The Analysis Of Seepage Mechanism And Anti-floating Head Value Of Foundation Pit

This paper focuses on the problem of anti-floating head value in foundation pit,and studies the foundation pit under different geological conditions and different types.Through the seepage mechanism of groundwater between inside and outside the foundation pit and the rainwater collection mechanism under rainfall conditions analysis,puts forward the calculation formula of anti-floating design head values to determine the anti-floating water level,provide the basis for effective anti-floating design.The main research contents are as follows:Firstly,the occurrence form of groundwater and the related mechanism of seepage are analyzed,and different supporting structures,waterproof curtain and backfill soil are investigated,the structural characteristics and construction technology of pile anchor support,composite soil nailing wall,SMW construction method,cement soil retaining wall and underground continuous wall are summarized,and the influence of them on groundwater seepage inside and outside the foundation pit is analyzed.The problem of anti-floating water level value in foundation pit is put forward,which is the preparation for theoretical analysis.According to the actual engineering,the method of determining the relevant parameters in the formula is determined,and the permeability coefficient of shotcrete and backfill is determined by experiments.Secondly,according to different geological conditions,taking different support structure and waterproof curtain form foundation pit,the calculation formula of groundwater seepage flow inside and outside the foundation pit is deduced.According to the actual engineering,the method of determining the relevant parameters in the formula is determined,and the permeability coefficient of shotcrete and backfill is determined by experiments.SEEP/W software is used to simulate and analyze the groundwater seepage flow inside and outside the foundation pit under different geological conditions and different support sealing forms.Third,analyze the amount of water under rainfall conditions in the foundation pit during the construction process and the use process.Theoretical analysis and calculation of rainwater accumulation and groundwater level in foundation pit are carried out directing against different backfill,catchment area,rainfall,different supporting and waterproof curtain and other factors in the construction process,the catchment area,topography and other factors in the process of using.Fourth,combined preceding analysis of different supporting,curtain effects on groundwater seepage and under rainfall conditions in the foundation pit of anti-floating head value,and proposed the calculation formula of anti-floating head value in foundation pit during construction and operation.