Model Experiment And Numerical Simulation Study On Torsional Bearing Capacity Of Root Foundation

Root foundation,as a new bionic foundation form,has been proposed for a short time.It squeezes the root key into the soil around the foundation through a multi-head jacking device,and then forms an organic whole to bear external loads through concrete pouring and foundation.The root key enhances the bonding force between the foundation and the surrounding soil,thus enhancing the stability and bearing capacity of the foundation.The proposed technology is an extension and supplement to the traditional bored pile,which can achieve the same bearing capacity as the traditional bored pile with a smaller structural self-weight.To a certain extent,it enlarges the scope of application of pile foundation in engineering.It has far-reaching significance to improve the bearing capacity and scope of application of bored pile,and has good economic and practical value.Based on the indoor model test and the numerical simulation results,the torsional bearing characteristics of the root foundation are analyzed and studied in this paper.The main research results are as follows:Firstly,the bearing capacity of root-type pile foundation under torsion is studied by indoor model test.The test is divided into two working conditions: considering different depth of root-key and number of root-key layers,and the response mechanism of the torsional bearing capacity of root-type pile foundation is discussed respectively.The effect of the root key under different bearing characteristics of the root pile foundation is analyzed.It is concluded that the existence of the root key can significantly improve the ultimate torsional bearing capacity of the pile foundation.Secondly,by analyzing the Torsion-Rotation curve of the root-type pile foundation under torsion,it is concluded that the number of key layers has a significant impact on the torsional bearing capacity of the pile foundation.Rational arrangement of key layers will significantly improve the torsional bearing capacity of the pile foundation,while excessive arrangement of key layers will affect the torsional bearing capacity of the pile foundation.The deeper the root key is buried,the stronger the embedding effect between the pile and the soil around the pile is,the stronger the bearing capacity of the root pile foundation is.Thirdly,the FLAC3 D software is used to simulate the indoor test.While verifying the main conclusions of the indoor test model,the stress and displacement nephograms of the root key,the soil around the pile and the pile itself are analyzed from the point of view of numerical simulation.It is concluded that the root key can transfer the pile torsion to the soil around the pile very well,and can effectively reduce the distribution of the pile torsion.The shear stress of the soil around the pile peaks at the root key.The root pile foundation can keep the shear stress of the soil around the pile at a high level and give full play to the bearing characteristics of the soil.