路基振动压实动力学响应机理研究

为研究路基振动压实过程中振动轮动力学响应的产生机理，进而为连续压实监测技术中的谐波比类指标提供理论支撑，基于有限元方法，分别考虑了纯弹性和弹塑性2种土体本构模型，针对振动压实过程中的加速度信号进行了仿真分析，分别研究了几何非线性、接触非线性以及材料非线性对加速度信号畸变的影响，探讨了加速度信号频谱中谐波分量和次谐波分量的产生机理，并对其随弹性模量、黏聚力等土体参数的变化规律进行了分析。其中，弹性模型在发生跳振之前，可以分析几何非线性和由于接触面积变化引起的接触非线性的影响，在发生跳振之后，可以用来考虑由于脱空引起的接触非线性的影响，弹塑性模型可以反映材料非线性的影响。研究结果表明:几何非线性对加速度信号畸变的影响不大，材料非线性和接触面积变化引起的接触非线性是加速度信号谐波分量的产生原因，而跳振引起的接触非线性是次谐波分量的产生原因。此外，随着压实过程的进行，土体模量和屈服极限同时提高，接触面积变化引起的接触非线性增强，但材料非线性的影响减弱，由于压实的中后期土体弹性因素占据了主导地位，塑性变形量很小，同时由于局部脱空的影响，导致实际工程中，随着压实过程的进行，二次谐波分量呈增大趋势。最后，跳振不仅会引起次谐波分量，还会导致谐波分量量值的减小，同时跳振发生前后加速度波形并不是连续变化，而是发生了突变。

Simulation Analysis of Vibratory Roller Response on Subgrade

To study the dynamic response mechanism of a vibratory roller during the process of subgrade compaction and provide theoretical support for the harmonic ratio index in continuous compaction control technology, based on the finite-element method, two elastic and elastic-plastic models were established, and the acceleration signal during compaction was simulated and analyzed. The effects of geometric nonlinearity, contact nonlinearity, and material nonlinearity on the distortion of the acceleration signal were studied. The generation mechanism of the harmonic and subharmonic components in the acceleration signal spectrum was illustrated, and their variations with soil parameters, such as modulus and cohesion, were analyzed simultaneously. During this process, the elastic model was used to determine the influence of geometric nonlinearity and contact nonlinearity caused by the change in contact area before jump vibration occurred. After the jump vibration, it was utilized to illustrate the impact of the contact nonlinearity caused by separation. Furthermore, an elastic-plastic model was established to reflect the effects of material nonlinearity. The results show that geometric nonlinearity has little effect on the distortion of the acceleration signal. Material nonlinearity and contact nonlinearity caused by contact area change lead to harmonic components in the acceleration signal, and contact nonlinearity caused by jump vibration induces subharmonic components. In addition, during compaction, the modulus and yield limit of soil increase at the same time, and the contact nonlinearity caused by the change in contact area is enhanced. However, the influence of material nonlinearity is weakened. Owing to the dominant elastic factor of soil in the middle and late stages of compaction, the plastic deformation is very small. Because of the influence of local disengagement, the second harmonic component increases during the compaction process. Finally, jump vibration not only causes subharmonic components, but also leads to a decrease in the harmonic components. Simultaneously, the acceleration waveform before and after the jump vibration does not change continuously but changes suddenly.