Experimental Study On Uplifting Of Expanded Bottom Piles

As a new form of pile foundation,the enlarged-bottom pile is an improvement on the traditional pile foundation.By artificially expanding the diameter of the pile end,the frictional force of a part of the pile body is sacrificed to improve the bearing capacity of the pile end.Compared with the traditional cast-in-place pile,the enlarged-bottom pile has the advantages of good reinforcement and weak underlying layer,small settlement after construction and good bearing pull-out performance.In recent years,the enlarged-bottom pile has become more and more widely used in the transmission line infrastructure and the high-rise weak underlying infrastructure.However,the existing form of the enlarged-bottom pile also has the characteristics of complicated construction,high cost,long construction period,and large noise and dust pollution.However,the research on the foundation of the enlarged-bottom pile is mostly in the stage of numerical simulation and simulation experiment.In view of these situations,a new type of enlarged-bottom pile form and construction method are developed and developed in the actual environment.The pile foundation was subjected to an experimental study on the pullout resistance.The following is the main content of this article:(1)Introduced the development process of the enlarged-bottom pile foundation at home and abroad,as well as the existing basic form and problems of the expanded pile.The in-depth explanation of the bottomed uplift piles was carried out.(2)The feasibility of using static expansion agent for this new type of enlarged-bottom pile foundation was explored.Through a series of exploration experiments,the basic composition of static expansion agent,expansion ratio,product formed after reaction,and silicic acid were explored.The reaction situation of salt and cement in the case of mutual mixing.And based on the conclusion of the experiment,summarize the improvement and prepare for the experiment in the soil.(3)Through the previous experimental conclusions on the static expansion agent,the experiment of expanding the enlarged-bottom pile in the soil is designed,and the experimental research on the pullout resistance of the enlarged-bottom pile is mainly carried out.After the experiment,the collected data is calculated and analyzed,and the conclusion is obtained.(4)In addition,the outer protective layer of the new type of expanded pile foundation was studied.The experimental research was carried out on the setting time,strength and microstructure of different mixing ratios and different admixtures.It is more suitable for the protective layer composition of this new type of expanded pile foundation,paving the way for future work.