The Research Of The Lateral Force In Composite Soil Nailing Wall

With the utilization and development of high-rise or multi-rise building and underground space .there are more and more deep foundating pit projects in practical engineering . The difficulty tends to be more serious and the scale tends to be larger. Conventional design methods of foundation pit bracing cannot meet the need of today's development, especially for deep foundation pit located in poor and complicated geological condition. Composite soil nailing wall(CSNW) is a new bracing structure of foundation pit, which has been used widely in the region of Shenzhen,Shanghai,Wuhan etc, and has obationed good economical and social performance.Compared with conventional bracing technology, not only soil nailing will actively support soil masses, but also the effect of soil nailing and soil mass will be mobilized leading to utilize in-site strength of soils to a maximam degree. The disturbed soil masses that originally induce loading effect on bracing structure are transformed into a part of bracing structure. Accordingly, the composite soil nailing bracing technique begins to applied to reinforcement of soft soils or foundations.But up to now, the working mechanism and stability study of the composite Soil nailing bracing technique is still a blank . There are no calculation analysis methods for it and the design main depends on experience .The behind schedule theories research obstructs the CSNW's further development. Therefore, the thesis focuses on this topic and following foundamental studies on the relate issues are performed.On the soil nailing and composite research foundation,according to CSNW's present research condition and the engineering effective demand, the stability of CSNW is studied systematically by methods of theories research and case research. Some beneficial results of the CSNW's behaviors are gotten. Main research contents as follows:(1) The four destruction models and respective stability analysis methods are discribed in this paper, whose working mechnism and calculating methods are given. In addition, some defects of every method are also discussed ;(2) On the basis of traditional active soil pressure method and expirical siol pressure method , the calculating model of the laternal earth pressure which is a tetragon with the largest value in the center side is addressed. This new model presents the distribution of lateral earth pressure of soil nailing wall more accurately and concisely;(3) Studied the work mechanism of composite soil nailing wall, the model of stability analysis of CSNW is established and three-dimensional nonlinear numerical computation based on finite element method is conduted to analyze internal forces and deformation of soil nailing;(4) Combined with a case ,the surveying data are also presented to examine the correctness of results of three-dimensional nonlinear numerical computation and the results calculating by the model addressed in this paper to give a further study for the working mechnism of CSNW.