DX桩桩周土应力场分布的模型试验研究

通过室内小比尺的模型试验，可以进一步为确定DX桩沉降计算公式提供必要的依据。在小型模型试验箱中，通过采用杠杆加砝码的装置对22 mm桩径的DX桩在砂土中进行研究，测定单桩的桩顶荷载-桩顶位移曲线，确定承载力，并与相同情况下的直孔桩进行对比；同时，利用微型土压力盒测定土中应力变化，研究荷载在土中的传递规律。试验结果表明，DX桩的承载力及沉降特性明显优于直孔桩；承力盘在上部和下部时，DX桩尽管承载力相差不大，但是盘在下部时会增大桩端附近土体的应力；两个承力盘的DX桩，两盘受力比较一致，且盘受力的影响范围，在竖

Model test study on surrounding soil stress distribution of DX pile

Through small scale model test of DX piles in lab, the test results can provide necessary basis for computing formula of settlement. A series of tests about DX piles with 22 mm diameter in sand are carried out in a small test chamber with the loading frame;the Q-s curves are derived, and then the bearing capacities are determined and compared with the straight piles in the same condition. At the meantime, miniature earth pressure cells are installed to test the stress in the surrounding soil of DX piles, so that the load transfer law in the soil can be researched. The test results show that the capacity and settlement characteristics of DX pile are much superior to the straight pile with the same parameters. For the single bell DX pile, the location of the bell has barely effect on the capacity. However, when the bell locates on the lower part of pile shaft, the stress of soil around the pile tip increases a lot. For two bell DX pile, the stresses around the two bells are similar, and the range of soil stress induced by bells in vertical is around two times of bell diameter. For the DX pile with three bells, the soil stress around the bells spread increasingly, while the amplitude is small.