Research On 3D Modeling Technology Of Railway Alignment Selection Decision Support System In Karst Region

With the comprehensive promotion of the "Go-West" Campaign in China and the rapid development of High-Speed Railway Technology,the high-speed railway constructed in rugged mountainous terrain has become a significant task to drive local social economic development.Mountainous karst geology is regarded as the most common,the most serious geological hazard,which should be taken cautious consideration in railway alignment design and construction organization process.The ever-changing computer technology has increasingly advanced new tools to solve engineering geological problems,various kinds of commercially geological modeling softwares have sprung up at present.This thesis mainly explores the modeling method of GOCAD software,and the conversion method from GOACD SGRID model to ABAQUS model hexahedral element model.The main works are going to be accomplished include the following:Firstly,a three-dimensional geological karst tunnel model which shows various spatial relationships among karst caves and tunnel will be built by GOCAD software.Thus,for the sake of data export and model conversion,the SGRID stratum grille model in short tunnel area is going to be established;Secondly,the structure of SGRID model and the node alignment law of hexahedral element in ABAQUS are going to be analyzed to craft conversion program from SGRID to ABAQUS.Then a three-dimensional numerical calculation model in tunnel is going to be established by using the conversion program;Lastly,a plane model in karst tunnel will be built by ABAQUS.Then a simulated calculation on tunnel excavation will be done.Thus,the effects of karst caves in various orientations on surrounding rock stress and displacement distribution after the tunnel excavation will be analyzed.The results show great effects of caves in various orientations on haunch stress.On displacement,the influences of top karst caves on tunnel excavation mainly positioned in the vault and the bottom arch,and these two vertical displacements are larger than that of no karst caves;the side karst caves mainly affect the horizontal displacements of surrounding rocks;the influences of bottom karst caves on the vertical displacements of bottom arches count the most,and the bottom heaves are the most distinct and serious after the tunnel excavation.