Thermal stress influence factors of asphalt overlay on cement concrete pavement cracking slab
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摘要: 为了防止水泥混凝土路面加铺沥青面层反射裂缝的产生, 采用有限元方法, 视路面结构为弹性层状体系, 建立沥青加铺层、补强层、破裂水泥混凝土路面板和地基组成的空间三维模型, 分析了破裂板块平面尺寸、降温幅度、沥青加铺层模量及厚度、结构补强层模量、混凝土路面板厚度等因素对沥青加铺层温度应力的影响。结果表明, 对破裂后的旧水泥混凝土路面板块, 沥青加铺层温度应力随其板块尺寸的减小而大幅度降低, 较大的降温幅度对加铺层温度应力的影响远大于车辆荷载产生的应力; 而降低沥青加铺层模量, 增大加铺层厚度等技术措施可明显改善破裂板接缝处的应力状况, 并能有效地防止沥青加铺层反射裂缝的产生。Abstract: In order to remove the reflective crack of asphalt overlay on cement concrete pavement, the paper adopted finite element method, took pavement structure as elastic layered system, founded a three-dimensional model of asphalt overlay, strengthening layer, cracked slab of cement concrete pavement and subgrade, and analyzed the influences of old cement concrete cracked size, temperature drop scope, modulus and thickness of asphalt overlay, structure strengthening layer modulus and thickness of cement concrete cracked slab on asphalt overlay thermal stress.The results indicate that the thermal stress of asphalt overlay decreases greatly with the size reduction of old cement concrete cracked slab, the influence of great temperature drop scope on overlay thermal stress is much larger than that of vehicle load, the measures such as decreasing asphalt overlay modulus and increasing asphalt overlay thickness etc can effectively improve the stress situation at cracked slab joints, and effectively prevent the reflective crack of asphalt overlay.
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表 1 计算参数
Table 1. Main calculation parameters
结构层 厚度/cm 弹性模量E/MPa 泊松比μ 导热系数/[W·(m·℃)-1] 线膨胀系数/℃-1 沥青加铺层(AC) 8~20 600~2 200 0.25 1.2 2.1×10-5 补强层 15 150~3 000 0.30 1.1 0.8×10-5 旧水泥混凝土路面(PCC) 18~26 25 000~32 000 0.15 1.5 1.0×10-5 基础 — 100 0.35 1.0 0.5×10-5 表 2 路面板破裂尺寸对温度应力的影响
Table 2. Influence of pavement slab cracked size on thermal stress of asphalt overlay
/MPa 板块尺寸 σx σy σz τxy τyz τxz σ1 σ2 σ3 σe τmax 500 cm×375 cm 3.616 1.033 0.181 -0.002 0.000 0.011 3.616 1.033 0.181 3.098 1.718 250 cm×188 cm 2.961 0.859 0.147 -0.001 -0.001 0.021 2.962 0.859 0.147 2.535 1.408 100 cm×94 cm 2.138 0.639 0.104 0.000 0.000 -0.001 2.138 0.639 0.104 1.826 1.017 50 cm×54 cm 1.392 0.437 0.064 -0.001 -0.001 0.000 1.392 0.437 0.064 1.187 0.665 表 3 降温幅度对沥青加铺层温度应力的影响
Table 3. Influence of temperature drop scope on thermal stress of asphalt overlay
/MPa 降温幅度/℃ σx σy σz τxy τyz τxz σ1 σ2 σ3 σe τmax -5 1.069 0.320 0.052 0 0 -0.001 1.069 0.320 0.052 0.913 0.509 -10 2.138 0.639 0.104 0 0 -0.001 2.138 0.639 0.104 1.826 1.017 -15 3.207 0.959 0.156 0 0 -0.002 3.207 0.959 0.156 2.739 1.526 -20 4.276 1.278 0.208 0 0 -0.002 4.276 1.278 0.208 3.652 2.034 -25 5.345 1.598 0.260 0 0 -0.003 5.345 1.598 0.260 4.565 2.543 -30 6.414 1.917 0.312 0 0 -0.003 6.414 1.917 0.312 5.478 3.051 表 4 模量对温度应力的影响
Table 4. Influence of asphalt mixture modulus on thermal stress
