连拱隧道双向施工力学行为特征研究

Characteristics of mechanical behavior of two-way construction of multi arch tunnel

为研究连拱隧道双向单洞开挖施工过程中的力学行为特征,以湖南省安慈高速雷家台连拱隧道为研究对象,采用有限元软件Midas GTS/NX建立三维数值模型,模拟连拱隧道双向单洞开挖过程与传统工况下的单向双洞开挖过程,对比分析连拱隧道中隔墙的应力应变、隧道围岩压力及围岩位移。研究结果表明:双向单洞开挖工期约为单向双洞开挖工期的2/3;双向单洞开挖与传统工法的单向双洞开挖所产生的隧道围岩压力和围岩位移在数值上相差不大;施工结束后,两种施工方案的中隔墙应力大小相差无几,但在施工过程中,双向单洞开挖时中隔墙会产生扭矩力,应对中隔墙抗扭做出相应的有效支护;双向单洞开挖时中隔墙的两端均出现向开挖段横向偏移的情况,在后续中隔墙的优化中应着重考虑。

To study the characteristics of mechanical behavior of the multi-arch tunnel in the process of two-way single-hole excavation,the Leijiatai multi-arch tunnel of Anxiang-Cili Expressway in Hunan Province is taken as the engineering background.A three-dimensional numerical model is established by using the finite element software Midas GTS/NX.The stress and strain of the middle partition wall,surrounding rock pressure,and surrounding rock displacement are analyzed by comparing the actual two-way single-hole excavation process with the traditional one-way double-hole excavation process.The results show that the construction period of two-way single-hole excavation is about 2/3 times that of normal excavation.The two-way single-hole excavation scheme and the normal excavation scheme do not produce largely different surrounding rock pressure and surrounding rock displacement in values.After the construction,the stress of the middle partition wall in the two schemes is almost the same.However,during the construction process,the two-way single-hole excavation causes torque force in the middle partition wall.Thus,corresponding effective support should be made for the torsion resistance in the two-way single-hole excavation scheme.In the two-way single-hole excavation,both ends of the middle partition wall have lateral offset to the excavated section,which should be considered in the design optimization of middle partition wall in the future.