考虑变荷载影响的水下盾构隧道双层衬砌力学特性分析

Analysis of Mechanical Characteristics of Shield Tunnel with Double-layer Lining Considering Variable Loads

为探究变荷载条件下的双层衬砌结构力学特性演变规律,依托武汉地铁8号线越江盾构隧道工程,基于水下隧道外部荷载的周期性变化规律,结合双层衬砌盾构隧道施工特点,采用有限元软件ANSYS,对水土荷载作用变化时双层衬砌结构的力学特性进行深入探究。研究结果表明:(1)在水位上涨和河床淤积的影响下,二次衬砌施作越早,其内力值越大,受管片接缝影响,内力分布的不均匀性越显著,管片衬砌结构的内力量值越小,其内力分布规律无明显变化;(2)二次衬砌施作得越早,管片轴力量值的降幅远高于管片弯矩降幅,管片可能发生偏心受拉破坏,同时二衬轴力、弯矩的量值也会显著增大,且轴力的增幅远高于弯矩增幅,此时二衬可能发生受压破坏;(3)水位上涨对管片的弯矩无明显影响,但会显著提高二衬的弯矩和轴力。

In order to explore the evolution law of mechanical properties of double-layer lining structure under variable load, Wuhan Metro Line 8 Cross River Shield Tunnel Project is referenced in view of the construction characteristics of the double-layer lining shield tunnel and finite element software ANSYS is employed to deeply explore the mechanical properties of the double-layer lining structure during the changes of soil and water load based on the cyclical variation of the external load of the underwater tunnel. Research results show that:(1) Under the influence of water level rise and riverbed siltation, the earlier the secondary lining is applied, the greater the internal force value of the secondary lining. Under the effect of the joint of the segment, the internal force distribution is more uneven, the internal force value of the segment lining structure is smaller, while the internal force distribution law has no obvious change;(2) The earlier the secondary lining is applied, the drop of the axial force value of the segment is much higher than the decrease of the bending moment, which could induce eccentric tensile failure;while the amount of axial force and bending moment of the second lining is significantly increased, and the increase of the axial force is much higher than the increase of the bending moment, which could lead to compression-controlled failure;(3) The rise in water level has no significant effect on the bending moment of the segment, but it will significantly increase the bending moment and axial force of the secondary lining.