Research On Visualization And Safety Early Warning Of Deep Foundation Pit Deformation Of Rail Transit Station Based On BIM Technology

With the acceleration of urban rail transit construction and the limit of land resources in cities,more and more deep excavation have been used in civil engineer,and the depth and scale of deep excavation also have been further increased,as a result,the risks of deep foundation pit projects have gradually raised a lot.A large number of data can be obtained through the monitoring of deep excavation,which plays a preventive and forewarning role for disasters.The traditional method only compares the single monitoring data with the forewarning values in code in some key parts of the foundation pit supporting structure,and to judge whether the requirement of safety forewarning.However,single monitoring data can only describe the local characteristics supporting structure,and the overall safety state cannot be represented of the deep excavation.Therefore,in order to evaluate the overall safety state of the deep excavation accurately and reasonably,the multiple monitoring projects in site should be used fully for comprehensive analysis and evaluation.In this study,the monitoring data are applied to the safety assessment method of deep excavation based on conditional information entropy.The secondary development of safety forewarning management of excavation has been carried out by using C# programming language based on Autodesk Revit software.A safety forewarning plug-in for monitoring management of deep excavation is developed to study the safety forewarning systematically during the construction,which improves the previous way of using single monitoring data to characterize the overall safety state,and makes the expression of monitoring information of deep excavation more convenient and efficient.The principal work of this paper as following aspects:(1)This paper expounds the application status of BIM technology in deep excavation engineering and the application status of safety assessment and forewarning methods for foundation pit on the basis of consulting references.(2)The deformation mechanism and related deformation characteristics of foundation pit excavation are analyzed aiming at the deep excavation of rail transit station.The main influencing factors of deep excavation are discussed from three aspects: engineering geological and hydrological conditions,structural form and design,construction scheme and management,and it is found that they interact with each other among the three factors.Combining with many safety assessment methods commonly used in the engineering,several evaluation methods and their application scope were compared and analyzed,andfuzzy synthetic evaluation method was decided to select as the main research method in this paper.(3)The safety assessment method of deep excavation based on conditional information entropy was investigated.A new method of weight determination based on conditional information entropy is proposed,according to the conditional information entropy of rough set,the weight is determined without processing the prior information of data,and the universality of the method is also improved,due to the weight calculation of proposed method is more comprehensive and reasonable.(4)The general idea of BIM technology applied in the safety forewarning of deep excavation in rail transit station is expounded.The Revit models were established finely applying the advantages of BIM technology in parametric modeling.A safety forewarning plug-in for deep excavation is created through the secondary development of Revit software to import and calculate the monitoring data to the models and show safety assessment results based on the design thought of information safety forewarning using C# as the programming language of the system,and visual studio 2017 software and Revit SDK secondary development tools were used as platforms.(5)Monitoring units of deep excavation were meshed corresponding to the type of retaining structure and the location of monitoring points combined with specific examples of engineering case.Safety evaluation index and grade distribution of deep excavation were explicit,and the safety evaluation index system based on monitoring data was established.Single factor was evaluated and summarized to form membership matrix using membership distribution function method combined with conditional information entropy and attribute importance to calculate the weight distribution of each evaluation index through the quantitative analysis of monitoring data to complete comprehensive evaluation.Visualization displayed through the secondary development of plug-in in the three-dimensional model of the foundation pit to provide an effective guarantee for the safe construction of the deep excavation.