框架结构顶进前基坑围护桩合理支护参数研究

Research on reasonable supporting parameters of foundation pit retaining piles before jacking of frame structure

合理的基坑支护参数是保障框架结构顶进下穿作业安全进行的前提。以某箱形框架结构顶进下穿既有铁路为工程背景,以抗倾覆安全系数作为基坑围护桩稳定性定量评价指标,设计四因素四水平共计16组正交试验方案,采用理正深基坑软件,对不同方案下围护桩的稳定性及经济性进行对比研究。研究结果表明:桩径、桩心距、冠梁高度、嵌固深度为影响围护桩安全稳定的四个主控因素;当围护桩桩径为1.0 m,桩心距为1.5 m,嵌固深度为8.0 m,冠梁高度为1.5 m时,基坑围护桩抗倾覆安全系数满足要求,同时经济效益最优。

Reasonable foundation pit support parameters are the prerequisites for ensuring the safe progress of the jacking and lowering operation of the frame structure.Taking a box-shaped frame structure under the existing railway as the engineering background,and using the anti-overturning safety factor as the quantitative evaluation index of the stability of the foundation pit retaining piles,a total of 16 sets of orthogonal test plans with four factors and four levels were designed.Deep foundation pit software,a comparative study on the stability and economy of retaining piles under different schemes.The results show that pile diameter,pile core distance,crown beam height and embedding depth are the four main control factors that affect the safety and stability of the enclosing pile,when the enclosing pile diameter is 1.0 m,the pile core distance is 1.5 m,and the embedding depth is 8.0 m,when the height of the crown beam is 1.5 m,the anti-overturning safety factor of the foundation pit retaining pile meets the requirements,and the economic benefit is optimal.