Study On Deformation Mechanism Of Deep Foundation Pit With Overlapped Miscellaneous Fills And Bamboo Reinforcement Support System

With the rapid extension and renewal of our cities,the urban construction is facing a newly serious situation.The severeness is mainly manifested in the fact that the waste landfill sites originally located in the suburbs and the hill sites which do not conform to the traditional urban site selection concept,and the old urban sites with complex pre-consolidation history and mixed with a large number of construction wastes are included in the urban construction planning,which leads to the support problem of foundation pit construction in the miscellaneous fill soil layer with great physical and mechanical variability and loose structure.The application of traditional bolting and shotcreting support,pile-anchor support and retaining wall support in miscellaneous fill temporary foundation pit engineering does not conform to the principle of engineering economy.at the same time,because of the loose structure characteristics of miscellaneous fill,the bolting and shotcreting support structure is easy to fail and cause slip failure of slope.Therefore,based on the analysis of deformation behaviors of deep foundation pit of miscellaneous fill,this paper proposes a new type of bamboo reinforcement supporting system for miscellaneous fill deep foundation pit and does some research about the construction technology and application of bamboo reinforcement supporting system considering engineering geological condition under the background of Guanshan lake Wanda plaza in Guiyang.Firstly,based on the study of deformation behaviors of deep foundation pit when excavated at home and abroad,combined with the basic physical and mechanical properties of miscellaneous fill,methods of excavation,the supporting form and the general situation of the field,the initial conditions are created.The deformation mechanism of supporting structure and the movement mechanism of surrounding strata are revealed during the excavation of foundation pit.And the influence of design factors,construction factors and natural environment factors on foundation pit deformation is systematically clarified.Secondly,according to the engineering geological environment of Wanda plaza,Guiyang,the selection of slope supporting structure is analyzed.The site deformation monitoring program for the foundation pit was compiled in detail,and the deformation monitoring data of the foundation pit were analyzed to reveal the deformation characteristics of the supporting structure and the surrounding soil during the excavation of the overlying mixed-fill foundation pit,and the supporting effects of different supporting structures were compared and analyzed.Thirdly,The parallel grain tensile and shear strength tests of bamboo from different parts of bamboo were conducted to determine the parallel grain tensile strength and shear strength of the grain in the main producing areas of Guizhou Province.The damage of the specimens was analyzed through the load-deformation curve obtained from the test.form.The component tanning process and construction method for the support system of bamboo ribs were expounded,and the load-sliding analysis was performed on the bamboo bar anchors.Finally,based on the finite element analysis software,the supporting effect of bamboo reinforcement supporting structure in miscellaneous fill foundation pit is further studied.By monitoring the geotechnical parameters and actual construction conditions of foundation pit project,the influence of bamboo reinforcement supporting system on the excavation of miscellaneous fill foundation pit is analyzed,moreover,the deformation of bamboo reinforcement supporting structure and movement of surrounding strata are analyzed,which verifies the feasibility of the application of bamboo reinforcement supporting system in temporary miscellaneous fill foundation pit.