Research And Application Of A Digital Model For Information Management And Dynamic-Synchronous Analysis In Foundation Pit Groups

When adjacent excavations are carried out in the close proximity of other foundation pits,or a large scale foundation pit is separated into several small pits,these adjacent pits forms a foundation pit group.In a foundation pit group,the stress and deformation of both supporting system and surrounding soil is generally affected by multi zoned excavation and becomes extremely complex due to the pit-soil-pit interaction when the adjacent foundation pits are excavated alternately or synchronously.Moreover,the characteristics of the pit-soil-pit interaction are normally manifested in the excavation of the adjacent foundation pit in limited time span and local region.On the other hand,when analyzing the interactive impact,huge amounts of data are usually encountered and requires an effective digital model to manage these data.In this paper,a one-stop solution concerning the recording,coupling,synchronization and dynamic analysis of both the excavation information and the monitor data is proposed.Combined with the developed applications,this solution is applied to a large scale and deep foundation pit group in Shanghai soft clay.The main contributions of this thesis are described as follows:(1)A data management system is developed based on Autodesk Revit.The system presents a description method for the 3D geometry of excavated soil,and optimized the data storage method in data type support,2D table support,data stability as well as long term maintenance.The system combines the information of 3D excavation geometry,excavation progress,instrumentations and field monitor data into a single file,and conquers the awkwardness that the shape of excavation geometry and the monitor data table cannot be stored together.(2)A digital analysis system is developed to synchronously and dynamically deal with the monitored data and construction information in deep excavation groups.The system uses Microsoft SQL Server,a database software based on the structured query language(SQL)standard,to facilitate the classification and management of the information of constructions and instrumentations,where the time related fields are selected as the reference for the synchronous analysis.Microsoft Visio and Excel are used for the visualized modeling of the excavation processes and the monitor data,respectively.(3)Based on the studies above,an analysis methodology of the stress and deformation of foundation pit groups on the basis the information modeling is proposed,and the steps from field construction to dynamic and coupling analysis are presented.The methodology is applied to the project of Shanghai Expo foundation pit group.The basic characteristics of the deformation and interactive impact in the adjacent and synchronously excavated foundation pit group are obtained in a global and local time/space domain from the analyses of lateral deformation of the diaphragm walls close to the confined soil between the adjacent foundation pits(neighboring zone)and those away from the adjacent foundation pits(distant zone),as well as the integral movement of the adjacent foundation pits,the settlement of the ground surface,and the heaves of columns and diaphragm walls.The process of analyzing shows the applicability and high efficiency of this methodology.