Research On The Horizontal Bearing Capacity Of Single Pile Under Scouring And Biaxial Loads

With the implementation of marine engineering and the rapid development of the national energy strategy in recent years,the development and utilization of marine resources is crucial for economic development in china.In order to a better exploitation and utilization of marine resources,more and more offshore oil drilling platform began to put into use.In the process of collecting oil and natural gas,the pile foundation is not only subjected to the action of the upper loads but also the combined effects of wind,wave and current loads,Pile legs failure in various forms due to excessive force.The piles suffered water erosion,will form the scour pitswith different scour depth around pile foundations when the offshore platform is in the service process,which will cause the pile foundation boundary condition changing and redistribution of body stress and the displacement.These effects will cause danger to the safety of offshore platforms.Therefore,it is very necessary to carry out a deeper research on the horizontal bearing capacity of pile foundation under different erosion depths and horizontal and vertical loads.In this paper,the different change regulations of the horizontal bearing capacity of pile foundation under different scour depths and biaxial loadsare discussed to provide useful references for improving the safety of offshore platform.The main work and results are as follows:(1)Research on the calculation method of pile horizontal bearing capacity theory.Through access to relevant literatures and books to determine the theoretical calculation method of horizontal bearing capacity of pile foundation under horizontal and vertical loads.(2)The indoor model test was carried out to study on the influence of the horizontal bearing capacity of pile foundation under different erosion depths and horizontal and vertical loads.By using model test tosimulate pile foundation under different biaxial stress states and different scour depths to master the change rules of horizontal bearing capacity of pile foundation by monitoring the change of pile displacement and pile body strain.Through the analysis of the model test results,with the deepening of the scour depth,pile horizontal bearing capacity decreases;with the increase of vertical load,there is a critical vertical load,when the vertical force is less than the critical load value,the level of pile bearing capacity increases with the increase of the vertical load,when the vertical force is greater than the critical load value,level of pile bearing capacity decreases with the increase of the vertical load.(3)The finite difference software FLAC3 D was used to verify and improve the calculation results of the model test.Then,the sensitivity of scour depths and vertical loads to the horizontal bearing capacity of pile foundation was analyzed.Through the calculation and analysis the results of numerical simulation are basically consistent with the experimental results.By further numerical simulation analysis a more accurate critical vertical load can be obtained than the model test results.The change of horizontal bearing capacity of pile foundation under larger vertical force and deeper scour pits can also be observed which is not analyzed in the model test.Only by combining the model test and numerical calculation,can we get a more accurate and useful conclusion.