【作者】 巢万里；

【导师】 王星华；

【作者基本信息】 中南大学 ， 土木工程， 2013， 博士

【摘要】 随着高速公路的建设逐渐进入山岭重丘区,桥梁隧道工程也日益增多。桥隧过渡工程最显著的特点是相互连接的桥梁与隧道之间存在着相互影响,桥梁、隧道和周边岩体受到的扰动更多,其力学行为更为复杂。但是,目前国内外对桥隧过渡工程的研究十分有限,如何对‘施工过程中进行优化,以及如何分析车辆荷载对桥隧过渡段结构的动力作用都是值得关注的问题。针对以往研究中的不足,本文建立室内相似模型,首次利用室内试验研究了桥隧连接工程在重复行车荷载下围岩及结构的应力应变特征,及疲劳损伤。随后利用数值模拟手段,研究了桥隧结构在周期行车荷载下的动力响应。随后根据桥隧连接处存在沉降差异的特点,推导了重载汽车通过沉降差异处的振动方程,并建立相应的隧道振动响应方程,以此求得隧道在车辆冲击荷载下的动力响应。以室内试验,数值模拟及理论分析等手段研究桥隧过渡结构在行车荷载作用下力学行为与动力响应,在此基础上分别针对隧道边仰坡的参数反演,稳定性分析以及隧道施工围岩的力学行为进行了研究,阐明了隧道围岩在施工过程中的力学行为变化,为桥隧过渡段的设计施工提供了理论依据。最后结合现场试验,将本文研究成果与实际测试结果进行对比,验证了本文的理论计算的正确性。本文获得的具体研究成果有如下几点：(1)在确定试验材料和试验方案的基础上,研究了不同工况下桥隧过渡段施工过程中,隧道围岩压力变化情况,洞口附近围岩及边仰坡土体的稳定性。在此基础上,研究了不同工况下桥隧邻接工程在后期运营阶段,汽车荷载及其冲击作用下,桥、隧结构各关键部位及洞口土体的受力、变形、位移和沉降情况,及工程中常见的病害机理。(2)利用有限元软件MIDAS-GTS,建立了桥隧过渡段的三维数值计算分析,并根据车辆动荷载的大小与时变规律,施加动力荷载。通过桥隧过渡段的围岩衬砌应力,位移的比对分析,研究车速与桥隧过渡段的不同形式对其稳定性的影响.对两种不同的基础形式在动荷载作用下的动力反应进行对比,分析提出合理的桥隧搭接过渡段结构形式,为方案比选提供理论依据。(3)在桥台与隧道衬砌的连接处,两者之间的沉降差异使车辆通过桥隧过渡段时对路面产生冲击作用。考虑车体自身的纵向转动与倾覆,车辆通过桥隧连接段的过程视为一定初始条件下的受迫振动,根据D’Alembert原理,建立了三自由度与五自由度下,车辆与路面的动力耦合计算模型并给出其振动方程。并利用Laplace变换,对该系统的动力响应进行分析,求得各车轮冲击力随时间的变化规律。为了研究上述冲击荷载对隧道断面的动力效应,将根据已有两相饱和介质Green函数,利用Lamb积分公式,结合隧道断面特征,以解析积分法推导了矩形和圆形断面隧道在上述衰减动力荷载下的振动反应,并研究了该荷载作用于隧道底部任意位置时的隧道振动位移反应表达式闭合解、反应时程曲线、瞬态和稳态的振动形态。(4)为了获取隧道的边仰坡物理力学参数,采用位移反分析技术对其进行研究。分别针对层状以及均质边坡,分别提出了基于模糊数学以及测斜曲线分析的反分析技术,并给出其目标函数。结合工程实例,计算了的目标函数的敏感度,证明其有效性。根据参数反演的结果,利用FLAC3D软件,利用多滑动面技术,分析隧道边仰坡的稳定性。(5)利用有限差分软件FLAC3D建立桥隧过渡段计算模型,分别模拟了不同围岩级别下,桥隧搭接段与邻接段的围岩应力、围岩塑性区、洞周位移及地表位移规律。并比较了不同施工方法(台阶法,侧壁导坑,CRD法)对围岩稳定性的影响,并对扩大基础与桩基础条件下,桥隧邻接段围岩以及桩体自身应力应变规律进行研究,为施工方案的选择提供指导。更多还原

