基于结构应力法的盾构刀盘安装焊缝抗疲劳设计  

Anti-Fatigue Design of Field Welds of Shield Cutterheads Based on Structural Stress Method

作　　者：王德福 WANG Defu(China Railway 14th Bureau Group Big Shield Engineering Co.,Ltd.,Nanjing 211899,Jiangsu,China)

机构地区：[1]中铁十四局集团大盾构工程有限公司,江苏南京211899

出　　处：《隧道建设（中英文）》2024年第6期1313-1319,共7页Tunnel Construction

摘　　要：为提升超大直径盾构刀盘安装焊缝在盾构施工过程中的抗疲劳性能,首先建立包括超厚钢板对接接头焊缝细节的有限元模型,以等效结构应力为核心参量将焊缝应力集中考虑在焊趾应力之中,然后对不同坡口角度和余高的接头疲劳寿命进行计算,得出坡口角度和余高对超厚钢板焊缝接头疲劳寿命的影响规律,最后以优选的焊缝接头尺寸参数采用子模型技术建立包括各焊缝接头局部精细网格的子模型,利用等效结构应力法对刀盘整体安装焊缝疲劳寿命进行综合评估。研究发现:1)随着焊缝坡口角度的增大,其抗疲劳能力呈现先增大后减少的趋势,55°左右的坡口角度是设计对称X型接头的最优坡口角度;2)当接头采用不对称X型坡口时,焊缝小端处焊趾的疲劳寿命低于同等坡口角度大端处焊趾的疲劳寿命,坡口大端和小端的坡口角度分别选取为40°和55°时,能综合提高非对称X型坡口接头的抗疲劳性能;3)焊缝余高对接头疲劳性能的影响不如坡口角度显著,对称X型坡口焊缝及非对称X型坡口大端焊缝余高e=2~3 mm,非对称X型坡口小端焊缝余高e=1 mm,可以满足盾构刀盘的抗疲劳设计要求。The fatigue resistance of field welds on the cutterhead of super-large-diameter shields is critical for shield tunneling.In this study,a finite element model of a super-thick steel butt joint,including the weld details,is established,with the weld stress concentrated into the toe stress and core parameter representing the equivalent structural stress.The multi-axis fatigue life of a joint with different groove angles and residual heights is then calculated to determine the influence of the groove angle and residual height on the fatigue life of super-thick plate welds.Finally,a sub-model,including a local fine mesh of welds,is established using sub-model technology based on the optimal dimension parameters of the welds.The fatigue lives of the welds installed by the cutterhead are comprehensively evaluated using an equivalent structural stress method.The results are summarized as follows.(1)The fatigue resistance initially increases and then decreases with increasing weld groove angle,and a groove angle of approximately 55°is the optimum for designing symmetrical X-shaped joints.(2)When the joint adopts an asymmetric X-groove,the fatigue life of the toe at the small end of the weld is lower than that at the big end of the same groove angle,and the fatigue resistance of the asymmetric X-groove joint can be improved by selecting 40°and 55°at the big and small ends,respectively.(3)The influence of the weld residual height on the fatigue performance of the joint is not as significant as that of the groove angle.The residual height of the symmetrical and asymmetric X-groove welds at the big end is 2-3 mm,and the residual height of the asymmetric X-groove at the small end is 1 mm,which meets the anti-fatigue design requirements of the shield cutterhead.

关 键 词：大直径盾构 刀盘 焊缝抗疲劳设计 等效结构应力 主S-N曲线 

分 类 号：U45[建筑科学—桥梁与隧道工程]