Based On The Subsidence Control Heating Caofeidian Project Variable Stiffness Composite Foundation Finite Element Analysis

Natural foundation and uniform initial vertical bearing pile composite foundation stiffness is uniform,when the base arranged on the uniform load,the foundation will appear in the big small dish settlement.The structure form in the upper structure of uneven loads,such as frame tube,frame shear wall structure,the conventional design of composite foundation treatment methods,the differential settlement will be more obvious.The differential settlement reliability of buildings has great influence,can improve the uneven settlement of the buildings,it becomes very important.Based on the previously proposed variable stiffness composite foundation design concepts and research results,finite element numerical simulation analysis of the influence factors of settlement behavior,the settlement characteristics of the.Taking Caofeidian development zone heating project in the variable stiffness composite foundation based on the project,using MIDAS GTS finite element program,deformation calculation of the project the main building and the podium two kinds of models of variable stiffness model of the foundation,predict the raft foundation settlement and differential settlement.Through the analysis of different raft thickness,different cushion modulus,different cushion thickness,different pile elastic modulus,different pile-soil deformation stiffness cloth settlement characteristics of pile composite foundation under the action of variable modulus of deformation modulus and pile end soil,effects of related parameters on the stiffness effect of composite foundation settlement characteristics pile,get relevant conclusion:(1)The change of pile end soil elastic modulus and thickness of raft to raft the total settlement of the greatest impact,influence on differential settlements of raft is large,the cushion modulus on the raft settlement characteristics of minimal impact:(1)With the increase of pile modulus,raft maximum settlement and uneven settlement decreased two,the reduction rate along with the increase of pile body modulus is also in decline;(2)With the increase of the thickness of the raft,the largest settlement difference of similar,are gradually decreased,the decrease amplitude decreases,increases to a certain extent,the change is not obvious.The raft foundation soil surrounding settlement increased;(3)The elastic modulus of cushion and raft when compared to the minimum,when the modulus increases,the maximum settlement of raft decreases,but the minimum amount decreases;with the cushion thickness increases,increases the raft settlement;(4)The soil between piles and pile raft soil modulus increases gradually,the maximum settlement and uneven settlement are significantly reduced.(2)Considering the settlement characteristics and engineering economy,put forward reasonable design parameters:(1)Vertical reinforcement should adopt the 2.55×10~4MPa;(2)The thickness of the raft foundation should adopt the 0.4m;(3)The cushion modulus of graded sand gravel 40MPa,reasonable thickness of 300mm.Some conclusions obtained in this paper,to meet the overall capacity of the premise,the deformation control of composite foundation,minimizing differential settlement,has certain significance in improving the building durability and service life etc.