填石路堤强夯加固施工参数及路基动应力响应规律研究

贵州西部山区的高速公路常采用高填石路堤,强夯法是控制高填石路堤填筑质量的有效方法之一。为确定填石路堤的强夯加固施工技术参数、探讨强夯冲击能量作用下填石路堤内部动应力响应规律,通过现场试验和FLAC3D数值模拟进行研究。采用动土压力盒、位移观测元件,测试强夯冲击能量作用下的动应力以及夯坑沉降量、夯锤周边地表变形等数据,并将现场测试结果与数值模拟结果进行对比分析。研究结果表明:在夯击能量3 000 kN·m下,强夯加固单点夯击次数为12击、夯点间距为4.5 m;强夯作用下填石路堤内部动应力峰值随深度呈指数形式衰减,并且根据动应力峰值的随深度衰减曲线,获得了夯击能量3 000 kN·m下填石路堤强夯有效加固深度为5.0 m。研究结果可为类似工程确定强夯加固施工参数及有效加固深度提供指导。

Dynamic stress response law and construction parameters study of rockfill embankment under dynamic compaction

The high rockfill embankments are often used for highway built in the western mountainous area of Guizhou province. The dynamic compaction method is one of the effective methods to control the filling quality. In order to determine the technical parameters of dynamic compaction and explore the dynamic stress response law of rockfill embankment under impact energy of dynamic compaction, field tests and FLAC3D numerical simulation were conducted. The dynamic stress, the settlement of tamping pit, and the surface deformation around the tamping pit were measured by using dynamic soil pressure cells and displacement observation element. The field test results were compared with the numerical simulation results. The results show that the peak dynamic stress inside the rockfill embankment attenuates exponentially with the depth under the dynamic compaction, when the tamping times of single tamping point are 12 and the tamping points spacing is 4.5 m under the tamping energy of 3 000 kN·m. According to the attenuation curve of the peak dynamic stress with the depth, the effective reinforcement depth of the rockfill embankment is 5.0 m under the tamping energy of 3 000 kN·m. The results provide guidance for similar projects to determine the construction parameters and effective reinforcement depth of dynamic compaction.