桩周土开挖状态带侧向支撑桩稳定性数值分析

Numerical analysis of pile foundation stability with lateral support under excavation condition of soil around pile

在既有建筑物增设地下空间,需要托换桩支撑上部结构,而随着土方的开挖,桩的稳定性会降低,采用桩身设置侧向支撑是提高桩稳定性的有效方法。文章采用ANSYS软件建立二维有限元模型,分析土方开挖条件下带侧向支撑桩稳定性的变化规律。结果表明:在与桩周土开挖值的比值为0.5倍位置处加设一道支撑时,桩屈曲极限荷载和支撑内力达到最大;桩屈曲极限荷载和支撑内力随着支撑刚度的增加而增大,但当刚度增加到一定数值,荷载值和内力值的增幅不明显;随着支撑数量的增加,桩屈曲极限荷载值逐渐变大,但提高的幅度逐渐降低。

In the existing building,additional underground space is required,and the pile supporting the upper structure is required to excavate the soil below.With the excavation of the earthwork,the stability of the pile will be reduced,and the lateral support of the pile body is an effective method to improve the stability.This paper uses ANSYS to establish a two-dimensional finite element model to analyze the variation of the stability of laterally supported piles under excavation conditions.The results show that the pile buckling ultimate load and the supporting internal force reach the maximum when a support is added at a ratio of 0.5 times the excavation value of the pile surrounding soil.The pile buckling ultimate load and the supporting internal force increase with the increase of the support stiffness.When the stiffness increases to a certain value,the increase of the load value and the internal force value is not obvious.With the increase of the support quantity,the ultimate buckling load value of the pile gradually increases,but the increase range gradually decreases.