【作者】 龚伦；

【导师】 仇文革；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2008， 博士

【摘要】 本文依托云南省盐津县白水江三级电站引水隧洞下穿内昆铁路手扒岩隧道近接工程,综合运用调查研究、数值分析、现场测试和经验类比方法,在归纳总结和批判吸收的基础上,对正交或大角度相交、深埋、新建/后修隧道上穿或下穿既有/先修隧道的上下交叉山岭隧道(矿山法施工)的静力、动力影响和对策进行研究。研究成果有:1、利用Peck沉降曲线经验公式,以既有线路轨道容许变位和既有结构容许应力为依据,确定了沉降阈值;运用既有结构物强度准则结合铁路隧道健康状况等级确定应力增量阈值;并基于风险管理理念,确定了不同研究方法应采用的控制标准。2、采用三维有限元法对引水隧洞下穿铁路隧道进行研究,分析了铁路隧道结构的应力增量、沉降规律,得到了引水隧洞对铁路隧道有影响的施工范围并不关于铁路隧道轴线对称,下穿引水隧洞施工过程中,铁路隧道将产生扭转变形;根据沉降和应力增量控制标准确定了两交叉隧道的相互影响范围和影响程度,对既有隧道和新建引水隧洞的结构进行安全检算,并得到了现场监测的验证:证明了采用三维数值模拟用于研究此类近接问题的可行性和计算结果的正确性。3、采用显式动力有限元方法分析了爆破振动影响,得到了掌子面靠近既有隧道时产生的振动速度大于相同距离处远离时产生的振动;考察点和振源连线与水平面夹角为45°是振动速度控制方向的临界角度等成果。通过爆破振动监测实现了信息化爆破施工,使振动速度得到了很好的控制,并与数值分析结果得到了较好吻合。4、铁路隧道中列车机车第1个转向架位于正上方时,引水隧洞结构产生的竖向位移、压力均最大,之后呈简谐波的动力响应;案例的检算结果表明,静力是控制荷载,且结构的疲劳强度满足要求。5、在单个方向地震波作用时,振动(加)速度的最大方向与加载方向一致;垂直于隧道轴线的水平方向振动下的最大响应在拱顶,其余均发生在边墙;隧道建成后的振动(加)速度有很大程度减小,但有应力集中;下穿隧道建成后,既有隧道交叉段的地震响应得到改善。6、以既有隧道应力增量作为判别标准,通过改变两隧道洞径、两隧道净距、隧道埋深及围岩级别等参数,得出既有隧道应力增量随单一参数改变的规律,并根据影响阈值确定两交叉隧道的相互影响范围;首次引入可拓学物元理论研究隧道近接施工影响,建立了近接影响程度等级判定模型,并采用插值法预测影响范围。7、将新建隧道对策、中间地层对策和既有隧道对策等分三类进行研究,得到了既有隧道应力增量与新建隧道拱顶下沉的关系,进一步得到了与新建隧道预留变形量折扣率的关系;通过分段组合措施工况研究,得到了既有隧道应力增量和新建隧道拱顶下沉与掌子面距离的关系曲线;确定了对策措施选择原则,提出现场量测项目及断面和测点布置原则。8、在动力影响中,通过新建隧道洞径、两隧道净距、进尺长度、起爆方式和围岩级别等的改变,得出炸药药量、考察点至爆源距离、围岩级别三个因素与振动速度的关系式,推导了隧道开挖爆破振动速度计算公式,并可通过变换公式计算工况的振动速度、允许进尺长度及安全距离等;根据振动速度和主应力与新建隧道掌子面关系曲线、控制标准作出变轨曲线,进而确定不同爆破参数适用的范围;提出了对策确定原则、爆破振动监测项目及断面和测点布置原则。9、编制了上下交叉隧道近接影响预测程序,可对上下交叉隧道的静力、动力影响程度和影响范围进行预测,并选取相应的对策措施。更多还原

