【作者】 滕旭秋；

【导师】 戴经梁；

【作者基本信息】 长安大学 ， 道路与铁道工程， 2009， 博士

【摘要】 柔性基层沥青路面以其优良的路用性能成为我国半刚性基层沥青路面的必要补充形式。相对于半刚性基层沥青路面而言，随着其沥青层厚度的增加，路面结构层受力必然要发生一定的变化，在此条件下如何进行柔性基层沥青路面的结构设计就成为其在我国得以推广应用迫切需要解决的问题。在沥青路面结构服务期内，我国沥青路面设计采用的弯沉指标及国外采用的路基顶面压应变、沥青层底部拉应变指标均不能真实反映实际道路的破坏情况，本文以柔性基层沥青路面的病害为切入点，提出以车辙、Top-Down裂纹、反射裂纹(仅对混合式基层沥青路面)为设计指标，建立了相应的柔性基层沥青路面性能预估模型，在此基础上完成了路面结构车辙深度及疲劳寿命的计算。最后以青岛-银川高速公路采用混合式路面试验段为依托工程，进行了车辙深度和反射裂纹、Top-Down裂纹疲劳寿命的预估计算。首先通过频率扫描试验确定了三种不同沥青混合料在不同温度下对应的动模量及相位角，根据粘弹性力学中的时温等效原理，应用WLF方程，通过Sig-moidal函数及非线性最小二乘法确定某一温度下沥青混合料的动态模量主曲线及相位角主曲线，并在此基础上通过傅立叶变换确定广义Maxwell模型的粘弹性参数，为后期的车辙计算奠定了基础。此外，由于ANSYS有限元程序自身对材料模型的要求，需把通过试验确定的松弛模量转化成剪切模量及体积模量再用于有限元计算，鉴于此，推导了广义Maxwell模型的三维本构方程，应用留数定理确定了蠕变函数的系数，基于以上研究，确定了沥青混合料的剪切模量及体积模量的表达式。同时，应用FWD实测试验路段的弯沉值，根据BP神经网络的L-M动量项法确定了路基土及半刚性底基层材料的动模量值，并在沥青混合料频率扫描试验的基础上，结合有效深度的定义确定了沥青混合料在一定的设计车速、结构层厚度情况下对应的模量值，为试验段路面性能预估提供必要的参数。车辙计算时，利用概率统计理论计算了不同荷载偏移距离下路面不同位置的荷载作用的概率，应用有限元程序计算路面结构的车辙。应用所建模型，进行了基于荷载大小、行车速度、荷载作用次数、轮胎中线偏移距离及土基模量等五个因素的车辙正交计算。通过方差分析法确定了各因素对车辙影响的显著程度，以期为今后的路面设计及养护工作提供必要的参考。Top-Down裂纹疲劳寿命计算时，采用概率统计的方法将荷载按正态分布的原则作用到路面结构模型上，应用改进的Paris公式及四阶龙格-库塔法则计算不同荷载作用位置、不同裂纹位置对应的路面结构的疲劳寿命。在此基础上，根据Miner损伤原则，确定了基于Top-Down裂纹的路面结构疲劳寿命。对于混合式基层沥青路面进行反射裂纹疲劳寿命计算时，考虑车辆荷载每次经过裂纹时对裂尖造成的影响不同，根据断裂力学原理及修正后的Miner法则计算路面结构反射裂纹的疲劳寿命。最后以青银高速公路混合式路面试验段为依托工程，进行了车辙深度及Top-Down裂纹、反射裂纹等疲劳寿命的预估计算。本文从柔性基层沥青路面的病害入手，提出车辙、Top-Down裂纹、反射裂纹为设计指标，建立了柔性基层沥青路面性能预估模型，为柔性基层沥青路面在我国的推广应用起到一定的推进作用。更多还原

【Abstract】 The flexible base is the necessary supplement to simi-rigid base for its excellentperformance. Its stress in the structure layer, which is caused by the vehicle load, is changedcertainly with the increase of depth of asphalt layer against the simi-rigid base. Under thecondition, it is a problem that calls for immediate solution in order to do the adoption andapplication of asphalt pavement with flexible base.The indexes of deflection, compressive strain on the top of subgrade and tensile strain onthe bottom of asphalt layer, couldn’t reflect the real pavement distress. The indexes of therutting, Top-Down crack and reflecting crack are proposed as the pavement design indexbased on the distress of asphalt pavement with flexible base. The performance forecastingmodels of asphalt pavement with flexible base are built. Upon the above research, the ruttingdepth and fatigue life of pavement are calculated. At last, taking Qindao-Yinchuan freewayfor instance, the rutting depth and fatigue life which originate from the Top-Down cracks andreflecting cracks, are calculated.The dynamic modulus and phase angle of three kinds of asphalt mixture are determinedbased on the Frequency Sweep Test at different temperatures. In accordance with thetime-temperature equivalence principle, the master curves of dynamic modulus and phaseangle are determined through the applying of WLF equation and Sig-moidal function. Uponthe above research, the viscoelastic parameters of the generalized Maxwell model arecalculated by the Fourier transform. The achievements lay foundations of the ruttingcalculation. Moreover, the relaxation modulus determined by the test must be transformedinto bulk modulus and shear modulus in order to be applied by the finite element calculation.In view of this, the three-dimensional constitutive equation of generalized Maxwell model isdeduced. The coefficients of creep function are determined by the residue theorem. Uponthe above research, the expressions of bulk modulus and shear modulus are confirmed. At thesame time, the modulus of subgrade and simi-rigid material is backcalculated through the BPneural network according to the FWD. At last, the modulus of asphalt mixture are calculatedunder the circumstances of the certain vehicle speed and thickness of structure layer, based on the Frequency Sweep Test and considering the definition of effective depth. The above studiesprovide necessary parameters for the performance forecasting of test road.When the rutting is numerically computed by using a commercial FEA program, ANSYS,the probability of loading at different pavement position is calculated according to theprobability and statistics theory under the circumstances of the different wander distance. Fivefactors including the magnitude of wheel loading, the wander distance, the speed of wheelloading, the number of load repetitions, and the modulus of subgrade are studied to evaluatetheir contributions of rutting development for asphalt pavements. The significance that eachfactor impacts on the rutting is analyzed in order to offer necessary, support for the pavementdesign and maintenance in the future.When the fatigue life derived from the Top-Down crack is calculated, the load is appliedto the FEA model according to the rule of normal distribution. The improved Parisexpressions and fourth-order Runge-Kutta principle are adopted to calculate the fatigue life ofcorresponding pavement structure at different loading position and cracking position. On thebasis of this, the whole fatigue life derived from the Top-Down crack is calculated accordingto the Miner damage principle.The fatigue life derived from the reflecting crack is calculated according to the Minerdamage principle, considering the factor that the development of the top for crack is differentwhen a vehicle load passed the crack.At last, taking Qindao-Yinchuan freeway for instance, the rutting depth and fatigue lifewhich originate from the Top-Down cracks and reflecting cracks, are calculated.更多还原