Study On Deep Foundation Pit Support And Application Of A Project In Shanghai

With the development of society,the scale of the city is expanding step by step,urban land is becoming more and more tense,this makes the city's high-rise buildings more and more high,the foundation pit is getting deeper and deeper,and relevant research shows that more than 10%of the accidents occurred in foundation pit engineering are caused by deep foundation pit engineering.The painful price has aroused more and more attention to the deep foundation pit engineering of high-rise building.In view of this,this paper is based on the example of deep foundation pit project of Shanghai fan Hai Residence Intemazionale,the deep foundation pit technique under special stratum condition in Shanghai area is studied,focus on the following aspects:First,foundation pit excavation,after argument and scheme comparison,basin type excavation method is adopted.In order to control the deformation during foundation pit excavation,according to the space-time effect theory,the construction of "layered,sectional,block,retaining wall,time limited symmetrical balance support excavation" is adopted.Two is foundation pit enclosure,the design was followed by practice,specific program for:cast-in-place pile + three shaft mixing pile,waterproof curtain structure +two reinforced concrete horizontal support system.Three is pit reinforcement,in the pit,a 8?10m width of phi 700@1000,double shaft mixing pile and lining reinforcement are adopted in the pit,the reinforcement range from second to the end of the borttom support under 4m,to control the deformation of the enclosure structure,among them,the pit is filled with 800@600 high pressure jet grouting pile for reinforcement,and grouting in the whole enclosure.Four is site monitoring,during construction,state of foundation pit(including column pile,pile top horizontal and vertical displacement of adjacent roads,buildings and pipelines;the horizontal and vertical displacement of surrounding buildings;skew;the pile body and the surrounding deep soil displacement;underground water pit monitoring;axial force)monitoring,and prepare emergency plans,the foundation pit itself is controlled strictly in the controlled range.Through meticulous construction and strict management,the two deep foundation pit project of Shanghai Fan Hai Residence international has been successfully completed and the quality of the project is excellent.