| In recent years,because of the advantages of fast construction speed,guaranteed project quality and simple maintenance in the later stage,prefabricated structure has been widely used in the construction of above ground structures and subway in China.With the rapid development of railway tunnel construction in our country,but due to the complex engineering geological environment,the construction quality is not easy to control,the daily maintenance is not in place and other reasons,the tunnel disease is also relatively serious.The railway prefabricated tunnel lining structure is also a new direction of tunnel construction technology development,which is conducive to saving resources,reducing construction pollution,improving labor production efficiency and quality safety level.At present,the application and research of prefabricated lining in railway tunnel are few.The thesis was funded by the major project fund of CARS "New Prefabricated Structural System and Key Technologies at the Bottom of the Tunnel"(2017YJ024),the paper systematically studies the mechanical behavior of prefabricated lining joints in railway tunnel by means of theoretical analysis,numerical calculation and solid load test,etc In order to provide support for the application of prefabricated lining in railway tunnel,the main research contents and achievements are as follows:1.Experimental study on mechanical properties of assembled lining jointThe full-scale axial bending load test was carried out on eight types of joints,including flat joint,straight bolt,inclined bolt and curved bolt under the assembly lining and mortise groove joint.The mechanical behavior of each joint under different axial force and bending moment was studied systematically.The surface crack,surface concrete stress,vertical displacement and joint of each joint under different load conditions were analyzed Head angle and other evolution laws.Through the comparative analysis of the mechanical properties of different joint types,the influence laws of axial force,bending moment and bolt type on the bending stiffness are mastered,and the empirical formula of classified bending stiffness and simplified bending stiffness formula of joint under different load conditions are given.2.Numerical simulation of mechanical properties of assembled lining jointAccording to the full-scale test of joints,161 finite element models of different bolt connection types are established.The mechanical properties of joints under different axial forces and bending moments,such as stress,angle,displacement and bending stiffness,are studied.The bending stiffness of joints under different bolt connections is compared,and the joint test results are verified and supplemented.3.Study on the block of prefabricated liningThrough the establishment of 96 "load structure" finite element models,the section types of single track and double track tunnels of high-speed railway are designed and divided into two parts,one is the minimum bending moment and the other is the maximum bending moment.The influence of different surrounding rock grade,joint stiffness and block method on prefabricated lining structure is studied.The structural stress,displacement response and safety factor are systematically evaluated.4.Simulation study on mechanical properties of full ring assembled liningThrough the establishment of refined finite element model,the mechanical properties of the whole ring prefabricated lining in the excavation process under different block methods are studied,and the typical indexes such as lining displacement and stress are compared with the cast-in-place whole tunnel.The dynamic response of prefabricated lining under the action of high-speed train is studied by establishing the vehicle track tunnel rock coupling finite element model.The vibration acceleration,dynamic displacement and structural dynamic stress are compared with the whole castin-place tunnel.The assembly lining is studied systematically from static and dynamic aspects. |
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