隧道锚围岩抗拔机制及抗拔力计算模式初步研究

发布时间：2018-12-15 07:52

【摘要】：在普立特大桥隧道锚现场模型试验的基础上,采用数值模拟技术揭示了隧道锚围岩变形破坏过程:围岩破坏面从锚体底部与围岩接触面附近启裂,并逐渐向外呈圆台状扩散,破坏形式为拉剪破坏。并且,锚体前部临空岩体被拱出而发生拉破坏。破坏面上的应力分布随着拉拔荷载增大而发生复杂变化。基于此,通过在破坏面上建立力的平衡关系,提出了隧道锚围岩抗拔力计算模式。该计算模式与现有文献不同,体现了夹持效应以及破坏面上的复杂应力变化。破坏面上的应力分布需要通过模型试验和数值模拟论证得到。今后,在针对不同强度、不同结构特征的岩体进行全面试验分析的基础上,可以对破坏面形态和应力大小进行取值建议。采用该模式验证了试验结果,估算得到大桥原型锚碇的极限抗拔力非常大。目前隧道锚设计普遍偏于保守,隧道锚在中、软岩中仍然可以使用。讨论了破坏面形态特征可能的变化、岩体结构特征对抗拔力的影响等问题。
[Abstract]:On the basis of field model test of anchor in Puli super bridge tunnel, the deformation and failure process of surrounding rock of tunnel anchor is revealed by numerical simulation technique: the failure surface of surrounding rock starts to crack from the bottom of anchor body to the contact surface of surrounding rock, and gradually diffuses outward in a circular shape. The failure form is tensile and shear failure. In addition, the front face rock mass of anchor body is arched and damaged by tension. The stress distribution on the failure surface changes with the increase of drawing load. Based on this, a model for calculating the uplift resistance of tunnel anchor surrounding rock is proposed by establishing a force balance relationship on the failure surface. The calculation model is different from the existing literature and embodies the clamping effect and the complex stress variation on the failure surface. The stress distribution on failure surface needs to be proved by model test and numerical simulation. In the future, on the basis of comprehensive test and analysis of rock mass with different strength and different structural characteristics, the shape of failure plane and the magnitude of stress can be suggested. The model is used to verify the test results, and the ultimate uplift resistance of the bridge prototype Anchorage is estimated to be very large. At present, tunnel anchor design is generally conservative, tunnel anchor in medium, soft rock can still be used. The possible changes of the morphological characteristics of the failure surface and the influence of the rock mass structure characteristics on the uplift force are discussed.
【作者单位】：长江科学院水利部岩土力学与工程重点实验室;
【基金】：国家自然科学基金青年基金(No.51409013);国家自然科学基金面上项目(No.51579016)~~
【分类号】：U448.25

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