【作者】 潘宝峰；

【导师】 王哲人； 邵龙潭；

【作者基本信息】 大连理工大学 ， 结构工程， 2010， 博士

【摘要】 二十世纪八十年代以来,随着高等级公路的建设和发展,半刚性基层沥青路面得到了广泛应用,但由于荷载、自然因素等共同作用下,其早期损坏现象日益突显出来,而多种破坏现象均与水有关。围绕水损坏广大道路工作者做了大量研究与工程实践。当前,九十年代末发生的大面积水损坏已得以控制,但局部路段的水损坏仍时有发生,细糙面统一了抗滑与水损坏的矛盾,但满足不了降噪等环保的要求；对半刚性基层的认识仍然得不到统一,而冲刷唧泥已经影响到水泥路面在高速公路上的推广应用。由于问题的复杂性,水损坏并没有很好的解决,无论在评价指标与方法以及机理方面或者是路面抗滑、降噪音、排水对策方面都需深化。鉴于此,本文在损伤理念的指导下,一方面就HMA研究了多次冻融过程下的损伤,另一方面提出了动水压力法,重点研究了半刚性路面材料在水、荷载耦合作用下的损伤。1.所研制的高频高压动水压力发生器,最大压力可达1Mpa,最高频率25Hz,压力和频率均可调,用以模拟车辆荷载施加和卸除(泵吸作用)过程中,路面结构中的动水压力对材料的重复作用。与三轴试验配合,可分析研究三向应力条件下路面材料在水与荷载不同耦合类型的重复作用下的损伤过程。2.应用动水压力发生器针对半刚性材料进行的松弛试验：①能测定松弛模量在动水压力重复作用下表现出随条件而不同的衰变过程类型与机理。②论文提出以松弛模量作为动水压力损伤的宏观力学指标,结合石灰稳定铁尾矿砂的测定,建议用10分钟应力松弛的相对值来评价该种材料抵抗水损坏的能力。③论文以上海外环(一期)路面结构早期损坏为典型的再分析,论证了半刚性基层在动水压力作用下的损伤及其机理；还指出,所开发的动水压力损伤试验,能较为完善地用以评价水泥路面基层的抗冲刷性能。3.在动水压力法控温装置还没能实施的条件下,采用多次冻融的方式进行了HMA抗压与抗拉强度衰变过程的研究。HMA力学性能的衰变过程不仅采用超声波法进行了无破损试验,且基于支持向量机的沥青混合料马歇尔试件抗压强度预测模型,解决了小样本数据建立数学模型的复杂性与推广能力之间的矛盾,避免了BP网络的“过学习”问题。基于HMA冻融损伤的研究还论证了HMA的级配选型,分析了中空纤维对沥青混合料性能的影响与有效性。更多还原

【Abstract】 Asphalt pavements with semi-rigid bases have been widely used since 1980s, with the construction and development of high-grade highway. Because of the effect of load and natural factors, the premature failures are increasingly evidently, many of which are water-related. In pavement engineering area, lots of researches and practices about moisture damages have been done. The large-area moisture damages happened in 1990s has been controlled currently, but the ones on local road sections occur sometimes. The fine rough-surface unifies the contradiction between skid-resistance and moisture damage, while failing to satisfy the requirement of noise reduction. The understanding of semi-rigid base is still not widely accepted. The erosion and pumping have already affected the application of cement concrete pavement on expressways. The problem of moisture damages is still not solved perfectly because of its complexity. The evaluation indexes and methods need to be further investigated, as well as the damage mechanism, as well as damage mechanism, anti-slide measure, noise reduction and internal drainage. Therefore, by means of damage theory, this paper studies the damage of HMA after multiple freeze-taw cycles and proposes the hydrodynamic pressure method focusing on the damage of semi-rigid materials under the coupling application of water and load.1.The hydrodynamic pressure generator developed in this research is used to simulate the repeated application of hydrodynamic pressure in pavement structure to materials in the process of infliction and remove of vehicle load (pump-absorb action). Its maximum pressure is IMPa and highest frequency is 25Hz. The pressure and frequency are both adjustable. The device, in conjunction with tri-axial test equipment can be used to study the damage process of pavement materials under repeated application of different coupling types of water and load in three-dimensional stress state.2.The relaxation test of semi-rigid materials using hydrodynamic pressure generator:①It can determine the condition-depended deterioration process and mechanism of relaxation modulus under the repeated application of hydrodynamic pressure.②The relaxation modulus is proposed as the macroscopic mechanical index of hydrodynamic pressure damage. The relative value of stress relaxation at 600s is suggested to evaluate the material capability of resisting moisture damage.③The damage and its mechanism of semi-rigid base under the application of hydrodynamic pressure are demonstrated, based on the reanalysis of the premature failures on the pavement of Shanghai Outer Ring (first stage).It is also indicated that the developed hydrodynamic pressure damage test can be used to evaluate the erosion resistance capability of the base course of cement concrete pavement relatively well.3.Study on the deterioration process of compressive and tensile strength of HMA is carried out by means of freeze-thaw cyclic tests, due to the lack of temperature controlling equipment in hydrodynamic pressure test. The deterioration process of mechanical properties of HMA is evaluated by non-destructive test using ultrasonic. The contradiction between complexity and generalization ability of mathematical model from small sample data is solved by the prediction model of compressive strength of HMA Marshall test specimens based on support vector machine, avoiding the over-learning problem of BP network. The gradation selection of HMA is analyzed and demonstrated though the study on freezing-thawing damage of HMA, as well as the influence and effectiveness of hollow fiber to asphalt mixture. An evaluation method that using the strength deterioration of asphalt mixture after multiple freeze-thaw cycles to appraise its moisture damage properties is proposed.更多还原