Deep Soft Soil Section Of High-speed Railway Bridge Pile Load Mechanism And Settlement Characteristics

Based on the project item of Hangzhou-Ningbo passenger special line, the bearing mechanism and settling character of bored piles that in the soft soil area were studied and discussed. The main works and conclusions as follows:(1) By means of static load tests, the load transfer mechanism of pile-soil system was researched. Sedimentation on the top of piles, behaviors of skin resistance and axial force were included. It shows that the pile still had potential bearing capacity; skin resistance was the first to work in the upper side of the pile. With the increasing load on the top of the pile, skin resistance at the middle and lower part begins to work.(2) Compression behaviors of pile and soil among piles were monitored for a long-term. The results indicated that both of them increase as upper load increases, and become more and more gently as time goes on.(3) According to the underlying principle, computational method and applicability, several kinds of calculation method about Sedimentation of single pile that are summed up and sorted out in this paper.A method from the current railway bridge standard is recommend to calculate the deformation of single pile.(4) According to the computational method, assumptions, and calculation methods about Sedimentation of pile group were compared and discussed. Deformations of pile group in 666# pier of Ningbo Super-major Bridge were calculated by several methods from different standards. It shows that the sedimentation values are very close, but the depths of compressive stratum which calculated by different methods are not the same.(5) By the finite element software——ADINA, pile-soil interaction of bored pile in the soft soil area was simulated. There are differences between computed values and observed values,but their relatively errors decrease gradually when upper load increase.