Study On The Key Problems In The Construction Of The Xinwushaoling Tunnel "Unmanned" Arch Erection

In China’s‘13th Five-Year’development plan and the outline of building a transportation power,it is clearly proposed to strengthen the research and development of frontier key technologies,and the research on prospective and disruptive technologies that lead to the transformation of the transportation industry.At present,China is in the golden opportunity period of constructing transportation network.Among them,railway tunnels have exceeded16,000,and the total length has exceeded 20,000 km.Large-scale mechanized tunnel construction represented by rock drilling trolley is increasingly perfect,and the tunnel construction gradually changes from manual construction to mechanized construction.Meanwhile,some innovative technologies with complex structure,information management and intelligent construction have emerged.Nowadays,China’s comprehensive strength has undergone a qualitative leap,and the construction of mountain tunnels is moving forward towards full process intelligent construction.However,mountain railway tunnels still need to process various problems in the implementation of mechanized and unmanned construction.Therefore,supported by the horizontal project"Research on key technology and equipment of unmanned arch erection drilling,anchoring and grouting integrated operation"（2021025-1）of Lanzhou engineering construction headquarters,this paper studies the longitudinal connection structure of arch frame,the deformation characteristics of surrounding rock and the construction efficiency in the mechanized construction of Xinwushaoling tunnel by field investigation,finite element numerical simulation,field monitoring and statistical analysis.The research shows that:（1）First,the issues encountered in the“unmanned”arch construction from project approval to early R&D are analyzed and summarized.The key issues restricting this development are emphatically analyzed and classified to solve the problems in a planned and organized way;（2）In this paper,the longitudinal connection form of steel arch frame suitable for’unmanned’vertical arch construction is proposed audaciously,and the design optimization process of this structure from nothingness to being and from the shallower to the deeper is expounded in detail.The feasibility of construction and mechanics are demonstrated and studied respectively.The structure form proposed in this paper has been applied to practical engineering,and has certain advantages in construction efficiency and economic benefits;（3）One of the distinctive characteristics of’unmanned’arch erection is different from the time of traditional arch.To understand the deformation law or value of surrounding rock in the time from no support to support,and adjust the time and management scheme of’unmanned’arch erection,it is necessary to calculate the deformation of surrounding rock in real time.Therefore,through the statistical regression analysis of field monitoring data,the analytical solution of vault settlement of surrounding rock in dynamic construction is given on the basis of existing theoretical research,and the numerical model is established by FLAC^3D to simulate the construction mechanical response of surrounding rock in real time;（4）Through the comprehensive index analysis method and the combination of qualitative and quantitative analysis,the work efficiency of traditional artificial arch erection and‘unmanned’arch erection is evaluated.According to the characteristics of engineering and construction method,the useful information is discriminatively assembled,the two arch erection methods are objectively evaluated on the same benchmark,and the existing problems and advantages of‘unmanned’arch erection method are pointed out,which provides a reference for the organization,management and planning of arch erection construction.