【作者】 陈孟乔；

【导师】 施仲衡； 刘建坤；

【作者基本信息】 北京交通大学 ， 城市轨道工程， 2014， 博士

【摘要】 随着我国地下空间的大规模开发利用,盾构隧道工程的环境条件越来越复杂,施工中出现了诸多问题,其中较为突出的是支护压力不足造成的开挖面失稳及地层变形过大。特别是近年来我国水下盾构隧道工程快速发展,由于覆土厚度一般较浅、水压较大,开挖面稳定难以控制,稍有不慎就有可能发生开挖面坍塌和水体倒灌等事故。因此,研究高水压条件下盾构隧道开挖面失稳风险具有现实意义。本文结合南京地铁10号线江心洲站～中间风井区间过江隧道工程,通过理论分析、数值模拟以及现场调查和实测等方法,对高水压条件下砂土地层中泥水盾构隧道施工过程中的开挖面稳定性相关问题进行了研究,主要工作和研究成果包括以下几个方面：(1)利用Handy拱效应理论和Mohr-Coulomb准则得出了失稳土体形状的计算方法,失稳土体形状类似贝壳形。基于极限平衡分析理论建立了盾构隧道开挖面稳定性分析模型,并将模型的计算结果与其他理论分析方法、离心试验以及数值模拟分析的结果进行了对比。提出了可用于指导施工的开挖面支护压力极限值工程参考图。(2)利用FLAC3D有限差分程序计算了高水压条件下砂土地层中大直径泥水盾构隧道开挖面支护压力极限值,分析了砂土内摩擦角、黏聚力、弹性模量、隧道埋深、直径、水位等因素对开挖面支护压力的影响,研究了失稳破坏模式以及失稳过程中土压力的变化规律。结果表明,高水压条件下开挖面支护压力极限值比无水压时增大约一个量级。(3)借鉴W. Kent Muhlbauer提出的在管道风险管理领域应用广泛的肯特法的基本思想,对泥水盾构隧道开挖面失稳风险进行了分析,将风险因素分为地质指数、隧道指数、设计指数、施工指数等项,建立了风险评估模型。修改肯特法中相关指数的评分准则,采用风险指数先相加、再与后果系数相乘的算法计算相对风险评估值,得分越高,风险越大。(4)结合南京地铁10号线江心洲站～中间风井区间过江隧道工程,利用本文建立的泥水盾构隧道开挖面失稳风险评估模型,选取了开挖面失稳风险相对较大和较小的2个典型断面进行了开挖面失稳风险评估,并根据评估结果分析了导致事故发生的主要风险因素,给出了在施工过程中对盾构施工参数进行有针对性的动态调整的建议。更多还原

【Abstract】 With the large-scale development of underground space in China, The environmental conditions of shield tunneling is increasingly complex. Many problems appear during the construction process and one of the more prominent problems is face instability and large ground deformation, which is caused by lack of face supporting pressure. Especially with the rapid development of underwater shield tunnel project at home and abroad in recent years, face stability is difficult to control due to shallow depth and high hydraulic pressure. Therefore, the research on instability risk of shield tunneling face subject to high hydraulic pressure has practical significance,In this dissertation, combined with the cross-river shield tunneling project of Jiangxinzhou sation～Zhongjianfengjing interval in Nanjing Metro Line10, face stability during the construction process of slurry shield tunnel in sands under high hydraulic pressure were studied by theoretical analysis, numerical simulation and on-site survey. The main work and achievements are as follows.(1) According to the Mohr-Coulomb failure criterion, the Handy soil arching theory was used to determine the position and shape of unstable soil. The shape of unstable soil is similar to the shell-shaped. Based on the theory of limit equilibrium analysis, face stability analysis model of shield tunnel was established. The calculation results of this model were compared with the results of other theoretical analysis method, the centrifuge test and numerical simulation analysis. The engineering reference of face limit supporting pressure was proposed, which could be used to guide the construction.(2) Based on FLAC3D finite difference calculated program, face limit supporting pressure of large diameter slurry shield tunnel in sands under high hydraulic pressure was studied. The influences of soil internal friction angle, cohesion, elastic modulus, tunnel depth, diameter and water level on face supporting pressure were analyzed. The failure mode of tunnel face and the variation of earth pressure in the instability process were researched. The results show that, compared to the value under no hydraulic pressure, the limit supporting pressure under high hydraulic pressure increases by about an order of magnitude.(3) Learned from the basic idea of the Kent Method, which was proposed by W. Kent Muhlbauer and was widely used in the field of pipeline risk management, the instability risk of slurry shield tunneling face was analyzed. Risk factors included geological index, tunnel index, design index and construction index. A risk assessment model was established and the scoring criteria of risk index in the Kent Method were modified. The relative risk assessment value was calculated by using the algorithm that risk index adding together, and then multiplying with the consequences coefficient. The risk is proportional to the assessment value.(4) Combined with the cross-river shield tunneling project of Jiangxinzhou station～Zhongjianfengjing interval in Nanjing Metro Line10, two typical sections were selected to assess the face instability risk by the risk assessment model which was established in this dissertation.更多还原