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针对水泥稳定碎石(简称水稳碎石)等半刚性基层在青藏高原高海拔地区频繁冻融循环作用下,易造成材料强度与耐久性下降,影响路面整体使用性能问题。以拉萨—贡嘎机场专用公路新建工程为依托,从水稳碎石的抗冻融性能出发,采用室内试验模拟冻融循环过程,分析水稳碎石经不同次冻融循环作用后的强度损失规律,引入抗压强度耐冻系数与劈裂强度耐冻系数作为抗冻融性能评价指标,对比分析水泥用量、养生温度和冻融循环次数与水稳碎石耐冻系数的相关性;以水稳碎石耐冻系数为主参数,水泥用量、养生温度与冻融循环次数为变量,引入温度修正系数对基层养生温度影响进行修正,并对耐冻系数进行回归,建立二元线性预测模型,计算模型计算值与试验实测值的相对误差,验证模型的拟合精度。研究结果表明:水稳碎石的强度与耐冻系数随冻融循环次数的增加而降低,强度在0~5次冻融循环周期内下降较为明显;较高的水泥用量与养生温度可有效降低水稳碎石冻融后的强度损失,建议工程中控制水泥用量为4%(质量分数,下同),同时保证养生温度大于10℃可有效提高材料抗冻融性能;所建二元线性预测模型具有较高的拟合精度和很好的再现性,可为水稳碎石抗冻融性能研究提供参考,为特殊地区半刚性基层设计施工提供技术指导。
For the semi-rigid base course of cement stabilized macadam (referred to as water-stabilized gravel) under the frequent freeze-thaw cycles in the high altitude area of the Qinghai-Tibet Plateau, the strength and durability of the semi-rigid base will easily decrease, which will affect the overall performance of the pavement. Based on the Lhasa - Gonggar airport dedicated highway construction, based on the freeze-thaw resistance of water-stabilized gravel, the indoor experiment was used to simulate the freeze-thaw cycle, and the strength loss of the stabilized stabilized gravel after different sub-freeze-thaw cycles Law, the compressive strength of the freezing resistance coefficient and the splitting strength of the freeze-thaw coefficient as the evaluation index of anti-freeze-thaw performance, comparative analysis of the cement dosage, temperature and freeze-thaw cycles and freeze-thaw resistance coefficient; Freezing resistance of the stabilized gravel as the main parameter, the amount of cement, the temperature of the health and the number of freeze-thaw cycles as variables, the temperature correction coefficient was introduced to modify the temperature of the grass-roots health temperature, and the regression coefficient of the freezing resistance coefficient was established. The binary linear prediction model was established, Calculate the relative error between the calculated value of the model and the measured value of the experiment and verify the fitting accuracy of the model. The results show that the strength and the freezing resistance coefficient of water-stabilized macadam decreases with the increase of the number of freeze-thaw cycles, and the intensity decreases more obviously in 0 ~ 5 cycles of freeze-thaw cycles. Higher cement content and temperature can be effectively reduced It is suggested that the amount of cement controlled by the project should be 4% (mass fraction, the same as below), and the temperature should be kept above 10 ℃ to improve the freeze-thaw resistance of the material. The linear predictive The model has high fitting precision and good reproducibility, which can provide references for the research of freeze-thaw resistance of water-stabilized gravel, and provide technical guidance for the design and construction of semi-rigid base in special areas.