1.3　Structure of CRTSⅡBi-blockBallastless Track in Tunnel

The CRTSⅡbi-block ballastless track in tunnel is composed of steel rail，fastener，bi-block sleeper，track bed slab and pedestal.In tunnel with inverted arch sections，the supporting layer shall firstly be constructed on back-filling layer，and then the track bed slab shall be constructed； in tunnel without inverted arch sections，the reinforced concrete bed plate shall firstly be constructed on back-filling layer，and then the track bed slab shall be constructed.The tunnel with inverted arch track bed structure refers to Figure 5 and Figure 6.

Figure 3　Cross Section for Ballastless Track in Straight Line Section on Bridge（Unit：mm）

Figure 4　Cross Section for Ballastless Track in Curve Section on Bridge（Unit：mm）

Figure 5　Cross Section for Ballastless Track in Straight Line Section in Tunnel（With Inverted Arch，Unit：mm）

Figure 6　Cross Section for Ballastless Track in Curve Section in Tunnel（With Inverted Arch，Unit：mm）

The thickness of track bed slab in tunnel section is 280 mm，18 vertical rebars in straight line section，20 vertical rebars in curve section，C40 concrete shall be used.The concrete track bed slab，except for the expansion joint set on track structural gap，shall be continuously poured.The concrete track bed slab shall be poured one piece after another，the length of standard concrete track bed slab is 6.44 m，for other girder type other than 32 m simply supported beam，the length of track bed slab at girder terminal can be adjusted based on girder length，slab length shall not be less than 4.0 m and shall not be more than 8.0 m，one 10 cm expansion joint shall be set between adjacent two concrete track bed slabs，and two anti-shear convex plates shall be set for every track bed slab unit.

The structural height of ballastless track in tunnel section：570 mm（from top surface of inner rail to the surface of tunnel back filled layer）.The high rail superelevation in tunnel shall be set on concrete track bed slab.