| The design and construction of the foundation should not only consider the safety and use requirements of the superstructure,but also pay attention to the nature and state of the formation.The foundation depth has a great influence on the overall stability of the structure.When the foundation depth is insufficient,the structural anti-overturning bending moment will be insufficient to cause the overall collapse.In view of the problems caused by insufficient foundation depth,this paper uses different calculation software to compare and analyze the structural response of the buried depth layer(model 1)and the buried depth layer2(model 2)in the numerical model to solve some problems caused by insufficient foundation depth..In this paper,based on the actual engineering case,using Yingjianke structural calculation software,through the response spectrum and elastic time history analysis,the macroscopic parameters such as the inter-layer displacement angle,the structural apex displacement and the base shear force under the conditions of frequent earthquakes and fortified earthquakes are Compare the structural response of the same model with different buried depths.On this basis,the general finite element software Abaqus is used to calculate the elastoplastic time history analysis of the main structure under different rare earthquakes,and based on the Winkel ground model theory,the basic raft is established and the corresponding The load gives the stress distribution of the foundation raft.Finally,through the comparative analysis of the failure mode,plastic energy consumption and damage energyof the basement shear wall and the upper main structure at different foundation depths,the influence of the foundation depth on the structural response of the main part is obtained.This paper mainly carries out research work in the following aspects:(1)In order to study the structural response of the buried depth and buried depth two-layer model under the same working conditions,after the structural response spectrum analysis,the macroscopic parameters of the model 1 and the model 2 under the same working condition are obtained.Conclusion: In terms of structural self-vibration,the first natural vibration period of model 2 is 0.111 s smaller than the model,which is 4.79% lower due to the different soil constraints of the two models.The second and third cycles will still decrease,and the influence coefficient will gradually weaken.However,the vibration modes are almost the same,so changing the base depth has little change to the vibration mode,and the two tend to be almost identical.In the response spectrum analysis,the apex displacement and the maximum interlayer displacement angle of the structure are reduced.After adding a layer of buried depth,the displacement of the apex of the structure is reduced by 11.76%,and the maximum displacement angle of the interlayer is decreased by 3.61%.Under the normal earthquake,both model 1 and model 2 are almost in the elastic deformation stage,and the base shear force and the interlayer displacement angle of model 2 are about 5% smaller than the model,while the structural vertex displacement is about 20%.In the fortification earthquake,the seismic performance of Model 2 is significantly better than that of Model 1.The base shear force,interlayer displacement angle,vertex displacement and minimum stress value of the raft are all smaller than the model one.The interlayer displacement angle of the second model is about 3%-5% smaller than the base shear force of the model.Therefore,the requirement of the foundation burial depth is of great significance for structural earthquake resistance.In terms of substrate stress distribution,the minimum base shear force of model 2is smaller than that of model one under seven conditions.The maximum compressive stress of model one is 0.5077 MPa,and the minimum value is 0.0146 MPa(case 6).The maximum compressive stress of model 2 is 0.4966 MPa,and the minimum value is 0.0265MPa(case 6).Therefore,it can be seen that under the action of frequent and fortified earthquakes,the structure is biased to be safer when the foundation depth is larger.(2)In order to more comprehensively evaluate the seismic performance and damage modes of the two models,Abaqus was used to establish a calculation model and set the plasticity and damage factors.In the rare earthquake,the displacement and acceleration of thevertices of Model 1 and Model 2 both show a difference of about 10%.In terms of the interlayer displacement angle,the model 2 is only reduced by about 4% compared with the model one,and the displacement curves of the two are basically the same,and the number of layers at which the maximum displacement angle is located is almost the same.Model 1’s basement shear wall is seriously damaged,while model 2’s shear wall damage is much smaller than the model.Under the rare earthquake,the damage of the underground structure of the model one is mainly concentrated at the bottom of the structure,and the whole wall penetration damage appears.When the model 2 that meets the specification requirements is adopted,the centralized damage of the underground structure is transferred to the top of the underground structure.For the superstructure,the damage location and extent of the two models are almost the same.Therefore,when the local structure does not meet the design requirements,it is almost ineffective to change the foundation depth.(3)In order to study the influence of the base area of the seesaw on the structural response,a circle frame is added to the basement of the basement and the area of the base raft is expanded to the edge of the frame(model 3)on the basis of model one,The next analysis compares the difference between model one and model three.By comparing the structural responses of the two models,the following conclusions are drawn: the displacement,acceleration and bottom bending moment of the structure are almost unchanged,but the failure mode of the structural shear wall is quite different.Under the seven working conditions,the damage of the bottom of the model-basement is the most serious.After adding a frame around the local lower chamber,the most severe damage is transferred to the top of the basement.Therefore,when the buried depth of the structure is insufficient,the rigidity of the underground structure can be appropriately increased.However,the rigidity of the adjacent layers should be considered when strengthening the basement to prevent excessive stiffness and local damage.It can be seen from the structural plastic energy consumption and the damage energy consumption that the damage of the model three is not as serious as the model.According to the stress map of the foundation raft,it can be seen that compared with the model one,the maximum value of the tensile stress of the base is reduced due to the increase of the area of the three slabs of the model,but it cannot be completely eliminated.In terms of structural plastic energy consumption and structural damage energy consumption,Model 3 is basically smaller than the model.Therefore,when the foundation depth isinsufficient,the seismic performance of the structure can be effectively improved by increasing the area of the foundation raft and the stiffness of the underground structure. |
