Research On The Deformation Performance Of Composite Bracing Technique Of Soil Anchors And Soil Nails For Deep Foundation Excavation

As a provisional project,more and more deep foundation pits come forth with the rapid development of city construction.Therefore, composite bracing technique of soil anchors and soil nails applies widly to deep foundation pit for its safety,economy and speediness.However,the theoretical research on it is far behind engineering. Deep foundation pit accidents happen some times because of design unsuitable.So the deep research on this technique is significance in theory and realism.Relying on the east square deep foundation pit of west Jinan railway station of Beijing-Shanghai high speed railway,this paper researches on the composite bracing technique of soil anchors and soil nails systemic and in-depth through the practical data and FLAC3D,to guide the construction and provide a reference to the design of deep foundation pit.The main production of this research is as follows:(1)This paper firstly discusses the principle and reliance of foundation pit design,then separately introduces single soil anchors bracing technique,single soil nails bracing technique and composite bracing technique.What is more,this paper explores the effect performance of composite bracing technique.(2)This paper analyses more deeply on the existing foundation pit measurement,principle,contents and equipments based on the results of people forehead.It has very important significance to insure the data's precision,direct the construcion correct and avoid foundation pit accident.(3)Through the analyse of data by the effect performance and factors of composite bracing technique,this paper discusses the relationship between deformation,internal force and excavation,research the deformation and internal force performance of soil nails and soil anchors as well as soil pressure.This paper also does a contrastable analyse among the factors which affect the deformation.(4)This paper makes a part 3D model through FLAC to simulate the development of deformation.The result is accordance to the practical data.This paper also research on the rule of deformation and internal force of the bracing structure and soil when the foundation pit is excavated in steps,which provides theoretic referance to the design and control of composite bracing technique of soil anchors and soil nails.