Experimental Research On The Root Foundation Anti-Pull Bearing Properties By Laboratory Model

As a new type of bionic variable cross-section pile,root foundation is used to make the surrounding soil compact by setting the root,so as to give full play to the bearing capacity of the soil around the pile,enhancing the vertical compression,vertical pull-up capacity of root foundation.The current research on root foundation is mainly focused on the field in situ test and numerical simulation analysis of its compressive properties.However,there are few researches on the theoretical research and engineering application of the vertical anti-pulling characteristics of the root foundation,and there are no relevant standards for its anti-pulling load characteristics.Therefore,it is of great significance to carry out research on the mechanism of the root foundation anti-extraction mechanism.This paper analyzes the root foundation through indoor model test and numerical simulation.The main research results are as follows:Firstly,based on the number of root,the root position,the root depth and the spacing of the root,the anti-pulling load characteristics of the root foundation and its influence were studied and analyzed through four groups of tests using the laboratory model box filled by sand.Then comparing the ultimate pull-out bearing capacity of the foundation under various conditions,it is concluded that the ultimate pull-out bearing capacity of the pile increases greatly due to the presence of the root.Secondly,the stress conditions of the pile itself,such as the axial force of the pile body,the frictional resistance of the pile,the resistance at the root key and the earth pressure on the pile are analyzed emphatically when considering the uplift bearing characteristics of the root foundation test model.It was concluded that the internal force of the pile was mutated at the root and the soil pressure was sharply reduced near the bottom of the pile.Thirdly,by using FLAC 3D numerical modeling software,the experimental pile is simulated in vertical simulation.While verifying the feasibility of the model,the initial state of the root foundation and the stress and displacement cloud images of the pile-soil model after loading are comparatively analyzed,and the stress of the soil at the root is also analyzed.The results show that the stress of the soil at the root is abrupt,the maximum compressive stress occurs at the end of the root and the maximum tensile stress occurs at the root of the root.