The Influence Of Deep Foundation Pit On Surrounding Building Structure And Its Countermeasures

With the rapid development of China's urban construction and industry,city land resources become increasingly tense,city building density increasing,the effective use of land resources has become more and more important,so a large number of high-rise buildings and underground buildings appear in the city,the deep foundation pit is applied more and more extensive,more and more large scale,which has another problem,namely the deep foundation pit construction will have adverse effects on the adjacent buildings and surrounding facilities if the protective effect is not good in the construction process of deep foundation pit,for example,the surrounding building structure may be partially damaged,the underground pipeline is broken,and the surrounding road surface will be seriously damaged in the construction process of deep foundation pit.This paper focuses on the deep foundation pit construction on the surrounding of different position and distance of the frame structure building basement displacement,the internal force of the structure changes,and the deformation caused by foundation has been strengthened by way of building structure local damage.In this paper,the numerical simulation is used to analyze the influence of the foundation pit on the building,in which the finite element software FLAC 3D is used to the simulation of the foundation pit,and the ETABS is used to establish the building models,the specific research contents are as follows:(1)the two situations of construction from the pit of different spacing and different locations were studied,when the building in the long side direction perpendicular to the pit from near to far move,relative displacement of substrate is increased first and then decreased,about 20 meters from the pit turning,and the change of internal force follows the same law.And the another situations about the change of the relative displacement increases first,the middle part changes little,and then decreases when the building is parallel to the long side of the foundation pit.And in the process of moving the same changes in the structure of the building,it is not difficult to find that the two have a strong correlation.(2)The absolute value of the displacement of the foundation in the excavation of the foundation pit is not always increasing,for example,when the excavation reaches a certain depth,the vertical displacement starts to rebound,and the absolute value decreases with the excavation.In the excavation process of foundation pit,the turning point of displacement should be paid special attention to,because the movement direction of the soil may change,and the deformation of the foundation pit should be strengthened.But the vertical relative displacement is increasing,so the internal force of the building is still growing,through reading the literature,it is found that there are two kinds of simulation methods of foundation pit excavation,that is,one time whole excavation and gradual excavation.In this paper,the results of two excavation methods are compared,and the settlement of the foundation and the internal force of the structure with gradual excavation are larger than those of one time whole excavation,and the gradual excavation is more in line with the true process of excavation.(3)In this paper,the structure near the foundation pit is chosen,and the PKPM is used to calculate the structural reinforcement,because the building had already existed,it is not suitable for large area operation,and the reinforcement speed is fast,can not take too long,can not affect the normal life of the residents,so the method of steel and steel plate are used to strengthen the beams and columns in this paper.In this paper,the displacement and internal force of the structure at different positions and different distances are analyzed,and some conclusions are obtained,which can provide some reference for practical engineering.