Study On The Influence Of The Numbers Of The Bearing Plate On The Failure State Of The Soil Surrounding The Extended-plate Pile Under Horizontal Force

The Concrete Extended-plate Pile is a variable cross section design,which increases the bearing capacity in different soil layers,increases the contact area of the pile and soil,and makes it more advantageous in the bearing capacity.As a result of the improvement of the pile forming process,it has the advantages of saving material consumption,environmental protection and environmental adaptability.But according to the actual research results,the research of this pile is still at the primary stage,and it can't completely meet the actual needs of the project,The results are mostly concentrated on the vertical load,but the research on the performance of pile under horizontal load and the effect of pile soil failure,load transfer mechanism,bearing capacity,failure mechanism,settlement and group pile effect are relatively lack.In this paper,the effects of the number of plates on the horizontal bearing capacity of the concrete pile and the failure state of the soil under the effect of horizontal force are studied through the combination of experimental and theoretical analysis.In the aspect of experimental research,the test method of undisturbed soil half face pile model is put forward innovatively,the design of special soil collector and half face pile is used to overcome the problem of soil sample distortion in buried soil test,and to observe the form of pile soil failure in the whole process,so that the test results are closer to the actual project.At the same time,ordinary pile is used as the control group,according to the actual size of the concrete enlarged pile,the model pile is made according to the ratio of 1 to 35,the number of plates is a single variable,and the comparison test is carried out.From the aspect of pile soil interaction and displacement load curve,the relationship between the number of plates and the failure of surrounding soil of the Extended-plate Pile is analyzed.The results show that: from the viewpoint of pile-soil interaction,under the action of horizontal force,The rigid body rotation of the Concrete Extended-plate Pile is taken place.And the compression between pile and soil,As the angle increases,the scope of action under the plates increases,the range of plate is slip line shape convergence,until the occurrence of slip failure,at the top of the pile,the soil is arched and the center position of the pile is cracked.With the increase of the number of plates,the rotation point changes,and it moves downward towards the direction of the pile end.The range of soil slip increases under the plate,resistance to bending moment increases at the expansion plate of the bearing,and improve the bearing capacity of piles and reduce the force of straight piles.From the aspect of displacement load curve,with the increase of plate number,the horizontal displacement of pile top becomes smaller and smaller.Therefore,the increase of plate number effectively reduces the horizontal displacement of pile.In terms of theoretical research,ANSYS software is used to model and analyze the same size concrete enlarged pile according to 1:1 ratio,and the corresponding displacement and stress data are extracted.The study shows that the maximum shear stress is mainly concentrated in the part of the bearing plate,and the corresponding positive shear stress is produced at each bearing plate to reduce the force of the pile,which shows that the number of bearing plates has a favorable effect on the improvement of the horizontal bearing capacity of the concrete expansion pile.In addition,from displacement cloud diagram of displacement load curve,it can be concluded that the number of bearing enlargement plates has a significant effect on reducing horizontal displacement of pile top.At the same time,the consistency and accuracy of the test and theoretical analysis are verified through comparative experimental research and theoretical analysis.And it is found that the contribution rate of the pile to the horizontal resistance of the pile is gradually weakened,which indicates that there is a reasonable range for the number of large plates.That is to say,one or two is the best,and three is acceptable,but cannot be more.Through the research in this paper,the influence of the number of plates on horizontal bearing capacity and failure state of the Concrete Extended-plate Pile will be more clearly.Further improve the model test method,test device and the Concrete Extended-plate Pile theory research of undisturbed soil half pile surface,and promote the popularization and application of the Concrete Extended-plate Pile.