Field Grouting Experiment on Reinforcing the Pile-Raft Composite Foundation of High-Speed Railway

With the rapid development of China's high-speed railway construction in recent years, there are more and more railway lines constructed on the soft ground, especially in the southeast coastal areas. After a long period of train operation, there are some local settlement, non-uniform deformation and other diseases occurred in the subgrade. In order to explore the rational and effective reinforcement measures for the subsidence disease of soft soil subgrade, it was combined with an actual engineering practice that the field experiments were carried out on whole layers continuous grouting and part layers discontinuous grouting. Based on the results analysis on the monitored data, such as ground surface deformation, subsoil lateral deformation and pore water pressure etc., the stratum disturbance mechanism and its influence range caused by grouting was concluded, and finally a new reinforcement scheme is proposed. These results can not only provide effective recommendations for the design and construction of later formal reinforcement activities but also serve as reference for future similar projects.