自平衡试桩法在沿海软弱地层中的试验研究

以浙江舟山大陆连岛工程宁波连接线项目为依托,选择1根典型摩擦桩开展了自平衡试桩法在沿海软弱地层中的试验研究,并对自平衡测试后的试桩进行了传统桩顶堆载验证试验。介绍了自平衡试桩法从设计、现场试验及数据分析的全过程及各阶段的设计要点,并对容易引起测量误差的现有位移测量方法进行了改进,避免了易发缺陷的荷载箱处虚位移的影响。试验测得了试桩的负摩阻力系数值及单桩承载力值,其结果符合试验设计要求,试桩承载力满足设计要求,相关试验设计及测得的参数可以作为此类地层中自平衡测试的参考。经与传统桩顶堆载验证试验对比可知,自平衡试桩法在工程上的应用具有合理性与准确性。

Experimental study on self-balanced test method in soft strata in the coastal area

Based on the connecting line project of Zhoushan Island-Mainland Link Project, the experiment of a friction pile was developed to study the application of self-balanced test method in soft strata,and it was verified with the traditional piling-up weights method. The paper introduced the whole process and design points of the method in design, field test and data analysis stage. And an improved method for the use to measure the displacements of the upper and lower shaft was put forword. This new method can avoid the influence of the latent concrete defect in the cell position. The coefficient of negative skin friction in soft strata and the bearing capacity of the test pile was also measured in the experiment. The test results fit the designed requirements, while the bearing capacity of the test pile also meet the designed requirements. This design and the coefficient can be a reference for the soft strata, and the self-balanced test method has its rationality and accuracy in engineering application.