Experimental study on dynamic performance and long-term durability of high-speed railway subgrade rehabilitated by polymer injection technology

The excessive settlement of high-speed railway subgrade will adversely affect the durability of railway structures and the safe operation of trains, therefore the uplift of track structures will be demanded to restore the vertical alignments of the railway. An engineering attempt with injection of polymer materials between the roadbed surface and the concrete base of the slab track is adopted to uplift the track structures uniformly. Large-scale physical model tests are performed to study the dynamic performance and long-term durability of the uplifted track-subgrade system. The change of stiffness of the track-subgrade system after the uplift process is investigated based on the fixed-point cyclic loading tests. The test results indicate that the stiffness of the track structures is slightly reduced after the uplift process, but the change of the natural vibration frequency of the track-subgrade system is very limited. The investigation on cumulative settlement and dynamic stiffness of the uplifted track structures under very large cycles of simulated train moving loads shows that the uplifted track has satisfactory dynamic stability.