Retaining Structure Design Theory And Its Deformation Law Research Of The Loess Area Foundation Pit With SMW Method

This paper studied the steel shapes and cement-soil composite beams in the process of interaction relations,the load bending stiffness change rule and flexural bearing capacity and failure mode of composite beams,etc;By the test of shaped steel and cement-soil composite beam.Based on elastic fulcrum method gives the formula of internal force and displacement of foundation pit supporting structure.And the theoretical calculation results of Xi'an example of a foundation pit support are compared with FLAC3D simulation and field test results.Studied the design theory and deformation law in loess area of foundation pit retaining structure by SMW technology.The main work and conclusions are as follows:(1)Analyzed the steel cement-soil composite beams test can draw the following conclusions:The working process of the composite beam undergoes a common action,and the steel is used in two stages.The composite beam is developed at different stages,and the change of the steel strain and the change of the joint stiffness are significant And the stiffness,bearing capacity and failure behavior of composite beams are different in different stress states.The stiffness,bearing capacity and failure behavior of composite beams are different in different stress states.The effect of cement-soil coating on the stability and bearing performance of composite beams is favorable,and the composite beams show good ductility.The stronger the bearing effect of cement-soil on steel,the stronger the bearing capacity and deformation ability.When the actual engineering design calculation is carried out,the deformation of the wall is smaller and the cement soil is more complete.The stiffness of the composite structure is improved greatly,and the beam stiffness can be calculated by the formula given in this paper.When the deformation of the wall is large,the cement soil cracking seriously quit work,by the steel alone bear the load at this time should not consider the contribution of cement soil.(2)Based on the elastic fulcrum method and the principle of horizontal displacement superposition of structure,the formulas of support displacement and internal force are given.And a certain foundation pit project in Xi'an was calculated,The results show that the horizontal displacement of the support structure is the "S-shaped" development.The horizontal displacement law of the supporting structure can provide reference for similar projects.(3)Against the background of foundation pit engineering in Xi'an,used numerical simulation software FLAC3D.Analyzed the horizontal displacement of the foundation pit is analyzed and compared with the actual monitoring data,and the change rules are similar.In addition,the settlement of the surrounding environment and the base uplift of the foundation pit are analyzed.It is found that there is a "spoon-like" distribution in the settlement of the foundation pit.The maximum settlement value does not occur at the edge of the foundation pit,and the settlement and influence range are small.The uplift of the bottom of the foundation is small,which indicates that the deformation of the retaining pile has a great limitation on the deformation of the post-pile soil.The conclusion is useful for the design and construction of the SMW method in the loess area.