基于重庆地层TBM隧道衬砌结构纵向稳定性研究

发布时间：2018-08-11 10:23

【摘要】：伴随着TBM隧道在我国的快速发展,TBM隧道在地层中的稳定性问题显得尤为重要,尤其是在以重庆地层为特点的广大复合地层地区。TBM隧道衬砌结构稳定性受到周围地层环境、自身结构形式和施工技术等多重因素的影响,目前还没有成熟的理论成果,只能参照盾构隧道经验对TBM隧道衬砌结构进行设计,但为了保证衬砌结构的长期稳定性,一般设计时偏于保守,造成了巨大的浪费。因此本文针对以重庆地质为特点的复合TBM隧道衬砌结构纵向稳定性进行了研究。论文主要从衬砌结构稳定性的影响因素和不同模型方法两条路线进行了研究。包括在梁-弹簧模型的基础上对梁-弹簧模型进行修正研究,对接头抗弯刚度、地层抗力系数、侧压力系数以及管片拼接方式等影响衬砌结构稳定性的因素进行了分析;另外,在对TBM隧道衬砌管片稳定性的另一研究方法-纵向等效连续化模型进行了理论性推导和有限元数值模拟验证,主要是把反映管片横向性能的横向刚度有效率考虑进纵向等效连续化模型中。论文的主要研究如下:(1)针对梁-弹簧模型在模拟实际管片结构时存在的一些问题,结合梁-接头不连续模型和壳-弹簧模型的理论基础得到了一种改进的、以梁-弹簧模型为基础的新模型:修正梁-弹簧模型。主要创新点为在接头上采用梁-接头不连续模型的双节点形式以解决其实际受力的不连续性问题,在接头弹簧上引入径向和切向抗弯刚度以及剪切刚度理论。(2)通过模拟外径6m级和10m级的TBM隧道衬砌管片接头在不同荷载作用下力学性能,找到荷载、管片接头转角与接头抗弯刚度之间关系曲线,以此对管片接头处弯曲刚度进行研究。在横向轴力一定时,弯矩(正负弯矩的绝对值)会使管片接头转角增大,当M较小时抗弯刚度K_θ基本趋于稳定状态,当M增加到一定数值时抗弯刚度K_θ逐渐变小并在一定数值趋于稳定;另外,轴力对接头抗弯刚度有增强作用。对θ-M曲线采用切线法原理获取抗弯刚度K_θ的取值范围。(3)通过对影响TBM隧道衬砌管片稳定性的地层因素和拼装方式进行研究得知,地层抗力系数、侧压力系数以及管片拼装方式对TBM隧道衬砌管片稳定性都有一定的影响,分析了以上各种因素对其稳定性影响的规律和程度。(4)采用理论推导与有限元数值模拟验证对比的方法,得到了横向刚度有效率与纵向等效刚度之间关系曲线及公式,以及横向刚度有效率对纵向等效弯曲刚度影响程度;通过有限元数值模拟验证了考虑横向刚度后采用纵向等效连续化模型分析管片结构纵向稳定性的准确性。
[Abstract]:With the rapid development of the TBM tunnel in China, the stability of the tunnel in the formation becomes more and more important, especially the stability of the lining structure of the tunnel is affected by the surrounding stratigraphic environment in the complex formation area characterized by Chongqing formation. The influence of many factors, such as the form of its own structure and the construction technology, is not mature at present, so it can only design the lining structure of TBM tunnel according to the experience of shield tunnel, but in order to ensure the long-term stability of the lining structure, General design is conservative, resulting in a huge waste. Therefore, the longitudinal stability of composite TBM tunnel lining is studied in this paper. This paper mainly studies the influence factors of lining structure stability and two routes of different model methods. Based on the beam-spring model, the modification of the beam-spring model is carried out, and the factors affecting the stability of lining structure, such as joint bending stiffness, formation resistance coefficient, lateral pressure coefficient and segment splicing mode, are analyzed. The longitudinal equivalent continuum model, another research method for the stability of lining segments of TBM tunnel, is theoretically deduced and verified by finite element numerical simulation. The efficiency of lateral stiffness which reflects the transverse performance of segments is considered in the longitudinal equivalent continuum model. The main research contents are as follows: (1) aiming at some problems existing in the beam-spring model in simulating the actual segment structure, an improved method is proposed based on the theory of beam-joint discontinuity model and shell-spring model. A new model based on beam-spring model: modified beam-spring model. The main innovation is to adopt the two-node form of beam-joint discontinuous model to solve the discontinuity problem of the actual force on the joint. The theory of radial and tangential bending stiffness and shear stiffness is introduced into the joint spring. (2) by simulating the mechanical properties of TBM tunnel lining segment joints of 6m and 10m outer diameters under different loads, the loads are found. In order to study the bending stiffness of segment joint, the curve between the corner angle of segment joint and the bending stiffness of joint is obtained. When the transverse axial force is constant, the bending moment (the absolute value of positive and negative moment) will increase the turning angle of the segment joint, and when M is small, the bending stiffness K _ 胃 tends to be stable. When M increases to a certain value, the bending stiffness K胃 decreases gradually and tends to be stable at a certain value, in addition, the axial force enhances the bending stiffness of the joint. The value range of bending stiffness K _ 胃 is obtained by using tangent method for 胃 -M curve. (3) by studying the formation factors and assembling methods that affect the stability of TBM tunnel lining segment, it is found that the formation resistance coefficient is obtained. The lateral pressure coefficient and the assembling mode of segment have certain influence on the stability of TBM tunnel lining segment. The law and degree of the influence of the above factors on the stability are analyzed. (4) the method of theoretical derivation and finite element numerical simulation is used to verify the stability of TBM tunnel lining segment. The relationship curve and formula between the efficiency of transverse stiffness and the longitudinal equivalent stiffness are obtained, and the influence of the efficiency of transverse stiffness on the longitudinal equivalent bending stiffness is also obtained. The accuracy of using longitudinal equivalent continuum model to analyze the longitudinal stability of segment structure is verified by finite element numerical simulation.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U451.4

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