Study On Foundation Bearing Capacity Modification In Grade Ⅱ Area Of Xi’an Hi Tech Zone

Driven by one belt,one road,the Xi’an economy has taken off again.The needs of the urban development process have promoted a great deal of engineering construction projects.Today,more and more buildings are developing towards higher and deeper,and the foundation is expanding to depth and width.At present,the subgrade bearing capacity is determined according to the Code for Design of Building Foundation（GB 50007-2011）^[1],we can Calculate bearing capacity of foundation,and the correction coefficient of depth and width is given line with the soil category.Although it provides general reference and guidance for engineering construction,it does not have regional characteristics.In a large number of engineering practice,the characteristic value of the bearing capacity of the foundation measured by the load plate test is larger than that of the standard value.Therefore,the bearing capacity of the foundation should be optimized to avoid redundancy of design and waste of construction.This paper summarizes the determination method and influencing factors of foundation bearing capacity,and the calculation formula of Prantel Risner ultimate bearing capacity by collecting the actual engineering data of the new school in 2020 on the grade II terrace of Xi’an high tech Zone,and analyzes the depth and width of the foundation bearing capacity theoretically.Finally,using Midas finite element software,the foundation foundation of grade II terrace in Xi’an high tech Zone is analyzed The law of depth width correction of bearing capacity is studied,and rely on a certain project example in the relevant area to verify.The main results are as follows:（1）Through numerical simulation,it is concluded that characteristic value of subgrade bearing capacity has positive correlation with the width and depth of foundation footing,which is agreed well with the results of theoretical analysis.Based on the study of the law that degree of depth correction of the subgrade bearing capacity in the second terrace foundation of Xi’an Hi-Tech Industries Development Zone,it is found that the depth compensation gradually decreases with the increase of depth.The power function relationship between depth correction coefficient and depth is fitted by original software.（2）The characteristic value of bearing capacity of grade II terrace foundation in Xi’an high tech Zone is linear with the width of foundation by changing the width of load plate.In order to further study the law of width correction of bearing capacity of foundation,the width correction coefficient is constant by inverse calculation.At the same time,the value of the modified width of foundation is still taken as 6m from the original specification value based on its settlement control.（3）When the load of the soil around the foundation is different and the bearing capacity of the foundation is modified,the buried depth d is taken as the buried depth of the soil layer converted by the minimum load of the soil around the foundation.（4）Combined with the depth correction coefficient,width correction coefficient and the modified width of foundation obtained by controlling settlement,this paper propoes the modified equation of subgrade bearing capacity for the second terrace of Xi’an Hi-Tech Zone,and then,makes the modified value of subgrade bearing capacity compare with the standard value in the code.