基坑支护中桩身刚度对桩顶边坡稳定性的影响

Influence of Deep Excavation Soldier Pile Stiffness on the Stability of Slope above Pile Head

常采用钻孔灌注桩加桩顶放坡的支护方案进行基坑设计,可以达到施工方便、减少工程造价的目的;与天然土坡不同,基坑开挖过程中是对已有土体开挖,存在应力释放过程,其稳定性比对应的天然土坡要低,同时桩顶的位移量大小也对桩顶边坡稳定性产生不利影响。采用有限元软件ABAQUS,通过模拟土方开挖过程中的应力释放过程,调整支护桩的抗弯刚度EI大小,采用强度折减法对桩顶边坡的稳定性进行分析;计算结果表明,桩顶边坡稳定性大小、与支护桩刚度、桩顶位移成正比关系。

In the design of the deep excavation support, the bored cast-in-place reinforced concrete piles with slope are frequently used to facilitate the construction schedule and to reduce project cost. Different from the natural soil slope, the process of the foundation excavation is the removal of the existing soil, and there is a stress release process. The stability is lower than the corresponding natural soil slope with similar slope angle. At the same time, the displacement of the pile head also has a negative impact on the stability of the slope above the pile. The finite element software ABAQUS was used to simulate the stress release process during excavation. The slope stability was investigated by adjusting the bending stiffness EI of the support pile and by using the strength reduction method. The analytical results show that the stability of the slope above the pile head is proportional to the stiffness of the supporting soldier pile and the lateral deflection of the pile head.