Numerical Simulation Analysis Of Composite Soil Nailing Support Of Foundation Pit Based On Seepage Field Theroy

The composite soil nailing technology is combined with the development of a newtype of support technology and other support types on the basis of the soil nails to makeup for the deficiencies of the traditional soil nailing, and its increasingly broad range ofapplications. Many scholars at home and abroad in the field range for a large number ofstudies, including theoretical calculations, design methods, in situ experiments andindoor test simulation, etc., and they obtain meaningful results，But in the process ofdeep foundation pit excavation, due to the wide variation in water lever, the huge headdifference will make the soil water movement trend pore fierce, thus affecting thedeformation of the foundation pit supporting structure, this paper focused on this issue,the research and analysis:(1) Introduced the composite soil nail at home and abroad and the research statusand not precipitation conditions and precipitation conditions, the failure mechanism andtype of existing theoretical calculations and design methods, which must be analyzedand summarized.(2) Discusses the precipitation of deep foundation pit supporting structure when thegroundwater seepage characteristic of around, according to the supporting structurewater-resisting layer and the relation between the positions of seepage flowcharacteristic will be divided into three categories, this paper discusses the three kindsof cases supporting structure of the groundwater seepage field around the characteristic,establishing the mathematical model and solution.(3) Describes the foundation pit dewatering seepage field and stress field whencalculating model and parameter determination, and generally summarized in theseepage field and stress field of the coupling under the action of the classification of theseepage analysis theory and the coupling analysis of the calculation model and whencontrol of parameters, based on the calculation model and parameter is determined, andfurther discusses the foundation pit in anisotropic analysis of coupled seepage finiteelement equations, the numerical simulation for the follow-up to lay the foundation.(4) Use of geotechnical analysis software, reasonable selection of the soil nail andanchor element, established under the condition without precipitation and precipitationconditions two kinds of model, the finite element numerical simulation analysis of thetwo conditions of foundation pit whole displacement field, horizontal displacement ofpanel, horizontal and vertical displacement of soil nail， the trend of the axial force ofthe soil nails with the excavation analysis and discussion, and analysis shows that in due the influence of the precipitation, and produced the permeability volume force, andfurther intensify the level of the supporting structure and vertical displacement, but theamount of foundation pit of uplift less influence, and at the same time, sliding surface isnot necessarily through the corner of the pit, depending on the soil nailing support tocircumstances.(5) The establishment of seepage field and stress field coupled finite elementmodel to take into account the interaction between the supporting structure, water andsoil to overcome the traditional method the supporting structure and the role of soilconsidered separately and consider the lack of change in the permeability of the soilwith the stress state, and make the results more closely tied to the actual characteristicsof the soil and the supporting structure. During the three aspects of the analysis, onlywith a fixed element mesh, the entire coupling and iterative process, in the form of thegrid and the computational domain is always remain the same, thereby overcoming thetraditional moving mesh France has brought many problems.In summary, this paper centers around study of the pit in the support structure andproperties not precipitation conditions and precipitation conditions, derived byanalyzing the changes of the pit under the conditions of precipitation support thestructural deformation and foundation stability, as follow-up work has laid a certainfoundation.