Beijing-shanghai High-speed Rail Deep In Soft Soil Segment Bridge Pile Performance Test Study

High-speed railway has strict requirements for smoothness, therefore, it's very important for studying performance of the bridge pile foundation by testing, especially for the bridge foundation in deep-soft soil.Relying on the Ministry of Railways'key project "Monitoring and Test on Bridge Foundation's Subsidence in Deep-Soft Soil of Beijing-Shanghai High-speed Railway", this paper tested and analyzed performance of bridge pile foundation in typical deep-soft soil, obtained the following results.(1)Bridge foundation settlement monitoring schemes of Beijing-Shanghai high speed railway were laid out respectively. The specific implementing technologies of pile foundation deformation monitoring such as the basic requirements, the technical standards, layout of benchmark, re-observation of base point, the leveling line, overall layout of deformation monitoring system and specific measures to obtain reliable field data were proposed through research and practice. Field test results showed that the monitoring method for deformation was effective and the components and instruments were reliable, thus it is worth promoting.(2)The combined monitoring method of precise leveling and hydrostatic leveling was proposed to observe the settlement of bridge pile foundation, which was successfully applied in the typical section of the Beijing-Shanghai high-speed railway. Obtained the accurate and reliable data about bridge pile foundation long-term settlement data and pile body compression deformation.(3)Considering location of long-large pile foundation on the soft clay on the Beijing-Shanghai high-speed railway, the joint monitoring method of the settlement gauge and strain gauge was firstly proposed to observe the compression of soil layer under pile foundation. Installing technique of settlement gauge was studied and a reliable technical method for monitoring the thickness of compressible soil layer beneath pile foundation was presented.(4)Obtained compression modulus value of the pile bottom soil in different pressure levels by high pressure consolidation test in laboratory, obtained the soil of the pile bottom compression layer in the 100-200kPa stress range corresponding compression modulus Es0.1-0.2 and gravity stress to gravity stress additional stress range corresponding compression modulus Es, getted empirical formula between them.(5)The stress-strain-time curves of soil samples under different load, beneath the long-large pile foundation of the typical section on the Beijing-Shanghai high-speed railway, were obtained through creep test. Discussesed the pile bottom ground soil creep deformation features to chose the creep model and parameter inversion. The Schiffman viscoelastic model fit the deformation characteristic of soil layer under the pile better.(6)Prepared a data management software about pile monitoring, which was operated conveniently. The software has great and practical value, with which data can be easily exchanged.