximum surface settlement of the shield tunnel underpassing the subgrade is smaller than the predicted value of the Peck formula.