冲击载荷下摊铺机振捣机构对混合料的压实特性

Compaction Characteristics of Paver Tamper to Mixture Considering Shock Load

为了提高沥青摊铺机对铺层混合料的初始密实度,针对振捣机构动力学特征,考虑振捣冲击载荷对混合料的影响,建立了铺层材料密实度与振动参数、系统参数之间关系仿真模型,剖析振捣机构对混合料密实度与动态响应关系,揭示振捣压实特性机理.进行振捣机构对混合料摊铺密实效果的试验研究,得到振捣频率对材料密实度的影响特性曲线,通过不同阻尼参数下的模型分析,确定了振捣峰值密实度出现时的最佳振捣频率,同时对振捣密实度随各谐波频率的变化规律进行仿真计算和试验验证.研究结果表明:当频率比小于最佳振捣频率比时,密实度对振捣频率变化敏感,随着频率的增加,铺层密实度变化平缓,仿真与试验结果变化规律基本一致;当振捣频率接近最佳振捣频率时,除了与激励频率相同的稳态响应外,还存在频率为2倍激励频率的振动成分;当匹配振捣频率比大于0.45时,会产生高效密实效果.研究结果可为摊铺机实现对铺层混合料的高效压实提供依据.

To improve the initial density of a paving mixture behind the paver,the research of the dynamic characteristics of tamper is needed.In the impact compaction,the vibration shock force will impact mixture.A simulation model reflecting the relationship between paving material compactness and vibration parameters,system parameters was established to analyze the relationship between the compactness and dynamic response of the tamper,and reveal compaction mechanism of tamper.By testing the paving compaction effect of the tamper on the mixture,the paving compactness-frequency curve was obtained.Through analysis of the model with different damping coefficients,the best vibration frequency corresponding to maximum density peak could be determined.Meanwhile the influence of vibration frequency on paving density was analyzed through simulation and experiment.The results show that,when the frequency ratio is less than the best vibration frequency ratio,mixture compactness is sensitive to vibration frequency,and the compactness changes gently with increasing frequency when vibration frequency is larger than the best vibration frequency ratio,so the simulation results are basically consistent with the experimental results.When the vibrating frequency is close to the best vibrating frequency,besides the steady-state response with the same excitation frequency,there is a harmonic vibration component whose frequency is equal to 2 times the excitation frequency.When the frequency ratio is greater than 0.45,the high compacting effect would be obtained for the paving mixture.The research results provide the basis for pavement effective compaction.