Study On Settlement Regularity Of Pile With Bearing Base Composite Foundation In High-Speed Railway

The requirements of the offline structure's stability and smooth are strict in High-speed railway. Soft soil foundation settlement control is one of the key technologies in high speed railway. However, due to the soil model is so complex, the level of composite foundation's settlement computation is far behind the engineering practice. At present, the study of the pile with bearing base composite foundation's stress field and displacement field are insufficient. The full-scale field test data is more fewer. Composite foundation settlement calculation theory is not mature. So enhance the study of composite foundation settlement calculation theory is extremely significance.This paper relying on the field test of JingHu high-speed railway pile with bearing base composite foundation, and got plentiful field test data. Relying on the data the carrier pile composite foundation's settlement development with time and load was analyzed, settlement regularity of other composite foundation forms are analyzed and compared.Combined with the mechanical characteristics under embankment load, several calculation methods of composite foundation settlement were introduced. Three important issues in settlement calculation were discussed:(1) The calculation method of additional stress coefficient and average additional stress coefficient under trapezoidal load was introduced; (2) Three kinds of thickness of compressible stratum calculation methods were introduced, and find that the stress ratio of less than 0.1 method and control strain method are close to measured value; (3)The influence of compression modulus in settlement calculation was analyzed, and find that MaJianLin method and LiuZiTong method are close to measured value;Combining with the measured data, pile with bearing base composite foundation's settlement was predicted by four methods. And find that hyperbolic fitting method and grey system fitting method can better predict the settlement's development regularity.