Study Of Supporting Structure And Surrounding Environment Influence In Deep Foundation Pit Excavation

Modern city have high-rise buildings and highways,if want to set up high-rise buildings and excavation deep foundation pitin such a complex environment,need to have a strict control of foundation pit and surrounding environment deformation.Jiuzhou international edifice is the third high of mansions in Nanning city,the deep foundation pit engineering is rare in Nanning area because of the supper depth and large excavation acreage.The shape is an acute quadrant.Surrounding environment is complex,and requires a high degree of deformation control.In order to reduce the influence of excavation on the displacement under the complicated environment,the foundation pit supporting structure selection,support structure,the excavation way,three aspects are optimized,and combined with monitoring results of the deformation law of foundation pit supporting structure and surrounding environment.It uses the form of "pile-anchor(rope)-supports" combined support and the suitable excavation method in construction practice tub partition in out-of-shape foundation pit,can control deformation and environment influence as far as possible.Following results are obtained:(1)"pile-anchor(rope)-supports" combined support is rare,and only applicable in complex surrounding environmentfoundation pit engineering."pile-supports" combined support can ensure the overall stiffness and stability of foundation pit,Anchor rope(rod)supporting structure can effectively control the deep foundation pit top displacement and the ground surface settlement.So for different profile needs to use different combination forms of support.Reasonable use "pile-anchor-hold" combination support system to a greater use of space resources,reduce the deformation of supporting structure and the environment,can also be more convenient for construction smoothly.(2)Proposes a structure optimization method based on the theory of the redundancy optimization design method,and optimized the ring beam structure,get rid of some of the redundant link,make the whole structure of each bar power transmission way and the stress distribution is more reasonable,at the same time control the deformation of foundation pit,and save the steel and concrete materials and the cost.(3)Use MIDAS GTS NX finite element software to establish three-dimensional model of the foundation pit excavation.Select the HS soil constitutive model for numerical simulation.Respectively study of two different way of excavation,the island and the basin type.Analyzes the deformation characteristics and deformation law and have a comparison.Island excavation method can be set up in advance inside support,earlier than tub excavation deformation control,and greater use of the space effect to control the deformation of the horn side.(4)Having analysis of theresults for real-time monitoring of deep foundation pit construction,the deformation of supporting structure in the process of its construction,surface subsidence,change of the foundation pit uplift,strut axial forces as well as the study of the surrounding structures,and the same results with the numerical simulation,it’s reliable for the design and construction of deep foundation pit provides the beneficial reference.