运河开挖卸载下水下盾构隧道纵向上浮量预测研究

Prediction of the Longitudinal Uplift of an Underwater Shield Tunnel During Canal Excavation

文章基于弹性地基梁弯曲微分方程,变形、转角、剪力以及弯矩协调方程和边界条件,建立了运河开挖卸载下水下盾构隧道纵向上浮量预测模型,并对模型进行了求解。算例结果表明:预测模型获得的解析解与数值解几乎吻合,最大误差在2.7%以内,可运用于类似工程上浮量预测;盾构隧道纵向上浮量随地层反力系数的增大而减小,但非线性递减关系,当地层反力系数大于10 000 k N·m-3后,其上浮量几乎不受地层反力系数影响;实际工程可通过壁后注浆技术控制地层反力系数在10 000 k N·m-3左右,达到经济与安全的平衡。

A prediction model for the longitudinal uplift of an underwater shield tunnel during the excavation of a canal was set up and solved based on the bending differential equation of the elastic foundation beam, compatibility equations of deformation, rotation angle, shearing force and bending moment, and its boundary conditions. The results show that the analytical solutions obtained by the prediction model are consistent with the numerical solutions within a maximum error of 2.7%, and can therefore be used to predict uplift in similar projects. The longitudinal uplift of the shield tunnel decreases nonlinearly with the increase of the ground reaction coefficient, while it is not affected by the reaction coefficient when the ground reaction coefficient reaches i0 000 kN· m-3. In practical engineering, it is possible to keep the ground reaction coefficient around 10 000 kN·m-3 by backfill grouting to realize a balance between economy and safety.