###### Abstract
The main shortcomings are the following: cracks are likely to occur on the joint surface of the track bed slab and the old and new concrete of the sleeper, and crack control is difficult; the tool rail construction is used, and the construction quality is affected by the tool rail, fasteners, etc. ; it is also difficult to repair during operation. Figure 1: Heavy-haul train with increasing axle load. Figure 2: DBT structure. * LSBT The LSBT structure (Figure 3) mainly includes concrete track bed slabs, perforated sleepers and supporting fasteners [12; 13; 14]. LSBT uses pre-stressed long sleepers, poured into a reinforced concrete track bed. In order to ensure the connection between the sleepers and the track bed, 5 lateral reserved holes are set on the sleepers, and longitudinal steel bars are used to penetrate the track bed to enhance its integrity. The main advantages of the LSBT structure are the following: simple structure, good integrity, strong track gauge retention ability; good economy; concrete pouring and molding of the track bed are conventional construction techniques, easy to master; Sleeper manufacturing, transportation and hoisting are convenient. The main shortcomings are the following: the new and old concrete junction area is larger, crack control is more difficult; the weight of prefabricated sleepers is larger, compared with DBT, it is more difficult to transport, assemble and lay. * LVT The LVT structure (Figure 4) mainly includes concrete track bed slab, elastic support block (concrete support block, rubber boot cover, rubber pad under the block) and supporting fasteners [15]. LVT is composed of rubber or other elastic composite boots at the lower part and around the double-piece sleeper (or two independent support blocks). There is a rubber elastic cushion between the bottom of the sleeper block and the boots, and concrete is poured around the boots. The main advantages of the structure are the following: the track structure has good elasticity; the construction process is simple; the structure can be repaired and the performance is better; the prefabricated parts are easy to hoist. The main disadvantages are the following: poor waterproof and dustproof performance of boots; durability of elastic elements in the structure; relatively weak retaining ability of track geometry. Since the three ballastless track structures all have good safety and reliability, they can be applied to heavy-haul railway operating conditions after the structural design is perfect. However, in view of the operational characteristics of heavy-haul railways, the selection analysis of the ballastless track structure is carried out from the aspects of low dynamic characteristics, repaira  
Figure 4: LVT structure. Figure 3: LSBT structure. Both DBT and LSBT track structures are cast-in-place sleeper monolithic track bed structures, and the track elasticity is mainly provided by the fastener system. Under heavy-load transportation conditions, if the fastener structure is to maintain the gauge and the elastic cushion has good fatigue resistance, the stiffness of the elastic cushion of the fastener should not be too low. This makes the overall rigidity of the track larger, and the impact load of the train will be aggravated, which will adversely affect the integrity and durability of the track structure. In addition, the joint surface of the new and old concrete of the sleeper and the track bed slab is prone to cracks, and its mechanical characteristics still need further theoretical analysis and experimental comparative research. At present, there is no experience in large-scale use of DBT and LSBT in China's mixed passenger and freight lines, and the long-term suitability of the track structure is still lacking in operational practice. According to relevant data, DBT has been laid in several tunnels on the Sui-Yu line of China Railway.