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摘要: 沥青混合料疲劳试验的荷载控制模式有应力控制模式和应变控制模式。而在应变控制的疲劳试验过程中, 沥青混合料的应力应变状态更符合沥青路面的实际情况。试验得出的弯拉应变与疲劳寿命之间的关系便于应用。运用MTS81 0材料试验系统, 进行了5种级配的沥青混合料的应变控制模式的疲劳试验, 得出了它们的应变疲劳方程, 并对疲劳方程进行了比较和分析。研究表明, 同一应变(或应变比) 下, 若干试件的对数疲劳寿命表现为正态分布, 而且应变、应变比与疲劳寿命分别在双、单对数坐标上表现为直线关系; 单对数坐标下以应变比表示的疲劳方程较双对数坐标下的以应变表示的疲劳方程稳定, 而双对数坐标下的疲劳方程更易区分出沥青混合料疲劳性能的优劣; 应变控制模式下的疲劳试验, 其它条件相同时, 沥青混合料的模量越小, 疲劳寿命越长。Abstract: There are two kinds of load controlling mode for asphalt mixtures fatigue testing: stress controlling mode and strain controlling mode. However, the latter is more practical. Firstly, five kinds of asphalt mixtures were experimented with the fatigue testing of control strain mode using MTS810. By the experiment, a fatigue function between fatigue life span and the value of repeated strain as the ratio of strain level was set up. In addition, their fatigue properties were analyzed. It is shown that at the same strain level, asphalt mixtrues logarithm fatigue life is normal school, meanwhile, relation of strain level with logarithm fatigue life is linear. In the fatigue testing of control strain mode, when asphalt mixtrues modulus is much lower, its fatigue life is much longer.
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Key words:
- asphalt mixtures /
- fatigue properties /
- testing /
- strain controlling
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表 1 试验用沥青的技术性能
Table 1. The technology properties of using asphalt
指标 25℃针入度/0.1 mm 软化点/℃ 15℃延度/cm 闪点/℃ 密度/g·cm-3 Shell70# 67.2 47 大于200 大于280 1.031 规范值 60~80 44~54 不小于100 不小于230 实测 表 2 试验用沥青混合料的矿料级配
Table 2. The aggregate gradation of asphalt mixtures
级配类型 通过下列筛孔(方孔筛/mm) 的质量百分率/% 37.5 31.5 26.5 19 16 13.2 9.5 4.75 2.36 1.18 0.6 0.3 0.15 0.075 AC-16Ⅰ 100 100 100 100 97.5 82.5 60 52.5 41 29.5 22 16 11 6 AC-20Ⅰ 100 100 100 97.5 82.5 71 62 48 37 27 21 15 10 6 AC-25Ⅰ 100 100 97.5 82.5 71 63 53 42 33.5 25 19 13 9 5 沥青稳定1# 100 100 90 75 67 58 50 35 25 17 12 9 7.5 6 沥青稳定2# 100 90 78 68.7 60 52 44 37 30 23 17 12 8 6 表 3 沥青混合料弯曲试验结果(平均值)
Table 3. The testing result of asphalt mixtures curving (average)
混合料类型 弯拉强度/MPa 最大弯拉应变×10-2 弯拉模量/MPa 平行试件个数 AC-16Ⅰ 1.1852 1.0125 117.0568 4 AC-20Ⅰ 2.1694 0.5100 425.3725 4 沥青稳定基层2# 3.3600 0.3975 845.2830 4 AC-25Ⅰ 3.2267 0.3450 935.2754 4 沥青稳定基层1# 3.0491 0.2700 1129.2963 4 表 4 试验沥青混合料应变疲劳方程汇总
Table 4. The fatigue-equation of asphalt mixtures expressing as strain or strain ratio
混合料类型 应变表示的疲劳方程 应变比表示的疲劳方程 AC-16Ⅰ lgNf=-4.8201-3.7412lgε lgNf=5.8108-4.1344 (ε/εmax) AC-20Ⅰ lgNf=-3.7414-2.9170lgε lgNf=5.8348-4.4236 (ε/εmax) AC-25Ⅰ lgNf=-4.8073-3.0756lgε lgNf=5.6509-4.3181 (ε/εmax) 沥青稳定基层1# lgNf=-5.59205-3.1240lgε lgNf=5.5265-4.7380 (ε/εmax) 沥青稳定基层2# lgNf=-4.0195-2.8523lgε lgNf=5.8164-4.6797 (ε/εmax) -
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