黄土区深大基坑开挖变形预测及邻近既有地铁隧道安全性分析  

Deformation prediction of deep and large foundation pit excavation in loess area and safety analysis of adjacent existing subway tunnel

作　　者：刘义 朱武卫 杨焜 席宇 李哲[2] 王宝玉 杨晓 LIU Yi;ZHU Wuwei;YANG Kun;XI Yu;LI Zhe;WANG Baoyu;YANG Xiao(Shaanxi Architecture Science Research Institute Co.,Ltd.,Xi'an 710082,China;School of Highway,Chang’an University,Xi'an 710064,China)

机构地区：[1]陕西省建筑科学研究院有限公司,陕西西安710082 [2]长安大学公路学院,陕西西安710064

出　　处：《四川建筑科学研究》2021年第5期61-70,共10页Sichuan Building Science

基　　金：陕西省科学技术厅重点研发计划项目(2021SF-459);陕西省住房城乡建设科技科研开发计划项目(2019-K27);陕西省科技统筹创新工程计划项目(2016KTZDSF04-4);陕西省建筑科学研究院有限公司科研项目(2020-10-331)。

摘　　要：西安火车站北广场基坑项目具有面积大、开挖深、地下水位高和支护措施复杂的特点,且为特殊的"坑中坑"形式。本文建立了该基坑的三维有限元模型,并进行了开挖模拟,且结合前期施工监测数据对模型的有效性加以了验证。结果表明:模拟结果与实际情况吻合较好。外坑支护桩在后续的内坑开挖过程中仍将产生较大的变形增长,基坑开挖完成后其最大水平位移达到28.96 mm,采用桩撑支护的内坑支护桩变形则较小,最大水平位移为9.27 mm。基坑开挖过程中,邻近地铁隧道的变形符合城市轨道交通结构的安全控制要求,但存在着隧道轴向变形差较大、隧道在侧方及上方基坑开挖时变形趋势相异的特点。本文根据隧道在基坑开挖过程中的变形规律,提出了相应的施工措施。The North Square foundation pit of Xi’an Railway Station has the characteristics of large area,deep excavation,high groundwater level and complex supporting measures,and there is also a special"pit in pit"form.The three-dimensional finite element model of the foundation pit was established for excavation simulation,and the effectiveness of the model was verified by combining with the pre-construction monitoring data.The results show that the simulation results are in good agreement with the actual situation.The supporting piles of the outer pit will still produce large deformation growth during the subsequent excavation of the inner pit,the maximum horizontal displacement of the supporting piles of the outer pit will reach 28.96 mm after the excavation is completed.The deformation of the supporting piles in the inner pit is small,and the maximum horizontal displacement is 9.27 mm.The deformation of the adjacent subway tunnel during the excavation of the foundation pit meets the safety control requirements,but there are characteristics in that the axial deformation difference of the tunnel is large,and the deformation trend of the tunnel is opposite when the side and above the foundation pit is excavated.According to the deformation law of the tunnel during the excavation of the foundation pit,corresponding improvement measures are proposed in this paper.

关 键 词：坑中坑 邻近既有地铁隧道 开挖模拟 支护桩变形 隧道变形 

分 类 号：TU753[建筑科学—建筑技术科学]