振动轮两侧加速度差异及连续压实指标优化研究

Research on Difference in Acceleration on Both Sides of Drum and Optimization of Continuous Compaction Indexes

连续压实控制技术主要通过振动轮单侧振动响应描述土体压实状态,已在工程中得到广泛应用。然而,研究发现压实过程中存在振动轮两侧加速度响应不一致的现象,这可能导致现有测试方法在相同位置出现不同的刚度测试结果,因此研究振动轮两侧振动差异性对提高连续压实测试精度具有重要意义。结合现场试验,采集压路机振动轮两侧的加速度信号,重点分析了不同压实遍数、振动频率下两侧加速度峰值、倍频幅值的变化与分布规律;以双侧响应为基础提出平均指标,通过相关性分析对指标适用性进行验证。研究结果表明:随着压实遍数的增加,两侧加速度峰值差异逐渐减小,经4遍压实后差异由24.4%降至13.3%;振动轮结构偏心会造成振动轮两侧加速度频谱中基频幅值差异的产生,被压土体两侧刚度不均会造成2倍频、3倍频幅值差异的产生;双侧平均指标μAICV与动态变形模量的相关性为0.75,表明双侧平均指标μAICV可用于路基压实质量控制,相比单侧连续压实控制指标,可有效提高现场质量控制精度。

The continuous compaction control(CCC)technology,widely used in civil engineering,mainly describes the compaction state by the single side of drum dynamic response.However,differences are found on the acceleration response between each side of the drum during the compaction process,which could lead to different stiffness test results on the same location using existing testing methods.It is important to investigate the vibration differences between both sides of the drum for improving the continuous compaction testing accuracy.Based on the in-situ tests,the acceleration signals on both sides of the drum were obtained to analyze the changes and distribution laws of the acceleration peak and harmonic amplitude under different compaction passes and vibration frequencies.An average index was put forward based on bilateral response,and its accuracy was verified through correlation analysis.The results show that the difference in peak acceleration between both sides gradually decreases with the increase of the number of compaction passes,with the difference decreasing from 24.4%to 13.3%after 4 compaction passes.The fundamental frequency amplitude differences of the 1.0 f in the acceleration spectrum on both sides of the drum are caused by the eccentric structure of the vibration drum.The amplitude differences of the 2.0 f and 3.0 f are caused by the differences about the uneven stiffness of the compacted soil under each side of the drum.The correlation between average indexμAICV of both sides and dynamic deformation modulus is 0.75,indicating that the average index can be used for subgrade compaction quality control,which can effectively improve the in-situ compaction quality accuracy compared with single side CCC indexes.