双向八车道小净距公路隧道支护反力上限分析与支护参数优化研究

【作者】 吴贲；

【导师】 杨小礼； 高长胜；

【作者基本信息】 中南大学 ， 土木工程， 2011， 硕士

【摘要】 为适应不断增大的交通量,双向八车道小净距隧道己越来越多的出现在人们眼中。八车道的大断面小净距隧道具有大断面和小净距隧道各自的施工、设计难点。断面过大,受净空的要求,势必会造成隧道的扁平率过大,对支护的要求就强于一般隧道；过小的净距会使后行洞开挖对先行洞的稳定性造成较大的影响,同时,中间岩柱成为另一个施工设计中需重点加固的位置。由于对这种形式的隧道研究仍处在起步阶段,目前还没有完善的规范能对此种类型的隧道设计进行指导。本文根据极限分析上限定理,结合牛头山小净距大断面高速公路隧道实际施工设计情况,采用大型有限差分软件,通过理论和数值计算的手段对大断面的小净距隧道施工力学和支护参数进行了研究。主要内容包括：1.利用极限分析上限法则,讨论了由库伦材料组成的双平行圆形隧道支护反力最小上限解,并采用数值分析软件Matlab对最小上限解的一些影响参数进行了分析研究。2.采用有限差分软件对牛头山隧道锚杆支护进行优化研究。主要研究其锚杆的布置形式,在不同围岩等级下,根据规范中对三车道锚杆间距的建议,推广到四车道大断面隧道的锚杆间距取值范围,分别对矩形布置或是梅花形式布置进行计算比较,改变不同的横向与纵向锚杆间距,最后得出较为合理的布置形式和横、纵向间距,为施工和设计提供参考。3.分析主要的几种支护组合对围岩稳定性的影响,包括开挖、锚杆、喷混和二衬。在不同的支护组合下,得出各种支护对围岩稳定性的影响。对小净距隧道中间岩柱加固的方式进行了研究探讨,采取不同的加固方式进行计算,最后得出适合不同条件的加固方式。4.对牛头山隧道现场监测数据进行简单的分析,并与计算结果进行比较,为计算结果提供一定的可靠性证明。更多还原

【Abstract】 The eight lanes bidirectional tunnel has been normally built, so as to accommodate the increase busy traffic nowadays. Thereby brought many difficulties for the construction and design which assembles the one of large-span tunnel and the close-distance tunnel. Firstly, the large-span tunnel has a higher demand for support than the traditional tunnel due to the span-ratio augmented by clearance requirement. Secondly, for small-distance tunnel, the stability of the former tunnel will be significantly impacted by the later excavated tunnel and the shared rock between the neighboring tunnels needs to be particularly consolidated. While the research on this field is still in its infancy, there is no delicate design criterion refer to.Based on the limit analysis upper bound law and the example of Niutou Mount highway tunnel with large-span and small-distance, the paper will study on the construction mechanics and support parameter of the closely build tunnels with small distance between by the large infinite difference software and theoretical and numerical computation. The study mainly includes:1. Discuss the minimum upper boundary solution of the support counter-force of the circular bi-tunnel parallel build in linear elastic medium by the limit analysis upper bound law, and study the relevant parameters by Matlab.2. Research on how to improve the way of distribution of the anchor support. The norm has given guidance on the inter-distance of anchor, under different rock level, in three lanes tunnel. In order to extend the guidance to four lanes tunnel, the paper has done a comparison for the rectangle and quincuncial arrangement of anchors within a set of latitude and longitude distances, then given the optimal result serving as a reference to the practical engineering.3. Analyze the stability of the surrounding rock by several support style combined by excavation, anchor, shotcrete and lining. Study on different way of consolidating the rock in middle of the closely built tunnels, and find out the best way of consolidation for different conditions.4. Simply analyze the monitor data obtained from the Niutou Mount tunnel project, and compare it with the computation result, which can used as a verification for the calculation method in the paper.更多还原