考虑应力应变时间效应的桩基长期沉降计算方法

土体的应力应变时间效应对桩基长期沉降有重要影响。在长期荷载作用下桩基的沉降主要包括两个部分：桩尖刺入量和桩底土体的蠕变压缩沉降。采用Mesri蠕变模型描述土体的蠕变行为，用桩的Mindlin应力公式计算桩端和桩侧荷载在桩端平面以下产生的附加应力，用Boussinesq应力公式计算承台分担荷载产生的应力。分别给出了桩尖刺入量和桩底土体蠕变压缩量的计算方法，从而提出了一种考虑土体蠕变效应的桩基长期沉降计算方法。计算结果与桩基长期监测结果较为吻合，表明在获得可靠的计算参数后可用提出的方法估算桩基长期沉降。

Method for long-term settlement prediction of pile-foundation in consideration of time effect of stress-strain relationship

The time effect of the soil’s stress-strain relationship has a significant influence on the long-term settlement of pile-foundation. Long-term settlement of pile foundation includes at least two components: penetration of pile tip and compressed settlement of subsoil. By Mesri creep model, using the Mindlin stress formula to calculate the stress induced by the load of pile; and using Boussinesq stress formula to calculate the stress induced by the load of raft; a simple but practical method for predicting long-term settlement of pile-foundation was developed. The comparison between the calculated and true settlement demonstrates that this method is reasonable and useful.