Research purposes: With continuous construction of passenger dedicated line,the ballastless track becomes more and more.However,with the increase of the traffic volume and service life,the roadbed default often occurs in tunnel,which disturbs the traffic safety.Especially the fracture of monolithic concrete bed in the tunnel built in 1960s or 1970s becomes common default.This paper analyzes the causes for the fracture and puts forward the treating measures for tile fracture.
Research conclusions: The fracture of monolithic concrete bed in tunnel has t}le characteristics of concealment.Sudden occurrence and continuity.The causes for the fracture are the dissolution and corruption of underground water,defaults of construction and maintenance and shoItage of maintenance.The measures of dredging underground water,adjusting the track gradient partly and mud jacking can be taken for the fracture.The practices show the perfect result has been got by taking these measures.