Analysis Of Subway Shield Construction Mechanics Behavior And FAI Evaluation Methodology

Presently,there were no mature engineering experience to follow due to the specific geological conditions and surroundings of Hefei.Two typical conditions during shield construction,underneath passing the first Ring Road and South Fei River,were taken as examples in this thesis to carry out dynamic numerical simulation analysis of subway shield construction process. Ground surface sedimentation and strata deformation and stress during construction were studied,using Failure Approach Index to study stability evaluation of surrounding rock and soil mass and research the key technical problems in construction. And hopefully it can provide significant value for future underground shield construction in both theoretical level and engineering level.The main work of this thesis were:(1) Giving result summary of shield construction research at home and abroad by referring to huge amount of literature and the main contents of this thesis according to the background and purpose;(2) Briefing fundamental theory in ground deformation, fluid-structure coupling caused by shield construction and introducing Failure Approach Index and relevant basic theory;(3) Simulating shield excavation by using FLAC3D to solve potential danger posed by underneath passing the First Ring Road and analyzing tunnel structure and stress-strain rules in shield excavation;(4Simulating shield excavation by using FLAC3D to solve potential danger posed by underneath passing South Fei River, comparing fluid-structure coupling analysis and elastic-plastic calculation result in same conditions to prove that water seepage must be considered during tunnel shield excavation;(5) Analyzing rock and soil mass stability based on FAI, it could accurately evaluate the stability of tunnel surrounding rock mass through FAI and it could provide important guide to research prevention measures during construction by studying distribution and evolution laws of FAI.