双荷载箱自平衡法在超长桩基承载力测试中的应用

Application of Double-load Box Self-balancing Method in Bearing Capacity Test of Super-long Pile Foundation

在黄河中游山西小北干流范围,地下以砂土、粉质黏土层等物理力学指标较低的地层为主。在这种复杂的地质条件下,为保证桥梁桩基承载力和上部结构的安全性要求,设计多采用大直径超长桩为主,施工难度较大,造价较高。双荷载箱自平衡法是指根据试验方案规定,在桩身特定位置依次嵌入两个荷载箱,然后按照加载试验方案对荷载箱进行逐级分段加载,分别得出3段桩身的承载力,可以解决超长桩基试桩试验中的很多问题,为桩长优化设计提供数据支撑,具有广泛的应用前景。

In the middle reaches of the Yellow River,the main stream of Shanxi Province,the underground is mainly composed of sand,silty clay and silty clay layers with low physical and mechanical indexes.In this complex geological condition,in order to ensure the bearing capacity of bridge pile foundation and the safety of superstructure meet the requirements,large-diameter and super-long piles are mainly used in design,which is difficult to construct and expensive.Double-load box self-balancing method refers to embedding two load boxes in a specific position of the pile in turn according to the test scheme,and then loading the load boxes step by step according to the loading test scheme to obtain the bearing capacity of the three sections of the pile respectively.The method can solve many problems in the test of super-long pile foundation,provide data support for the optimal design of pile length,and has a wide application prospect.