The effective stress iterative method of estimating neutral point and downdrag on a single pile was presented in this paper.

采用有效应力迭代法确定中性点的位置和计下拉荷载,并通一个实例说明迭代试的。

Analysis results show that location of pile neutral point is the lowest and downdrag caused by NSF is maximal if neglecting working load on pile top.

析结果表明，不考虑桩顶荷载的中性点位置是最低的，下拽力是最大的。