【作者】 苑红凯；

【导师】 钱振东；

【作者基本信息】 东南大学 ， 道路与铁道工程， 2006， 硕士

【摘要】 当前,我国的公路建设正处于一个快速发展的阶段,就已开通的高等级公路的使用状况来看,普遍存在十分严重的早期破坏问题,特别是半刚性基层沥青路面的开裂问题。沥青路面结构开裂必然改变其本身的应力状态,加快其破坏速度,缩短其使用寿命。而传统沥青路面结构设计所采用的弹性层状体系模型未能反映沥青路面结构在整个寿命周期内,大部分时间是带裂缝工作的现状。本论文的研究目的是依据对高速公路路面裂缝的调查结果,对含裂缝沥青路面结构的力学特性进行研究,以达到指导设计、施工、养护,改善道路结构性能,延长其使用寿命的目的。本论文大致可分为以下三个部分:1.道路结构温度场的数值分析。根据气候学、传热学的基本原理,本论文采用有限元数值方法得出了自然边界条件下层状体系道路结构非稳态温度场的数值解,作为道路结构温度应力分析的依据。2.静力学特性研究。根据我国高速公路沥青路面结构开裂的状况,分别建立含贯通裂缝和裂缝扩展过程中的有限元分析模型,对前者考察路面结构完全开裂后,在车辆荷载的作用下,沥青面层顶部及底部的应力变化,计算结果表明含贯通裂缝的沥青路面结构在交通荷载的作用下,处于更不利的受力状态;对后者,则依据断裂力学理论,以反映裂缝尖端应力场的应力强度因子为参量,分别考察在温度荷载和交通荷载的作用下,裂缝尖端及沥青面层沿裂缝扩展方向上的应力状况,结果表明,在温度荷载的作用下,影响裂缝扩展的关键因素是沥青面层模量和基层温缩系数,沥青面层厚度对基层反射裂缝的影响较小。而在交通荷载作用下,沥青面层的厚度、模量,对裂缝尖端区域应力场的影响较大,而基层的厚度、模量对裂缝尖端区域应力场的影响较小;对基层反射裂缝而言,温度荷载的作用效应,远大于交通荷载的作用效应。3.动力学特性研究。分别建立含贯通裂缝和裂缝扩展过程中的有限元分析模型,对前者主要进行了模态分析和谐响应分析,模态分析结果表明,沥青路面结构开裂后,路面结构的自振频率大为提高,也就是说路面结构开裂后,相对于完整路面结构,其对高频率、短周期的荷载作用更为敏感;谐响应分析结果表明,在外载作用下,导致其产生较大反应的敏感频率范围也产生了变化;对后者,分析了裂缝尖端动应力强度因子随道路结构体阻尼、车辆荷载作用周期以及路面结构参数的变化规律。动应力强度因子分布规律与外荷载变化曲线相似,随着阻尼比的增加,应力强度因子衰减的很快,同时应力强度因子峰值出现的时间逐渐后移。应力强度因子最大值随荷载作用周期的变化呈倒“S”状变化,在高频和低频荷载作用时,逼近静载作用时的应力强度因子值,在一定的频率出现最大值和最小值,但应力强度因子的变化幅度不大。动应力强度因子随沥青面层模量的增大而增大,随沥青面层厚度的增大,基层厚度的增大,基层模量的增大而减小,其中沥青面层模量变化对动应力强度因子的影响较大。本论文以京秦高速公路为工程背景依托,对含裂缝沥青路面结构的力学特性进行了较全面的研究,可为沥青路面的抗裂设计,路面长期性能的研究提供理论基础。更多还原

【Abstract】 Currently, the construction of highway in our country is in a rapid development phase, but early damage to the highway in service is a common phenomenon, especially the cracks of asphalt pavement based on semi-rigid type base. The cracks of asphalt pavement will certainly change stress state of itself, accelerate the speed of destroiration, shorten its working life. This also shows the mechanical analynsis model of traditional asphalt pavement structural design is far from being perfect, and dosen’t reflect the actual status of the structure in most of all its life. The purpose of this dissertation is based on the study on the mechanical characteristics of asphalt pavement with cracks, acting by temperature load and vehicle load, so as to master the rule of cracking generation and propagation, to direct the design, construction, maintenance of asphalt pavement.Firstly, the temperrature field of asphalt pavement was presented through numerical simulation by finite element mothod. Based on climatological and thermal theory, this dissertation got numerical solution of one-dimensional unsteady temperature field under natural boundary condition, the solution accorded with the distribution law of road structure. This established basis for analysis and study on temperature stress in the next chapters.Secondly, the statical charatiristics of asphalt pavement with a crack was presented. Based on the state of asphalt pavement crack , the finite elment analynsis model was set up, included mechanical model with a cross-crack and mechanical model with a expanding crack. To the former, the result indicated that ,acted by vehicle load, the structure of asphalt pavement with a cross-crack is being worse stress state; To the later, based on fracture mecanics theories, the stress intensity factors was adopted as the parameter reflecting the stress condition at the crack tip. The result shows key factors effecting the expanding of crack are modulus of asphalt surface layer and the thermal coefficient of contraction of base layer, the effect of tempreture load is more than that of vehicle load.Thirdly, the dynamical charatiristic of asphalt pavement with a crack was presented. Based on dynamic theory, the finite elment analynsis model, including mechanical model with a cross-crack and mechanical model with a expanding crack was set up. To the formerl, this dissertation has been done modal analysis and harmonic reponse analysis. The result indicates that, since the crack emerged in asphalt pavement, its dynamical charatiristic has been changed greatly, such as inherence frequency and vibration model. To the later, this dissertation has been done transient dynamic analysis, calculated the stress intensity factors changing with the damp of asphalt pavement, the cycle of load action and the parameters of pavement structure.This dissertation is supported by the engineering of Beijing to Qinhuangdao freeway. The research has done a full-scale research on the mechanical charatiristic of aspalt pavement with cracks, the research result can provide theory base for design method to prevent the crack extend and research on long term charatiristic of asphalt pavement .更多还原