【作者】 陈贵红；

【导师】 漆泰岳；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2011， 博士

【摘要】 20世纪90年代以来,我国的高速公路迅速向西部延伸,在山区高等级公路中,由于路线选线困难或受到其它因素的影响,连拱隧道越来越多地成为设计师们的首要选择。根据交通部门的规划,在未来相当长的一段时间内,我国高速公路的发展具有相当大的空间。我国是一个多山国家,由于连拱隧道自身的优点,在未来的公路建设中必将具有广阔的应用前景。然而,连拱隧道设计、施工经验不足,设计技术很不成熟,目前已经建成的连拱隧道暴露出了不少问题,所有这些都为连拱隧道的大量推广形成了障碍。因此,展开连拱隧道设计关键问题的研究对于连拱隧道的推广应用具有十分迫切的现实意义。本文的研究主要包括以下几个方面的内容：通过与分离式隧道、小净距隧道的技术、经济分析比较,阐述了连拱隧道的优缺点及其适用条件。采用定性分析与定量计算相结合的手段,综合分析了连拱隧道各种断面型式的优缺点及其适用条件。所得结论为连拱隧道的合理应用奠定了基础。以分离式隧道设计荷载计算方法及深、浅埋判别标准为基础,通过理论解析与数值模拟,引入连拱隧道影响系数,提出了采用荷载—结构法进行结构计算时,连拱隧道设计荷载的计算方法及深、浅埋判别标准,为连拱隧道的结构计算打下了基础。利用结构力学的基本理论,分别针对整体式中墙连拱隧道与三层式中墙连拱隧道的结构特点,建立了采用荷载—结构法进行结构计算时初衬、二衬及中墙内力的具体计算模型与方法。采用数值模拟详细分析了两侧主洞施工顺序、支护时机、应力释放系数等因素对中墙最终受力的影响,提出了采用地层—结构法计算连拱隧道中墙最终内力的简化计算方法。通过对鞋底坡连拱隧道某断面中墙内力的计算分析表明,不论是荷载—结构法还是地层—结构法计算所得中墙轴力均与现场量测结果比较接近,这初步说明本文有关连拱隧道设计荷载、结构计算以及中墙内力的计算方法是合理的,为连拱隧道中墙的合理设计奠定了基础。采用中墙内力的简化计算方法详细分析了中导洞、中墙厚度、埋深、中墙与顶部围岩接触状态等对中墙最终受力的影响。分析结果表明：中导洞对中墙的最终受力影响较小；在其它条件相同的情况下,中墙轴力随着中墙厚度、埋深的增加而增加；中墙与顶部围岩接触越早中墙受力越大,因此,当围岩稳定性较差时,应早将中墙顶回填密实,以尽快发挥中墙对围岩的支撑作用,但对于稳定性较好的围岩,则应在中墙顶部预留适当的变形量,以推迟中墙的受力时间、充分发挥岩体的自承能力,减少中墙受力。采用三维有限元数值模拟,研究了三层曲中墙连拱隧道中墙在施工中的强度和稳定性。分析结果表明中墙的稳定性较好,不需要对中墙进行临时支撑,由于分析中未考虑顶部围岩对中墙提供的水平抗力,因此,该分析结论对于整体式中墙仍然成立,但由于在V级围岩条件下中墙的稳定系数较小,所以,在V级围岩条件下整体式中墙宜设置临时支撑,以确保中墙在施工中的稳定。另外,通过对施工过程中围岩塑性区分布、围岩变形、支护结构受力特征的分析,提出了施工过程中的注意事项及设计应采取的工程措施,为连拱隧道支护体系的合理设计提供了依据。开展了连拱隧道现场试验,研究了连拱隧道支护体系的受力特征和发展变化过程。试验结果表明：初期支护内力在施工初期发展迅速并很快趋于稳定；钢支撑未能充分发挥应有的支护能力,因此,在围岩稳定性较好的情况下应优先采用格栅钢架；二次衬砌应力水平较低,具有较高的安全储备；中墙受力较大,这说明在整体式中墙连拱隧道的支护体系中中墙是主要的承载结构；中墙的量测结果与施工实践均显示施工过程中中墙的稳定性较好,一般情况下不需要对中导洞进行回填或支撑。根据连拱隧道结构特征,完善了连拱隧道现场监控量测内容和方法,修正了位移收敛计算方法,通过引入连拱隧道影响系数,初步提出了连拱隧道位移收敛控制基准,并通过部分收敛量测资料进行了初步验证。虽然本文的研究成果还不完善,很多内容还有待进一步深入研究,由于资料的有限性,文中的一些结论也还未能得到证实或完全证实,还需要在实践中不断修正和补充,但本文还是对连拱隧道设计中存在的关键问题进行了较为详细的论证分析,其成果必将为连拱隧道的合理应用与推广提供重要的技术支撑。更多还原

