强夯动应力的量测及现场试验研究

Field tests on measurement of dynamic stress of dynamic compaction

结合常吉高速公路强夯补强加固路基工程,做了大型的现场试验。在试验路段布置了43个土压力盒,运用动态应变仪记录了强夯动应力的传播和衰减过程,并尝试用动应力的传播与衰减曲线说明冲击波在土体中的传播。试验结果表明:强夯对红砂岩填土路基的加固效果明显,强夯动应力也相当明显,强夯动应力在水平方向的衰减速度比竖直方向快,竖直方向的影响范围比水平方向大;强夯法加固地基的影响深度远大于有效深度;随着夯击次数的增加,有效加固范围内的动应力增加明显,但在3～5击后基本稳定;从动应力等值线图上也可分析出强夯作用时压缩波、剪切波、瑞利波的作用范围。

A large field test was conducted in the project of Chang-Ji Expressway. Forty-three soil pressure cells were embedded in the test section of road. Dynamic strain gauge was used to record the stress dispersion and stress decay caused by dynamic compaction. It was tried to explain the spread of shock waves in the soil mass with the stress dispersion and stress decay curve. It was shown that the reinforce effect on the red sandstone fill in subgrades and dynamic stress of dynamic compaction were obvious. The decay speed of dynamic stress in the horizontal was faster than that in the vertical, and the range of influence of dynamic stress was much extensive than that in the horizontal. The effective reinforced depth was deeper than the influence depth. With the compaction numbers increased, the dynamic stress in the reinforced range obviously increased and it tended to be stable after three to five hits. The effective range of P-wave, S-wave, R-wave could be analyzed from the contours of dynamic stress.