软岩大变形高速铁路隧道二次衬砌支护时机研究

发布时间：2018-07-15 09:27

【摘要】：进入二十一世纪以来,我国经济建设速度明显提高,获得了前所未有的发展。经济发展带来对交通运输的需求,因此,我国高铁建设在近些年获得了长足的发展。高速铁路建设需要修建隧道工程的情况很多。在实际工程当中,由于隧道本身施工进度慢、难度大,因此许多隧道工程会成为整条高铁隧道的控制工程。虽然在地质较好的情况下隧道的工期、质量以及安全能够得到很好的保证,但是在某些地质条件较差的情况,如遇到高地应力软岩大变形的情况,就会因为围岩变形量大导致工期延长、安全性下降和造价提高。在长期的研究中,将初期支护承受全部荷载二次衬砌作为安全储备的理念深入人心。初期支护承受全部荷载,指围岩在初期支护的作用下完全可以实现自稳；二次衬砌作为安全储备,并不是二衬不受力,而是二衬受力与其承载能力相比可以忽略,二衬的主要作用是提高复合衬砌结构的耐久性,抵抗围岩可能发生的恶化。围岩的自承载能力在当今隧道工程的设计与施工中越来越受到重视,将围岩与支护视作一个统一体来承受荷载。为了使围岩的自承能力充分得到实现,可以允许围岩在隧道开挖以及后期中具有一定的变形,充分发挥围岩自承能力,这样同时也会减小围岩对支护结构的作用,有效地改善围岩的应力状态。为防止围岩变形过大进入松动状态,满足二衬在合理范围内发挥作用,支护时机就必须合理。支护过早,围岩应力得不到释放,施加在二衬上的荷载过大,必须要求二次衬砌具有更高的刚度强度,同时也会存在较大的安全隐患,如支护过晚,围岩位移受不到限制,会因为围岩破坏给二衬施加更大压力,由于位移过大造成。所以选择合理的支护时机成了隧道工程的重点。
[Abstract]:Since entering 21 century, our country economy construction speed has improved obviously, has obtained the unprecedented development. Economic development brings the demand of transportation. Therefore, the construction of high-speed railway in China has made great progress in recent years. The construction of high-speed railway requires the construction of tunnels. In the actual project, due to the slow construction progress of the tunnel itself, many tunnel projects will become the control project of the whole high-speed railway tunnel. Although the time limit, quality and safety of the tunnel can be guaranteed well under the condition of good geology, in some cases of poor geological conditions, such as large deformation of soft rock with high ground stress, Because of the large deformation of surrounding rock, the construction period is prolonged, the safety is decreased and the cost is increased. In the long-term research, the idea that the initial support bears all the load and the secondary lining as the safety reserve is deeply accepted. The initial support bears all the loads, which means that the surrounding rock can completely realize self-stability under the action of the initial support; the secondary lining, as a safe reserve, is not the second lining without force, but the second lining force can be neglected compared with its bearing capacity. The main function of the second lining is to improve the durability of the composite lining structure and to resist the possible deterioration of surrounding rock. The self-bearing capacity of surrounding rock is paid more and more attention in the design and construction of tunnel engineering nowadays. The surrounding rock and support are regarded as a unity to bear the load. In order to fully realize the self-supporting capacity of surrounding rock, we can allow the surrounding rock to have certain deformation in tunnel excavation and later period, and give full play to the self-supporting capacity of surrounding rock, which will also reduce the function of surrounding rock to the supporting structure at the same time. The stress state of surrounding rock is improved effectively. In order to prevent the deformation of the surrounding rock from entering into loose state and to meet the need of the secondary lining to play its role within a reasonable range, the supporting time must be reasonable. If the support is premature, the stress of surrounding rock can not be released, and the load applied on the second lining is too large, the secondary lining must be required to have higher stiffness and strength, and at the same time, there will be larger hidden dangers of safety, such as too late support, the displacement of surrounding rock can not be restricted. The second liner will be subjected to more pressure because of the failure of surrounding rock, and the displacement will be too large. Therefore, the selection of a reasonable supporting time has become the focus of tunnel engineering.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U455.7

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