湿陷性黄土中单桩负摩阻力时效性研究

桩侧负摩阻力问题广泛存在于桩基工程中,由于湿陷性黄土浸水沉降过程缓慢,桩基负摩阻力具有明显的时效性.笔者首先探讨了黄土的湿陷以及负摩阻力产生的机理,重点研究了桩和土的相对位移与时间的关系,引入荷载传递模型,推导出桩侧负摩阻力与时间的关系.通过计算表明,单桩的负摩阻力随时间的增长而增大,但增长速率逐渐减小,最终负摩阻力将趋于一个稳定值.该计算结果能够很好的体现湿陷性黄土中单桩负摩阻力的时效性,并对湿陷性黄土中桩基础的施工具有很好的指导意义.

Study on the Time of Negative Skin Friction of Single Pile in Collapsible Loess

The problem of negative skin friction on pile side is widely existed in pile foundation engineering. Due to the slow process of water infiltration and settlement of collapsible loess, negative skin friction on pile foundation has obvious timeliness. Firstly, the mechanism of the loess's subsidence and negative friction resistance is discussed, and the relationship between the relative displacement and time of pile and soil is studied. The calculation shows that the negative friction resistance of single pile increases with the increase of time, but the increase rate decreases gradually, and the negative friction resistance will reach a stable value eventually. The calculation results can well reflect the timeliness of negative friction resistance of single pile in collapsible loess and have a good guiding significance for the construction of pile foundation in collapsible loess.