粉质粘土路基冲击压实动力响应数值模拟研究

依托实际工程，应用有限差分软件FLAC 3D分层建立高速公路粉质粘土路段路基模型；通过在路基模型顶面施加1次动力荷载和施加不同次数动力荷载，对路基模型的动力响应进行数值模拟分析，研究了冲击作用下动应力、竖向位移沿深度和径向距离的变化规律。结果表明:冲击轮冲击路基表面破坏土体结构，从而使路基土体密实，冲击碾压加固路基效果显著；土体中加固区近似为椭球体，其剖面为椭圆形；土体中动应力、竖向位移沿径向的衰减速度大于竖向的衰减速度，径向的影响宽度小于竖向影响深度；当冲击压路机保持正常的工作速度12 km·h^-1，路基填筑高度为1 m时，冲击碾压次数宜在20次左右。

Research on Numerical Simulation About Dynamic Response of Silty Clay Subgrade Under Impact and Grind

Relying on the actual project, a subgrade model of silty clay in highway was built by using the numerical calculation software FLAC 3D. Numerical simulation analysis about dynamic response of subgrade model was carried through applying one time dynamic load and different times dynamic load on the top of the subgrade model, and the change laws of dynamic stress and vertical displacement along depth direction and radial direction were researched. The results show that the soil structure is damaged by impact roller impacting subgrade surface, so that the subgrade soil is compacted, impact compaction has obvious reinforcement effect on subgrade. The reinforcement area in soil is like ellipsoid, and its profile is like ellipse. The attenuation velocities of dynamic stress and vertical displacement along radial direction are faster than those along vertical direction, and the radial influence width was greater than the vertical influence depth. When impact roller keeps the normal working speed 12 km·h^-1 and subgrade filling height is 1 m, the time of impact roller compaction should be about 20.