【作者】 彭念；

【导师】 张永兴；

【作者基本信息】 重庆大学 ， 岩土工程， 2010， 博士

【摘要】 随着经济建设的迅速发展,交通隧道的建设迅猛增长,对公路隧道日交通量的要求也越来越高。在一些经济发达地区,双向四车道乃至双向六车道公路隧道已不能适应交通量日益增长的需求,在原有公路隧道基础上改建或新建成为双向八车道公路隧道的建设显得尤为迫切。隧道原位扩建是指在原隧道基础上将隧道断面扩大,从而形成跨度更大的公路隧道。隧道原位扩建最显著的特点是必须拆除原有隧道的支护结构,施工工序复杂,原隧道支护结构的拆除及扩挖对隧道围岩扰动较大,围岩经过的应力路径较为复杂,破坏了围岩体和原有支护结构的平衡状态,力图达到新的平衡和稳定状态,其应力和应变开始一个新的变化过程,变化的结果使得围岩应力重新分布并向扩挖的隧道空间变形。本文以福建某隧道为依托工程,结合理论分析、数值分析以及现场监测试验,旨在探究原位扩建隧道施工围岩变形特征及力学机理,进而为原位扩建隧道设计、施工、监控提供理论依据,指导高速公路隧道扩建工程的实施。进行的主要研究工作有:①影响公路隧道围岩分级的因素有,岩石单轴饱和抗压强度、岩体完整性系数、地下水、软弱结构面产状、初始地应力状态,而对于扩建隧道,还应考虑隧道跨度。这些影响因素有定性、也有定量的,对各种定性和定量因素进行深入剖析,建立了完整的考虑隧道跨度的围岩分级模糊综合评判体系。②扩建隧道是非圆形的,对非圆形隧道,寻找一个单值的解析函数,在非圆形隧道所在的无限平面与有圆孔的无限平面之间建立起一一对应的函数关系,解得非圆形隧道的外廊形状的数学模型,也即外域映射函数,然后利用平面弹塑性力学问题的解法来求解非圆形隧道的应力和位移;通过量测锚杆轴力反分析原位扩建隧道围岩相关状态。③隧道原位扩建分为层层剥皮法和台阶法,采用等代圆法对原位扩建隧道进行计算简化,利用复变函数理论及Schwarz交替法对原位扩建隧道进行求解,通过对围岩应力、位移特征的分析,确定了单次扩挖宽度。掌握了原位扩建隧道围岩位移、应力分布特征及规律。④采用平面弹塑性有限元方法,应用大型通用有限元计算软件ANSYS,对依托工程公路隧道进行扩挖的数值仿真分析,建立了各向同性弹塑性原位扩建隧道施工力学模型,全面分析了隧道在两种扩建方式下围岩的位移、应力状态以及衬砌结构的内力和锚杆轴力等施工力学行为。⑤结合理论、有限元分析,对两种扩建型式的施工开挖顺序、控制爆破以及施工控制体系指标进行研究。更多还原

【Abstract】 With the rapid development of economic construction, construction of traffic tunnel growths rapidly , and the demand for volume of traffic on the highway tunnel is also getting higher and higher.In some economically developed regions, two-way four-lane or even two-way six-lane highway tunnel is unable to meet the growing demand for traffic.The construction of builting two-way eight-lane highway tunnel or converting the existing highway tunnel to two-way eight-lane is specially urgent.Tunnel expansion in situ is expangding the tunnel sections on the basis of the original tunnel to form a larger span highway tunnel.The most significant feature of tunnel expansion in situ is the need to remove the supporting structure, construction process is complex. The removal of supports of the original tunnel and expansion digging will disturbe tunnel rock largerly, and rock stress path is complicated. The equilibrium state of rock body and the original structure supports are destroyed, and try to reach a new equilibrium and steady-state.,the stress and strain start a new process of change. These changes led to a stress redistribution in surrounding rock and spatial deformation towards tunnel digging direction.Relying on a tunnel project in Fujian, combined with theoretical analysis, numerical analysis and monitoring trial on-site together , the deformation characteristics and mechanical mechanism during tunnel expansion in-situ construction are explored. The results provide a theoretical basis for tunnel design, construction,and monitoring in tunnel expansion in situ,also can guide the implementation of highway tunnel extension project . The main research work contains:①The factors that affect rock classification include: rock saturated uniaxial compressive strength,rock integrity coefficient,weak structural surface occurrence,and the initial stress state, but to the tunnel for extension, the tunnel span also should be considered. Through taking depth analysis of various qualitative and quantitative factors, complete rock hierarchical fuzzy comprehensive evaluation system which considers the tunnel span factor is established.②The tunnel for expantion is non-circular,and to non-circular tunnel, looking for a single-valued analytic function, establish a one to one function between the infinite plane where the non-circular tunnel located and the infinite plane with a round hole in it .Through the function, a mathematical model for veranda shape of non-circular tunnel can be solved,which is called outland mapping function. Then using the plane elastic-plastic method to solve the stress and displacement in non-circular tunnel. Last,through the measurement of axial force , relevant state of surrounding rock in tunnel expansion in-situ can be analysised.③Tunnel expansion in-situ is divided into layers of peeling method and step method, using the equivalent circle method to simplify the calculation of tunnel expansion In-situ,then use the complex variable function theory and the Schwarz alternating method to solve the tunnel expansion In-situ problems.Finally,by analysing of rock stress and displacement characteristics , the width of a single extended dig can be determined.④Using the planar elastic-plastic finite element method and large-scale general- purpose finite element software ANSYS, highway tunnel excavation works will be numerically simulated. By establishing Isotropic elastic-plastic tunnel expansion in-situ construction mechanical model, displacement、stress state in surrounding rock、internal forces in lining structure、bolt axial force and other acts of construction mechanics in both expansion modes can be comprehensivelly analysed.⑤Combined with theoretical analysis, excavation sequence, controlled blasting and indexes of construction quality controlling system in the two kinds of expansion types will be studied.更多还原