软土地层大型盾构工作井合理支护参数研究

STUDY OF REASONABLE SUPPORT PARAMETER FOR LARGE-SCALE SHIELD SHAFT IN SOFT SOIL AREA

控制超大盾构工作井的变形和结构受力状态是跨江跨海盾构隧道工程设计和施工的技术难点。以南京纬三路过江隧道江北盾构始发工作井为例,通过采用四因素三水平正交试验法进行多因素系统分析,研究环梁厚度、连续墙厚度、内衬墙厚度和支撑截面对盾构工作井支护结构的变形和受力的影响规律,得到各个支护结构之间的相互作用关系,并进行分析;对工程的材料成本进行量化分析,在确保结构安全的基础上,提出材料成本最低的设计方案。研究成果表明:使用正交试验设计方法确定工作井合理的支护参数可以大大减少计算数量,在确保结构安全的前提下获得最优的支护参数组合,达到技术、经济最优的效果。

It is a technical difficulty to control the deformation and the stress condition of the structure of large-scale shield shaft in over-river shield tunnel project.This case study how to deal with the excavation of Jiangbei shield shaft of Weisan Road over-river tunnel at Nanjing City.Use four-factor at three-level orthogonal array experimental design method to proceed multifactor system analysis,studying the effect rule of deformation and stress of the whole support structure caused by the change of the thickness of ring beams,retaining wall,lining wall and bracings.The interaction relationships between each support component are obtained and analyzed;and through the quantification analysis of the total cost,a design scheme of the minimum total material cost is proposed which has been conditional on the security of the whole structure.This study indicates that：using orthogonal experimental design method to decide the reasonable support parameters of the shield shaft can minimize the calculation,obtain the optimal combination of the support parameters with the confirmation of stability,and achieve the best technical and economical result.