【作者】 李祖仲；

【导师】 张登良；

【作者基本信息】 长安大学 ， 道路与铁道工程， 2009， 博士

【摘要】 在沥青面层与旧路面或基层之间设置应力吸收层,能大幅度地降低沥青面层层底荷载应力和温度应力,减少接缝或裂缝处应力集中现象和裂尖应力强度因子的幅值,有效地消散及吸收由交通荷载及环境温度变化所产生的应力及变形,延缓反射裂缝在沥青面层中形成及扩展,提高了沥青面层的使用寿命。目前,国内对于应力吸收层材料组成研究还是一个空白,开发应用于应力吸收层的沥青结合料,进行应力吸收层沥青混合料配合比设计及其抗裂性能研究,推荐应力吸收层的合理厚度,对于推广应力吸收层技术具有重要的现实意义。采用三维有限元法对基于应力吸收层的沥青路面结构进行数值模拟计算,分析了轴载变化对应力吸收层荷载应力的影响,表明应力吸收层处于复杂的受剪、抗拉受力状况,抗拉伸与剪切可作为评价该混合料技术性能；分析了应力吸收层模量变化对沥青面层层底接缝处荷载应力和温度应力的影响,低模量的应力吸收层能显著降低加铺层层底的荷载应力与温度应力,结合应力吸收层结构要求及材料组成特性,常温下,应力吸收层回弹模量约在400～600MPa较为合适,为混合料配合比设计提供了重要参考。随后,根据应力吸收层的功能特点,提出应力吸收层混合料设计空隙率应在1.0～2.0%之间较为合理。通过大量的室内试验,研发了Sampave特种改性沥青结合料,并研究其粘温特性,确定合理的拌和与压实温度,为施工工艺中温度控制提供了重要依据。对基于Sampave特种改性沥青结合料的胶浆进行了较深入的研究,分析粉胶比对胶浆高、低温性能及粘温特性的影响,提出了合理的粉胶比范围。采用贯入与直接拉伸试验,发现矿料的贯入耗散形变能和混合料的贯入剪切形变能、拉伸形变能是衡量矿料及混合料变形特性的重要指标,权衡混合料的抗剪和抗拉性能,推荐出应力吸收层矿料级配走向,为配合比设计中的级配选取提供了方向。进行旋转压实试验,分析旋转压实次数与油石比对混合料压实度的影响,确定合理的设计旋转压实次数。分析了矿料级配、油石比对回弹模量的影响,完善应力吸收层混合料配合比设计指标体系,以贯入和拉伸试验优选级配,确定最佳油石比,提出了基于抗剪和抗拉性能的配合比设计方法。自行设计试验夹具,进行DTT拉伸破坏、蠕变及损伤与愈合试验,建立了各试验指标及试验参数,验证了Sampave特种改性方案的可行性；检验了配合比设计中的优选级配和最佳油石比确定的可靠性,有力地支持了混合料配合比设计成果。研制出沥青路面反射裂缝扩展模拟试验装置,验证了基于Sampave特种改性沥青路面结构的抗反射裂缝效果,推荐应力吸收层的合理厚度为2～3cm,为基于应力吸收层的沥青路面结构设计提供了试验依据。更多还原

【Abstract】 The stress-absorbing layer between the asphalt surface course and old pavement or base course, can significantly reduce the load stress and thermal stress at the bottom of asphalt surface course, decrease the phenomenon of stress concentration in the cracks or joints and the amplitude of crack-tip stress intensity factor, effectively dissipate or absorb the stress and deformation caused by the traffic load and environmental temperature factor, delay the formation and propagation of reflective cracking in the asphalt surface course, and at last increase the service life of asphalt surface course. At present, domestic research about the material composition of the stress absorbing layer is still a gap, and so developing a type of special asphalt binder for stress-absorbing layer, researching the mixture ratio design of stress-absorbing layer asphalt mixture and anti-crack performance, and recommending a reasonable thickness for the stress-absorbing layer are of great significance to popularize stress-absorbing layer technology.Asphalt pavement based on stress-absorbing layer is analyzed with the 3-D finite element numerical simulation method to study the impact of traffic load on load stress of stress-absorbing layer and the impact of its module on load stress and thermal stress at the bottom of asphalt surface course joints, The results indicate stress-absorbing layer is in composite shear and extension condition and the performance of stress-absorbing layer mixture is evaluated by anti-shearing and extension, stress-absorbing layer with low module may significantly decrease load stress and thermal stress at the bottom of asphalt surface course. Considering its requirement in construction and material performance, it is reasonable that its module is about 400-600MPa under the normal temperature. Furthermore, from its function of proof-water, the design void rate of its mixture should belongs to 1.0-2.0%.Through a large number of lab experiments, the Sampave special modified asphalt binder was finally developed. The reasonable mixing and compaction temperatures was determined by viscosity-temperature characteristics, which was very useful for the temperature control during the construction. Based on the in-depth research about Sampave special modified asphalt binder mastic, analysed the influence of filler bitumen ratio to high and low temperature properties and viscosity-temperature characteristics, a reasonable range of filler bitumen ratio was recommended.Penetration test and direct tensile test were used, and it’s found that the penetration dissipation energy of mineral aggregate and penetration shear deformation energy, tensile deformation energy of the mixture are important indications of mineral materials and mixture. Balancing the shear and tensile performance of the mixture, and the aggregate grading tendency of stress-absorbing layer was recommended, which was useful for the choice of aggregate grading during the mixture ratio design.Based on SGC test, the influence of gyration compaction numbers and asphalt content on the mixture compaction were analyzed, the reasonable design gyration compaction numbers was determined. The impact of aggregate grading and asphalt content on modulus was analyzed, and then the mixture ratio design index system of stress-absorbing layer was perfected, which use penetration test and direct tensile test to choose grading and determine the optimum asphalt content. Finally, the mixture ratio design method based on shear and tensile performance was proposed.In order to conduct DTT tensile fracture, creep, damage and healing test, author developed a device and established parameters of experiment. The DTT experiment verify feasibility of Sampave special modified program and the reliability of the preferred mix design gradation and optimum asphalt aggregate ratio, which strongly support for the mix design results.A simulation device of reflection cracks extension in asphalt pavement was developed, The anti-cracking performance of asphalt pavement structure with sampave was verified. Finally, there is a reasonable scope for Sampave thickness and suggest it belongs to 2.0～3.0cm, which provided test basis for asphalt pavement structure design with stress-absorbing layer.更多还原