砂土中抗拔群桩承载力的分析与计算

Analysis and calculation of bearing capacity of pile groups in sandy soil

为了通过模型的方法预测砂土中抗拔群桩承载力,对抗拔单桩承载公式中的参数C进行了改进,并对此参数提出了一个预测公式。当抗拔单桩承载力未知时,不能逆分析C值,可以用预测公式计算C值。基于此推导了m×n型等距抗拔群桩承载力计算公式。结合2组模型试验的数据,验证了不同桩距、长径比和桩型下抗拔群桩承载力计算公式的合理性以及群桩效率和桩距的关系,并与其他3种计算方法的结果作比较。结果表明,4种方法都能很好地预测抗拔群桩承载力,但在预测长径比较小的群桩时,改进方法的预测结果更加接近试验值;在其他参数不变的情况下,群桩的效率随着桩距的增大而增大。

To better predict the uplift capacity of pile groups in sandy soil by model method,parameter Cof the formula of the uplift capacity of pile were improved and a prediction formula for parameter Cwas put forward.When the uplift capacity of single pile is unknown,Cvalue can’t be reversly calculated except using the formula.On the basis of analysis and literature,the calculation formula of the uplift bearing capacity of m×nshape pile groups was deduced.Combined with the data of the two pile groups in model tests,it proves the formula validity of pile groups with different pile spacing,the pile length to diameter ration and the shape and studies the relationship between pile group efficiency and pile spacing.In contrast with the other three calculation methods,the results show that the four methods can predict reasonable results of the bearing capacity of pile groups,but the method approximates the test results under small length to diameter ratio.While other parameters keep constant,pile group efficiency increases with the increase of pile spacing.