Research On The Basic Design Of Super High-Rise Buildings With Natural Foundation

At present,the development of super high-rise buildings in Xi’an has become a major trend,and for a city that is developing towards super high-rise,there are few research on the foundation design of super high-rise buildings,which brings certain inconvenience to the subsequent related building foundation design.Therefore,it is very necessary to study the foundation design of supertall buildings in Xi’an.Considering that the bearing characteristics of pile foundations are the main factors affecting the stability of supertall buildings,this paper analyzes and studies the characteristics of pile foundations of super high-rise buildings to withstand vertical and lateral loads by combining numerical simulation and vertical compressive static load test of single pile with a project of a supertall building in Xi’an,and obtains the most reasonable foundation selection in Xi’an,which provides a reference for the subsequent foundation design in Xi’an.The most reasonable foundation selection in Xi’an was obtained,which provides a reference for the subsequent foundation design in Xi’an.The main work is as follows.(1)Through the analysis of the static load experiment of a super high-rise building project in Xi’an,the vertical bearing characteristics of monopile are analyzed and the ultimate bearing capacity of monopile is determined;using finite element simulation of the static load experiment,based on the comparison of the ultimate bearing capacity and curve obtained from the simulation and the experiment,it is found that the results obtained from the simulation are similar to those obtained from the experiment,thus verifying the reliability of the finite element model of single pile and the reasonableness of the selection of soil layer parameters,and laying the foundation for the establishment of group pile model-pile raft foundation.(2)Based on the above study of the ultimate bearing capacity of a single pile,9 groups of pile foundation schemes with different pile lengths and different pile diameters corresponding to different pile numbers are obtained through calculations,and the finite element method is used to establish a group pile foundation model for these 9 pile layout schemes,Simulating the bearing characteristics of super high-rise piled raft foundation under the same level of load.The research shows that most of the piled raft foundations exhibit the characteristics of large dish-shaped settlement in the middle and small edges,which verifies the pile group effect of the piled raft foundation.(3)On the basis of the research of the above 9 kinds of pile layout schemes,considering the influence of different factors on the settlement of the pile group foundation,81 sets of piled raft foundation models under different combinations were established.The single control variable method of variable pile spacing has carried out research on the factors affecting the vertical bearing characteristics of piled raft foundations.The results show that under the vertical load of the superstructure,appropriately increasing the pile diameter.pile length or pile spacing will have a positive effect on the ultimate bearing capacity and differential settlement of the pile group foundation,but when the above value exceeds a certain limit,The positive effect will no longer be significant;then based on the settlement results of each model,a more reasonable form of foundation pile layout is selected,and combined with the variable rigidity leveling theory,the reasonable selection of foundations is adjusted by variable pile length and variable pile spacing.Adjusting the rigidity of the piled raft foundation,the study found that the pile arrangement method when the core tube pile length is 70m,the pile spacing is 3m,the frame column area pile length is 60m,and the pile spacing is 4m can minimize the differential settlement of the piled raft foundation and make it more economical.(4)In order to study the bearing characteristics of super high-rise piled raft foundation under lateral load,a wind load model based on super high-rise lateral load as the main controlling factor was established,and the downwind wind pressure standard values of corresponding super high-rise buildings at different heights were obtained.,Perform numerical fitting on the standard value of wind pressure and the height of the building to obtain the characterization equation of the standard value of wind pressure,and then obtain the effect of the actual building on the foundation when the actual building is subjected to wind load.The most reasonable foundation form in the above research content is in the vertical Under the combined action of directional load and lateral load,through finite element simulation analysis,the horizontal displacement value of the piled raft foundation is 1.5mm and the inclination angle is 0.0002 degrees,both of which are less than the allowable value,thus verifying the stability of the foundation selection And the rationality of selection.