Study On The Uplift Bearing Capacity And Stability Of Helical Anchors In Sand

The helical anchor foundation has been gradually promoted and applied in construction,ocean,power,soil and other projects due to its advantages of large tensile bearing capacity and convenient installation and construction.However,there are few studies on the dynamic or cyclic load of helical anchors.Therefore,this paper studies the bearing performance of helical anchor under cyclic pulling load,analyzes the influence of the change of sand compaction on the cumulative displacement on the existing test data,and uses the finite element software ABAQUS for numerical modeling,considering the attenuation of sand stiffness under cyclic load,so as to provide reference for the design of helical anchor foundation of transmission line.The main research contents and the obtained conclusions of this paper are as follows:(1)According to the existing single anchor disc in sand helical anchor cycle pull test data,analysis of different compaction sand in the helical anchor cycle after bearing characteristics and its relationship with cumulative on displacement,contrast found that in the helical anchor geometry parameters and cycle loading parameters under the same conditions,the cumulative displacement of helical anchor in dense sand is less than the dense sand;however,the relationship between the ratio of helical anchor in the soil is analyzed.(2)Based on ABAQUS finite element software,the analysis model of helical anchor static force and dynamic pull in sand is established.By setting the soil elastic modulus and soil temperature field,the temperature changes with time to realize the decay process of modulus vibration(time)with load,namely "stiffness attenuation".Change of the anchor plate diameter,To analyze the rule of the vertical cycle load,The results show that: properly increasing the disc diameter can effectively reduce the cumulative displacement and displacement accumulation rate of the helical anchor under the cyclic load,And the stress,displacement and equivalent plastic strain levels of the anchor soil,Also increase its axial cyclic stiffness,Thus reducing the risk of the destruction of the helical anchor structure;The development pattern of displacement accumulation rate of different helical anchors is similar,Fast drop during the previous cycle loading,Then the decline rate slowed to basically stable,And the larger the disk diameter,the more stable the displacement accumulation rate corresponds to the smaller the vibration.(3)Numerical modeling by the ABAQUS software,Change the number of anchor plates,To analyze the rule of the vertical cycle load,The results show that increasing the number of disks can effectively reduce the cumulative displacement,soil stress,displacement and equivalent plastic strain level of the helical anchor,Increase its axial cyclic stiffness,So as to improve the bearing capacity,safety and stability of the helical anchor structure;The development rule of displacement accumulation rate of helical anchors is similar,Fast drop during the previous cycle loading,After the decline rate slowed down to remain basically stable,And the more the disk it is,the smaller the vibration of the displacement rate is.