【作者】 孙可；

【导师】 王宝军； 张巍；

【作者基本信息】 南京大学 ， 地质工程， 2016， 博士

【摘要】 近年来,城市轨道交通发展迅速,地铁列车运行所引起的环境振动问题逐渐受到关注。本文搭建了一套专用于地铁环境振动快速测定的无线传感器网络系统,以苏州星海广场地铁站邻近地下空间为例,将其应用于现场测试;基于有限元方法,对该地下空间结构的振动响应进行了数值模拟与分析;建立了联合烦恼度评价模型,对测区振动环境中人群的舒适性做出了定量评价。全文主要成果与结论如下:(1)基于Imote2无线传感器网络平台,采用高精度加速度传感器板SHM-H与嵌入式软件平台ISHMP ServicesToolsuite,搭建了用于地铁环境振动快速定量评价的无线传感器网络测试评价系统;基于TinyOS开源操作系统,采用组件式结构程序语言nesC,编写了嵌入式振动信号预处理组件,可在传感节点内实现振动数据的嵌入式计算,提高了测试效率。(2)分析实测数据发现,振动加速度峰值随测点距离的增加而降低,近轨道处测点加速度峰值约120 mm/s2,在测线最远端40m处降至20 mm/s2以下;40Hz以下频段的振动分量较弱,且各频率上的振幅变化不大,其中,1.64Hz处出现的峰值,推测为楼板基频;40～80Hz频段内,振动幅值变化较复杂,优势频率主要集中在60～70Hz内,此频段内振动幅值随距离衰减显著,由50mm/s2降至10 mm/s2以下;近轨道部分测点在中心频率63Hz处振级接近70dB,可能使人体产生烦恼或其它不良反应;利用二阶傅立叶函数,线性拟合出各测线上振级随距离变化的规律,整体而言,高频衰减迅速,低频衰减缓慢,峰值频率由高频向低频漂移。对比振动环境评价标准限值,可认为列车振动基本不会对结构安全造成影响,但会对人体舒适程度造成明显影响。(3)采用PLAXIS2D有限元软件,结合两种动荷载模拟方法,计算了实际工况下的结构动力响应。模拟结果与实测数据吻合程度较好,验证了模型的准确性;采用正交实验方法,对地下结构振动响应进行了参数分析,发现结构振动响应与列车荷载大小呈正相关;但振动响应并非随车速加快而单调递增,而是表现为,随车速增加振动响应开始快速增大,当车速提升到12 m/s左右时,地下结构出现最大的振动响应,随后振动响应随车速增加呈现缓慢减小的趋势;结构振动响应整体随距离而递减的,在前20m范围内的衰减较大,其后随距离的增加而趋于平缓。但当下卧层土体的阻尼比大于0.2时,在20m距离处,会出现振动响应放大现象。此外,地下结构振动幅值与下卧土层的重度、黏聚力、内摩擦角及泊松比基本无关。(4)通过耦合模糊隶属度函数及正态分布函数,描述人体在振动环境中主观反应的模糊性和随机性,构建了一个可以同时评价建筑物振动及其二次噪声的联合烦恼度模型,并将人体烦恼度划分为6个等级。然后结合现场实测数据,对苏州星海生活广场地下结构内的振动与二次噪声的联合烦恼度进行计算分析,最后将联合烦恼度计算结果与JGJ/T170-2009标准进行对比,验证了模型的合理性与优越性,并可为区域空间规划开发提供指导意见。更多还原

【Abstract】 In recent years,as a result of the rapid development of the urban rail transit,the subway train-induced ambient vibration is being gradually concerned.In this paper,a specific wireless sensor network system is developed for fast assessment of subway train-induced vibrations.Then the system was applied to the field test at an underground space adjoing Xinghai Square subway station of Suzhou.Based on the finit element method,the numerical simulation and analysis is also implemented for the vibration reponses of the underground space.The combined annoyance degree model is developed to quantitatively evaluate the comfort of the people in the vibration environment.The main results and conclusions are as follows(1)The specific wireless sensor network system is developed for the fast quantitative assessment of subway train induced ambient acceleration;the system is based on Intel Imote2 wireless sensor network platform,combining the high-precision acceleration sensor board SHM-H with the embedded software platform ISHMP Services Toolsuite.Based on the open-source operation system TinyOS,we use component structural programming language nesC to program the embedded application for vibration signal preprocessing,so as to embeddedly compute the ambient vibration level,which may greatly improving the work efficiency.(2)By analyzing the measured data,it is discovered that the peak values of the vibration acceleration gradually decrease with the increase of the distance.The maximum acceleration of the measure point nearby the testing area is about 120 mm/s2;while the minimum acceleration reduces to 20 mm/s2 or less at the distance of 40m on the farthest end of the measured line.The vibration of the frequency band below 40 Hz is weak,and the change of vibration amplitude is unconspicuous.The peak value at 1.64 Hz can be inferred to be the fundamental frequency of the floor slab.Within the frequency band from 40Hz to 80 Hz,the vibration amplitude varies intricately,and the dominant frequency mainly focuses on the band from 60 to 70 Hz,in which the vibration amplitudes decrease obviously with the distance extension,namely form 50 mm/s2 down to less than 10 mm/s2.Moreover,the vibration levels on the central frequency of 63 Hz approach to 70 dB at some measure points near subway tracks,which may cause annoyance and other negative influence on human body.Using the second-order Fourier functions,the trends of the vibration levels with the distance variation of all the measure lines are fitted.Basically,the trend is that the high frequency compents attenuate rapidly and the low frequency compents attenuate slowly,with the peaks shifting from the high frequency to the low frequency.Comparing with the limits in the environmental vibration evaluation standards,it is implied that the structural safety is influence little by the the subway train-induced vibration,but the human comfort may be affected obviously.(3)Using PLAXIS 2D finite element software and combining two dynamic load simulation methods,the structural dynamic reponses of the practical scenario are calculated.The simulation results agree well with test ones,suggesting the soundness of the numerical models.The orthogonal experiment method is used for the parameter analysis of the vibration reponses of the underground structure.The investigation results show that the structural reponses are positive correlate to the train load.But the reponse does not simply enhance with the train speed increase.Initially,the reponse increases rapidly with the increase of the speed until the maixal reponse occur at the speed of 12 m/s.Then,the reponse drops slowly with the increase of the train speed As for the reponse with the distance,it attenuates sharply with the 20 m distance to the train track,then tend to be flat with the increase of the distance.Response amplification occurs at the distance of 20 m when the damping ratio of the underlying soil layer is greater than 0.2.Besides,structural vibration intensity does not show correlation with the unit weight,cohesive force,internal frictional angle and the poission’s ratio of the underlying soil layer.(4)A fuzzy membership function and normal distribution function were coupled to describe the fuzziness and randomness of human annoyance responses;a combined annoyance degree model was proposed to assess the building vibration and its secondary structure-borne noise;and the human annoyance was classified into six grades.Subsequently,using field test data,we calculated and analyzed the combined annoyance degree of an underground structure adjacent Xinghai Square subway station.The results of combined annoyance degree were compared with the JGJ/T170-2009 standard,in which the rationality and superiority of the proposed model was verified.The results also show that the proposed models can serve as a reference for spatial planning and development in the region researched.更多还原