超大直径盾构施工引发的上软下硬地层地表沉降规律

为预测超大直径盾构施工引发的上软下硬地层地表沉降量,基于某过江隧道北线盾构段施工引起的横向地表沉降监测数据,采用线性回归拟合方法,引入最大地表沉降修正系数α和沉降槽宽度修正系数β,修正Peck公式。结果表明,沉降槽沿横向呈近似正态分布,盾构施工引发的地表沉降超过总沉降量的60%;当α、β分别取0.4~0.8和1.2~2.4时,修正后的Peck公式比传统Peck公式精度更高;与常规盾构相比,超大直径盾构施工引起的上软下硬地层最大地表沉降相对较大、沉降槽较宽、影响范围更大。

Ground Subsidence in Upper-Soft and Lower-Hard Stratum Caused by Super-Large Diameter Shield Construction

Ground subsidence may be occurred in the upper-soft and lower-hard stratum during the super-large diameter shield construction. In order to predict the subsidence, the monitoring data of transverse ground subsidence caused by shield construction in the north line of a river-crossing tunnel were taken for research. By using a linear regression fitting method, the correction coefficient α of maximum ground subsidence and correction coefficient β of subsidence width were introduced to modify the Peck formula. The results show that the subsidence is approximately in normal distribution along the transverse direction, and the ground subsidence caused by shield construction exceeds 60% of the total subsidence. When α and β are 0.4-0.8 and 1.2-2.4 respectively, a higher precision can be obtained by the modified Peck formula than the traditional Peck formula. Furthermore, as compared with the conventional shield construction, the super-large diameter shield construction will cause relatively larger and wider ground subsidence in the upper-soft and lower-hard stratum, leading to a wider range of area to be affected.