近距离侧邻既有结构砂层隧道开挖面失稳极限平衡分析

Analysis of Lim it Equilibrium of Excavation Face of Adjacent Existing Structures Sand Tunnel

随着城市化进程的推进,地下空间的开发利用是缓解交通拥堵、拓展城市空间的有效途径。地下空间中侧邻既有结构的施工具有高风险性,施工过程中带来的开挖面稳定性问题不容忽视。因此,以北京地铁3号线朝石联络线隧道暗挖工程为背景,采取数值模拟与相似模型试验的方式,探究了侧邻既有结构条件下砂层隧道开挖面失稳破坏特征。考虑不对称破裂角的隧道开挖面破坏特点,基于太沙基松动土理论,改进了传统模型中侧土压力系数和上部剪切带破裂角,提出了不对称开挖面失稳极限平衡分析模型,并推导出了上覆松动土压力与假想支护力计算公式。该研究成果和方法可为同等条件下侧邻既有结构暗挖隧道开挖面土体稳定性分析与加固设计提供参考。

With the advancement of urbanization,the development and utilization of underground space is an effective way to alleviate traffic congestion and expand urban space.The construction of adjacent structures of underground space has high risks.And the stability of excavation surfaces caused by the construction process isn't ignored.Therefore,taking the underground excavation project of the Chao-Shi Connection Line Tunnel of Beijing Metro Line 3 as an example,numerical simulation and similar model experiments were adopted to explore the instability and failure characteristics of the excavation face of the sand layer tunnel with the adjacent existing structural conditions.Considering the characteristics of tunnel excavation face failure with asymmetric rupture angle,based on the Terzaghi loose soil theory,the lateral soil pressure coefficient and upper shear band rupture angle of the traditional model were improved to propose a limit equilibrium analysis model,and derive the calculation formulas for overlying loose soil pressure and hypothetical support force.The research results and methods can provide reference for the stability analysis and reinforcement design of soil in the same conditions.