土压平衡盾构斜切大直径主筋桩群施工技术

针对盾构直接切削大直径主筋桩群的工程难题，以广州地铁12号线官洲站—大学城北站区间工程为例，开展盾构直接切削桩径1 200mm、主筋直径25 mm和28 mm桩群的实践研究，分析盾构施工关键措施、切桩效果。实践表明：滚刀和撕裂刀搭配的刀具配置具备切削主筋直径25 mm和28 mm混凝土桩基的能力；镶齿滚刀难以直接切断钢筋，撕裂刀二次作用时对钢筋的剪切作用力可将滚刀切口位置切断；采用“低推速、高转速、稳扭矩”方式掘进可有效切断桩体及钢筋；采用分体式液压钢筋剪可较好处理盾构仓内缠绕钢筋。

Earth Pressure Balance Shield Construction Technique for Angled Cuttingof Large-Diameter Reinforced Pile Groups

This study examines shield direct cutting techniques on large-diameter piles within the construction project linkingGuanzhou Station to University Town North Station on the Guangzhou Metro Line 12. Focusing on piles with diameters of 1,200 mm and reinforcing bars with diameters of 25 mm and 28 mm, the research evaluates the efficacy of critical measures andthe resultant quality of pile cutting within shield construction. Findings indicate that a cutter head configuration, incorporatinga hob and a tearing knife, successfully penetrates concrete pile foundations containing rebar of the specified diameters.However, a challenge arises when a toothed hob attempts to sever the reinforcing bar directly. It is observed that the tearingknife’s secondary action exerts adequate shear force to dissect the reinforcement at the pre-cut location by the hob.Furthermore, employing a boring strategy characterized by a low advancement rate, high rotation speed, and consistent torquehas proven to enhance the cutting process for both the pile body and its embedded steel bars. Additionally, the use of splithydraulic rebar shears delivers an improved response to the complications presented by intertwined steel bars within the shieldmachine’s path.