正断层错动下乌鲁木齐地铁1号线隧道结构受迫影响研究

以乌鲁木齐地铁隧道穿越九家湾活动正断层工程为例,建立穿越活动正断层隧道结构的三维弹塑性有限元模型,模拟分析在正断层错动作用下隧道二次衬砌应力、塑性区分布规律及裂缝分布特征;通过大比例尺跨活动正断层隧道剪切错动室内模型试验,明确隧道结构在断层剪切错动下的破坏范围及破坏形态。结果表明:数值模拟结果与模型试验结果的规律一致性较好;断层面处隧道衬砌承受压—剪—扭的组合作用,衬砌破坏最严重;二次衬砌开裂主要以纵向裂缝为主,集中在仰拱内侧、墙脚外侧及拱顶内侧;剪裂缝集中在断层迹线处的隧道拱脚,环向裂缝多出现在拱腰位置;上盘二次衬砌开裂范围均大于下盘;设防时应加强环向主筋及箍筋,使隧道整体结构形成环—纵向骨架,从而减少纵向和斜向开裂,并防止纵向裂缝的贯穿。

Research on Influence upon Tunnel Structure of Metro Line 1 in Urumqi Forced by Normal Fault Dislocation

Taking the subway tunnel in Urumqi crossing Jiujiawan normal active fault as an example, a three-dimensional elastic- plastic finite element model of tunnel structure crossing active normal fault was established to simulate and analyze the stress and plastic zone distribution laws as well as crack distribution characteristics in the secondary lining of the tunnel under the action of normal fault dislocation. Through the large-scale indoor model test of tunnel shear dislocation crossing active normal fault, the damage ranges and failure modes of tunnel structure under fault shear dislocation were clarified. Results show that the numerical simulation results are in good agreement with model test results. The tunnel lining at the fault plane is subjected to the combined action of compression, shear and torsion, where the lining damage is the most serious. The cracks of secondary lining are mainly longitudinal, which are concentrated on the inside of the inverted arch, the outside of the wall footing and the inside of the vault. The shear cracks are concentrated on the arch springing of tunnel at the fault trace, and the annular cracks mostly appear on the hance position. The secondary lining cracking range of the upper plate is larger than that of the lower plate. To reduce longitudinal and oblique cracking and prevent longitudinal cracks from penetrating, circumferential main ribs and stirrups should be strengthened so that the overall structure of the tunnel forms a ring-longitudinal skeleton.