Numerical Simulation Analysis Of The Characteristics And Regularity Of Reducing Expansion Hole In Foundation Pit

In North China,northeast China and northwest China,winter takes up a quarter or even half of the year.More than half of the area is covered with seasonal frozen soil.At present,at present,the anti-freezing measures,such as the use of thermal insulation materials,are expensive,which is not scientific for temporary foundation pit support in winter.Therefore,in order to reduce frost damage,it is necessary to take measures to reduce frost heave.For temporary foundation pit retaining project in seasonal frozen soil area,the process of frost heave will cause problems such as engineering durability and foundation pit instability.Frost heave response test based on the deep foundation pit of PVC pipe as the foundation,by FLAC3 D to reduce billge hole model is set up,and the seleection of boundary coniditions,the selectideon of parameters,to A,B two test chamber model of the whole process of frost heave is simulated,and the test valuee and simulation value carries on the anjualysis comparison,verrtify the vallidity of the modell and the rationallity of parameters.Then,the effct of the dilatancy effect of the dilatancy hole in the soil was simulated under different conditions.Based on the thermal coupling module of the software,the factors affecting the soil frost heaving were simulated.In other words,the effect and law of soil water content change,soil property change,tube diameter change and external freezing rate change on the effect and law of soil water content change,soil property change,tube diameter change and external freezing rate change are discussed.Specific research contents are as follows:(1)Based on the frost heave response test of PVC pipe in deep foundation pit,the simulation was carried out,and the stress of pipe wall A and pipe wall B in the cooling process and the displacement change of pipe wall at the same position were compared with the test results to verify the correctness of the model.(2)on the basis of the simulation software FLAC3 D,by controlling the single variable method,a condition change affects the effect of expansion,to study the different moisture content(23%,25%,28%,32%),the different soil(silt,silty clay,clay),different pipe diameter(115 mm and 110 mm,105 mm and 100 mm),the frost heaving force under different freezing rate factor change rule.(3)Under the conditions of four different influencing factors,the frost heaving force of pipe wall and box wall in the process of cooling was extracted and compared,and the dilatancy reduction law of dilatancy reduction hole under each factor was obtained.