Research status and prospect on deformation control of high-speed railway subgrade in goaf site

China’s coal production ranks first in the world,and the extraction of large amounts of coal resources leaves a large area of goaf site.With the rapid development of high-speed railway in China,some key lines will inevitably pass through some goaf sites.The foundation deformation and the activation deformation under the dense dynamic load of high-speed train have great hidden danger to the safe operation of high-speed railway in goaf site.How to ensure the safe operation of high-speed railway in goaf site is a key problem,and the research on the deformation control of high-speed railway subgrade in goaf site is the core of this kind of problem.First,the research status of high-speed railway subgrade dynamics and ground deformation in mined-out areas are summarized from four research methods:theoretical research,field measurement,model test and numerical simulation.Then,the research on the deformation of high-speed railway subgrade in goaf site is introduced from the following four aspects:the distribution and transmission law of dynamic load of high-speed railway,the requirements of post construction settlement of high-speed railway subgrade,the interaction mechanism between goaf ground and high-speed railway subgrade,and the feasibility study on the deformation of high-speed railway sub-grade in goaf site.Finally,the goaf ground treatment technology and anti-deformation measures of high-speed railway subgrade are summarized,and the field improvement projects and the anti-deformation measures of sub-grade taken by Taiyuan to Jiaozuo and Hefei to Fuzhou high-speed railway line through the goaf site are explained.Based on the analysis of the existing research results,the paper explores how to determine the maximum disturbance depth of the dynamic load of the high-speed railway,how to select the constitutive model of the goaf ground under the action of high-speed railway,how to apply the dynamic load of the high-speed railway in the similar model test and how to improve the treatment system of the goaf ground,and looks forward to the development direction of this research field.