考虑固结效应的高填方夯实地基桩侧负摩阻力计算方法

依托在高填方夯实地基上进行的桩侧负摩阻力现场试验,根据负摩阻力测试结果,提出考虑固结效应的高填方夯实地基桩侧负摩阻力计算方法。该方法对高填方地基强夯加固区与非加固区分段进行侧摩阻力计算,采用太沙基一维固结理论计算桩侧土沉降,反映固结效应对桩侧摩阻力的影响,利用土-混凝土界面直接剪切试验得到桩土荷载传递函数,反映桩土相对位移对侧阻力发挥程度的影响,采用有限差分法求得计算公式的数值解,并将计算结果与现场试验结果对比分析。结果表明,采用文中推导的公式计算的桩侧负摩阻力沿深度的变化趋势与现场试验测试结果一致,现场实测桩侧负摩阻力值约是理论计算值的1/2,工程应用时可将理论计算的桩侧负摩阻力值乘以0.5的折减系数。

Study of calculation of negative skin friction on piles in high filled embankment after dynamic compaction considering consolidation effect

The paper put forward the method of calculating the values of negative skin friction with the consolidation time on piles based on the field tests on high filled embankment after dynamic compaction. The proposed method calculate the values of skin friction respectively according to the improvement depths by dynamic compaction and non-improvement depths, using Terzaghi consolidation theory to calculate soil settlements to reflect the influence of consolidation effects on skin friction, using interference shear tests with soil and concret to get load transfer function between soil and piles to reflect the influence of relative deformation, and calculating the values of negative skin friction by finite difference method. Based on the comparative analyses of the results of the calculation and field testing, it is proved that the changing tendency of negative skin friction with depth by the calculation corresponds with that by field testing. The values of negative skin frication by field testing are about 0.5 of theoretical values by the calculation, and it is advisable to multiply the latter by a reduction coefficient of 0.5 when using them in projects.