Numerical Modeling And Optimizing Construction Schemes For Transition Section Complex Structure Of Large Scale Underground Railway Station And Tunnel

The transition section structure form of Beijing-Zhangjiakou inter-city railway Badaling underground station and tunnel is very complicated--tri-arch cross-section transition for large-span variable cross-section single arch. Such a large-scale underground railway station is extremely rare in the world, it is the first at home and abroad that in the field of depth, span, height, depth-span ratio and so on. Based on the engineering background of New Beijing-Zhangjiakou Inter-city railway Badaling underground station and tunnel transition section construction, the problem of tri-arch and large-span variable single arch construction schemes in the transition section launched research, This paper draws some basis and the law as reference in construction process by the simulate calculation of ABAQUS finite element analysis software. Major work and results as follows:(1) This thesis summarizes the overseas and domestic research status of large-span tunnel construction methods, sketches the mechanics concept, construction methods and surrounding rock mechanics law in the field of underground engineering.(2) This thesis discuss the frequently-used methods(middle cell method, one-side wall drift heading method, CRD-4holes method, CRD-6holes method) that is used in large-scale variable cross-section tunnel engineering research, analysis the stress, deformation and plastic areas distribution of surrounding rock by the simulate calculation of construction process.(3) By comparative analysis, confirm the best construction scheme of transition section: middle cell method applies to tri-arch cross-section and CRD-4holes method applies to large-span single arch of variable cross-section.It can offer direct guidance to the Badaling underground station and tunnel transition section project, and some reference to similar underground projects.