盾构隧道双层衬砌横向力学特性影响因素及影响规律研究

发布时间：2018-05-07 06:10

本文选题：盾构隧道 + 双层衬砌　；参考：《西南交通大学》2017年硕士论文

【摘要】：随着盾构技术大量运用地下交通的建设中,其所面对断面要求越来越大,所在赋存环境越来越复杂。现有的单层管片衬砌盾构隧道已难以满足承载、耐久、防水的要求,为满足以上要求,国内一些城市已经开始在盾构隧道中施作二次衬砌,但目前仍缺少有关于赋存条件、结构形式、结构缺陷对于盾构隧道双层衬砌结构力学特性的影.响。本文结合公路、铁路以及地铁隧道工程原型,采用理论分析与模型试验相结合的方式,就不同侧压力系数、水压作用、盾构隧道规模、二衬厚度、二衬是否置筋、二衬缺陷深度及其空间分布对盾构隧道双层衬砌结构承载的力学特性进行了系统的研究,并取得以下研究成果:(1)随侧压力系数增大,双层衬砌结构极限承载能力增大,但其破坏过程逐渐由渐进性变为突发性,当侧压力系数低于0.5的时候,施作二次衬砌对于提升双层衬砌极限承载能力效果更为明显;(2)在一定范围内,水压增加能够提高管片与二次衬砌的极限承载能力,但其破坏过程则趋于突发性,在循环水压作用下,水压变化幅度越大,管片极限承载能力越低,此时及早施作二次衬砌对结构整体承载更为有利;(3)基于目前盾构隧道设计参数的选取情况,随盾构隧道规模的增大,管片与二次衬砌结构的横向刚度相对较小,从而导致管片与二次衬砌极限承载能力越低,当盾构隧道外径超过10m,施作二次衬砌在改善管片与二次衬砌的受力状态及提高极限承载能力方面的效果更为显著;(4)在管片厚度一定的条件下,增加二衬厚度能够明显提升管片与二次衬砌极限承载能力,其破坏过程则趋于突发性,但当二衬厚度超过30cm以后,增加二衬厚度对提升双层衬砌极限承载能力的幅度逐渐减小;(5)二次衬砌配筋能够增加双层衬砌的延性,有效提升双层衬砌结构极限承载能力,延长其失稳破坏的过程,改善双层衬砌结构整体力学特性;(6)二次衬砌缺陷对双层衬砌结构的受力状态及极限承载力影响显著,缺陷规模越大,双层衬砌结构极限承载能力越低,整体失稳破坏特性趋于突发性;拱顶和拱腰位置处的二次衬砌缺陷对双层衬砌结构极限承载能力降低程度更为显著。
[Abstract]:With the construction of shield tunneling technology, it faces more and more demands of cross section, and the existing environment is becoming more and more complex. The existing single-layer segment lining shield tunnel has been difficult to meet the requirements of bearing, durability and waterproofing. In order to meet the above requirements, some cities in China have already begun to implement secondary lining in shield tunnel, but at present there are still few conditions for its occurrence. The form of structure and the influence of structural defects on the mechanical properties of double-layer lining structure of shield tunnel. Ring. Combining with the prototype of highway, railway and subway tunnel engineering, this paper combines the theoretical analysis with model test, according to different lateral pressure coefficient, water pressure effect, shield tunnel size, thickness of second lining, whether the second lining is reinforced or not. The mechanical properties of double-layer lining structure of shield tunnel are studied systematically by the depth of two-liner defect and its spatial distribution. The following results are obtained: (1) with the increase of lateral pressure coefficient, the ultimate bearing capacity of double-layer lining structure increases. However, the failure process gradually changed from gradual to sudden. When the lateral pressure coefficient is lower than 0.5, the effect of secondary lining on raising the ultimate bearing capacity of double-layer lining is more obvious in a certain range. The increase of water pressure can improve the ultimate bearing capacity of segment and secondary lining, but the failure process tends to be sudden. Under the action of circulating water pressure, the greater the variation of water pressure, the lower the ultimate bearing capacity of segment. Based on the selection of design parameters of shield tunnel at present, with the increase of shield tunnel size, the transverse stiffness of segment and secondary lining structure is relatively small. As a result, the lower the ultimate bearing capacity of segment and secondary lining, When the outer diameter of shield tunnel is more than 10 m, the effect of secondary lining on improving the stress state of segment and secondary lining and increasing the ultimate bearing capacity is more remarkable. Increasing the thickness of the second liner can obviously enhance the ultimate bearing capacity of the segment and the secondary lining, and the failure process tends to be sudden, but when the thickness of the second liner exceeds 30cm, Increasing the thickness of the second liner to the ultimate bearing capacity of the double-layer lining decreases gradually) the secondary lining reinforcement can increase the ductility of the double-layer lining, effectively enhance the ultimate load-bearing capacity of the double-layer lining structure, and prolong the process of instability and failure. To improve the overall mechanical properties of double-layer lining structure, the secondary lining defects have a significant influence on the stress state and ultimate bearing capacity of double-layer lining structure. The larger the scale of defects, the lower the ultimate bearing capacity of double-layer lining structure. The failure characteristics of the whole instability tend to be sudden, and the secondary lining defects at the arch roof and the arch waist are more significant to reduce the ultimate bearing capacity of the double-layer lining structure.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U455.43

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