摘要
以西安砂卵石和黄土地层中地铁施工为依托,采用数值分析方法和原位监测等手段,针对"先隧后井"法横通道施工期间横通道的开挖方法、地层和既有盾构管片的预加固方案,进行优化分析和评价。结果表明,(1)增加风井横通道的开挖层数会引起地表沉降增大和施工作业空间不足问题,建议采用4层台阶、预留核心土法开挖,上、下台阶长度不宜超过3m;(2)风井横通道外侧砂卵石、黄土地层的注浆厚度不低于2.0 m,加固后地层弹性模量应提高至少0.2倍以上,应配合超前小导管和大管棚超前预支护措施,可以增强横通道开挖期间地层的稳定性和临近盾构管片的安全性;(3)既有管盾构片破除前应放松横通道两侧4~6环管片的联结螺栓,降低横通道开挖引起的盾构管片纵向挤压应力集中效应;(4)横通道垂直穿过既有盾构管片时应采取静力破除法,从上至下垂直分块拆除管片,再进行横通道与盾构区间隧道接口部位混凝土浇筑和钢筋植入施工,并针对接口范围内地层进行WSS注浆加固,进行接头防渗处理。
The subway construction in sandy cobble and loess layers in Xi'an is selected as the background.Applying numerical methods,in-situ monitoring and other means,,in view of the excavation methods during the construction of cross passage by tunneling and back well method,the pre-reinforcement schemes of existing shield pipe segment is proposed,optimized analyzed and evaluated.The results show that the increase of excavation layers will result in the surface settlement and the shortage of construction work space.It is suggested to use the 4 steps,and the core soil method is reserved for excavation.The length of the upper and lower steps should not exceed 3 m.The grouting thickness of the gravel and loess stratum from outside of the cross passage is at least 2.0 m,and the elastic modulus of the stratum should be increased by more than 0.2 times after the reinforcement.The advanced support methods of small and large pipe sheds can be used to enhance the excavation stability of the stratum and the safety of the shield tunnel segments.Before the existing pipe shield segment is broken,the connecting bolts of 4 to 6 ring segments on both sides of the transverse channel should be loosened to reduce the effect of longitudinal compression stress concentration of the shield segment caused by the excavation of the transverse channel.When the horizontal cross passage passes through the existing shield segment,the static breaking method should be adopted to remove the segment vertically from top to bottom.Then the concrete pouring and reinforcement implantation should be carried out at the interface between the air shaft cross passage and the shield segment.The WSS grouting should be used to reinforce the soil stratum and implement the anti-seepage treatment at the joint.
作者
朱才辉
兰开江
段宇
贺红
ZHU Cai-hui;LAN Kai-jiang;DUAN Yu;HE Hong(State Key Laboratory of Eco-hydraulics in Northwest Arid Region,Xi'an University of Technology,Xi'an,Shaanxi 710048,China;Institute of Geotechnical Engineering,Xi'an University of Technology,Xi'an,Shaanxi,710048,P.R.China;China Railway City Development and Investment Group Co.,Ltd.,Xi'an,Shaanxi 710013,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2020年第S01期379-386,共8页
Rock and Soil Mechanics
基金
西安理工大学省部共建西北旱区生态水利国家重点实验室(No.2019KJCXTD-12)
国家自然科学基金项目(No.51678484)
国家留学基金委项目(No.201808610061)
关键词
先隧后井法
西安地铁
盾构管片
施工技术
力学响应
tunnel first then well method
Xi’an subway
shield lining segments
construction technology
mechanical response
