| In foundation pit engineering,the supporting scheme of foundation pit directly affects the progress,cost and quality of the project,and also relates to the safety and stability of the foundation pit project.The foundation pit engineering accident,the consequences are very serious,reasonable selection of foundation pit excavation engineering is a prerequisite for the smooth implementation,also must ensure that the selection of the safety of foundation pit supporting scheme is scientific and reasonable,reliable,convenient and feasible,economical cost,so it is necessary to verify the optimal selection scheme in many aspects.The main work of this paper is as follows:(1)According to the engineering properties of soft soil in Guangzhou endemic area of Nansha,combined with the local soft soil deep foundation pit,the influence factors in the supporting schemes involved,both qualitative and quantitative factors,factors,resulting in relatively small subjective fuzzy hierarchy analysis method to the four programs selected the best scheme.(2)In view of the deep foundation pit engineering,to investigate the determination method of m are summarized.The parameters of coefficient of subgrade reaction,according to the local engineering properties of soft soil,the value of soft soil deep foundation pit engineering and related geological exploration report concluded that the project of m.Based on the m value,using the elastic fulcrum method and elastic-plastic common deformation method for theoretical calculation of deep foundation pit engineering,analyzed the excavation scheme from the angle of elastic foundation beam method,the calculation results of two kinds of calculation method and the measured values are compared and analyzed,found the elastic-plastic common deformation method was more close to the true value.(3)In this paper,based on the calculation method of elastic foundation beam,numerical simulation of deep foundation pit engineering is carried out by using GEO5 geotechnical engineering finite element analysis software.With the theoretical calculation results confirm each other,the simulation analysis of the law and the supporting structure of the displacement law of surface subsidence caused by excavation,little difference between the simulated and measured values,obtained the support scheme is safe and feasible.(4)In the finite element simulation,found only on the deep foundation pit passive zone reinforcement effect and in the active zone and passive zone reinforcement effect were little difference for more economic purpose,can be carried out only in the passive zone reinforcement;at the same time,the combination in the simulation of different reinforcement width and depth,the combination of optimal width with the depth of the soft soil foundation pit passive zone reinforcement width is about 5 m in depth,the best in the 4~6 m.Make sure the foundation pit is safe and economic.Moreover,the effect of increasing soil shear strength index on horizontal displacement of retaining structure is demonstrated.(5)On the basis of numerical simulation,the deformation characteristics of the foundation pit and the inside and outside of the foundation pit are discussed,and the main factors affecting the deformation of the retaining structure are analyzed.At the same time,for the soft soil deep foundation pit engineering,it is effective to improve the soil quality and ensure the safety of the foundation pit by dealing with the site and strengthening the passive zone.To sum up,this paper uses fuzzy analytic hierarchy process to select the best scheme,and in order to verify the safety and reliability of the scheme,apply the mature calculation theory –elastic-plastic joint deformation method is used to verify the scheme.On the basis of the scheme in order to verify the numerical simulation,the optimized support scheme,which works to provide economic,safe and feasible excavation and supporting scheme.The optimization method used in this paper has certain reference value for other similar projects. |
PDF Full Text Request