基于吊脚桩支护土岩二元深基坑的勘察与设计要点探析

Dicussion about Investigation and Design of Soil-Rock Duality Deep Foundation Pit Supported by Hanging Foot Piles

随着基坑开挖深度的不断增加,由土层和岩层共同组成开挖面的基坑越来越多,对于该类基坑的支护可采用桩脚仅嵌入下部强度较高且稳定的岩层而无需深入基坑坑底的吊脚桩支护方式,采用吊脚桩可以降低成桩难度,缩短工期,减少投资而受到工程界的欢迎。但目前对于吊脚桩在勘察设计中存在很多误区而易引发基坑破坏甚至失稳,通过对吊脚桩支护形式的基坑工程中勘察和设计现状进行分析,指出了该类基坑工程勘察设计要点,提出了按土岩相互影响的方法对吊脚桩支护体系稳定性进行验算。

With the continuous increase of the excavation depth of foundation pits,more and more foundation pits composed of soil and rock layers are used for the excavation surface.For the support of such foundation pits,the pile feet can only be embedded in the higher strength and the stable rock layer at the lower part,does not need to go deep into the foundation pit to support the hanging pile.The use of hanging piles can reduce the difficulty of pile formation,shorten the construction period,and reduce the investment and is welcomed by the engineering community.However,at present,there are many misunderstandings in the survey and design of the hanging foot pile,which may easily cause the foundation pit to be damaged or even unstable.By analyzing the current status of survey and design in foundation pit engineering in the form of hanging foot pile support,the main points of survey and design of this type of foundation pit engineering are pointed out.The influence method is used to check the stability of the supporting system of hanging piles.