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交通荷载作用频率随着车辆运行速度等因素变化而变化,目前对不同频率荷载下路基长期性能还缺乏一致性认识。为揭示不同频率荷载下路基粗粒土填料长期动力特性,利用GDS大型三轴试验系统对路基填料进行饱和排水循环荷载试验,分析不同应力路径下荷载频率对路基粗粒填料长期动力特性影响规律。试验结果表明,荷载频率增加使路基填料在密实阶段产生更大累积体缩应变而更密实,进而路基动力回弹模量随荷载频率增加显著增加。路基填料轴向累积变形在不同频率循环荷载下也呈现不同发展规律,路基填料密实阶段轴向累积变形在高循环应力比(ζ=3,5)下随荷载频率增加显著增大,但在低循环应力比(ζ=1)下,荷载频率对轴向累积变形影响较小;当填料进入变形稳定阶段,荷载频率对轴向累积变形基本无影响。该研究揭示了路基填料层在不同频率荷载下长期动力特性,发现降低路基中循环应力比,可大大减小荷载频率对路基长期动力特性影响,本研究可为准确预测和控制道路工后沉降提供参考。
The frequency of traffic load varies with the vehicle speed and other factors. At present, the consistency of long-term performance of subgrade under different frequency loads is still lacking. In order to reveal the long-term dynamic characteristics of subgrade-based coarse-grained soil filler under different frequency loads, the saturated drainage cyclic loading test was carried out on the subgrade filled with GDS large-scale triaxial test system to analyze the influence of load frequency on the long-term dynamic characteristics of subgrade filled coarse particles under different stress paths. The experimental results show that the increase of load frequency makes the subgrade filler produce more compact body shrinkage and denser in the dense stage, and the subgrade dynamic resilience modulus increases obviously with the increase of load frequency. The cumulative axial deformation of subgrade fillings also shows different development rules under different cyclic loadings. The cumulative axial deformation of subgrade fillings increases with the increase of load frequency under high cyclic stress ratio (ζ = 3,5) Under the cyclic stress ratio (ζ = 1), the load frequency has little effect on the cumulative axial deformation. When the filler enters the stable stage of deformation, the load frequency has little effect on the axial cumulative deformation. The study reveals the long-term dynamic characteristics of subgrade under different frequency loads. It is found that reducing the cyclic stress ratio in subgrade can greatly reduce the influence of load frequency on the long-term dynamic characteristics of subgrade. This study can provide accurate prediction and control of post-construction settlement reference.