【作者】 杨果岳；

【导师】 张家生；

【作者基本信息】 中南大学 ， 岩土工程， 2007， 博士

【摘要】 由于车辆动态荷载的存在,使得静力荷载模式下的分析结果与车辆行驶过程中对路面的实际作用力的差异较大,路面结构的动力学特性也远非静力学特性所能描述,这些缺陷和差异,现有的设计理论和方法是无法从根本上加以解决的。本文针对目前高速公路重型车辆与路面之间相互动力作用研究中的一些热点和难点问题(如车辆随机荷载的实测研究与随机荷载作用下柔性路面层状体系动力响应的研究),以车辆随机荷载及其激励下的路面结构响应为研究对象,将车-路作为相互作用的统一整体,进行了深入的理论分析和试验研究,主要研究内容如下:1.针对使车辆产生随机振动的激励——路面不平度,分析了高速公路路面不平度PSD的特点和规律。在此基础上,分析与评价了各种车辆振动模型,并用数值计算的方法,利用两自由度车辆模型和单自由度车辆模型对车辆随机振动进行了数值计算,分析了路面不平整度、路面的激振频率、路面波长及路面波数谱密度等路面参数和车辆轮重、行车速度、车轮承重体系刚度和阻尼等车辆参数对车辆动力荷载载的大小和分布的影响。2.引入多层次分析理论,根据影响车辆随机动荷载的主要因素,在设定的多层次指标体系的基础上,将层次分析法(AHP)用于随机动荷载的评定中。根据分析结果,建立了随机动荷载的分级标准,为合理荷载模型的确定提供了依据。3.成功地在常(德)张(家界)高速公路上进行了车辆随机载荷的现场试验,通过压电式传感器,测得了车辆轴头处竖向垂直振动加速度的时域曲线并对时域曲线进行了相关分析,在此基础上,得到了车辆垂直振动加速度的均方根值,计算了前后车轮的法向动荷载,研究分析了不同车速、不同载重下车辆随机振动的特点。并对车辆的随机振动进行了自谱与互谱分析,研究了不同车速与载重下车辆的随机振动频谱特性。并通过二次回归正交法,建立了车辆动态荷载与行车速度、载重及它们的二次效应来表示的数学模型,4.针对柔性路面的力学特性,利用层状粘弹性理论,采用传递函数矩阵,通过Fourier变换和Laplace变换,从而推导出移动简谐冲击荷载作用下动力方程的解析解;并针对解析解求解的困难性,提出基于ANSYS的粘弹性动力有限元数值法对多层体系动力响应进行求解的新途径。5.利用ANSYS数值计算软件,根据柔性路基路面多层粘弹性体系假设,建立了柔性路面3-D有限元模型,模拟研究了路基路面结构在车辆动荷载作用下的动态响应(主要包括动位移、动正应力、动剪应力、动应变等)及其影响因素,并探讨了在车轮制动力作用下,路面结构层的各种动态响应,研究分析了柔性路面在车辆动荷载与制动作用下的疲劳损伤破坏规律和机理。在此基础上,与试验结果进行了对比,论证了有限元分析的可靠性。6.成功地在常张高速公路上进行了重型车辆荷载作用下柔性路面的表面垂直振动加速度和动位移试验。研究分析了不同车速、不同载重下路面振动加速度和动位移的特性,把车辆的振动激励与路面的响应作为有机整体进行了分析探讨,并分析了路表面的振动频谱特性。7.成功地在常张高速公路上进行了重型车辆荷载作用下柔性路基路面各结构层动态响应的试验研究。考察了车辆载重、车速、车道因素对路基路面的动态响应规律的影响,分析了路面结构层振动频谱的竖向变化规律。更多还原

【Abstract】 Due to the dynamic load,there is a more and more discrepancy between the mode of static load and the fact force on pavement of the running vehicle.Dynamic characteristic of pavement can not nearly be described by statics.It is impossible to resolve radically those defaults and discrepancies with the existing design theory and means.The dissertation targets on some heated and difficult issues(research on vehicle random loads and dynamic response of flexible pavement by experiment)and researches on vehicle dynamic load and pavement structure response.By regarding vehicle and road surface as synthesized system,deeper theoretic analysis and experimental research were made.1.To aim directly at pavement irregularity as a excitation for random vibration of vehicle,the input spectra matrix of pavement was deduced by analytical method of frequency domain,and these characteristics and rules of PSD of highway pavement’s irregularity were analyzed.Above these, various vibration models of vehicles were analyzed and evaluated.And then,through two degree of freedom and unidirectional vibration models of vehicles,vehicles random vibration was calculated by numerical method.These factors including Vehicle load、running speed、pavement irregularity、rigidity of wheel weight-bearing system、damping and so on that have influences on magnitude and distribution of dynamic wheel loading were analyzed.2.The Analytical Hierarchy Process(AHP)was used to assess the random dynamic loads of vehicle based on the specified hierarchical index system,according to the main factors which affects the random loads.With application of AHP method complex random loads of vehicle are disintegrated into several parts,and then quantitative evaluation is made for random loads.Based on the analytic results, classification criterion of random loads is established which can provide foundation for logical loads model.3.Field experiments were conducted on the ChangDe-ZhangJiajie freeway of vehicle random dynamic load.The time history curves of acceleration of vertical vibration at axis were gained by piezoelectric sensor.Based on it,the root mean square values of acceleration of vertical vibration were obtained and through the rms value,the normal loads of wheels were get.The characteristics of vehicle random vibration at various running speed and loading were researched and analyzed.Auto-power spectrum and mutual power spectrum of vehicle random vibration were analyzed,and then the spectra of the vibration at various running speed and loading were investigated.4.Based on physical mechanic properties of flexible pavement and with reference to pertinent files,transfer function matrix was adopted via theory of layered system after transformation through Fourier and Laplace integration;it predicts solution of dynamic equation of multiple viscoelastic system under moving harmonic loads.Due to the difficulties of analyzing viscoelastic,FEM numerical method applied in ANSYS was proposed as the way to analyze multiple-layered dynamic response.5.According to proposition of multiple-layered viscoelastic system of flexible roadbed and surface,3-D dynamic FEM model of flexible roadbed and surface was established by ANSYS.Based on it,dynamic responses of flexible pavement structure under dynamic load of vehicle were analyzed,influences on pavement structure as a result of vehicle speed and load were researched,and then destroy mechanism of the brake power of vehicles to pavement were investigated.Finally,numerical modeling results were compared with experimental values,which show that experimental value conforms to numerical solutions.Therefore,the viscoelastic 3D Finite model established in the dissertation is valid.6.Field experiments were carried out on the ChangDe-ZhangJiajie freeway of pavement dynamic displacement of flexible pavement under heavy vehicle loads.The traits of pavement dynamic displacement were investigated at various running speed and loading. Vehicle excitation and pavement response regarded as synthesized system were investigated.The features of vibration spectra of pavement were analyzed.7.Field experiments were conducted on the ChangDe-ZhangJiajie freeway of dynamic response of each structural layer of flexible roadbed and surface under heavy-load vehicle.With consideration to impact of vehicle load,speed and freeway lane on the dynamic response regularity of roadbed and surface,analyzed were portrait varying characteristics of vibration frequency.更多还原