多遍冲击碾压混凝土路面时路基的动力响应分析

Dynamic response of subgrade under impact compacted load with multiple times

采用三维动力弹塑性有限元,考虑冲击压路机沿面板纵向中线及板边行驶来冲击碾压破碎旧水泥混凝土板,对路基在不同冲击遍数下的变形、受力等力学响应进行了分析。研究发现,土基在3个方向均承受压应力,板角荷载作用位置路基竖向变形最大,板中最小。板中路线路基竖向变形总体小于板边路线。随着距冲击点距离减小,土体竖向变形逐渐增大,并存在有明显的波动滞后现象和残余变形。随着冲击遍数的增加,土基最大竖向变形逐渐变大;第3遍冲击完后已出现明显的塑性区;随着冲击遍数的增加,土基中土压力逐渐增大,但渐趋稳定。虽然冲击遍数增加,但土压力增大范围仅限于土基一定深度内。

The dynamic deformation and stress characteristics of subgrade under two impact loading routes with different compact times are analyzed based on three dimensional elastoplastic dynamic FEM. The results indicate that the three dimensional compressive stresses exist in the affected scope of subgrade underneath the slab. Vertical deformation of subgrade under slab comer is maximum; and vertical deformation of subgrade under slab corner is minimum. By comparison vertical deformation of subgrade, vertical deformation of subgrade is generally lower. Vertical deformation of subgrade increases with distance far away from impact point. And vertical deformation of subgrade exists obviously residual deformation, wave and hysteresis phenomenon. Vertical deformation of subgrade increases with increasing of compact times; and there exists plastic zone after the third compact time. Soil pressure increases with increasing of compact times; but increasing tendency tends to be stable. The range of increasing soil pressure is limited to certain depth of subgrade.