黄土地区桩基承载力特性试验研究

Experimental Study on Bearing Capacity of Pile Foundation in Loess Area

探讨黄土地区桩基础竖向承载力性能,依托新建工程针对单桩竖向抗压承载力进行了3根试桩的现场试验。通过试验及数据对单桩竖向静载的Q-S曲线和S-lgt曲线进行分析及研究,试验表明荷载主要由桩侧摩阻力提供反力承担,3根试桩桩身轴力并未传至桩端,竖向承载力主要靠桩土之间的摩擦力承担;桩身轴力随深度分布与桩顶荷载的大小及桩周围土体的性质有关,呈现出典型的摩擦桩特性,Q-S曲线为缓慢变化趋势。加载至4900kN时,3根试桩均未达到极限承载力而产生强度破坏,桩身沉降量3根桩依次为12.24、15.44和18.64mm。对比设计要求与试验结果,单桩竖向承载力满足设计要求,研究表明在黄土地区摩擦桩具有较高的竖向承载力,均匀较小的沉降,黄土地区较大荷载的建筑物基础可以采用桩基础。

This paper discusses the vertical bearing capacity performance of pile foundation in loess area.Based on the new construction project,three field tests are carried out for the vertical compressive bearing capacity of single pile.The Q-S curve and S-lgt curve of single pile’s vertical static load are analyzed and studied through the test and data.The test shows that the load is mainly borne by the reaction force provided by the side friction of the pile,the axial force of three test piles is not transmitted to the pile end,and the vertical bearing capacity is mainly borne by the friction force between the pile and the soil;the axial force distribution of the pile with depth is related to the size of the pile top load and the nature of the soil around the pile The Q-S curve shows a slow changing trend.When the load reaches 4900 kN,the strength of three test piles fails to reach the ultimate bearing capacity,resulting in strength failure.The settlement of three piles is 12.24,15.44 and 18.64 mm respectively.Compared with the design requirements and test results,the vertical bearing capacity of single pile meets the design requirements.The research shows that in the loess area,friction pile has higher vertical bearing capacity,uniform and small settlement,and pile foundation can be used for building foundation with larger load in the loess area.