1.1　Structure of CRTSⅡBi-block Ballastless Track on Subgrade

CRTSⅡbi-block ballastless track on subgrade is composed of steel rail，fastener，bi-block sleeper，track bed slab and supporting layer.The concrete supporting layer shall firstly be constructed，then the concrete track bed slab shall be constructed，whose structure refers to Figure 1 and Figure 2.

Figure 1　Cross Section for Ballastless Track in Straight Line Section on Subgrade（Unit：mm）

Figure 2　Cross Section for Ballastless Track in Curve Section on Subgrade（Unit：mm）

Steel rail：the steel rail for welding is 60 kg/m，U71Mn（K），cut-to-length is 100 m brand new steel rail without bolt hoe，its quality shall comply with Temporary Technical Condition for 60 kg/m Steel Rail of 350 km/h Passenger Dedicated Railway（Tiekeji[2004]No.120）and the related requirement in Tender Document of Steel Rail for Zhengzhou-Xi’an Passenger Dedicated Railway.

Fastener：WJ-8 B type fastener will be applied.The WJ-8 B type fastener is composed of screw spike，flat washer，insulating piece，elastic strip，track gauge baffle plate，iron cushion plate，elastic cushion plate，and the embedded sleeve located in concrete sleeper.The performances of fasteners shall satisfy the requirement in Technical Condition for WJ-8 B Type Fastener.The technical requirement for spare parts of fastener shall satisfy Production and Acceptance Technical Condition for Spare Parts of WJ-8 B Type Fastener.

Sleeper：generally the spacing of bi-block sleeper is 654 mm，the sleeper spacing shall be appropriately adjusted in section where the length of track bed slab varies，the spacing shall be no less than 600 mm and not more than 680 mm，and the distance between sleeper center and terminal end of track bed slab shall not be smaller than 250 mm.

Track bed slab：the track bed slab is reinforced concrete structure，width is 2 800 mm，20 mm，HRB335 grade rebar shall be used for vertical rebar，and one HRB335 grade transverse rebar of 16 mm，2.7 m long shall be set between two sleepers.

In subgrade section，the thickness of track bed slab is 240 mm，18 pieces of vertical rebar，C35 concrete shall be used，and the concrete track bed slab shall be continuously poured with reinforcing concrete without expansion joint.

The concrete supporting layer on subgrade shall be poured on the surface layer of foundation bed of graded broken stone；C15 concrete shall be used for concrete supporting layer，the thickness of supporting layer is 3 800 mm，and the thickness is 300 mm.One transverse dummy joint of 100 mm depth shall be set for the concrete supporting layer every about 3.27 m along the line，which shall be away from below the sleeper and 30 mm at both sides.The dummy joint can also be reserved by formwork transformation.If the dummy joint is formed by cutting style，it shall be completed 24 h after concrete pouring and preliminary solidification.The surface of supporting layer shall be under scuffing at an appropriate time before concrete preliminary solidification.

Ballastless track structural height：830 mm in subgrade section（from top surface of inner rail to ground surface of supporting layer）.The high rail superelevation on subgrade shall be set on antifreeze layer.The high rail superelevation shall be linear transited at easement curve range，curve radius 10 000 m corresponds to the high rail 125 mm，and curve radius 9 000 m corresponds to the high rail 140 mm.The curve radius 9 000 m corresponds to the high rail 130 mm before entering the station.