Research On Bearing And Deformation Characteristics Of Inclined Pile Foundation In Layered Soil

In recent years,with the development of engineering construction and construction technology in China,the characteristics of inclined pile genes,such as high bearing capacity and small settlement,have been widely used in the foundations of wharf construction,offshore drilling platforms,offshore wind farms,bridges,and large power transmission towers.In the project,the inclined pile foundation can simultaneously bear the vertical load and the lateral load caused by the action of water,wind and waves,earthquakes,etc.,and has better bearing characteristics than the vertical pile foundation.In addition,the inclined pile foundation can reduce the excavation of the earthwork during the construction,and reduce the damage to the surface vegetation.It has better economic and environmental protection functions,and therefore has a good application prospect.However,investigations show that there are few research reports on inclined pile foundations under combined loads,and practical applications are ahead of theoretical research,leading to over conservative design and prominent waste of resources.Further research is urgently needed to better serve Design and production requirements.Based on the collection and sorting of domestic and foreign documents and materials,this paper takes the selection of pile foundation of Zhuhai Hengqin Bridge as the supporting object of the experimental study,and constructs the vertical single pile,the inclined single pile and the vertical foundation pile and the inclined foundation respectively.Model of pile.Based on site survey and pile foundation design,with the help of indoor model tests and finite element numerical simulation methods,the bearing characteristics and deformation behavior of inclined pile foundations under combined loads are studied.The main research contents and results are as follows:(1)According to the pile foundation indoor model test experience and the principle of dimensional analysis,an indoor test with a model similarity ratio of 1:100was carried out,the foundation-soil ratio was carried out,the corresponding measurement originals were selected and the test points were arranged,and designed The load loading plan is selected,the pile deformation and the stress change aroundthe pile are selected as the monitoring objects,and the measurement point layout is optimized,and a relatively complete indoor pile foundation model loading test method is established.(2)The changes of vertical load-settlement characteristics,pile shaft force,soil resistance,pile-soil deformation,etc.of vertical single piles and inclined single piles under vertical load are studied through model tests.The results show that the steep drop point is used to determine the ultimate bearing capacity of vertical and inclined single piles under vertical loads.When the load is small,the load-settlement curve shows a linear change feature,and the increase of the load will cause the curve to drop steeply and incline.The vertical bearing capacity and axial force of a single pile are greater than that of a vertical single pile.As the inclination angle increases,the proportion of pile tip resistance gradually decreases.The inclined single pile mobilizes the pile tip resistance earlier than the vertical single pile to bear the upper vertical load.In addition,the load-settlement curve of the vertical pile group does not have a steep drop point.The settlement is used to determine the ultimate bearing capacity of the vertical pile group.The better the nature of the foundation soil,the faster the axial force decays.The axial force of each foundation pile: Corner pile>Side pile>Middle pile.(3)Through model tests,the lateral ultimate bearing capacity,bending moment,displacement field change,and soil resistance of pile groups with different inclination angles under predetermined vertical loads are studied step by step,and the combined loads are studied by using ABAQUS finite element numerical analysis method.The influence of the pile inclination angle,pile spacing,predetermined vertical load size,and plane load loading angle on the lateral bearing capacity,lateral displacement,pile-soil deformation and lateral displacement of inclined pile groups.The results show that the larger the pile inclination angle,pile spacing,and the pre-applied vertical load,the smaller the lateral displacement and the greater the lateral ultimate bearing capacity.The lateral load loading angle has an optimal inclination angle of60°.The influences on the inclined pile foundation under combined load are the pile spacing,pile inclination angle,pre-imposed vertical load,and plane load loading angle,from large to small.Under the action of predetermined vertical load,in the process of applying lateral load step by step,the larger the pile inclination angle,the smaller the lateral displacement of the pile body.(4)Based on the ABAQUS finite element analysis results,combined with the calculation method of the lateral bearing capacity of vertical pile groups under asingle lateral load,a calculation method for the lateral bearing capacity of inclined pile group foundations under combined loads is established,which is convenient for engineering application,and verified by indoor test results..