On Mechanical Response of Excavation Unloading and Support Evaluation of Diversion Tunnel in Complex Environment
Based on the case of Qingshui Tunnel of Tiegang-Shiyan Reservoir in Shenzhen,a three-dimensional ex-cavation model of diversion tunnel is established,and the mechanical response laws of different surrounding rock sections are compared and analyzed,and the support effect is evaluated.The results show that when excavating without support,the vertical stress and displacement of the initial excavation face rapidly increase and then tend to be stable after excavation,and the plastic zone is about 1.8 times the diameter of the tunnel.The vertical stress along the axis section is released greatly near the palm face,and the displacement curve converges near the palm face while the plastic zone is about 1 time the diameter of the hole.During support excavation,the interac-tion between surrounding rock and support structure reduces the stress and displacement of the initial excavation surface to a large extent,with a maximum decrease of 34％and 79％respectively.The stress and displacement a-long the axis section are reduced by 55.0％and 71.1％respectively,and the plastic zone is basically eliminated except for a small amount of distribution in Class Ⅲ surrounding rock zone.The research results are consistent with engineering data and can provide reference for similar tunnel design and construction.
万方数据
维普
