【作者】 李恒；

【导师】 张彬；

【作者基本信息】 辽宁工程技术大学 ， 桥梁与隧道工程， 2011， 硕士

【摘要】 公路隧道建设工程中,如何使围岩保持稳定性是工程设计和施工的重点和难点。隧道由于开挖方法不当而造成的围岩失稳事故时有发生,因此研究合理施工方式对隧道稳定性影响就成为工程设计人员关注的焦点。本文通过大量的文献资料,论述了影响围岩稳定的各种因素,综合分析隧道围岩变形破坏特征、力学机制。以东山隧道Ⅳ级围岩为例,在分析所有量测项目和当前常用围岩稳定准则的基础上,选取对围岩稳定影响较大的开挖方式这一因素,运用ANSYS有限元分析软件进行数值模拟,并对计算结果中的围岩应力场、位移场以及支护受力进行分析。分析结果显示,对于偏压浅埋隧道上台阶开挖对隧道影响比较大,其开挖变形量占总变形量的60%以上,所以在上台阶开挖前需提前进行支护。受偏压的影响,两个隧道开挖对围岩的稳定性影响是不相同的,埋深较深一侧隧道上台阶开挖后,监测断面的竖向位移和应力的增量在整个开挖过程中都是最大的,并且在隧道拱腰部位出现应力集中的现象。二次衬砌完成后,围岩的受力情况会得到改善,支护所承受弯矩轴力都不同程度的减小,但隧道拱脚处的支护出现应力集中,因此此处的支护层要进行加厚或者增加锚杆的数量。根据支持向量基的预测,Ⅳ级围岩在隧道开挖后30天左右变形量达到预计总位移的90%以上,拱顶下沉变形速率基本稳定在0.07-0.15mm/d以下,变形基本稳定。更多还原

【Abstract】 In highway tunnel construction, how to keep the wall rock steady is an important and difficult point of design and construction. The rock of the tunnel which lost stability is caused by unreasonably excavation method, so study the reasonable construction method is becoming a key topic.After reading a lot of related papers, this paper discusses the factors affecting the rock stability, Analyze the deformation characteristics and mechanism of the tunnel rock comprehensively. Based on four-grade rock of Dong-Shan tunnel, by analysis all measurement Items and stability criterion of the rock, choose excavation method which is more significant influences on the rock stability. Use finite element analysis software of ANSYS to simulate the tunnel construction process, and analyze the rock stress fields, displacement fields and force on the support. Results are shown that the excavation of upper step have a greater influence upon the shallow cover and unsymmetrical loading tunnel. The value of its excavation deformation up to 60% of the overall deformation, so should support to the upper step before excavating the step. Under the influence of unsymmetrical loading, the excavation of two tunnels is not the same for the rock stability, when excavate the upper step of the tunnel which cover more deeply, the monitoring sections vertical displacement and stress increases most in all construction process, and stress is concentrated at metro top plate. After the second lining, the stress of the support will be improved, the moments and axial-force on the support are all reduced in different degree, but the stress of arch feet is concentrated, so concrete support layer should be thicken or increase the number of the anchor. Based on prediction of Support Vector Machine, after excavation about 30 days four-grade rock’s deformation is up to 60% of the overall deformation, the rate of the roof deformation remains 1.5 mm/d, and the rock basically remained stable.更多还原