带帽单桩工作特性现场试验分析
In-situ experimental study on the field performance of single pile with cap

以杭甬铁路客运专线上虞北站带帽单桩现场静载试验为基础，对比分析置于不同持力层上的带帽单桩的荷载~沉降特性，探讨带帽单桩荷载传递与分担规律及其影响因素。试验结果表明：选择良好的桩端持力层可以显著提高带帽单桩的沉降控制效果；桩帽下土体分担荷载随桩帽荷载的增加而增加，且桩端土层越差，桩帽分担的荷载越多而且地基应力分布差异越大；桩帽的存在，削弱了桩身上部桩侧摩阻力，其影响范围约为5~6倍的桩帽宽度。
This paper presented the results of axial loading tests on two single capped piles located in different bearing strata. The piles were built on Shangyu North Station in the Hangzhou-Ningbo high-speed railway for the reinforcement treatment of deep soft soil. Based on test data, load settlement characteristics and load sharing of single piles with cap located in different bearing strata were compared. The results are as follows: good pile bearing layer can significantly reduce the settlement of pile top and improve settlement control effect; the load sharing ratio of cap-soil contact pressure increases with increasing total load. The more load pile caps share, and the greater difference of foundation stress distribution is, the worse is the bearing layer; the pile cap makes friction resistance of the upper pile shaft about 5~6 times width of the pile cap weak