【作者】 林存刚；

【导师】 夏唐代； 吴世明； 张忠苗；

【作者基本信息】 浙江大学 ， 岩土工程， 2014， 博士

【摘要】 目前国内水下盾构隧道建设方兴未艾,其施工环境效应及结构稳定性的研究应运而生。本文研究在杭州水下盾构隧道的建设背景下展开,依托于杭州庆春路过江隧道的工程实践,通过现场试验和理论计算研究了盾构掘进引起的地面隆陷及钱塘江潮汐对隧道结构受力性状的影响,旨在深入认识水下盾构隧道施工环境扰动及其长期结构性状。本文研究内容总体上分为2部分,分别为盾构掘进引起的地面隆陷和钱塘江潮汐作用下盾构隧道的受力性状。(一)盾构掘进引起的地面隆陷庆春路隧道建设期间,对盾构掘进引起的地面隆陷进行了大量的现场监测,并实时记录了盾构掘进参数。通过实测分析,总结了杭州软土中盾构掘进引起地面竖向位移的特征和规律,并对各传统地面沉降计算理论的适用性进行评析。在实测基础之上,引入土力学和流体力学的若干基本理论计算盾构掘进引起的地面隆陷。主要创新点如下：(1)提出了盾构非水平掘进时的地面隆陷Mindlin解数值积分算法。(2)在实测基础之上发现横向地面注浆隆起符合高斯分布,与地层损失沉降叠加,提出考虑注浆隆起效应的广义Peck公式。(3)基于源汇法推导得到在隧道围土不同收敛模式下的地面沉降计算公式,并在实测基础之上进行了经验性改进,提供了一种盾构隧道施工地层损失沉降估算的简单可靠方法。(4)提出了一种划分地层损失沉降与固结沉降的简单实用方法。(5)提供了一种盾构施工扰动超孔隙水压力及地面固结沉降的理论计算方法。(6)提出了一种考虑盾构掘进速度和停机时间的地面沉降计算理论。(7)探讨了同步注浆的时空效应,提出了考虑注浆效率和注浆分布模式的地面隆陷计算方法。(8)提出了一种基于切口超挖控制的地面隆陷计算方法。(二)钱塘江潮汐作用下盾构隧道的受力性状庆春路隧道在建设期间设计实施了结构健康监测系统,监测项目包括隧道位置钱塘江水位、隧道围压、衬砌钢筋应变、衬砌水平直径收敛以及隧道纵向沉降。依托于该健康监测系统的现场实测,主要有以下创新性研究：(1)分析了钱塘江水下盾构隧道围压及钢筋应变与水位的相关性。(2)针对隧道上覆土层透水性的不同,提出了2种水下盾构隧道衬砌设计模型,并以现场实测验证了其中之一的合理性。(3)采用惯用计算法计算水位波动引起的衬砌钢筋应变变化,并根据现场实测数据对计算弯矩进行了经验性修正,使其计算内力可用于衬砌结构应力应变分析。(4)基于上述两种水下盾构隧道衬砌设计模型,出于隧道结构安全的考量,对钱塘江极限容许水位进行了预测。更多还原

【Abstract】 There is an ever-increasing potential for construction of underwater shield-driven tunnels nowadays in China. Research on environmental impacts induced by excavation of underwater tunnels and their structural soundness has emerged under this circumstance. This study was initiated synchronously with the construction of underwater shield-driven tunnels in Hangzhou, for the purpose of deepening the insight into their environmental disturbances and long-term structural properties. A comprehensive series of in situ tests during construction and operation of the Hangzhou Qingchun Road Underwater Tunnel combined with analytical computations were conducted to study tunnelling-induced ground surface vertical deformations and responses of tunnel structures subject to the Qiantang tidal bores.The contents of this study are broadly classified into two parts:(1) tunnelling-induced ground surface heave and subsidence, and (2) mechanical characteristics of the shield-driven tunnels subject to the Qiantang tidal bores.1. Tunnelling-induced ground surface heave and subsidenceTunnelling-induced ground surface vertical deformations were measured from extensive field instrumentations during construction of the Qingchun Road Tunnel. Besides, the shield excavation parameters were recorded in real time. Characteristics and development of ground surface deformations induced by shield tunnelling in Hangzhou soft ground were summarized by means of field observations.In addition, the applicability of available subsidence calculation methods was assessed.Based on field observations, several fundamental theories in soil mechanics and fluid mechanics were applied for calculation of heave and subsidence at the ground surface induced by shield tunnelling. The main innovations were as follows:(1) A numerical integration method based on the Mindlin’s problem was proposed for calculation of ground surface vertical deformations due to shield tunnelling along an inclined alignment.(2) The transverse ground surface heave caused by shield tail synchronous grouting accords with the Gaussian distribution through field observations. A generalized Peck formula taking both ground loss settlement and grouting heave into account was put forward.(3) A formula for calculation of tunnelling-induced ground surface settlements under different surrounding soil intrusion models was deduced from the source-and-sink method in fluid mechanics. Subsequently, an empirical modification was conducted on the basis of field observations. The modified formula provides an easy and reliable means for estimation of ground loss settlement caused by shield tunnelling.(4) An easy and practical method to distinguish the time boundary between ground settlements arising from ground loss and consolidation was presented.(5) An analytical method for calculation of excess pore water pressures and consolidation settlements arising from disturbance caused by shield tunnelling was put forward.(6) A computation theory for tunnelling-induced ground surface settlement taking influences of shield advance rate and abnormal machine halt into account was presented.(7) The efficiency of tail void synchronous grouting was evaluated with respect to the time and spacial effects. A method for calculation of ground surface vertical deformations with account of grouting efficiency and distribution was proposed.(8) A simple method was formulated for estimation of ground surface vertical deformations based on over-excavation control at the cutting-face.2. Mechanical characteristics of shield-driven tunnels subject to Qiantang tidal boresA structural health monitoring system (SHMS) was designed and set up during construction of the Qingchun Road Tunnel to measure river stage of the Qiantang River, earth pressures acting on the tunnel linings, strains of the reinforcing steel bars, convergence of the tunnel linings along the springline and longitudinal settlements of the tunnel. Based on field observations from the SHMS, innovative research as follows was carried out.(1) Correlations between changes in earth pressures acting on the tunnel linings and strains of the reinforcing steel bars and fluctuations of river stages were assessed.(2) According to differences in permeability of the overburden strata, two kinds of design models were established for underwater shield tunnel linings, one of which was verified by field observations.(3) The uniform rigidity ring method was applied for calculation of changes in strains of reinforcing steel bars induced by fluctuations of river stages. Moreover, an empirical modification was made to the computed bending moment based on field observations. In this way, the modified computed member forces can be applied for stress and strain analysis of the tunnel lining.(4) The limit allowable river stage of the Qiantang river was predicted for structural safety of the tunnel linings with respect to the two above-established design models.更多还原