【Abstract】 This dissertation carried out a study on static、dynamic influence and countermeasures for up-down cross mountain tunnels(mining method), which are orthogonal or wide-angle、deep、newly-build/after-constructed tunnels crossing over or being underpass of existing/before-constructed tunnels, depending on diversion tunnel adjacent project for BaiShuiJiang third class power station in YanJin county of YunNan province, underpass of ShouBaYan tunnel of NeiKun Railway, by using methods of investigation、numerical analysis、in-situ test and analog.The following achievement and outcome was gained:1 .This dissertation predicts settlement threshold based on Peck settlement curve empirical formula、existing railway allowable displacement and existing structure allowable stress; Stress increment threshold based on existing structure intensity criterion combined with existing railway tunnel health status grade are given; Control standards for various research methods are given based on idea of risk management.2.This dissertation concludes that influential scope of railway tunnel by the construction of diversion tunnel is not symmetrical by tunnel axes and torsional deformation is generated, based on study of diversion tunnel underpass of railway tunnel and analysis of stress increment、settlement disciplinarian by the use of three-dimensional finite element method(3D-FEM); Mutual influence scope and degree of two cross tunnels are given based on control standards of settlement and stress, then safety check for existing tunnel and newly-build diversion tunnel are given and validated by jobsite monitoring: Feasibility and precision of 3D-FEM to simulate this kind of approaching excavation are proved.3.Blasting dynamical influence is studied by the use of Dynamic Explicit FEM, conclusions are: Vibration speed when excavation face is approaching existing tunnel is bigger than that when leaving existing tunnel at the same distance; The critical angle for vibration speed control direction is 45°,which is the separation angle between viewpoint-hypocenter line and horizon plane. Information-based construction of blasting excavation is realized by the use of blasting vibration monitoring, vibration speed is well controlled, and tallies numeric analysis.4.Vertical displacement and stress of underpass diversion tunnel reaches maximum value when the first bogie bolster of train in railway tunnel is just upward the diversion tunnel, then dynamical response like simple harmonic wave appears; Simulation result of cases shows that static stress is the control load and fatigue strength meets needs.5.Acting on seismic wave of single direction, the direction of maximum value of vibration speed and acceleration is coherent to loading direction; the maximum response takes place on the crown result from horizontal vibration upright of tunnel axes, the others take place on side wall; Vibration speed and acceleration attenuates to a big extent after tunnel is finished, but stress concentration occurs; Seismic response of cross section of existing tunnel is meliorated after tunnel is finished.6.Disciplinarian of tunnel stress increment influenced by single parameter change in existing tunnel is given, based on stress increment of existing tunnel and by changing radius、distance、depth、wall rock grade of two adjacent tunnels, mutual influential scope of two cross tunnels is given according to influence threshold; Matter element model of Extenics Theory is introduced to study the influence of tunnel approaching excavation, puts forward grading for up-down cross tunnels approaching influence degree, besides, influence scope is given by the use of interpolation method.7. This dissertation gives the relation between existing tunnel increment and arch crown subsidence of newly-build tunnel based on the research of newly-build tunnel countermeasure、middle stratum countermeasure and existing tunnel countermeasure, puts forward its relation with discount rate of preformed deformation; Curve for relation between existing tunnel stress increment and newly-build vault subsidence is given by weaving work condition of subsections. Criteria to choose countermeasure、jobsite monitoring item and monitoring point is given.8.This dissertation researches relational expression for detonator powder dose、distance from viewpoint to hypocenter, wall rock grade with vibration speed by changing radius of newly-build tunnel、clear distance of two tunnels、 footage、priming method and wall rock grade, and puts forward formula to calculate blasting vibration speed of tunnel excavation; Vibration speed、allowable footage and safe distance are changed based on the transformed formula. The dissertation develops orbit curve according to the relationship of vibration speed、principal stress、relation curve of newly-build tunnel excavation face and control standard, and puts forward scope of application of various blasting parameter; This dissertation puts forward criteria to choose countermeasure、blasting vibration monitoring item、section and monitoring point.9. This dissertation develops prediction model for up-down cross adjacent tunnels and realizes predicting static、dynamical influence degree and influence scope for up-down cross tunnels by the use of programming, and puts forward method to choose countermeasure.更多还原