Field Test on Controlled Grouting Technology for Soft Soil Subgrade of High-Speed Railway

This study proposes the controlled grouting technology to effectively control the influence of soft soil subgrade grouting on the surface and rail surface deformation of operating high-speed railway. Field tests on grouting uplift for soft soil composite subgrade of high-speed railway, located at the Yangtze River delta, demonstrate potential feasibility and effect of this technology. The effect of different construction control measures on the grouting uplift was studied using data on surface deformation, pore water pressure, and lateral displacement of the soil. Simulations analyzed the influence of the rail deformation on the operational safety of the train at different train speeds. The deformation limit of the rail caused by grouting was determined. The results show that the concept of controlled grouting technology includes grouting, controlling standards, controlling measures, and monitoring. Reasonable grouting parameters, appropriate grouting layer, feasible time interval, and staggered grouting can effectively control the rail deformation. A higher train velocity implies greater deformation of the rail, which leads to a larger derailment factor, axle load shedding rate, and axle lateral force. Therefore, when the train speed is greater than 200 km/h, the overall and differential deformation of the rail surface should not exceed 15 mm; when the train speed reaches 300 km/h, the deformation of the rail surface should be less than 10 mm.