【作者】 陈寅奕；

【导师】 徐永福； 李浩；

【作者基本信息】 上海交通大学 ， 岩土工程， 2008， 硕士

【摘要】 深埋隧道在开挖支护过程中经常遇到大变形、高地应力岩爆甚至拱顶塌方等工程问题,支护结构在高地应力条件下往往需要承受很大的支护压力,因此,对支护结构与围岩的相互作用进行深入研究,优化分析支护结构的设计参数和施作时机对提高工程安全性和经济性具有重要意义。本文以连云港后云台山公路隧道为工程背景,在系统总结和分析围岩与支护结构相互作用机理及围岩稳定性分析理论基础上,对隧道开挖支护过程进行了多种工况的数值模拟。主要内容和取得的成果包括以下几点:(1)利用FLAC3D建立数值模型,对圆形断面、矩形断面、直墙圆拱形断面以及曲墙式断面这四种不同隧道断面的位移场和应力场进行分析比较,确定断面形式;对II～V级围岩在六种不同埋深下的无支护开挖进行数值模拟,围岩参数依据相关规范分级标准确定,了解无支护开挖下各级围岩的洞周位移及应力变化情况,为复合支护设计分析提供依据。(2)根据各工况模拟结果,绘制隧道拱顶纵向沉降曲线(LDP)和围岩收敛曲线(GRC),并与经验公式比较分析,模拟结果与理论公式基本相符。总结各级围岩开挖面收敛比随埋深变化规律,了解隧道开挖引起的时空效应,通过隧道拱顶纵向沉降曲线为确定支护初始位移提供依据;分析各级围岩塑性区和塑性应力随埋深变化情况,了解围岩的破坏情况,应力集中系数随埋深和围岩级别的变化情况,支护结构所承受的压力介于塑性压力和最小围岩压力之间。(3)针对隧道工程区岩体取样,在室内进行岩石单轴抗压强度试验和三轴压缩试验,绘制相应的应力–应变关系曲线和莫尔圆,分析岩石试样的变形及强度特征,确定围岩的主要物理力学参数,为数值模拟奠定试验基础。(4)根据后云台山隧道设计资料和围岩参数,针对不同锚杆长度、锚杆间距、锚杆直径进行模拟分析,结果表明三者对围岩位移影响能力高低依次为:锚杆长度>锚杆间距>锚杆直径;对支护结构预设计方案进行模拟,根据围岩与支护结构相互作用关系,分析预设计方案和隧道结构的稳定性,并进行安全性评价,模拟结果表明隧道围岩是稳定的,结构安全性满足设计要求。更多还原

【Abstract】 Engineering problems like large deformations, high stress rock burst and crown collapse are often met during the excavation and support of deep tunnels. The supporting structure usually need to bear high support resistance under the condition of high ground stress. So, it is important to make further research in the interaction analysis of composite support and surrounding rock and make optimal analysis of design parameters and supporting time of supporting structure, it also has important significance to improve safety and economy of the project.The Hou-Yun-Tai-Shan road tunnel at Lianyungang is the engineering background of the paper. After the interaction mechanism of surrounding rock and support system and the analysis theory of surrounding rock stability is summarized and analyzed, the numerical simulation of excavation and support processes of multi-cases tunnel is made. Contents and resulting achievement of this paper are as follow:(1) The numerical model is made by FLAC3D. The stress field and displacement field of circular section, rectangular section, straight wall arch section and curved wall section are analyzed and compared to determine the section form of tunnel. After that, numerical analysis of unsupported excavation for surrounding rock of grade II~V in six different depth is done. The parameters of surrounding rock are according to related specifications. According to simulation results, the convergence and stress variation of tunnel inner are known, which provides evidence for design analysis of composite support.(2) According to the simulation results of multi-cases, the Longitudinal Deformation Profile (LDP) and Ground Reaction Curve (GRC) are drawn. And comparative analysis between simulation results and theoretical results are taken. It has a good accordance between these two results. The variation law that convergence ratio of excavation face varies with buried depth is summarized. According to this, time-space effect induced by excavation can be known. The LDP provides evidence for the determination of initial displacement of supporting system. After analyzing the change of plastic zone and plastic stress in different depth, we can know the damage of surrounding rock. The changes of stress concentration factor as depth and grade of surrounding rock is summarized. And the support resistance is between plastic stress and the minimum rock pressure.(3) The rock samples are taken from tunneling engineering area. After rock uniaxial compressive strength test and triaxial compression test are made, the stress-strain curve and mohr circle are drawn. According to the results, deformation and strength characteristics of the rock samples are analyzed, which can determine the physical and mechanical parameters of rock samples. These two tests establish experimental basis for numerical simulation.(4) According to the design information and rock parameters of Hou- Yun-Tai-Shan tunnel, the simulation analysis of different lengths, different intervals and different diameters of anchor are taken. The results shows that the impact on surrounding rock displacement of the three factors can be sorted as: anchor length>anchor interval>anchor diameter. The pre-design plan of support structure is simulated. The stability analysis of support structure and surrounding rock is made based on the interaction analysis of composite support and surrounding rock. The safety evaluation is summarized and the result shows that the tunnel has good stability and the structural safety meet the design requirements.更多还原