1　Overview for CRTSⅡBi-blockBallastless Track Structure

According to the unified arrangement of China Railway，Zhengzhou-Xi’an passenger dedicated railway adopted CRTSⅡbi-block ballastless track system.This system，based on Germany Zublin ballastless track，is an innovative ballastless track structure by combining with actual Chinese national conditions.The CRTS　Ⅱbi-block ballastless track is constructed by means of mechanical vibrating and embedding method（mechanical method），the primary working procedure on site is concrete pouring，the secondary working procedure is that the prefabricated bi-block sleeper is embedded evenly and continuously poured concrete ballast bed by mechanical vibrating method in fixed mound style，which is adaptable to the ballastless track structure of ZPW2000 track circuit，with much higher level of mechanization.Since the fixed mound replaces tooling rail to assemble track panel，the concrete ballast bed can effectively avoid the temperature stress variation of steel rail in solidification，and avoid the concrete crack caused by concrete creep effect.The design & construction philosophy and construction technology is the first one in China.

CRTS　Ⅱbi-block ballastless track can also be constructed by steel rail adjusting beam method（track panel method），which refers to rebar binding，sleeper and steel rail laying，track panel assembly，then the track panel will be tightly aligned by applying special steel rail to adjust beam，finally the track bed slab will be poured by concrete.Steel rail adjusting beam is assembled above track panel，and is supported on the pedestal at both sides of track bed slab or on the protective layer.Its gripping apparatus is fixed on the railhead of the tooling rail，and the level and height of the track can be adjusted by adjusting the horizontal threaded rod and vertical threaded rod on the beam.Related technology concerning this aspect will not be introduced in this book，please refer to The Prefabrication and laying Technology for CRTSⅠ Bi-block Ballastless Track Sleeper，also one this series of books.