Roadbed construction method based on large-thickness collapsible loess area column hammer punching and pile expanding and cement improved soil

The invention relates to the technical field of roadbed construction, in particular to a roadbed construction method based on large-thickness collapsible loess area column hammer punching and pile expanding and cement improved soil. The construction comprises roadbed column hammer punching pile expanding construction, roadbed cement improved soil sandwiched geogrid cushion layer construction, roadbed subgrade bed lower filling, roadbed subgrade bed bottom layer filling and roadbed subgrade bed surface layer filling in order. The high-speed railway foundation is treated by combining the advantages of the column hammer punching and expanding piles and the cement improved soil, the bearing capacity of the foundation soil is improved, foundation deformation is reduced, the stability and safetyof the roadbed in the collapsible loess area in the construction process and the train operation process are greatly improved, the construction difficulty is reduced, the construction cost is reduced, the damage caused by th