隧洞施工期有限元仿真分析

Analysis of tunnel in the construction period based on finite element simulation

利用ANSYS APDL参数化有限元分析技术和生死单元技术,对西藏高海拔地区某一工程的引水隧洞施工期进行有限元仿真计算,基于岩石力学方法的围岩——结构模型对初期支护方案进行内力和变形的分析计算,同时得出了围岩开挖后的应力状态、塑性区大小和洞周变形等,从而可判断初期支护参数的选择是否合理。结果表明:1开挖初期支护后在围岩应力的作用下,发生了指向临空面的位移,最大位移发生在底板,值为4.601 mm,方向铅直向上,洞周的收敛位移都不大,围岩在施工中是稳定的;2最大应力值出现在底板两侧的边角位置,顶拱的拱铰处发生应力集中;3应力应变符合施工期隧洞工程的一般规律。

A simulation of a hydraulic tunnel during the construction period in high altitude area of Tibet has been designed with ANSYS APDL based on the parameterized finite element analysis tech-nique and the technology of ＂element birth and death＂.The stress -strain status,the deformation value ,and the distribution of plastic zone were obtained from the result of the calculation and analy-sis on the internal force and deformation of the initial supporting scheme in the structure -rock mod-el under the main theory of rock mechanics .The results provided proof to make sure the scheme if is rational.The results show that：①After initial supporting,it would produce the displacement which pointed to the empty face; the maximum vertical displacement was 4 .601 mm at the bottom of the tunnel and the ultimate convergence displacements of surrounding rock is not large .The rock was stable during the construction;②The biggest stress was at the corners of the bottom board ,and stres-ses concentration occurred on the arch hinge;③The results accorded with the general rule of stress -strain of tunnel project basically .