【摘要】 地铁域城市地块开发不可避免地涉及到对既有城市轨道交通设施的影响与保护问题。但是,不同地区工程地质条件不同,呼和浩特地区深基坑开挖侧向卸荷诱发既有盾构隧道结构的影响与变形控制缺乏成功的工程经验。以新建振华购物中心项目基坑工程近邻呼和浩特市城市轨道交通2号线为背景,采用精细化的三维数值模拟方法,结合工程经验以及理论分析方法,针对深基坑开挖侧向卸荷条件下既有盾构隧道的影响进行研究。主要得到以下结论:①随着基坑向下开挖,盾构管片横向位移逐渐增大,基坑开挖完毕位移最大值为2.9 mm,临近基坑一侧的管片水平侧位移最大;②基坑施工引起2号线盾构区间的各项变形指标,均在安全控制要求范围内;③基坑开挖后侧向卸载影响较小,经检算,隧道结构的受力状态基本未改变,隧道主要呈压弯受力。隧道管片结构配筋满足正常使用极限状态要求。预期研究成果对内蒙古城市轨道交通的保护具有重要的工程实用价值。更多还原

【Abstract】 The development of urban land plots in the Metro region inevitably involves the impact and protection of the existing urban rail transit facilities.Different regions in China have different geological conditions, and there are no such successful engineering experiences in the influence and deformation control of existing shield tunnel structures resulting from the lateral unloading behavior induced by excavation of deep foundation pit excavation in Hohehot area.Based on the background of the newly-built Zhenhua Shopping Center project near the basement of Hohhot Urban Rail Transit Line 2, three-dimensional numerical simulation, engineering experience, and theoretical analysis method were used to study the influence of the shield tunnel caused by the lateral unloading of deep foundation pit excavation.The main conclusions are as follows: Firstly, the lateral displacement of the shield segment increased gradually with the excavation of the foundation pit, and the maximum displacement occurring near the side of foundation pit was approximately 2.9 mm in the end of the excavation of the foundation pit.Secondly, the deformation indexes of the existing 2 rd Metro Line induced by construction of the adjacent foundation pit did not exceed the scope of safety control requirements.The lateral unloading effect caused by the excavation of the foundation pit was smaller, and the stress state of the tunnel structure mainly subjected to compressing and bending mechanical behavior is basically unchanged.Thus the tunnel segment structure reinforcement meets the requirements of the normal use limit state.It is expected that the research results will have important engineering practical value for the protection of urban rail transit in Inner Mongolia.更多还原