Soft Ground Bridge Pile Foundation Settlement Testing And Prediction

High-speed railway requires track structure to keep long-lasting stability and smoothness, which put forward a strict requirement as to foundation post-construction settlement. Bridges take up a large proportion of the track line and almost all are pile foundations, so to control the pile groups foundation post-construct settlement, especially for the high-speed railway bridge pile groups foundation post-construction settlement in deep soft soil areas is one of the key techniques for high-speed railway bridge design and construction.This paper is based on the project "the bridge pile groups foundation settlement monitoring and testing of Beijing-Shanghai high-speed railway in deep soft soil", which is a major scientific research project of the Ministry of Railways.adopting a in-depth research on bridge pile foundation long-term settlement monitoring techniques, post-construction settlement prediction, and so on by combinning testing on site and theoretical analysis. The main work and achievements ara as follows:(1)The bridg piles group foundation settlement monitoring scheme of Beijing-Shanghai high speed railway was laid out. Specific implementation techniques of monitoring high-speed railway bridge pile groups foundation were proposed after beening researched and practiced, which including the basic requirements, measuring point arrangement methods, re-obsercation of base-points, the leveling line overall layout of deformation monitoring system, The filed testing results shows that the methods of monitoring high-speed raiway bridge pile groups foundation settlement is effective.(2) The method of joint settlement sensors and strain gauges to test the thickness of foundation compressed layer was proposed. The comparsion results betweeen from theoretical calculations and from the field monitoring shows that the method is feasible and reliable, which provide a reliable technology for testing the settlement of foundation compressed layer of bridge piles group foundation.(3)Deducing the effective stress and settlement formula of elastic soil under multi-level loading, modifying the "Three-dimensional composite analysis",which can simulate the process of the high-speed railway bridge foundation loads actually imposed on. And writting a corresponding program to improve the efficiency of calculation。(4)Predicting typical bridge pile groups foundations post-construction of the Beijing-Shanghai high-speed railway by using common predicted models. The results shows that these models has high precision, and the results predicted by these models can meet the requirements of High-speed Railway Design Standard in bridge pile groups foundation's post-construction.