泥炭质土不同赋存条件对盾构隧道衬砌结构动力响应特性影响分析

以昆明地铁3号线工程为依托,运用有限元动力分析研究泥炭质土不同赋存条件对盾构隧道衬砌结构动力响应特性的影响,为泥炭质土层盾构隧道衬砌结构抗震设计提供理论指导。结果表明:当隧道周围地层中富含泥炭质软弱夹层时,在地震荷载作用下,隧道结构受力形态呈"椭圆"状,隧道结构轴力、弯矩及主应力减小幅度较大,剪力略小,其中,两侧泥炭质土夹层组合减小幅度最大,对隧道抗震最为有利;当隧道上覆和下卧泥炭质土层时,地层交界面与隧道结构的接触点产生异常的动应力集中,是隧道结构抗震的薄弱环节,因此,盾构隧道的设计、施工应充分考虑隧道结构外侧岩土体的不均匀性,以确保隧道的长期安全性。

Analysis of Dynamic Response Characteristics of Shield Tunnel Lining Structure in Peat Soil of Different Deposit Conditions

In order to provide theoretical guidance for seismic design of shield tunnel lining structure in peat soil,the article uses the finite element dynamic analysis to study dynamic response characteristics of shield tunnel lining structure in peat soil of different deposit conditions based on Kunming Metro line 3.The results show that when surrounding strata is rich in peat soil interlayer,under earthquake load,the force pattern of tunnel structure is oval-shaped with decreased magnitude of axial force,large bending moment and principal stress and small shear force. The largest decrement magnitude of the peat soil interlayer on both sides is the most favorable for tunnel anti-earthquake. When tunnel is coved and paved with peat soil,the contact point between formation interface and tunnel structure produces abnormal dynamic stress concentration,and is the weak part in the design of seismic tunnel structure. Therefore,design and construction of shield tunnel should address the inhomogeneity of lateral rock-soil mass of tunnel structure so as to ensure long-term safety of tunnel.