客运专线路基工程中管桩应用机理研究

Research on Applicable Mechanism of Pipe Pile in Subgrade Engineering of Passenger Dedicated Line

研究目的:管桩已广泛应用于客运专线和高速铁路建设工程中,为深入探讨管桩的承载性能和路基实测沉降特性,并研究管桩的抗剪性能及在路基整体稳定中的作用,结合京津城际客运专线的设计、施工和沉降监测,系统地研究管桩在路基工程中的应用机理。研究结论:管桩具有高强、工期快、质量易于控制等优点,可满足客运专线建设标准高的要求,总沉降量和不同阶段的沉降速率明显优于其它加固方式;在水平力作用下土质地基中管桩是受弯破坏形态,按抗剪强度验算路基整体稳定性导致安全系数估值偏高;管桩承载有桩筏结构、桩板结构和桩网结构等方式,建议加强施工质量控制、提高桩间土强度、改善桩顶的连接方式并开展桩梁结构的研究。

Research purposes： Pipe pile has been widely applied in construction of passenger dedicated line and high-speed railway.Combining the design,construction and subsidence monitoring of the Beijing-Tianjin Intercity Railway,the applicable mechanism of the pipe pile in the subgrade engineering was systematically studyed for further understanding of the pipe pile＇s bearing capacity and the roadbed＇s actual settlement characteristics,and for the study on the pipe pile＇s shear performance and role in guaranteeing the subgrade stability. Research conclusions： Pipe pile featured with the high strength,short construction period and easy control of construction quality can meet the high demand of construction of passenger dedicated line with less total settlement and less settlement velocity at the different phases compared with other reinforcement methods.In the soil foundation,under the action of horizontal force,pipe pile is in failure state due to the bending moments.The check calculation of the entire stability of the subgrade is made with the shear strength,resulting in high safety coefficient valuations.The load bearing modes of the pipe pile include the modes of pile-raft structure,pile-board structure and pile-net structure.It is proposed to strengthen control of the construction quality,to improve the strength of soil between piles and the pipe pile＇s top connections and to do the research on pile-beam structure.