/MPa Ea/MPa σx σy σz τxy τyz τxz σ1 σ2 σ3 σe τmax 600 1.619 0.467 0.080 0 -0.001 -0.001 1.619 0.467 0.080 1.387 0.770 800 1.824 0.533 0.090 0 -0.001 -0.001 1.824 0.533 0.090 1.560 0.867 1 000 1.961 0.581 0.096 0 -0.001 -0.001 1.961 0.581 0.096 1.676 0.933 1 200 2.138 0.639 0.104 0 0.000 -0.001 2.138 0.639 0.104 1.826 1.017 1 400 1.146 0.644 0.102 0 0.000 0.000 2.146 0.644 0.102 1.830 1.022 1 600 2.151 0.663 0.102 0 0.000 0.001 2.151 0.663 0.102 1.834 1.025 1 800 2.170 0.677 0.102 0 0.001 0.001 2.170 0.677 0.102 1.848 1.034 2 000 2.170 0.685 0.101 0 0.002 0.001 2.168 0.685 0.101 1.846 1.034 2 200 2.159 0.691 0.099 0 0.002 0.002 2.159 0.691 0.099 1.836 1.030 表 5 加铺层厚度对温度应力的影响
Table 5. Influence of overlay thickness on thermal stress
/MPa ha/cm σx σy σz τxy τyz τxz σ1 σ2 σ3 σe τmax 8 3.044 0.901 0.153 -0.001 -0.002 -0.008 3.044 0.901 0.153 2.599 1.446 10 2.591 0.770 0.129 -0.001 -0.001 -0.005 2.591 0.770 0.129 2.213 1.232 12 2.138 0.639 0.104 0.000 0.000 -0.001 2.138 0.639 0.104 1.826 1.017 14 1.685 0.510 0.080 0.000 0.001 0.001 1.685 0.510 0.080 1.440 0.803 16 1.232 0.381 0.055 0.000 0.001 0.002 1.232 0.381 0.055 1.053 0.589 18 0.883 0.281 0.036 0.000 0.002 0.003 0.883 0.281 0.036 0.756 0.424 20 0.534 0.181 0.017 0.000 0.002 0.003 0.534 0.181 0.017 0.458 0.259 表 6 补强层模量对其温度应力的影响
Table 6. Influence of strengthening layer modulus on its thermal stress
/MPa 补强层模量EB/MPa σx σy σz τxy τyz τxz σ1 σ2 σ3 σe τmax 150 0.458 0.149 0.044 0 -0.001 -0.004 0.458 0.149 0.044 0.373 0.208 300 0.770 0.249 0.072 0 0.000 -0.006 0.770 0.249 0.072 0.628 0.349 500 1.061 0.340 0.097 0 0.000 -0.008 1.061 0.340 0.097 0.868 0.482 800 1.356 0.431 0.121 0 0.000 -0.010 1.356 0.431 0.121 1.113 0.618 1 000 1.499 0.473 0.131 0 0.000 -0.011 1.499 0.473 0.131 1.233 0.684 1 500 1.757 0.548 0.149 0 0.001 -0.014 1.757 0.548 0.149 1.450 0.804 3 000 2.183 0.659 0.179 0 0.002 -0.017 2.183 0.659 0.179 1.812 1.002 表 7 补强层模量对沥青加铺层温度应力的影响
Table 7. Influence of strengthening layer modulus on thermal stress of asphalt overlay
/MPa 补强层模量EB/MPa σx σy σz τxy τyz τxz σ1 σ2 σ3 σe τmax 150 0.151 0.120 0.052 0 -0.001 0 0.151 0.120 0.052 0.087 0.050 300 0.153 0.138 0.081 0 -0.001 0 0.153 0.138 0.081 0.066 0.036 500 0.157 0.148 0.101 0 -0.001 0 0.157 0.148 0.101 0.052 0.029 800 0.162 0.153 0.112 0 -0.001 0 0.162 0.153 0.112 0.046 0.025 1 000 0.164 0.154 0.114 0 -0.001 0 0.164 0.154 0.114 0.046 0.025 1 500 0.166 0.154 0.111 0 -0.001 0 0.166 0.154 0.111 0.050 0.028 3 000 0.164 0.149 0.093 0 -0.001 0 0.164 0.149 0.093 0.065 0.036 表 8 破裂板厚度对沥青加铺层温度应力的影响
Table 8. Influence of cracked slab thickness on thermal stress of asphalt overlay
/MPa 破裂板厚度hc/cm σx σy σz τxy τyz τxz σ1 σ2 σ3 σe τmax 18 1.910 0.579 0.093 0.000 0.000 -0.001 1.910 0.579 0.093 1.629 0.908 20 2.024 0.609 0.099 0.000 0.000 -0.001 2.024 0.609 0.099 1.728 0.963 22 2.138 0.639 0.104 0.000 0.000 -0.001 2.138 0.639 0.104 1.826 1.017 24 2.108 0.631 0.102 0.001 -0.001 0.000 2.108 0.631 0.102 1.801 1.003 26 2.077 0.623 0.100 0.001 -0.001 0.001 2.077 0.623 0.100 1.775 0.989 -
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