摘要
太原地铁2号线盾构隧道采用土压平衡盾构施工方式,盾构区间按照设计需要下穿湖泊穿越富水粉细砂层。为了保证盾构施工安全平稳通过,合理控制土压平衡盾构下穿湖泊的风险源,对风险产生的机理和如何控制风险进行了研究。分析了盾构穿越富水粉细砂层主要风险:含水地层盾构螺旋机喷涌机理,盾构通过后盾尾空隙沉降较大原因,盾尾密封失效风险。针对风险控制提出包括调整渣土改良参数,优化同步注浆配比,对盾构机尾刷改造等措施。工程实践表明,在富水粉细砂层中掘进,将高分子聚合物浓度创新性地提高到10/1000,可以有效控制螺旋机喷涌,降低盾构下穿湖泊时湖底坍塌、湖水倒灌风险;通过将第三道盾尾刷由钢丝尾刷改造为钢板尾刷,有效减小了盾尾刷磨损导致盾尾密封失效风险;优化盾构掘进过程中同步注浆浆液的配比,使其凝固时间由6 h变为4 h,有效控制了盾构通过后的盾尾空隙沉降过大风险,最终湖底监测点测得累计沉降25.33 mm,取得了较好的施工效果。
The earth-pressure balance shield construction method was applied for the shield tunneling of Line 2 of the Taiyuan Metro, and the shield section was designed to cross the water-rich fine silty-sandy layer beneath a lake. To ensure the safe shield tunneling and to control the risk from soil pressure balance, the mechanism of risk generation and controlling were studied. Factors of gushing from water-bearing stratum, the large settlement of shield tunneling through tail-gap of backer, and the failure risk of tail-shield seal were scrutinzed. The countermeasures such as adjusting residue-soil improvement parameters, optimizing synchronous grouting ratio, and reforming shield motor tail brush were recommended. The engineering practice shows that by tunneling in the water-rich fine sandy layer, polymer concentration is innovatively increased to 1%, which effectively controles the spiral jet and reduced the risk of lake bottom collapse and water backflow when tunnelling through below lake. By changing the third shield tail brush from steel wire tail brush to steel plate tail brush, the risk of shield tail seal failure caused by wear of shield tail brush is effectively reduced. The proportion of synchronous grouting slurry in the tunneling process of shield tunneling is optimized, by which the solidification time is shortened from 6 to 4 hours and the clearance settlement of shield tail after the shield tunneling is effectively controlled. In the end, the accumulated settlement of 25.33 mm is measured at the monitoring point at the bottom of the lake, achieving a good construction effect.
作者
闫潇
杨双锁
姜山
YAN Xiao;YANG Shuang-suo;JIANG Shan(Department of Underground Engineering,Taiyuan University of Technology,Taiyuan 030024,China;China Railway No.3 Engineering Group Co.,Ltd.,Taiyuan 030001,China)
出处
《科学技术与工程》
北大核心
2020年第18期7457-7463,共7页
Science Technology and Engineering
基金
国家自然科学基金(U1710111)
山西省重点研发计划(201703D111027)。
关键词
太原地铁
盾构隧道
富水粉细砂
风险分析
施工控制
Taiyuan metro
shield tunnel
water-rich fine silty sand layer
risk analysis
construction control
