Calculation Analysis And Top Beam Lateral Mechanism Of Top Beam Stiffness Of Deep Pit Spatial Effect

Top beam is in order to ensure the integrity of the enclosure structure,at the top of the retaining pile setting of a reinforced concrete beam,the effect is connect their discrete pile lateral structure,is indispensable in foundation pit supporting level retaining structures.Deep pit is a three dimensional size of the space structure,so the supporting design of it should be calculated according to the three dimensional space,and in the teaching material specifications,as well as many references will pit in deep pit design as an infinite long slope,according to the two-dimensional plane to the theoretical calculation,and will be no beam into account in the calculation process,thus giving designers at top beam stiffness calculation has brought a lot of difficulty,and deviation from the actual project.First of all,on the basis of some of the deep foundation pit accident,think a lot of problems are the designers in the design process is not clear the mechanism of the crown beam,blind to the beam stiffness assignment,makes the structure of repeated problem,in the summary in recent years;In reaction to the phenomenon,this article through in cantilever system,using FLAC 3D 5.0 three-dimensional numerical analysis software for calculation and analysis of spatial effect of foundation pit,put forward the concept of beam stiffness coefficient of the crown.Finally,in reference of FLAC 3D results in accordance with the method of structural mechanics by simplifying calculation model,so as to get a crown beam stiffness calculation formula.In the process of this paper studies the main conclusions are:1、Deep pit is a three—dimension spatial structure;Top beam displacement of retaining piles have obvious constraint function,constraint function depends on the position of supporting pile,;2、Excavation deeper,supporting piles more "soft",the greater the role of the top beam,and the effects of the more obvious effects top beam stiffness coefficient greater;short side during excavation shorter top beam binding effect on the long side of the more obvious,the greater the impact on the displacement of the pile;3、Top beam stiffness influence coefficient obeys the lnx function curve;The calculation formula of top beam stiffness under consideration in three-dimensional space.