【Abstract】 With the construction of highway in the mountainous areas, the number of bridge and tunnel engineering increases day by day. The significant characteristic of the bridge-tunnel connection section is the mutual influence between the connecting bridge and tunnel. What’s more, the bridge, tunnel and rock are disturbed frequently and mechanical behavior is more complex. However, the research on bridge-tunnel connection section is quite limited. According to the disadvantage in the previous research, a simulation test was modeled using similarity theorem. The characteristic of strain and stress and the fatigue damage for bridge-tunnel connection section under repeated traffic loading is studied, especially the surrounding rock and the construction. And the dynamic response of bridge-tunnel connection section under vehicular load in1or2periods is analyzed by numerical simulation. Because of the differential settlement at the junction of bridge and tunnel, the vibration equation of heavy duty vehicles passing the bridge-tunnel connection section is derived. And the vibration response equation of tunnel rock is established, the vibration response of surrounding rock under vehicles is obtained. After studying the mechanical behavior and vibration response under vehicles load by similar simulation test, numerical simulation and theoretical analysis, in the presented study, the back analysis and the stability analysis of the slope and is studied and the mechanical behavior of the tunnel surrounding rock is analyzed. Finally, with the field test, the research result and the actual results is compared to prove the correctness of the theoretical calculation. The main research content is as following:(1) The static force calculated model of bridge-tunnel connection section is built by Finite difference method software FLAC3D, the surrounding rock stress, plastic zone, side wall displacements and surface displacement of bridge-tunnel connection section under different rock grade is calculated. And, the influence of construction method (steps method, CRD method and siding head method) to surrounding rock stability is studied. What’s more, with the spread foundation and pile foundation, the stress and strain of surrounding rock and foundation is researched for guidance to the construction and design.(2) Using the finite element software MIDAS-GTS, the3-D dynamic calculated model of bridge-tunnel connection section is built and the dynamic load is applied by the size and time-dependent deformation of vehicle load. With obtaining the surrounding rock, linking stress and displacement, the stability of bridge-tunnel connection section is researched by various vehicle and different construction type. Comparing the dynamic response of two type of foundation under dynamic load, the reasonable foundation is presented for the theory basis of the project design.(3) On the basis of the experiment material and program, the tunnel surrounding rock stress distribution, the stability of tunnel portal and side and face upward slope in construction progress under different construction condition are studied. What’s more, considering the vehicle load and dynamic load, the stress, deformation, displacement and settlement of the key position of the construction and tunnel portal soil is studied. The common disease mechanism is also researched.(4) For obtaining the physical and mechanical parameters heading slope, the displacement back analysis technology is applied. Aiming at layered and homogeneous slope, the back analysis method is proposed based on fuzzy mathematics and inclination curve features characteristic analysis, and the objective function is presented. With the practice engineering, the effectiveness of method is proved by calculated objective function sensibility. Using the intensive parameter, the slope stability is analyzed with multi slide surface technology with FLAC3D.(5) Settlement difference occurs at the joint between bridge and tunnel, making impact action to tunnel-bridge section when vehicle passes, has significant influence to comfortableness of vehicle driving and the whole tunnel construction. Considering the rotation and overturn in longitudinal direction, the process of vehicle passing tunnel-bridge section is regarded as the forced oscillation with certain initial condition, by which the calculate model of man-vehicle-road is built under D’Alembert principle and vibration equation is given. What’s more, by Laplace transform, the acceleration of driver and the impact force to road is solved. And these magnitudes variation with time can be obtained. Finally, the influence factor to the impact is studied, to provide the theory basis of reduce the damage by impact loading result from settlement difference. For studying the above impact loading dynamic effect to tunnel section, with Green function and Lamb integral formula, combining the tunnel section features, the vibration response of rectangle and circle tunnel under the damping dynamic loading is derived by analytical integral method. And the closed solutions of vibration displacement response under impact or harmonic loads acting on inside of saturated soil tunnel, the travel time history of elastic wave and the transient and ordinary modes of vibration were obtained when the loading is in any position at the bottom of tunnel.更多还原