Settlement calculation method for over-length piles foundation based on field test in the Beijing-Shanghai high-speed railway

To determine reasonable settlement calculation method for high speed railway deep pile foundation, the rational depth for the settlement calculation and empirical factors of the settlement are important. This paper is based on a measured section of Beijing-Shanghai high-speed railway soft soil foundation. Single-point settlement gauge was adopted in the project to carry out a long-term observation. The settlement and the compressed stratum thickness is calculated by present standard and compared with measured values from the field test. The comparisons showed that it is more reasonable to determine the compressed stratum thickness according to stress control method, which method is thought that the additional stress is 10% of gravity at lower boundary of compressed stratum; the compressed stratum thickness difference determined is smaller between Mindlin-Geds stress solution and Boussinesq stress solution in the method of equivalent effect. There are two reasons why all the settlements calculated by present standards are greater than the data measured from the field: The calculated depth is larger, the empirical coefficient of subsidence is larger and method for determining the coefficient is unreasonable. Then the author give his suggestion to improve the empirical coefficients mentioned by using another code named proposed in Shanghai,and put forward the correction formula for pile foundation settlement calculation in soft ground. Furthermore, a calculation example indicates validation of method to determine the over-length pile settlement. © 2014 ejge.