Three-dimensional Finite Element Study of Tunnel Advancing to Adjacent Perpendicularly Crossing Tunnel

DOI：

 作者 单位 赵俞成1?覮，艾兵兵2，刘东2，宋强2，冯伟3，艾志伟3 （1. 浙江大学 滨海和城市岩土工程研究中心，浙江 杭州 310058； 2. 中铁二局集团有限公司 杭州地铁项目经理部，浙江 杭州 310058； 3. 杭州市地铁集团有限责任公司，浙江 杭州 310058）

为研究隧道施工顺序对隧道开挖的影响，采用三维有限元分析方法模拟某垂直穿越隧道的开挖过程. 基于砂土的亚塑性本构模型并考虑土体的小应变刚度，分析施工顺序对垂直交叉隧道的影响，研究对既有隧道附近土体的应力传递机制. 研究结果表明：与无既有隧道工况相比，既有隧道的存在使得最大沉降量降低14%；新建隧道在既有隧道上方时，地表沉降较大，但影响范围小，当掌子面接近既有隧道中心线时，既有隧道的应力由拱顶传递至拱肩；当掌子面距离既有隧道中心线后方3D和前方6D之间时，应力释放对既有隧道的影响显著；新建隧道在既有隧道下方时，既有隧道产生的变形和弯矩更大；在垂直交叉隧道施工中，应充分考虑施工顺序对地表沉降、既有隧道的影响.

In this study，a three-dimensional finite element analysis method was used to simulate tunnel excavation nearby a perpendicularly crossing existing tunnel，in order to investigate the effects of construction sequences on cross-cutting tunnels. The hypoplastic constitutive model of sand and soil is adopted and the soil small-strain stiffness is considered in the numerical analysis，so as to study the effect of construction sequences on cross-cutting tunnels as well as the stress transfer mechanism of the soil near the existing tunnel. The results show that the existence of the existing tunnel reduces the maximum settlement by 14% when compared with the condition without the existing tunnel; when the new tunnel is above the existing tunnel，the settlement is larger，but the impact range is smaller. When the tunnel face approaches the centerline of the existing tunnel，the stress of the existing tunnel is transferred from the vault to the abutment；when the tunnel face is between 3D behind and 6D in front of the centerline of the existing tunnel，the effect of stress relief on the existing tunnel is significant; when the new tunnel is under the existing tunnel，the deformation and bending moment of the existing tunnel are greater. In the construction of vertical cross tunnels，the impact of the construction sequence on the ground settlement and the existing tunnel should be considered comprehensively.