Research On The Excessive Settlement About The Piled Raft Subgrade Of Operating High-speed Railway In The Soft Soil Area

Along with the mileage of operating high‐speed railway increasing, more and more attention is paid to the problem of soft soil subgrade settlement.Therefore,we should analysisthe causes of the problem,studying countermeasures. Inthe design, construction and maintenance management of similar engineering, it has practical significance for us to research on the soft soil subgrade settlement of operating high speed railway.Based on the renovation case of the high‐speed railway pile raft subgrade set‐tlement,we analyzed the reasons of excessive settlement. In this paper, settlement rectification measures under the condition of operation are discussed.We put for‐ward the management measures and suggestions in the engineering design, con‐struction and operation management stages. The surrounding environment is closely related to the soft soil subgrade stability in the operation stage.The variation of groundwater level and load bias is the main external factors for the operation of high speed railway subgrade settlement.The applicability of pile raft foundation is worth discussing in design phase. Itneed attention in design for pile resistance horizontal load capacity, deep and soft soil crust layer lack of geological factors, affiliated engi‐neering heaped load bias problems. In addition, the construction quality of the pipe pile, need to strengthen control in the process.Aiming at the problem of the settlement of subgrade, we put forward three kinds of improvement methods in this paper.The one is to adjust the vertical profile of the line profile with the special tune and the high fastener.The next is the use of tube grouting in soft soil foundation reinforcement.Three is the use of subgrade shallow or rail structure grouting uplift technology, resumethe ride comfort of bal‐lastless track.It is validated by engineering practice, the methods can provide refer‐ence for subsequent similar issues.