软黏土条件下地下水位变化对桥梁桩基的影响分析

以京沪高铁DK119~DK123段桥梁桩基工程为依托，运用PLAXIS建立桩土模型，分析地下水位的变化引起地面沉降对桥梁桩基工程的影响，最终得到地下水位降幅的警戒值、临界值及地面沉降量与桥梁桩基础沉降量的关系式。研究结果表明:由于软黏土具有蠕变性，地面的沉降具有滞后性；地下水位的下降不仅使桥梁桩基础的中性点下移，也使最大负摩阻力的位置下移；大幅度降低地下水位，对桥梁桩基承载力削弱作用明显。

Analysis on the Influence of Groundwater Level Change to Bridge Pile Foundation under Condition of Soft Clay

The pile soil model is established with PLAXIS based on the bridge pile foundation project of DK119~DK123 section of Beijing-Shanghai High-Speed Railway to analyze the influence of ground settlement aroused by the change of groundwater level to the bridge pile foundation project and finally get the relationship between the warning value and critical value of groundwater level downrange and ground settlement and the settlement of bridge pile foundation. The results show that the ground settlement is lagging due to the creep of soft clay. The decrease of groundwater level not only makes the neutral point of bridge pile foundation but also the position of maximum negative friction move down. Sharp decrease of groundwater level could significantly weaken the bearing capacity of bridge pile foundation.