Design-type-selection And Key Construction Technologies Of Assembled Subrail Structure For Urban High-speed Shield Tunnel

Accelerating the development of high-speed railway is the inevitable choice of China's economic and social development,but also the inevitable trend of social development.Tunnel,as a structural form of high-speed railway infrastructure and construction process,plays a vital role in shortening line mileage,reducing line gradient,improving operation conditions and improving operation safety,in particular,the construction of tunnels in urban areas plays a fundamental role in alleviating urban traffic jams and protecting the environment.However,in the process of tunnel construction and operation,the quality,cost,efficiency and safety of tunnel construction have always been the focus of attention.As an optimal construction method,shield tunneling has become an effective method to solve the above problems.Especially in recent years,the development of assembly structure has provided more space for the development of this construction method.Therefore,based on the construction of high-speed railway shield tunnels under the urban area and the full analysis of tunnel deformation characteristics,this paper studies the selection method and key construction technology of assembled subrail structure,and carries out practical engineering application research.The main research contents and achievements are as follows:(1)The deformation characteristics of rock and soil during shield tunnel construction are systematically summarized.Based on the extensive investigation of relevant documents at home and abroad,based on the analysis of the current development and existing problems of underground engineering precast technology,the deformation characteristics of rock and soil in the construction process of single track double track tunnel of high-speed railway are systematically summarized,providing theoretical and methodological support for the design and selection of subrail structure.(2)The structural types of assembled subrail structure for urban high-speed railway shield tunnel are put forward and research on selection is developed.Based on the deformation characteristics of rock and soil in the process of shield tunnel construction,based on the newly built Tsinghua Yuan tunnel of BeijingZhangjiazhou high-speed railway,the box subrail structure and bracket subrail structure are put forward.Based on the three-dimensional numerical calculation model,the stress,acceleration and displacement deformation characteristics of two kinds of rail under four working conditions including unilateral static load,bilateral static load,unilateral dynamic load and bilateral dynamic load are analyzed and studied.The comprehensive analysis shows that box subrail structure is more suitable for the urban high-speed rail shield tunnel.(3)The key control technologies of box subrail structure construction are put forward.Aiming at the research results of the design and selection of the subrail structure of high-speed rail shield tunnel in urban area,the key control technologies,including precast mould,anti cracking concrete,assembling equipment,assembling process and bottom grouting,are put forward around the concrete construction technology of the box subrail structure,which provides technical guarantee for the safe and efficient operation of the tunnel.(4)Deformation monitoring of box subrail structure under construction stage is developed.Based on the construction of Tsinghua Yuan Shield Tunnel on the BeijingZhangjiakou High-speed Railway,the research results are applied in practice,and the key points of Subrail structure stress are monitored and analyzed on site.The analysis results show that the deformation law of monitoring results is basically consistent with the numerical deformation law,and the site construction is safe,which provides a reference for the future application of similar engineering assembling Subrail structure.