基坑开挖时立柱桩的沉降计算

在基坑工程中，立柱桩和工程桩形成了长短桩复合桩基础。通过有限元法模拟桩侧摩阻力分布的变化，认为在这种复合桩基础中短桩（工程桩）的存在会影响到长桩（立柱桩）桩侧摩阻力的分布。根据剪切位移法得到考虑短桩影响的计算方法，并将被影响后的长桩桩侧摩阻力分布形式做了等量简化，使之适用于Geddes应力法。提出了利用Geddes应力法计算长短桩复合桩基础沉降的方法，并编制了相应的计算程序PLS，根据实际工程资料进行验算的结果与实测数据基本一致。

Calculation of upright post pile deformation in processes of foundation excavation

In foundation excavating, upright post piles and engineering piles form a long -short pile composite foundation. According to the variation of shaft resistance around piles simulated by software ANSYS, we regard that short piles(engineering piles) will affect shaft resistance distribution around long piles(upright post piles). Based on shear displacement method，calculation formula for short piles’ influence is obtained. The affected shaft resistance distribution around a long pile is simplified at equal value, thus it can suit Geddes-stress theory. A new settlement calculation method of the long- short pile composite foundation is advanced; and a program PLS for settlement calculation of the upright piles is written. The calculation results accord with the engineering practice basically.