Study On Security Risk Management Of Constructing Large Foundation Pit Adjacent To Building Based On Influence Partition Theory

With the high growth of China’s economy, construction of infrastructure is developing greatly. First things first, the metro railway now faces a surge of construction. At the same time of the large scale construction, the situation that newly built metro railway tunnel adjacent to buildings is inevitable. And because of the complexity and uncertainty of the geology condition, once security accident happens economical lost and lost of lives will be both caused. In recent years, such accidents happened and caused bad influence. Now, foundation pit projects of metro railway tunnel are usually lack of systematic and efficient risk analysis and management. When the foundation pit is close to existed buildings, either conservative measures are adopted without thinking about whether it’s economic or not, or no security measures are taken thus causes accidents. It’s necessary to analyze the risk of the large scale constructing foundation pit close to buildings and the study of security management is also important, it will give a theoretical and technical reference to similar projects.Based on newly built railway Beijing to Shijiazhuang express way Shijiazhuang tunnel project, combining the research task of China minister of railway called metro railway large span tunnel constructing security techniques, using investigation, field test, numeric simulation and reliability theory, research on risk assessing and management techniques of constructing large foundation pit close to buildings is done, and main result and conclusions are written below:1. Based on conclusion of existed achievement, by statistic analyzing similar risky accident, and combining related questionnaire and expert consultant results,"possible index set" of constructing large foundation pit close to buildings are recognized, the general framework of the index system are developed. After index testing and screening process, final index system of constructing large foundation pit close to buildings is established.2. According to questionnaire investigation from the construction site and expert consultant, adopting AHP method, comparative matrix of each index in the security assessing index system is developed. And eigenvector of each matrix is calculated and tested, so relative weight of each index is obtained.3. Using strength reduction method to calculate the security rate, then influential partition of constructing large foundation pit close to buildings is done. The concept of close space initial risk is defined, and numerical simulation model is developed. Based on Monte Carlo theory, adopting FLAC3D software to repeatedly do the random sampling calculation, and then analyze the statistic result and get the risk probability of each partition.4. Depending on the coordinate relations of every construction unit in the logic layer of the risk analyze index system, adopting probability and reliability theory method, analyzing method of factor layer and logic layer in the risk index system is given. Based on Chinese condition and Shijiazhuang tunnel construction site situation, calculation equation is formulated.5. Analyzing the newly developed risk analysis index system by using a series of methods including weight dynamic regulation, fuzzy comprehensive judgement, close space initial risk analysis and logic layer risk analysis method, a security risk analysis method suitable for large scale constructing foundation pit close to buildings is established.6. Based on SQL Server, index database, accident database, principle database, page database, video database, webpage database, result database and space database are developed for collecting information, calculation and announcing information.7. Based on Visual C#language, risk analysis techniques and standard are studied, function module for large scale constructing foundation pit close to buildings is established. It fulfills the whole systematic function with web function module developed by China university of mining and technology, thus they consist the tunnel constructing security analysis and management system.