桩基础与临近地铁隧道施工相互影响研究

The Interaction between the Pile Foundation and the Adjacent Subway Tunnel Construction

地铁保护区内进行桩基础施工具有施工隐蔽且对地下空间扰动较大的特点,摸清其相互影响规律对保证地铁及临近建筑物的安全具有重要意义。针对深圳地区某临近地铁隧道的桩基础工程,采用有限元分析软件建立三维数值模型,对桩基础施工、建筑加载对隧道的影响以及隧道施工对桩基础的影响两种情况进行分析。研究表明,若隧道结构先施工完成,桩基础施工以及建筑加载后续对隧道的影响主要是附加应力引起的隧道岩土体竖向变形;若桩基础施工及建筑建成投产使用在先,后续隧道施工应力卸载以及可能引发的地下水位下降会使桩基础及建筑物产生竖向为主的变形,且竖向变形主要发生于地下水下降阶段;经计算分析本项目桩基础与临近地铁隧道施工对彼此的影响均在设计、权属单位以及规范允许范围内,但施工期间应做好监测及动态化施工相关工作。

The installation of piles in subway protection areas has the characteristics of concealed construction,and the significant disturbance to the underground space.Therefore,the interaction between the pile foundation and adjacent subway tunnels is significant and complex.Understanding this interaction is of great significance to the safety of subways and adjacent buildings.A pile installation project near a subway tunnel in Shenzhen case history is presented in this project.A threedimensional numerical model is established using finite element analysis software to analyze the effects of the pile installation,building loading on the tunnel,and tunnel construction on the pile performance of this project.Results indicate that if the tunnel structure is constructed first,the impact of pile installation and building loading on the tunnel is mainly due to the vertical deformation of the tunnel rock mass and the soil caused by the additional stress;If the piles the building are constructed first,the subsequent tunnel construction stress unloading and possible groundwater level drop will cause the vertical deformation of the pile and the building.The vertical deformation mainly occurs during the groundwater drop stage;After the analysis,the impact of the pile and the adjacent subway tunnel construction on each other is within the allowable range of different stake holder and design specifications.However,the real-time monitoring during the construction has a great importance to the safety during the construction and operation.