官地地下尾水岔洞开挖与衬砌稳定研究  

Stability Study on Excavation and Lining Structure of Guandi Tailrace Bifurcation Tunnel

作　　者：林鹏[1] 周雅能[1] 李子昌[1] 王仁坤[2] 周维垣[1] 

机构地区：[1]水沙科学与水利水电工程国家重点实验室(清华大学),北京100084 [2]中国水电工程顾问集团公司成都勘测设计院,成都610072

出　　处：《地下空间与工程学报》2010年第2期283-289,共7页Chinese Journal of Underground Space and Engineering

基　　金：国家自然科学基金资助项目(10772095);国家科技十一五支撑计划项目(042601001);国家基金委优秀国家重点实验室研究项目(50823005)

摘　　要：水利工程中地下大跨度尾水岔洞往往在结合交叉处形成复杂的三维空间结构,该部位受力性质复杂,位移较大,应力集中,一般需对其进行精细的三维数值模拟,分析开挖与衬砌结构的稳定性。文章利用FLAC3D,计算分析了官地水电站尾水岔洞围岩在开挖情况下的变形、应力及屈服区,对不同应力释放荷载条件下的喷锚支护效果及机理进行了分析评价;在此基础上根据运行和检修工况下的荷载作用情况,计算分析了衬砌结构应力,以及围岩锚杆的受力状态。指出控制作用工况,提出了保持岔洞稳定的措施和对策。计算分析表明:围岩开挖变形量较大,顶拱最大下沉约23 mm,边墙应力释放明显,最大拉应力约3.8 MPa,衬砌最大拉应力在2.0-2.6 MPa之间,岔角处岩体塑性区局部贯通,设计喷锚支护措施处于正常承载状态,支护措施能够满足围岩稳定性要求。计算分析得出的结论已用于指导工程设计,同时也可供其他同类工程的设计和施工参考。In underground excavation of hydraulic engineering, a three-dimensional structure exists in the junction of large-span tailrace bifurcation tunnel, which is hard to analyze with traditional methods due to its complicatedmechanical behavior, large displacement and heavy stress concentration. In. this paper, FLAC3D is employed to analyze the deformation, stress and yield zone in the surrounding rock mass under excavation of the tailrace bifurcation tunnel of the Guandi hydropower Station. The reinforcing effect of shotcrete and bolt supporting under different conditions of initial stress releasing load is reviewed. Then, according to the loads in excavation, operation and maintenance, the deformation and stress in surrounding rock mass and the lining structure are＂ analyzed. Finally the control case is indicated and measures to maintain the stability of bifurcation tunnel are proposed. The results show that the maximum subsidence displacement of vault is 23 mm, the maximum principal stress is 3.8 MPa for side wall and 2.0 - 2.6 MPa for lining, plastic zones are locally connected between two branch tunnels. The shotcrete and bolt supporting system are in rational condition and ensure the stability of surrounding rock mass. The conclusions from this study have been applied to the design of the tailrace bifurcation tunnel and are also beneficial to the design and construction of similar projects.

关 键 词：FLAC3D 官地工程 尾水岔洞 开挖与衬砌稳定 

分 类 号：U451.2[建筑科学—桥梁与隧道工程]