Anti-floating Analysis Of Underground Structure Considering Anchor Effect And Failure Of Anchor Group

With the acceleration of urbanization and the continuous growth of population,urban space is increasingly scarce,the utilization of underground space is deepening,and the anti-floating problem of underground structure is also followed.Due to its high economic benefits and convenient construction,the expansion bolt has become a common anti-floating measure in the anti-floating engineering of underground structures in recent years.However,in the actual anti-floating design,the designers have no systematic understanding of the joint action and synergistic deformation of the expansion bolt and the underground structure.In addition,the failure of the antifloating bolt occurs from time to time,which makes the anti-floating and reinforcement design more conservative,resulting in waste of materials.Through the study of the anchor group effect of the expansion bolt and the force and displacement of the interaction with the underground structure,it can provide some reference for the antifloating and reinforcement design of the underground structure.In view of the above problems,this paper has carried out the following research :(1)The finite element analysis software ABAQUS was used to establish the model of the expanded anchor bolt with different spacing and length.The parameters of the group anchor effect of the expanded anchor bolt were comprehensively analyzed by the orthogonal design method.The influence of the length of the expanded anchor bolt,the arrangement spacing and other factors on the group anchor effect was studied,and the arrangement of the expanded anchor bolt in the anti-floating design was proposed.(2)The interaction model of the expansion bolt and the underground structure is established.The Fortran subroutine is used to simulate the buoyancy load of the underground structure caused by the change of the groundwater level.Based on the relationship between the water buoyancy and the weight of the underground structure,the displacement and internal force of each component of the underground structure under the three working conditions of 2.0m,4.7m and 8.2m on the floor are discussed respectively.The variation and distribution characteristics of the axial force of the expansion bolt under different working conditions are analyzed,which provides a reference for the anti-floating design of the underground structure at different water levels.(3)Based on the actual engineering background of anti-floating anchor failure,the failure of a single expansion anchor under the combined action of the two is modeled and calculated.The influence of the failure of the expansion anchor on the stress and displacement of the components of the underground structure and the axial force of the surrounding non-failure anchor are further studied.The influence range of anchor failure is analyzed and summarized,which provides a reference for the reinforcement design after the failure of anti-floating anchor.