为解决曲线隧道与直线隧道开挖对周围土体和隧道结构产生影响的差异问题，首先，采用分别建立三维直线隧道和曲线隧道开挖数值模型的方法，对地层及盾构结构物理力学参数和盾构顶推力等施工荷载参数的选取进行研究；其次，将数值模拟结果与工程实测数据进行对比，验证该模型的合理性，并对比分析2种隧道模型(直线隧道和曲线隧道)的地层位移及管片应变差异情况；最后，通过7种不同顶推力比值及方向偏角工况，分析曲线隧道开挖过程中不平衡顶推力对土体位移和管片应变的影响。结果表明： 1）相比直线隧道，曲线隧道开挖会使拱顶上方土体沉降量增大，沉降范围扩大，且管片应变增大； 2）随着盾构顶推力差值及方向偏角的增加，地表的不均匀沉降增大，内、外侧土体水平位移不对称程度增大，以及管片的径向和轴向应变增量增大； 3）管片径向应变分布规律会因不同顶推力方向(内侧、外侧)产生差异，且当顶推力方向为外侧时，管片在75°~135°和180°~285°易发生开裂； 4）顶推力不平衡程度过大时，整个管片的径向应变会产生大幅度的变化，使结构受到不利影响。
To explore the difference between the excavation of
curved and straight tunnels on the surrounding soil and tunnel structure, 3D
numerical models for straight and curved tunnels′ excavation are established respectively to analyze the physicomechanical parameters of the strata and shield structure and the
construction load parameters such as shield jacking force are examined. Then,
the numerical simulation results are compared with the monitored data of the
project to validate the feasibility of the models and analyze the difference of
strata displacement and segment strain between the two models. Finally, the
influence of unbalanced jacking force on soil displacement and segment strain
during curved tunnel excavation is analyzed under conditions with various
jacking force ratios and deflection angles. The results show the following: (1)
Compared with the straight tunnel, the excavation of the curved tunnel results
in an increase in soil settlement above the crown, range of settlement, and
segment strain. (2) With the increasing jacking force difference and deflection
angle of shield, the uneven surface settlement increases, the asymmetry of
horizontal displacement of inner and outer soil increases, and the increment of
radial and axial strain of segment increases. (3) The distribution of radial
strain of segment varies due to different jacking force directions (inner side
and outer side), and when the jacking force direction is outer side, the
segment is prone to crack in the range of 75°~135° and 180°~285°. (4)
When the unbalance degree of jacking force is over large, the radial strain of
the entire segment varies sharply, bringing adverse affect to the structure.
