In order to study the improvement effect of the CG-2 curing agent and cement on loess, a series of physical and mechanical property tests and microstructure tests were carried out on loess improved with different dosages of curing agent and cement to study the physical and mechanical properties, durability and microscopic pore characteristics of the CG-2 curing agent and cement-improved loess. The results show that the unconfined compressive strength of improved loess increases gradually with the increase in curing agent and cement dosage, and the higher the compaction degree and the longer the curing age, the higher the unconfined compressive strength. In the case of the same cement content, the higher the dosage of curing agent, the more the unconfined compressive strength of improved loess increases. Under the condition of reaching the same unconfined compressive strength, the addition of curing agent can significantly reduce the amount of cement. The more the content of cement and curing agent, the less the unconfined compressive strength decreases after a certain number of freeze–thaw cycles, and the higher the dry-wet cycles index after a certain number of dry-wet cycles, indicating that the addition of curing agent can significantly improve the ability of the sample to resist freeze–thaw cycles and dry–wet cycles. According to the microscopic test results, it is found that the addition of curing agent can reduce the porosity of soil particles, change the contact and arrangement mode between soil particles, and enhance the agglomeration and cementation characteristics between soil particles, and obviously improve the physical and mechanical properties of soil. The research results can provide new ideas and methods for the improvement technology of loess.

It is very critical to understand the dynamic interaction of vehicle-track-subgrade for high-speed railway development. This paper presents a dynamic interaction model of vehicle-slab track-subgrade system, in which a slab track-subgrade structure is put forward as a substructure and is studied considering track irregularity excitation and displacement compatibility condition. In this model, both the actual structure of a vehicle and vibration characteristic of the substructure (including slab track, subgrade and foundation are) considered. This model not only reflects the interaction between vehicle and substructure completely, but also provides a theoretical foundation for determining design parameters of high-speed railway (especially for design parameters of track and subgrade). Research results can provide technical reference for design and construction of slab ballastless track and subgrade structure of high-speed railway.