【作者】 孟昭博；

【导师】 吴敏哲； 胡卫兵；

【作者基本信息】 西安建筑科技大学 ， 结构工程， 2009， 博士

【摘要】 西安钟楼是国家重点文物保护单位,环绕钟楼日渐增强的地面交通振动和即将运营的地铁列车振动将对西安钟楼的安全性产生重要影响。本文在对钟楼地面交通振动监测的基础上,就地面交通振动对钟楼的影响进行了研究;就绕钟楼四周的地铁列车振动对钟楼的影响进行了深入分析;依据国家标准(GB/T50452)对地面交通振动、地面交通振动和地铁振动叠加对钟楼的影响进行了综合评估。主要研究内容包括:(1)首次对西安钟楼的地面交通振动反应进行了连续24小时的监测,采用概率统计的方法对监测振动信号进行了研究,以置信度为95%的速度和加速度幅值的统计值作为振动评价量。(2)应用随机减量法获得了监测信号的自由振动响应,并首次用ITD法得到钟楼在交通振动幅值范围内的实测动力参数。在此基础上,通过反演得到木结构榫卯连接计算模型的刚度,解决了噪声环境中无法按传统方法进行动力参数识别及类似木结构由于榫卯连接刚度不能准确确定而无法进行合理计算的问题。(3)建立了多辆车并行时环形道路交通车辆引起的地面振动衰减实用计算公式,计算结果与监测值吻合较好。(4)视钢轨为Winkler地基上连续的Euler-Bernoulli梁,建立了列车-轨道-路基模型,同时考虑列车荷载的拟静力和轮轨动态接触力。根据由时间序列估计功率谱密度的周期图法原理,采用美国联邦铁路管理局FRA提出的五级轨道功率谱,通过Fourier逆变换得到轨道不平顺的时域样本,确定了轨道不平顺的幅值及对应的波长,以此为基础考虑轮轨动态接触力的影响;基于轨道路基系数的定义建立了求解路基均布弹簧刚度的计算模型,采用数值模拟得到了路基均布弹簧刚度;最后,基于Matlab程序平台编制了计算程序,得到了运行列车作用到路基上的荷载时程。(5)首次考虑加载时延,针对地铁二号线和六号线双列车运行引起的振动对钟楼的影响进行了数值分析,得到了钟楼的动力反应及其振动传播规律;采用SRSS叠加法对两个不同传播方向的竖向振动引起的钟楼的动力反应进行叠加,得到了多辆列车同时运行时钟楼的动力反应。(6)提出并验证了交通振动作用下建筑物的动力反应不能采用类似地震反应分析方法的单点输入进行计算,计算时必须考虑振动波的相位差和振动在传播过程中迅速衰减的影响。(7)为了解决国家重点文物保护单位-钟楼振动测点布置受限制的实际问题,建立了交通振动作用下钟楼木结构的分析模型,将钟楼二层楼板的振动速度转化为柱顶的振动速度,以便进行振动评估。(8)根据波动理论建立了钟楼高台基分析模型,得到了求解高台基的振动速度基本表达式。根据经验公式及钟楼的保护等级和地面交通振动频度,给出了高台基底部质点振动速度的容许值,填补了交通振动作用下古建筑高台基的评估标准的空白。(9)依据国家标准(GB/T50452)和高台基底部质点振动速度容许值,对地面交通振动、地面交通振动和地铁振动叠加对钟楼木结构和高台基的影响进行了综合评估。更多还原

【Abstract】 Xi’an Bell Tower is a key cultural relic under the state protection.The growing vibration induced by ground traffic and the future subway will exert a serious impact on the Xi’an Bell Tower.In this paper,based on vibration monitoring,the impact of ground traffic on the Bell Tower is studied;the impact on Bell Tower of the vibration induced by subway around the Bell Tower is thoroughly analyzed;in addition,according to the national standards (GB/T50452),the impact of the superposition of ground traffic vibration and subway vibration to Bell Tower is comprehensively evaluated.The main contents include:(1) The ground traffic vibration response of Xi’an Bell Tower was continuously monitored in 24 hours for the first time.The probability statistics method is employed to analyze the monitor vibration signal,and the statistical values of velocity and acceleration with degree of confidence of 95%are used as the assessment index of vibration.(2) The free vibration response of the monitored signal is obtained by Random Decrement Method.ITD is adopted to get dynamic parameters of Bell Tower within traffic vibration amplitude for the first time,on this basis,the stiffness of mortise and tenon joint calculation model is derived through inversion,the questions of dynamic parameters unable to be identified with the traditional methods in environmental noise and the similar timber structure is unreasonably calculated due to tenon and mortise connection stiffness cannot be accurately determined are solved.(3) The formula for calculation of ground vibration attenuation induced by the parallel vehicles on a ring road is established,and the computed results are better agreement with the measured value.(4) Regarded the rail as a continual Euler-Bernoulli beam in Winkler ground,the train-track-roadbed model is established,with the consideration of pseudo-static load of train and dynamic contact force between wheel and rail.According to by the time series estimate power spectral density’s periodogram law principle,the research adopts five level of orbital power spectra which US Federal railway Administrative bureau FRA proposed;then,through the Fourier inverse transformation,the orbital not smooth time domain samples are obtained, which determine the track irregularity peak-to-peak value and the corresponding wave length; on the basis of the research,the influence of the wheel track dynamic contact force are considered.Based on the orbital roadbed coefficient’s definition,computation model is established to solve the roadbed equispaced spring constant,and the roadbed uniform spring stiffness is obtained by using the numerical simulation method.Finally,based on the Matlab procedure platform,the computational procedure is established,and the load time interval caused by the moving train acts on the roadbed is obtained.(5) Taken loading time delay into consideration for the first time,the impact of the vibration on Bell Tower,induced by double row train movements on subway No.2 and No.6 lines,is numerically analyzed,and then the dynamic responds and the vibration dissemination rule of Bell Tower is obtained;the dynamic responds of Bell Tower induced by vertical vibration in two different propagation directions is superposed by ways of SRSS superposition,as a result,the dynamic response of Bell Tower is obtained when several trains are simultaneously moving.(6) It is proposed and verified that under the traffic vibration,the dynamic response of building can not be calculated by single particle import similar to earthquake response analysis method,moreover,the impact of vibration wave phase difference and vibration rapid attenuation during the propagation must be take into consideration.(7) In order to solved the practical problem of the limitation about vibration observation point arrangement on Bell Tower,a key cultural relic under the state protection,the timber structure analysis model under traffic vibration has been established,and then the Bell Tower two-story building floor’s vibration velocity is transformed into vibration velocity at top column.(8) The analysis model for the high-station base of Bell Tower is established based on wave theory,and the basic expression for solving vibration velocity of high-station base is derived. The allowable value of panicle vibration velocity at bottom of high-station base is given,in line with empirical formula and the protection grade of Bell Tower,which fill the appraisal standard blank of the historic building with high-station base under traffic vibration.(9) According to the national standards(GB/T50452) and the allowable value of panicle vibration velocity at bottom of high-station base,the impact of the superposition of ground traffic vibration and subway vibration to timber structure of Bell Tower and its high-station base is comprehensively evaluated.更多还原