【Abstract】 Since 1990s, there have been more and more highways constructed in the western China. In the mountainous area, the multi-arch tunnel becomes the engineer’s first choice due to the difficulty of the route selecting and other factors influence. Since China is a mountainous country, the multi-arch tunnel with its own advantages will have a very broad application of highway construction in the future. However, the design and construction experience of the multi-arch tunnel is limited, and we do not have the robust mechanics of the multi-arch tunnel theory. Currently, there are some noticeable problems in the multi-arch tunnel. It becomes the obstacle to the wide application of the multi-arch tunnel. It is very important and urgent to do the theoretical research for the wide application of the multi-arch tunnel. The followings are included in this paper.The application conditions of the multi-arch tunnel with advantage and disadvantage are studied by comparison of the separate tunnel and neighborhood tunnel in terms of the technology and the economics. The application conditions of the multi-arch tunnel’s cross-section with advantage and disadvantage are analyzed by both theoretical method and computational method. The conclusions of this research are the foundation of the application of the multi-arch tunnel.Considering the load design method of the separate tunnel as well as the criteria of the deep or shallow depth, the theoretical method and the numerical method are studied. When the load-structure method is employed to conduct the structure computation, the influence parameter of the multi-arch tunnel is considered. The load design computational method for the multi-arch tunnel and the criteria of the deep or shallow depth are the foundation of the multi-arch tunnel design.Based on the theory of basic structural mechanics and according to the specific characteristics of the multi-arch tunnel with the integral middle-wall and the three-layered middle-wall, the internal force model and the method for the primary support, secondary lining and middle-wall are developed by the load-structure method.By the finite element analysis, the computational method of the middle wall internal force in the multi-arch tunnel by the stratum-structure method are developed, which is the foundation of the middle wall design. The followings are studied in the detail:construction sequences of the drift heading, parameter of the stress release, dimension of the drift heading, thickness of the middle wall, the depth, and the influence of the middle wall load capacity by the contact condition between the middle wall and the top surrounding rock. The results from this method are the same as the results from the load-structure method in the engineering application.The effect on the middle wall structural behavior by the middle guide tunnel, thickness of middle wall, depth, and the contact condition between the middle wall and the surrounding rock was analyzed in detail. The results showed that the effect of middle guide tunnel on the middle wall is not significant; the axial force in the middle wall increased with the thickness of middle wall, and the depth; the earlier the contact between the middle wall and the surrounding rock, the larger force in the middle wall. So the material with large elasticity should refill the middle wall as soon as possible in the condition of the weak surrounding rock. However, for the strong surrounding rock, the appropriate clearence is needed on the top of the middle wall to postpone the middle wall under loading and exploite the rock’s structural capacity.Using the 3D finite element analysis, the mechanic characteristics of the multi-arch tunnel with the three-layered curved middle-wall during the construction stage are researched in terms of the strength and the stability. The results shows that the stability of the middle wall is good and the temporary support of the middle wall is not needed. Since the stability parameter of the middle wall in the V surrounding rock is small, the integral middle wall shall have the temporary support in the V surround rock. Considering the distribution of the plastic zone in the surrounding rock, displacement of the surrounding rock, and the mechanical characteristic of the support structure, the construction requirements and procedures are developed.Based on the field testing of the separate tunnel, as well as considering the structural characteristics of the multi-arch tunnel, the mechanical characteristics and the development of the supporting system in the multi-arch tunnel are studied theoretically. Testing results shows that the supporting forces developed quickly and became stable during the construction stage. The capacity of the steel support is not exploited fully. The grid steel support should be the first choice in the condition of the stable surrounding rock. The middle wall in the supporting system is the main structural system. The stability of the middle wall is good enough. The refill or the support is not needed in the middle guide tunnel. The control criteria of the displacement convergence in multi-arch tunnel is developed by correction of the control criteria of the displacement convergence in the separate tunnel. The convergence computational method is corrected according to the structural characteristics of the multi-arch tunnel. The theoretical analysis is demonstrated by several field testings of the multi-arch tunnel. The theoretical computational method for the multi-arch tunnel is correct because the field testing of the middle wall internal force is the same as theoretical results. According to the measurement of the displacement convergence, the control measurement criteria for multi-arch tunnel is reasonable for the forgoing tunnel of multi-arch tunnel with integral middle-wall, but the different control criteria should be used for the following tunnel. According to the structural characteristics of the multi-arch tunnel, the method of field testing for the multi-arch tunnel is improved; the displacement convergence computational method is corrected, the displacement convergence criteria for the multi-arch tunnel is checked.Since the limitation of the literature review, some conclusions are not demonstrated fully and future research is needed. This paper analyzed the key problems of the multi-arch tunnel design in details, and the results will contribute to the wide application of the multi-arch tunnel.更多还原