为指导南京五桥夹江隧道运营安全评估，建立结构受力三维仿真计算模型，分析粉质黏土、粉砂等典型地层隧道结构在“横鸭蛋”和“竖鸭蛋”2种变形模式下的损伤演化过程，结合混凝土、螺栓、钢筋及结构整体受力状态，讨论运营期断面收敛变形的控制值。主要结论如下： 1）江中强透水地段极端7 m冲刷工况下，隧道整体上浮2.85 mm，螺栓应力变幅最为敏感，下调27.6%，混凝土应力变化最小。2）不考虑纵向差异沉降问题时，冲刷使结构向高轴压受力模式转变，对承载有利。3）水位升高引起隧道竖向变形增大0.22 mm，螺栓应力减小3.8 MPa；而水位降低引起隧道竖向变形减小0.05 mm，螺栓应力增大2 MPa。4）对比不同地质区段分析结果可知，“横鸭蛋”变形模式下，陆域段和江中段分别以10‰和12‰作为控制值；“竖鸭蛋”变形模式下，以9‰作为控制值。夹江隧道运营过程中，可依据上述标准评价变形的检测、监测数据，判定结构安全状态。
A threedimensional(3D) simulation
calculation model of structural stress is established to analyze the damage
evolution process of typical tunnel structures in silty clay and silty sand
under two deformation modes of horizontally and vertically oval shapes, to
provide a safety assessment for the Jiajiang tunnel operation in Nanjing,
China. Based on the overall stress state of the concrete, bolt, steel bar, and
structure, the control value of section convergence deformation in the
operation period is discussed. The following conclusions are drawn: (1) Under
the extreme scouring condition of 7 m in the middle river with strong
permeability, the tunnel as a whole rises 2.85 mm. The bolt stress amplitude,
which is the most sensitive, is reduced by 27.6%, and the concrete stress variation
is the least. (2) When the longitudinal differential settlement is not
considered, the structure changes to the mode of high axial compression due to
water scouring, which is beneficial to bearing capacity. (3) As the water level
increase, the vertical deformation of the tunnel increases by 0.22 mm, and the
bolt stress decreases by 3.8 MPa. Furthermore, the vertical deformation
decreases by 0.05 mm, and the bolt stress increases by 2 MPa. (4) The
comparative analysis results of different geological sections show that 10‰ and 12‰ are considered the settlement
control values for continental and middle river segments, respectively, under
the horizontally oval shape mode; whereas 9‰ under the
vertically oval shape mode. The results can be considered as reference points
for inspection, data monitoring, and structural safety state determination
during the operation of the Jiajiang tunnel.
