PartⅠ　Construction of Slab Type Ballastless Track in Turnout Area

1　Structure Overview of Slab Type Turnout Area

The Structure of slab type turnout area includes，from top to bottom，turnout part，prefabricated turnout slab，packing layer and base，basement treatment layer and offline foundation，etc.since the turnout is located on different subgrade or bridge，the structure and construction technology of packing layer and basement treatment are different from each other.

The transitional section is designed for the turnout slab of Beijing-Shanghai High Speed Railway with CRTS Ⅱ track slab.In the transitional section，compensation board，special board and bi-block ballastless track or ballast track are applied，and the compensation board and special board after being paved are shear connected with base plate.The size compensation between the compensation board，as the standard board（occupying 6.5m in pavement），and the turnout slab，its length is 3m＜L＜6.5m，and its appearance is the same as CRTS Ⅱ standard track slab，the difference lies in that finish rolled deformed bar is not reserved for transverse connection at the connection end of turnout slab.When the turnout slab is connected with the compensation board，one 100mm long expansion joint（which shall be stuffed with wood plates，and sealed with polyurethane or asphalt ointment，and its occupation shall be included in the compensation board）shall be set between the compensation board and the turnout slab，the finish rolled deformed bar reserved at the other end shall be longitudinally connected with the standard board；the prefabrication length of special board is the same as that of standard board（occupying 6.5m for pavement），its paving position is in between the bi-block track bed and CRTS Ⅱ standard board，the finish rolled deformed bar for longitudinal connection with bi-block ballastless track bed is not reserved，and 20mm expansion joint shall be reserved in between，and the finish rolled deformed bar reserved at the other end shall be longitudinally connected with the standard board.The bi-block ballastless track lies in turnout slab and special board，its base is reinforced concrete structure，the longitudinally overlapped rebar in turnout area and bi-block track bed shall be under insulation treatment as per design requirement；bi-block reinforced concrete base shall extend 5m below the CRTS Ⅱ track bed（the same requirement shall be applied for turnout slab connecting with compensation board），it shall be connected with the supporting layer on subgrade，20mm expansion joint shall be set，and dowel steel shall be set no the connection surface between reinforced concrete base plate and concrete supporting layer.The expansion joint shall，according to design requirement，be stuffed with polyethylene foam plastic board，and sealed at upper end with asphalt ointment or polyurethane resin.