The Effect Of Water Scour On The Function Of Pile Foundation In Loess Gully Regions And Its Safety Evaluation

As the transportation construction continuously expanding to the northwest region, more and more bridge pile foundation built on steep slope directly in loess gully region. Because of the complex conditions of terrain, geology, hydrology, bridge pile foundation in the region long suffered adverse effects of water scour that resulted in the soil around the pile varying degrees of missing, which not only caused bearing capacity, safety and durability reduced, differential settlement and other issues of the pile structure, but also produced a great security risk to the normal operation of the bridge structure. So it was necessary to research on the influence of water scour on the function of the bridge pile foundation and safety evaluation in the loess gully region and to make scientific and rational protection program. The main works of the paper were as follows:(1)Based on the domestic and foreign research theory and application, combined with engineering practice, summarized the reasons for water scour disease and its impact on the function of bridge pile foundation in loess gully region, and studied on the evaluation methods of the water scour on the function of bridge pile foundation.(2)Based on the analysis of water scour depth, simulated the process of water scour by finite element software MIDAS/GTS, analyzed the variation of displacement, axial force and lateral friction resistance of the pile under different scour depth, studied on the influence of water scouring on the pile vertical ultimate bearing capacity under different circumstances.(3)Established a safety evaluation system of water scouring on functional effects on the pile in loess gully region by the fuzzy comprehensive evaluation method, assessed the safety of actual project bridge pile in loess gully region, and made pile protective measures corresponding to the injury level to provide scientific security protection for bridge pile foundation.The achievement of the thesis has important theoretical significance and practical value to bridge pile foundation in loess gully region and act an important role for the improvement of the specifications for design and construction.