【作者】 曹军军；

【导师】 晏启祥；

【作者基本信息】 西南交通大学 ， 建筑与土木工程（专业学位）， 2021， 硕士

【摘要】 盾构隧道施工期间管片衬砌上浮对隧道后期的运营维护非常不利,且容易造成安全隐患,这里以广州地铁某区间盾构隧道为工程背景,通过理论计算与数值模拟相结合的方法,得到该工程在不同注浆压力作用下浆液在盾尾间隙与地层裂隙中的填充扩散规律;综合考虑浆液多种时效参数,分析管环上浮量以及地层与管片的受力状态,最后基于优化的地层抗力系数以及管片横向刚度有效率,建立管片在上浮荷载下的精细化三维荷载-结构模型,并进一步讨论管片以及螺栓在上浮荷载作用下的受力特性,主要的研究内容如下:(1)对盾构隧道常用的三种注浆方式进行了简单的介绍,然后进一步详细的阐述了浆液注入盾尾后的扩散过程。从管片的上浮机理出发,解释了盾尾间隙的产生与组成部分,并总结了八大类使管片衬砌上浮的原因;结合上浮荷载特性,将上浮荷载归纳为“静态上浮力”与“动态上浮力”。(2)以同步注浆为出发点,引入随机裂隙实现对裂隙发育地层的模拟,对计算域进行浆液填充扩散相场→渗流场两个物理接口的耦合计算。提取管片环向浆液填充压力,并与理论值进行对比,验证了仿真模型的可靠性。最后基于该数值模型并设置不同的注浆压力,研究了浆液注入盾尾后300s内浆液的填充扩散规律,并进一步分析了注浆对地层渗流场的影响。(3)在计算模型中同时考虑同步注浆时注浆压力的耗散、浆液的变形模量、渗透系数、动力粘度随时间的变化,然后分析地层与管片的位移与受力随浆液时效特性的变化特征。(4)基于刚度等效原理对Muir Wood解中的地层变形模量进行修正,其中,不仅引入了浆液弹模的时效函数,且考虑了管片在注浆层中发生整体上浮,浆液填充层的不均匀分布,最终得到不同注浆时间下地层的等效抗力系数分布极坐标曲线。通过修正均质圆环代替拼装管片环横向抗弯性能,推导出横向刚度有效率与接头抗弯刚度的关系,最后基于单筋截面适筋破坏理论推导了接头的抗弯刚度计算方法。(5)引入优化后的地层抗力系数以及横向抗弯刚度有效率,并结合实际工程参数建立精细化三维荷载-结构模型。基于该模型分析了盾构隧道在上浮荷载作用下不同施工步以及纵向竖曲线对管片和螺栓的位移与受力特征。更多还原

【Abstract】 The segment up-floating during the construction of shield tunnels is very unfavorable to the operation and maintenance of the tunnel,and is likely to cause safety hazards.Taking a shield tunnel project in Guangzhou Metro as the background,this paper obtained the filling and diffusion law of slurry in the shield tail gap and stratum fissure under different grouting pressure by means of theoretical calculation and numerical simulation.Considering the floating volume of the segment ring and the formation’s and segment’s stress state as well as various aging parameters of slurry,a refined three dimensional load-structure model of the segment rings subject to floating load is established based on the optimized formation resistance coefficient and the transverse stiffness efficiency of the segmental lining.Subsequently,the stress characteristics of the segment and bolt under floating load are discussed.The main contents are as follows:(1)Three grouting methods commonly used in shield tunnel were introduced briefly and the diffusion process of slurry injected into shield tail was expounded.Based on the mechanism of segment up-floating,the generation and components of shield tail gap are explained,and eight reasons for segment floating are summarized.According to the characteristics of buoyancy load,the buoyancy load can be divided into static buoyancy and dynamic buoyancy.(2)From the perspective of synchronous grouting,the simulation of fracture development in actual condition is realized by introducing random fractures.The unidirectional coupling calculation of two physical interfaces,slurry filling diffusion field and seepage field namely,is carried out in the calculation domain.The circumferential slurry filling pressure of the segment was extracted and compared with the theoretical results,which verified the reliability of the numerical model.Finally,based on the numerical model and setting different grouting pressure,the filling and diffusion law of slurry in 300 s after grouting into shield tail is studied,and the influence of grouting on formation seepage field is further analyzed.(3)Considering the time effect of grouting,the dissipation of grouting pressure,deformation modulus of slurry,permeability coefficient and dynamic viscosity of grouting variation with time were taken into account in the calculation model,then the characteristics of displacement and stress of stratum and segment related with time effect of grouting are analyzed.(4)Based on the principle of stiffness equivalence,the deformation modulus of strata in Muir Wood theory was modified,in which not only the time-dependent function of slurry elastic modulus was introduced,but the uneven distribution of slurry filling layer and segment integral floating in grouting layer are considered,then the equivalent resistance coefficient distribution of strata in the polar coordinates at different grouting time are obtained.By evaluating the equivalence of the transverse bending performance of the modified homogeneous ring and the assembled segment ring,the relationship between the effective rate of the transverse stiffness and the bending stiffness of the joint is deduced.Finally,the calculation method of the bending stiffness of the joint is deduced based on the theory of the suitable reinforcement failure of the single reinforcement section.(5)The optimized ground resistance coefficient and lateral bending stiffness efficiency are introduced,and the refined three-dimensional load-structure model is established based on the actual engineering parameters.Based on the model,the displacement and stress characteristics of segment and bolt in different construction stages and longitudinal vertical curve of shield tunnel under floating load are analyzed.更多还原