【作者】 于鹤然；

【导师】 周晓军；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2013， 博士

【摘要】 本文基于深埋立体交叉铁路隧道这种特殊的结构形式,综合运用理论分析、数值模拟、工程实践等研究方法对既有隧道衬砌变形、围岩压力变化规律、隧道结构内力变化及列车动荷载响应进行了系统研究,并以乌蒙山隧道与新梅花山隧道立体交叉的实际工程为依托,对立体交叉隧道结构形式进行比选分析,论文研究获得了以下成果：1)利用三维数值模拟方法,通过对大量工况计算结果的归纳总结,得出了以两隧道最小净距、立交段围岩条件、两隧道先后修建顺序为变量,既有隧道道床最大竖向位移值和道床竖向位移曲线的预测公式。并给出了对既有隧道高速铁路运营安全不产生影响的净距容许建议值。2)无论是新建隧道下穿或者上跨既有隧道,在两隧道立交点处,既有隧道各部位围岩压力均有不同程度的下降现象,其中以拱脚、边墙、拱肩三个位置处最为明显。并对多种围岩级别、多种最小净距工况下既有隧道受影响的范围作出了判定,在围岩条件较好时,对既有隧道而言,上跨形式的影响范围要小于下穿形式。并以围岩压力变化幅度为评价准则,对深埋双线立交隧道间无相互影响的净距临界值给出了推荐值,以期对类似工程提供一定的指导作用。3)对于深埋双线椭圆形断面的隧道而言,在既有隧道周围修建新隧道,对既有隧道立交点处衬砌结构会造成全环轴力下降的现象,随着两隧道间净距的增大,衬砌结构轴力下降的趋势有所减缓；随着围岩级别降低,相同净距情况下的衬砌结构弯矩、轴力变化量呈线性递减。在新隧道下穿修建的工况下,既有隧道衬砌全环轴力下降,弯矩上升,受力状态明显恶化。而在新隧道上跨既有隧道状况下,与下穿方式不同,在轴力下降的情况下,弯矩也普遍下降。而且在相同净距、相同围岩级别条件下,上跨方式中横、纵向安全系数发生下降的位置均少于下穿的方式,由此判断上跨方式对既有结构的受力状态影响范围较小,故类似工程应优先考虑新隧道上跨的修建方式。4)对常用的列车动荷载—维正弦激振力模型进行修正,解决了原模型在模拟高速列车时产生对钢轨向上的拉力问题,使其适合v≥3501km/h高速铁路的研究需要,并把该模型推广到三维模拟当中。5)与常规段相比,不论是位移、速度还是加速度,立交段均有着显著的放大作用,设定了三种不同的立体交叉结构形式,分别为分修、半分修、合修结构,经位移响应、振动衰减及横向、纵向内力状况分析比选,结果表明,立交框架—挡头墙连接上下上下隧道的合修结构形式为最优选择。6)对于两隧道同时施工的情况,每条隧道均有向对方变形的趋势,先行通过立交点的隧道围岩所受到的位移扰动最终量将小于后通过者。围岩扰动越低,施工风险越小,结构越安全,故可根据两隧道的不同重要程度及实际施工条件,来判断各个隧道的施工进度关系,即重要的结构尽量先行修建。7)本文通过详尽的动态仿真计算,证明了框架—挡头墙形式的立体交叉设计方案及施工工序是合理可行的,该施工方案已成功应用于乌蒙山隧道和梅花山隧道立体交叉工程中,值得类似工程借鉴。更多还原

【Abstract】 This dissertation focused on deeply buried over-cross railway tunnels, via the comprehensive approaches of theoretical analysis, numerical simulation and engineering practice, did a systematic study on the existed tunnel lining’s deformation, the rule of surrounding rock pressure variation, the tunnel structure internal force alteration and dynamic response with train load, and combined with the actual project, Wumengshan tunnel&Xinmeihuashan tunnel over-cross tunnels project, carried out a comparation research on different forms of over-crossing structures. This dissertation obtained the following achievements:1) Using the method of three-dimensional numerical simulation, summarizing from a large number of conditions calculation results, this dissertation deduced the track bed deformation prediction formula, which included the variables of the minimum spacing, the surrounding rock conditions and the building consequence of the two tunnels, and gave out the suggested interval allowable values to avoid any impacts on the security of the existing tunnel’s high-speed railway operation.2) Whether the new tunnel building beneath or on-acrossing the existing tunnel, the surrounding rock pressure of the existing tunnel would decrease in varying degrees. At the three positions of arch foot, side wall and spandrel, this phenomenon was much more obvious. This dissertation made a determination on the existing tunnel’s influenced scope under different spacing and rock classifications. When the surrounding rock conditions were good enough, for the existing tunnel, the influence scope of on-acrossing style was smaller than the building beneath one. Took the rock pressure variation amplitude as the evaluation criteria, we provided critical value of uninfluenced clearance for over-crossing tunnels project, which will bring forward reference to the similar projects.3) For the deep double track tunnels with elliptical section, building a new tunnel closely would lower the whole ring’s axial force of the old tunnel’s lining structure. Along with the increase of the clearance between two tunnels, structure axial force downward trend slowed down; Along with the surrounding rock conditions turning worse, the structure bending moment and axial force under the same clearance decreasing linearly. In the condition of the new tunnel building undercrossing, full ring of axial force dropped, while bending moment rose, stress state significantly turning worse. In the case of new tunnel building over across, with the axial force dropped, in different ways, bending moment also generally decline, and the positions where transverse or longitudinal structure safety factor decreased would be less than the building under cross style, So to the building over pass form exert less impact to internal force of existing tunnel lining than the building under pass style. So that the similar project should firstly consider the former construction style.4) This dissertation corrected the commonly used one-dimensional sine vibration force model for train dynamic loads, so that solved the problem that it would generates upward tension to the rail when using the original model to simulate high-speed train load, now made it much more suitable for v≥300km/h high speed railway research, and this dissertation also put the model forward into three dimensional simulation.5) Compared with conventional section, all the displacement, velocity and acceleration in overpass section were significantly amplified. At the cross point, this dissertation set three different structures, they were separated building, half-separated building and building in union, via the comparison study on displacement response, vibration damping and transverse longitudinal internal force analysis of each style of the three, and the results showed that the framework-connecting walls structure form, which connecting the two tunnels together, was the best choice.6) For the case of two tunnels were under construction simultaneously, each one had the trend of producing deformation towards the other. Research revealed that the surrounding rock final displacement disturbance of the first tunnel would be less than the later built one. The lower the disturbance to surrounding rock, the smaller construction risk would be and the more safety structure was. Therefore, we could determine each tunnel’s construction progress according to different important degrees of the two tunnels and the actual construction conditions. It means that the more important one should be build first.7) In this dissertation, through detailed dynamic simulation calculation, this dissertation proved that, the design scheme and construction process plan of the framework-connecting walls form for over cross section was reasonable and feasible, and this construction scheme has been carried out successfully in the WuMengShan tunnel&Xinmeihuashan tunnel over cross tunnels project, and that were worth reference for similar project.更多还原