（北京市勘察设计研究院有限公司， 北京 100038）

［摘要］大面积荷载下非饱和软土场地单桩负摩阻力在采用《建筑桩基技术规范》（JGJ 94—2008）进行计算时，会遇到桩侧软弱土层深度确定困难、负侧摩阻力分布形式与该规范建议方法确定的形式有差异等问题，导致基桩负摩阻力计算困难。为解决上述问题，基于《建筑桩基技术规范》（JGJ 94—2008）对正负侧摩阻力规定或推荐的做法，国内外对单桩负侧摩阻力的研究、实测成果，结合某工程场地形成后大面积填土荷载作用条件及地层分布等，建立了大面积荷载作用下基桩负侧摩阻力分布的概念模型；基于实测桩侧土变形数据，对场区土层的变形数据进行对数曲线拟合，确定场区沉降计算经验系数及桩侧土固结度，并以此来计算桩及桩侧土考虑时间效应的分层沉降，然后基于桩及桩侧土变形相等的原则确定考虑时间效应的中性点。最后给出了大面积荷载下单桩负摩阻力计算的具体方法和步骤。以某工程项目为例的实际计算结果表明，所述方法对大面积荷载下单桩负摩阻力计算具有较强的工程实践及应用价值。

［关键词］大面积荷载；单桩；非饱和软土；负摩阻力；概念模型；时间效应

中图分类号：TU433文献标识码：A文章编号：1002-848X(2021)06-0123-06

Calculation method of negative friction resistance of single pile considering time effect on unsaturated soft soil site under large-area load

XUE Xiang, ZHU Chunjie, ZHENG Yi, CHEN Yuanhao, HOU Dongli, YANG Suchun, ZHOU Honglei

（BGI Engineering Consultants Ltd., Beijing 100038, China）

Abstract:When Technical code for building pile foundation（JGJ 94—2008）is used to calculate of the negative friction resistance of single pile in unsaturated soft soil site under the large-area load, problems such as difficulties in determining the soft soil layer deep on the pile side and differences between the form of negative friction resistance distribution and the form of negative friction resistance determined by the recommended method of the code are encountered, which result in difficulties in calculating the negative friction resistance of foundation piles. In order to solve the above-mentioned problems, based on the practice of Technical code for building pile foundation（JGJ 94—2008）on the regulation or recommendation of positive and negative friction resistance, the research on the negative friction resistance of single pile at home and abroad, the measured results, the large-area load acting conditions and the load distribution after the site formation of a certain project, etc., the conceptual model of the distribution of the negative  friction resistance under the action of a large-area compacted fill load was established. Based on the measured pile side soil deformation data, the deformation data of the soil layer in the field area were subjected to logarithmic curve fitting, the empirical coefficient of the settlement calculation of the field area and the consolidation degree of the pile-side soil were determined, which was used to calculate the layered settlement of the pile and the pile-side soil taking into account the time effect of consolidation, and then the neutral point was determined taking into account the time effect based on the principle that the pile and the pile side soil are equal to the deformation. Finally, the calculation method and the step of the negative friction resistance of single pile under the large-area load was given. The actual calculation results of an engineering project as an example show that the method described has strong engineering practice and application value for the calculation of negative frictional resistance of single piles under large-area loads.

Keywords:large-area load;single pile;unsaturation soft soil;negative friction resistance;conceptual model;time effect

作者简介：薛祥，硕士，高级工程师，Email:snowmatic@126.com。