Research On The Application Of Long Spiral Pressure Grouting Occluding Pile In Top-down Construction Of Basement

In In recent years,with the continuous development of urban construction,urban construction has changed from extension to connotation,and how to upgrade and transform the old city has become a hot topic in urban construction.Due to the current dense buildings,obsolete infrastructure and lack of underground space development in the old city,the residents' living intelligence is low and parking is difficult.However,the old city renovation project is generally located in the downtown area,with narrow construction site and limited land resources.The surrounding environment is complex,so it is not suitable for deep excavation.High environmental protection requirements,construction noise control,high dust control requirements,prohibit mud pollution.In the project construction,the influence of site construction on the daily life of the surrounding residents should be considered.So,how to transform the more appropriate problem in front of people.Taking the reconstruction project of Xiangnan neighborhood center as the background,this paper studied and solved the key technical problems in the application of long auger bored compression-filled concrete pile in reverse construction of basement by means of field construction practice,engineering measurement,combined with design calculation and finite element numerical analysis,and obtained the following main research results:(1)to analyze the construction technology characteristics and the key technical problems of long spiral drilling pressure filling concrete pile wall,and put forward the verticality control technology of long spiral drilling pressure filling concrete occlusion pile during construction,and perfect control problem for retarded time of the super retarding concrete in plain pile.Through analysis of the field test results,the feasibility of the process was verified,and the drilling occlusive piles construction is completed successfully.(2)this paper discusses construction technology of steel pipe concrete column and the long spiral drilling pressure filling pile as a pillar pile in the basement engineering with top-down method.Nodal structure between steel pipe concrete column and the basement structure beam slab structure are analyzed.Design and implementation method of steel pipe concrete column node connected to the pillar pile and basement structure beam slab structure are also analyzed.Key control technologies for the steel pipe concrete column position and verticality are studied and putted forward.The field test results show that the control method is feasible,which provides the basis for promotion application of the long spiral drilling pressure filling pile.(3)The construction design of each node between occluded pile wall and basement structure is discussed to provide reference for similar projects in the future when long spiral drilling pressure filling concrete occlusion pile is used as the permanent structure of the basement outer wall,(4)this paper discusses the design and calculation method of the occlusal quantity between the reinforced concrete pile and the plain concrete pile.And through the test,the applicability is determined to ensure the quality of the external wall of the permanent basement.(5)when the occluded pile wall is replaced by the underground continuous wall by the calculation method of equivalent stiffness,the stiffness of plain concrete pile is also considered from the action of plain concrete.Through the analysis of field monitoring data and the calculation results using MIDAS GTS NX finite element analysis software,it is proved that it is feasible to use the equivalent stiffness principle to replace the occlusal pile with the underground continuous wall.