考虑空间协同效应的排桩斜撑支护体系分段拆撑法研究

Design of removing diagonal brace in sub region considering coordinating role of space support systems

与水平内支撑比较,排桩斜撑支护体系用于深大基坑开挖时具有诸多优越性。但关于斜撑拆除的研究相对滞后,使该支撑形式的利用受到一定的限制。内支撑的拆除多采用"先撑后拆"方案,文中从排桩斜撑支护体系的协同变形理论出发,提出了分区分段"先拆后撑"的思路;利用最小势能解,推导了该类支护体系在分段拆撑过程中,拆撑区段长度的计算方法;并结合具体工程实例,对该计算理论和结果加以验证。通过研究,冠梁弯矩、排桩弯矩和位移是决定分段长度的主要因素,并提出了该类支护体系的全过程优化设计的概念,可为今后该类支护体系的拆撑设计和施工提供依据和借鉴。

Comparing with horizontal support,the bracing systems of pile and oblique bracing have obvious advantages in big and deep foundation pit.Because the study about the removal of diagonal bracing is rare,the use of this system is limited.The accustomed removal method of the internal supporting is supporting followed removing.Based on the coordinating role of space support systems,according to the minimum potential result,the removing design thinking of supporting followed removing in several sub region and sections is proposed;and the calculation method of the length of sub region is derived.Finally,the feasibility and rationality of the proposed method are verified by the practical engineering.Acoording to the research,the top beam moment and the moment and displacement of the pile are the key factors which decide the length of the sub sections.The concept of the overall process design is came up.All of these can provide reference for this design and construction.